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γ-Valerolactone-introduced controlled-isomerization of glucose for lactic acid production over an Sn-Beta catalyst
Combined experiments and density functional theory (DFT) calculations provided insights into the role of environment-friendly γ-valerolactone (GVL) as a solvent in the hydrothermal conversion of glucose into lactic acid (LA) over the post-synthesized Sn-Beta catalyst. By introducing 2.0 wt% GVL, a much higher yield of LA (72.0 wt%) was obtained than that in pure water (60.1 wt%) at 200 °C, 4 MPa N2, and 30 min in a batch reactor. The GVL effectively suppressed the isomerization of glucose into fructose in a controlled-transfer mode, resulting in a lower fructose concentration. Thermogravimetry-differential analysis and DFT calculations demonstrated that the competitive adsorption between GVL and glucose happened at the open Sn sites over the Sn-Beta catalyst, which led to a controlled isomerization rate in water. Further increasing the content of GVL to 20.0 wt%, the higher yield of LA (74.0 wt%) was attributed to the more efficient competitive adsorption while also inhibiting carbon deposition.
Zhao, Xinpeng,Zhou, Zhimin,Luo, Hu,Zhang, Yanfei,Liu, Wang,Miao, Gai,Zhu, Lijun,Kong, Lingzhao,Li, Shenggang,Sun, Yuhan
supporting information
p. 2634 - 2639
(2021/04/22)

Asymmetric Synthesis of Optically Active 3-Cyclohexene-1-carboxylic Acid Utilizing Lactic Ester as a Chiral Auxiliary in the Diastereoselective Diels–Alder Reaction
The optically active 3-cyclohexene-1-carboxylic acid was synthesized through a TiCl4-catalyzed diastereoselective Diels–Alder reaction utilizing lactic acid ester as a chiral auxiliary, which can be removed by washing with H2O. The (S)- and (R)-isomers were both derived from easily available ethyl l-lactate.
Fujita, Ryunosuke,Hayashi, Wakana,Kubota, Shunichi,Nishi, Tatsuya,Nishiyama, Akira,Ochiai, Hidenori,Sasagawa, Miwa
supporting information

(2022/02/09)

METHODS FOR SYNTHESIZING ANHYDROUS LACTIC ACID
A method of synthesizing anhydrous lactic acid is provided by reacting a compound of formula (Ia): with an acid compound of formula HnX in a first solvent to produce a reaction mixture comprising a compound of formula (Ib) and a lactic acid compound of formula (I) in solution with the first solvent and/or water. n is an integer other than 0, x is 0, or an integer other than 0, M is an alkali metal or alkaline earth metal and X is the conjugate base of the acid compound of formula HnX. The resulting reaction mixture is filtered to produce a filtrate containing lactic acid in solution. The filtrate is crystalized from a second solvent to produce anhydrous lactic acid.
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(2021/11/13)

Discovery, Total Synthesis, and SAR of Anaenamides A and B: Anticancer Cyanobacterial Depsipeptides with a Chlorinated Pharmacophore
New modified depsipeptides and geometric isomers, termed anaenamides A (1a) and B (1b), along with the presumptive biosynthetic intermediate, anaenoic acid (2), were discovered from a marine cyanobacterium from Guam. Structures were confirmed by total synthesis. The alkylsalicylic acid fragment and the C-terminal α-chlorinated α,β-unsaturated ester are novelties in cyanobacterial natural products. Cancer cell viability assays indicated that the C-terminal unit serves as the pharmacophore and that the double-bond geometry impacts the cytotoxicity.
Brumley, David A.,Chen, Qi-Yin,Gunasekera, Sarath P.,Luesch, Hendrik,Paul, Valerie J.
p. 4235 - 4239
(2020/06/27)

Epimerization-suppressed organocatalytic synthesis of poly-L-lactide in supercritical carbon dioxide under plasticizing conditions
Herein, an efficient (>95% yield, >99.0% ee) Br?nsted acid-catalyzed synthetic method of poly-L-lactide (PLLA) in supercritical carbon dioxide (scCO2) under plasticizing conditions is presented. High-performance liquid chromatography analysis of the PLLA hydrolysis products indicated that, as opposed to the case of organic solvents, the use of a nucleophilic catalyst in scCO2 suppressed the epimerization. The highly stereochemically pure PLLA prepared by the developed method under metal-free conditions meets the criteria of medicinal/engineering applications.
Mase, Nobuyuki,Moniruzzaman,Yamamoto,Sato,Narumi, Tetsuo,Yanai, Hikaru
supporting information

(2019/08/06)

Polyoxomolybdates catalysed cascade conversions of cellulose to glycolic acid with molecular oxygen via selective aldohexoses pathways (an epimerization and a [2+4] Retro-aldol reaction)
Selective cascade conversion of cellulose into valuable C2 or C4 products over acid catalysts is still not fully explored because glucose-fructose isomerization followed by fructose conversions is thermodynamically easy to occur during the reaction, leading the formation of C6, C5, C3 and C1 products such as 5-hydroxymethylfurfural (HMF), levulinates, lactates, formates, and so on. In this study, phosphomolybdates (PMo) with the Keggin structure was found to promote cascade oxidation of cellulose conversion via selective aldohexoses pathways, i.e. an epimerization and a [2 + 4] retro-aldol of glucose/mannose, rather than aldo-ketohexoses routes, i.e. a glucose-fructose isomerization and a [3 + 3] retro-aldol of fructose, which produced glycolic acid (GlycA) (C2) as the main product (～50% selectivity). Either in aerobic or anaerobic state, PMo selectively catalyzed glucose epimerization into mannose at 100 °C. This behavior is completely different from that of molybdate in MoO3 which is only effective for the epimerization reaction (the Bilik reaction). In this cascade oxidation reaction, PMo was reduced into heteropoly-blue (PMored) as observed by the color change of the solution, UV-VIS and FT-IR measurements. In this case, the molecular oxygen was found to reoxidize PMored into PMo, leading the catalytic activity to be remained stable. The results shown in this study provide an insight for the catalyst development on selective synthesis of C2, C4 and/or other novel valuable chemicals from carbohydrates via the aldohexose pathways.
Bayu, Asep,Karnjanakom, Surachai,Yoshida, Akihiro,Kusakabe, Katsuki,Abudula, Abuliti,Guan, Guoqing
p. 28 - 34
(2018/05/28)

Chiron approach towards optically pure γ-valerolactone from alanine
A concise synthesis of both enantiomers of γ-valerolactone has been developed from commercially available Alanine. The key steps in the synthesis of these γ-Lactones are DIBAL-H reduction of ester (9) followed by in situ Wittig reaction with EtO2CCH = PPh3 ylide (13) (Z/E = 1: 3.5) and one pot lactonization triggered by deprotection of O-TBS ether (14).
Datrika, Rajender,Kallam, Srinivasa Reddy,Katta, Rambabu,Siddaiah, Vidavalur,Pratap
supporting information
p. 2801 - 2808
(2018/12/04)

Metal Nanoparticles Supported on Perfluorinated Superacid Polymers: A Family of Bifunctional Catalysts for the Selective, One-Pot Conversion of Vegetable Substrates in Water
We describe the rational design of a new versatile family of bifunctional catalytic materials based on the combination of supported metal nanoparticles (Pd, Rh, Ru) and the superacid, perfluorinated Aquivion PFSA polymer. The heterogeneous catalysts were tested in the multi-step valorisation of representative plant derivatives to high-added-value chemicals. Particularly, the conversion of (+)-citronellal to (-)-menthol and levulinic acid to γ-valerolactone was achieved in one pot and in one stage in the water phase and shows full selectivity at a high conversion level under mild reaction conditions. The results are discussed in terms of the catalyst micro-structure.
Moreno-Marrodan, Carmen,Liguori, Francesca,Barbaro, Pierluigi,Caporali, Stefano,Merlo, Luca,Oldani, Claudio
p. 4256 - 4267
(2017/10/12)

Emissive Synthetic Cofactors: An Isomorphic, Isofunctional, and Responsive NAD+ Analogue
The synthesis, photophysics, and biochemical utility of a fluorescent NAD+ analogue based on an isothiazolo[4,3-d]pyrimidine core (NtzAD+) are described. Enzymatic reactions, photophysically monitored in real time, show NtzAD+ and NtzADH to be substrates for yeast alcohol dehydrogenase and lactate dehydrogenase, respectively, with reaction rates comparable to that of the native cofactors. A drop in fluorescence is seen as NtzAD+ is converted to NtzADH, reflecting a complementary photophysical behavior to that of the native NAD+/NADH. NtzAD+ and NtzADH serve as substrates for NADase, which selectively cleaves the nicotinamide's glycosidic bond yielding tzADP-ribose. NtzAD+ also serves as a substrate for ribosyl transferases, including human adenosine ribosyl transferase 5 (ART5) and Cholera toxin subunit A (CTA), which hydrolyze the nicotinamide and transfer tzADP-ribose to an arginine analogue, respectively. These reactions can be monitored by fluorescence spectroscopy, in stark contrast to the corresponding processes with the nonemissive NAD+.
Rovira, Alexander R.,Fin, Andrea,Tor, Yitzhak
supporting information
p. 15556 - 15559
(2017/11/14)

Characterization of methylated azopyridine as a potential electron transfer mediator for electroenzymatic systems
N,N'-dimethyl-4,4'-azopyridinium methyl sulfate (MAZP) was characterized as an electron transfer mediator for oxidation reactions catalyzed by NAD+- and pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenases. The bimolecular rate constant of NADH reactivity with MAZP was defined as (2.2?±?0.1)?×?105?M?1?s?1, whereas the bimolecular rate constant of reactivity of the reduced form of PQQ-dependent alcohol dehydrogenase with MAZP was determined to be (4.7?±?0.1)?×?104?M?1?s?1. The use of MAZP for the regeneration of the cofactors was investigated by applying the electrochemical oxidation of the mediator. The total turnover numbers of mediator MAZP and cofactor NADH for ethanol oxidation catalyzed by NAD+-dependent alcohol dehydrogenase depended on the concentration of the substrate and the duration of the electrolysis, and the yield of the reaction was limited by the enzyme inactivation and the electrochemical process. The PQQ-dependent alcohol dehydrogenase was more stable, and the turnover number of the enzyme reached a value of 2.3?×?103. In addition, oxidation of 1,2-propanediol catalyzed by the PQQ-dependent alcohol dehydrogenase proceeded enantioselectively to yield L-lactic acid.
Tetianec, Lidija,Chaleckaja, Ana,Kulys, Juozas,Janciene, Regina,Marcinkeviciene, Liucija,Meskiene, Rita,Stankeviciute, Jonita,Meskys, Rolandas
p. 41 - 48
(2017/06/05)

Preparation of Sn-Β-zeolite via immobilization of Sn/choline chloride complex for glucose-fructose isomerization reaction
Well dispersion of tin species in an isolated form is a quite challenge since tin salts are easily hydrolyzed into (hydr)oxides during aqueous stannation of β-zeolite. In this study, immobilization of tin species on high silica commercial β-zeolite by using SnCl2/Choline chloride (ChCl) complex followed with calcination provided a convenient way to get well dispersed Sn in β-zeolite in the aqueous condition, which was observed based on electron microscopy images, UV visible spectra and X-ray diffraction pattern. The existence of ChCl facilitated tin species to incorporate into zeolite. (1?2) wt% of Sn loaded β-zeolites exhibited good catalytic activity and high selectivity for glucose-fructose isomerization reaction.
Bayu, Asep,Karnjanakom, Surachai,Kusakabe, Katsuki,Abudula, Abuliti,Guan, Guoqing
p. 426 - 433
(2017/04/04)

Effect of redox properties of LaCoO3 perovskite catalyst on production of lactic acid from cellulosic biomass
Cost-effective conversion of cellulosic biomass to value-added lactic acid with heterogeneous catalysts has attracted much attention recent years. While both solid Lewis acids and bases have been extensively studied, the role of redox catalysts for the production of lactic acid is barely understood. Herein, the LaCoO3 perovskite metal oxides with strong redox properties and a good stability in hydrothermal media were used as the catalysts for the conversion of a variety of cellulosic biomass to lactic acid. The effects of reaction conditions such as reaction temperature, catalyst loading, and gas atmosphere were investigated. At the optimum conditions, the yields of approximately 40%, 38%, and 24% lactic acid were obtained from glucose, xylose and cellulose, respectively. The key intermediates such as pyruvic acid were used as the probe reactants to explore the reaction mechanism. Unlike Lewis acid or base catalysed sugar conversion reactions, the redox pathway might start from the oxidative decarboxylation of aldose sugars and the lattice oxygen atoms in the LaCoO3 perovskite structure participate the redox cycles in the conversion of sugars to lactic acid. Lastly, the stability of the LaCoO3 catalyst in hydrothermal reaction media was discussed.
Yang, Xiaokun,Yang, Lisha,Fan, Wei,Lin, Hongfei
p. 56 - 64
(2016/05/10)

Kinetic and solvent isotope effects on biotransformation of aromatic amino acids and their derivatives
Aromatic amino acids such as l-phenylalanine, l-tryptophan, 3′,4′-dihydroxy-l-phenylalanine (l-DOPA), and their derivatives 3′,4′-dihydroxyphenylacelaldehyde (DOPAL) and 3′,4′-dihydroxyphenylethanol (DOPET), play an essential role in human metabolic processes. Incorrect or slow biotransformation of these compounds leads to some metabolic dysfunctions and in some cases to some neurodegenerative diseases. Therefore, studies of the biotransformation mechanisms of these metabolites draw biochemists' and medical researchers' attention. This study investigates the mechanisms of biotransformation of the aforementioned compounds using kinetic (KIE) and solvent (SIE) isotope effect methods. The overview presents the results and the numerical values of KIE and SIE methods, obtained in the study of biotransformation of l-phenylalanine, 5′-chloro-l-tryptophan, and l-DOPA, catalyzed by the enzymes from the lyases group (phenylalanine ammonia lyase, tryptophan indole-lyase, and tyrosine decarboxylase). Deuterium KIE was also determined during the deamination of 2′-chloro-l-phenylalanine in the presence of the enzyme l-phenylalanine dehydrogenase, as well as in the conversion of DOPAL into DOPET catalyzed by the enzyme alcohol dehydrogenase. The values of KIE and SIE have been determined using a noncompetitive spectrophotometric and a competitive (combined with internal radioactivity standard) radiometric methods.
Kańska, Marianna,Jemielity, Jacek,Paj?k, Ma?gorzata,Pa?ka, Katarzyna,Podsadni, Katarzyna,Winnicka, El?bieta
p. 627 - 634
(2016/12/26)

α-Aminoxy Oligopeptides: Synthesis, Secondary Structure, and Cytotoxicity of a New Class of Anticancer Foldamers
α-Aminoxy peptides are peptidomimetic foldamers with high proteolytic and conformational stability. To gain an improved synthetic access to α-aminoxy oligopeptides we used a straightforward combination of solution- and solid-phase-supported methods and obtained oligomers that showed a remarkable anticancer activity against a panel of cancer cell lines. We solved the first X-ray crystal structure of an α-aminoxy peptide with multiple turns around the helical axis. The crystal structure revealed a right-handed 28-helical conformation with precisely two residues per turn and a helical pitch of 5.8 ?. By 2D ROESY experiments, molecular dynamics simulations, and CD spectroscopy we were able to identify the 28-helix as the predominant conformation in organic solvents. In aqueous solution, the α-aminoxy peptides exist in the 28-helical conformation at acidic pH, but exhibit remarkable changes in the secondary structure with increasing pH. The most cytotoxic α-aminoxy peptides have an increased propensity to take up a 28-helical conformation in the presence of a model membrane. This indicates a correlation between the 28-helical conformation and the membranolytic activity observed in mode of action studies, thereby providing novel insights in the folding properties and the biological activity of α-aminoxy peptides.
Diedrich, Daniela,Moita, Ana J. Rodrigues,Rüther, Anja,Frieg, Benedikt,Reiss, Guido J.,Hoeppner, Astrid,Kurz, Thomas,Gohlke, Holger,Lüdeke, Steffen,Kassack, Matthias U.,Hansen, Finn K.
p. 17600 - 17611
(2016/11/28)

Enzymatic Resolution by a d-Lactate Oxidase Catalyzed Reaction for (S)-2-Hydroxycarboxylic Acids
Oxidase-catalyzed kinetic resolution is important for the production of enantiopure 2-hydroxycarboxylic acids (2-HAs), which are versatile building blocks for the synthesis of many significant compounds. However, in contrast to that of (R)-2-HAs, the production of (S)-2-HA is challenging because of the lack of related oxidases. Herein, suitable enzymes were screened systematically through the analysis of numerous putative d-lactate oxidase sequences and identification of several required properties. Finally, a d-lactate oxidase from Gluconobacter oxydans 621H with advantageous characteristics, such as good solubility, broad substrate spectrum, and high stereoselectivity, was selected to resolve 2-HAs into (S)-2-HAs. A variety of (S)-2-HAs was produced successfully using this d-lactate oxidase with excellent enantiomeric excess values (>99 %). The presented screening criteria and approach for target biocatalysis suggested a guideline for the production of optically active chemicals such as (S)-2-HAs.
Sheng, Binbin,Xu, Jing,Ge, Yongsheng,Zhang, Shuo,Wang, Danqi,Gao, Chao,Ma, Cuiqing,Xu, Ping
p. 2630 - 2633
(2016/08/30)

Characterization of a novel marine microbial esterase and its use to make D-methyl lactate
A novel marine microbial esterase PHE14 was cloned from the genome of Pseudomonas oryzihabitans HUP022 isolated from the deep sea of the western Pacific Ocean. Esterase PHE14 exhibited very good tolerance to most organic solvents, surfactants and metal ions tested, thus making it a good esterase candidate for organic synthesis that requires an organic solvent, surfactants or metal ions. Esterase PHE14 was utilized as a biocatalyst in the asymmetric synthesis of D-methyl lactate by enzymatic kinetic resolution. D-methyl lactate is a key chiral chemical. Contrary to some previous reports, the addition of an organic solvent and surfactants in the enzymatic reaction did not have a beneficial effect on the kinetic resolution catalyzed by esterase PHE14. Our study is the first report on the preparation of the enantiomerically enriched product D-methyl lactate by enzymatic kinetic resolution. The desired enantiomerically enriched product D-methyl lactate was obtained with a high enantiomeric excess of 99% and yield of 88.7% after process optimization. The deep sea microbial esterase PHE14 is a green biocatalyst with very good potential in asymmetric synthesis in industry and can replace the traditional organic synthesis that causes pollution to the environment.
Wang, Yilong,Zhang, Yun,Sun, Aijun,Hu, Yunfeng
p. 1396 - 1402
(2016/09/07)

Hydrothermal conversion of glucose into lactic acid with sodium silicate as a base catalyst
In this paper, the hydrothermal conversion of glucose to lactic acid (LA) using sodium silicate (Na2SiO3) as a mild base catalyst was investigated. The results showed that Na2SiO3 was effective catalyst for the conversion of glucose. The highest LA yield of about 30% was obtained from glucose with a lower concentration of Na2SiO3 at 300 °C for 60 s. It was also found that the use of Na2SiO3 led to a much less corrosion and a higher LA yield than that with NaOH at the same pH value. This process provides an environmentally friendly and highly effective method toward the synthesis of useful LA from glucose.
Duo, Jia,Zhang, Zhengshuai,Yao, Guodong,Huo, Zhibao,Jin, Fangming
p. 112 - 116
(2016/02/03)

Aluminium complexes containing N,N′-chelating amino-amide hybrid ligands applicable for preparation of biodegradable polymers
Five aluminium complexes containing N,N'-chelating ligands ([2-(Me2NCH2)C6H4N(R)]-; R = H, SiMe3 or benzyl (Bn)) were prepared and structurally characterized by NMR and crystallographic techniques. Aluminium atoms in all compounds are pseudotetrahedrally coordinated with extremely short intramolecular interaction of the pendant amino group (d(Al-N) = 1.96-2.00 ?). The catalytic performance of selected complexes (～0.1-0.2 mol. %), either with or without an external co-initiator, in ring opening (co)polymerization of ε-caprolactone, l-lactide and trimethylene carbonate was tested yielding satisfactory to excellent amount of polymeric material with Mn ～ 15-70 kg/mol for ε-caprolactone, and ～30 kg/mol for trimethylene carbonate with good degree of control over the molar mass distribution, initiation efficiency. An excellent conversion of l-lactide to methyl (S,S)-O-lactyllactate is observed upon catalysis by one of the complexes at room temperature.
Kampová, Hana,Riemlová, Emílie,Klikarová, Jitka,Pejchal, Vladimír,Merna, Jan,Vlasák, Petr,?vec, Petr,R??i?ková, Zdeňka,R??i?ka, Ale?
p. 35 - 41
(2015/06/17)

Recovery method of highly pure organic acid and organic acid alkyl ester from organic acid fermentation solution
The present invention refers to organic acid purity acids from fermentation liquors organic acid and an organic acid alkyl esters method relates to a layer composed of 1, specifically the present invention into the conventional electrodialysis device or membrane and a waiting time without the need for pretreatment device, without an additional catalyst at low temperature organic acid alkyl esters can be produced and an organic acid of economical and than method, in addition the ammonium salt is separated easily may be reused as well as, organic acid alkyl esters by using a thin film distillation and an organic acid generally conventional polyamideimide for optical communication and higher recovery and method, purity. can be recovered.
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(2016/12/26)

Isomerization of hexoses from enzymatic hydrolysate of poplar sawdust using low leaching K2MgSiO4 catalysts for one-pot synthesis of HMF
A cost-effective K1.5Mg/SiO2 catalyst with a K2MgSiO4 component was employed to help transfer several hexoses into hydroxylmethylfurfural (HMF) in a biphasic water/butanol system. The solid catalysts with rod-like structures and moderate base sites could promote the aldose-ketose isomerization of glucose and have potential for the synthesis of lactic acid via a retro-aldol condensation. In the presence of sulfonated titania/mordenite solid acid, the K1.5Mg/SiO2 catalyst presented heat-stability and prolonged activity in the one-pot conversion of glucose to HMF, leading to an optimal yield of 62.2%. The one-pot catalysis of saccharides from the enzymatic hydrolysate of poplar sawdust achieved a high HMF yield of 56.9% at a glucose conversion of 91.6%.
Shen, Xiang,Wang, Yanxin,Ahring, Birgitte K.,Lei, Hanwu,Gao, Qiang,Liu, Hui
p. 96990 - 96996
(2015/11/24)

Synthesis of tertiary and quaternary amine derivatives from wood resin as chiral NMR solvating agents
Chiral tertiary and quaternary amine solvating agents for NMR spectroscopy were synthesized from the wood resin derivative (+)-dehydroabietylamine (2). The resolution of enantiomers of model compounds [Mosher's acid (3) and its n-Bu4N salt (4)] (guests) by (+)-dehydroabietyl-N,N-dimethylmethanamine (5) and its ten different ammonium salts (hosts) was studied. The best results with 3 were obtained using 5 while with 4 the best enantiomeric resolution was obtained using (+)-dehydroabietyl-N,N-dimethylmethanaminium bis(trifluoromethane-sulfonimide) (6). The compounds 5 and 6 showed a 1:1 complexation behaviour between the host and guest. The capability of 5 and 6 to recognize the enantiomers of various α-substituted carboxylic acids and their n-Bu4N salts in enantiomeric excess (ee) determinations was demonstrated. A modification of the RES-TOCSY NMR pulse sequence is described, allowing the enhancement of enantiomeric discrimination when the resolution of multiplets is insufficient.
Laaksonen, Tiina,Heikkinen, Sami,W?h?l?, Kristiina
supporting information
p. 20873 - 20886
(2015/12/23)

Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
supporting information
p. 4149 - 4151
(2015/02/02)

Novel urushiols with human immunodeficiency virus type 1 reverse transcriptase inhibitory activity from the leaves of Rhus verniciflua
Two novel urushiols, 1 and 2, and two known urushiols, 3 and 4, were isolated from the leaves of Rhus verniciflua and were examined for their human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) inhibitory activity. The novel urushiols were found to be 1,2-dihydroxyphenyl-3-[7(E),9(Z),11(Z)-pentadecatrienyl]-14-ol (1) and 1,2-dihydroxyphenyl-3-[8(Z),10(E),12(E)-pentadecatrienyl]-14-ol (2) by spectroscopic analyses. The absolute configuration at C-14 in 1 and 2 was determined to be a racemic mixture of (R) and (S) isomers by ozonolysis. Compound 2 (IC50: 12.6 μM) showed the highest HIV-1 RT inhibitory activity among the four urushiols, being 2.5-fold more potent than the positive control, adriamycin (IC50: 31.9 μM). Although the known urushiols were isolated from the sap and leaves of R. verniciflua, 1 was exclusively present in the leaves, and higher amounts of 2 were found in the leaves than in the sap. Present findings indicate that the leaves of R. verniciflua represent a new biological resource from which novel and known urushiols may be prepared, and the possible use of novel urushiols as bioactive products.
Kadokura, Kazunari,Suruga, Kohei,Tomita, Tsuyoshi,Hiruma, Wataru,Yamada, Motoyuki,Kobayashi, Akio,Takatsuki, Akira,Nishio, Toshiyuki,Oku, Tadatake,Sekino, Yoshihiro
p. 148 - 153
(2015/02/19)

Facile synthesis of α-hydroxy carboxylic acids from the corresponding α-amino acids
An effective and improved procedure is developed for the synthesis of α-hydroxy carboxylic acids by treatment of the corresponding protonated α-amino acid with tert-butyl nitrite in 1,4-dioxane-water. The amino moiety must be protonated and located α to a carboxylic acid function in order to undergo initial diazotization and successive hydroxylation, since neither β-amino acids nor acid derivatives such as esters and amides undergo hydroxylations. The method is successfully applied for the synthesis of 18 proteinogenic amino acids.
Stuhr-Hansen, Nicolai,Padrah, Shahrokh,Str?mgaard, Kristian
supporting information
p. 4149 - 4151
(2014/07/22)

Selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol on Ni/C and basic oxide-promoted Ni/C catalysts
The selective hydrogenolysis of xylitol to ethylene glycol and propylene glycol was examined on Ni/C catalysts in the presence of solid bases, e.g. Ca(OH)2 and CeO2, physically mixed with or co-supported with Ni on C. Compared with Ru/C, the Ni/C catalysts were more selective to the two target glycols under identical conditions, apparently as a result of their lower hydrogenation activity and consequently favored the CC cleavage of xylose intermediate by the base catalyst over its competitive hydrogenation on the Ni particles. Noticeably, the presence of the solid bases rendered the Ni particles resistant to leaching and sintering, and thus stable in the xylitol hydrogenolysis. Supporting the solid bases, especially CeO2 and CaO, with the Ni particles on C led not only to a reduction in the amount of solid bases required, but also efficient formation of the two glycols with negligible lactic acid. For instance, on Ni-CaO/C (at a CaO/Ni molar ratio of 0.66), the combined selectivity to ethylene glycol and propylene glycol, together with glycerol, reached 69.5% at nearly 100% xylitol conversion at 473 K, 4.0 MPa H2. These features of the basic oxide-promoted Ni catalysts show their promising advantages over the noble Ru catalysts, upon optimization of their compositions and structures, and the reaction parameters, for the efficient hydrogenolysis of xylitol and other lignocellulose-derived polyols to produce the two target glycols.
Sun, Jiying,Liu, Haichao
p. 75 - 82
(2014/07/07)

L-(+)-Lactic acid production by co-fermentation of cellobiose and xylose without carbon catabolite repression using Enterococcus mundtii QU 25
The use of lignocellulosic biomass for the production of optically pure lactic acid remains challenging because it requires efficient utilisation of mixed sugars without carbon catabolite repression (CCR). Enterococcus mundtii QU 25, a novel l-lactic acid-producing strain, was used in this study to ferment mixed sugars. This strain exhibited apparent CCR in a glucose-xylose mixture; however, replacement of glucose by cellobiose (cellobiose-xylose mixture) led to simultaneous consumption of both sugars without CCR. The production of lactic acid and activity of enzymes related to xylose metabolism were also investigated. Xylose isomerase and xylulokinase specific activity in cellobiose-xylose grown cells was three times higher than that in glucose-xylose grown cells. The addition of yeast extract and ammonium hydroxide effectively improved sugar utilisation and cell growth. Under the optimal conditions with simulated lignocellulosic hydrolysates, a high l-lactic acid concentration (up to 163 g L-1) was produced with a yield of 0.870 g g-1 and maximum productivity of 7.21 g L-1 h-1 without CCR in the fed-batch fermentation. Thus, we could establish rapid and simultaneous consumption of hexose and pentose sugars by using a lactic acid bacterium strain, which significantly increased production of high-purity l-lactic acid. This journal is the Partner Organisations 2014.
Wang, Ying,Abdel-Rahman, Mohamed Ali,Tashiro, Yukihiro,Xiao, Yaotian,Zendo, Takeshi,Sakai, Kenji,Sonomoto, Kenji
p. 22013 - 22021
(2014/06/23)

Direct conversion of cellulose into acetol on bimetallic Ni-SnO x/Al2O3 catalysts
The direct conversion of cellulose into acetol was studied on SnO x-modified Ni/Al2O3 catalysts with different Sn/Ni atomic ratios in the range of 0-2.0. The selectivity to acetol strongly depended on the Sn/Ni ratios, which reached the highest value of 53.9% at the ratio of 0.5, compared at similar cellulose conversions (～20%). On Ni-SnOx/Al2O3 (Sn/Ni = 0.5), cellulose, glucose and fructose converted to acetol in high yields of approximately 35%, 53% and 73%, respectively, at 210 °C and 6 MPa H2. The effects of the Sn/Ni ratios on the acetol selectivity appear to be related to their effects on the hydrogenation activity of the Ni-SnOx/Al2O3 catalysts that decreased with increase of the Sn/Ni ratios, and to the relative rate between the hydrogenation of C6 sugar intermediates (e.g. glucose and fructose) and their degradation intermediates (e.g. glyceraldeyde and dihydroxyacetone) involved in the cellulose reaction on the Ni particles and the isomerization of glucose to fructose and their CC bond cleavage by retro-aldol condensation on the SnOx domains. Comparison of SnO x with CeOx, ZnOx and AlOx supported on Al2O3 with different basicity suggested that the larger concentration of stronger basic sites on SnOx facilitated the isomerizaiton of glucose to fructose and its subsequent CC bond cleavage. These results and their understanding provide guidance for improving the acetol production from cellulose by tuning the catalytic functions required for the involved reactions of hydrogenation on the metal surfaces, and isomerization and CC bond cleavage on the basic sites.
Deng, Tianyin,Liu, Haichao
p. 66 - 73
(2014/06/09)

Bridging racemic lactate esters with stereoselective polylactic acid using commercial lipase catalysis
A productive and enantioselective hydrolysis of racemic mixtures of lactate esters with commercial Candida rugosa lipase was performed. This step contributes to a novel envisioned route for stereoselective PLA production by combining recent chemocatalytic developments with this biocatalytic contribution, foreseeing two separate l- and d-lactate enantiomer streams. A study of the hydrolysis kinetics identified an unexpected rate determining step at the origin of an unprecedented ester reactivity order.
Van Wouwe, Pieter,Dusselier, Michiel,Basic, Aurelie,Sels, Bert F.
supporting information
p. 2817 - 2824
(2013/10/08)

Characterization of d-amino acid aminotransferase from Lactobacillus salivarius
We searched a UniProt database of lactic acid bacteria in an effort to identify d-amino acid metabolizing enzymes other than alanine racemase. We found a d-amino acid aminotransferase (d-AAT) homologous gene (UniProt ID: Q1WRM6) in the genome of Lactobacillus salivarius. The gene was then expressed in Escherichia coli, and its product exhibited transaminase activity between d-alanine and α-ketoglutarate. This is the first characterization of a d-AAT from a lactic acid bacterium. L. salivarius d-AAT is a homodimer that uses pyridoxal-5′-phosphate (PLP) as a cofactor; it contains 0.91 molecules of PLP per subunit. Maximum activity was seen at a temperature of 60 °C and a pH of 6.0. However, the enzyme lost no activity when incubated for 30 min at 30 °C and pH 5.5 to 9.5, and retained half its activity when incubated at pH 4.5 or 11.0 under the same conditions. Double reciprocal plots of the initial velocity and d-alanine concentrations in the presence of several fixed concentrations of α-ketoglutarate gave a series of parallel lines, which is consistent with a Ping-Pong mechanism. The Km values for d-alanine and α-ketoglutarate were 1.05 and 3.78 mM, respectively. With this enzyme, d-allo-isoleucine exhibited greater relative activity than d-alanine as the amino donor, while α-ketobutylate, glyoxylate and indole-3-pyruvate were all more preferable amino acceptors than α-ketoglutarate. The substrate specificity of L. salivarius d-AAT thus differs greatly from those of the other d-AATs so far reported.
Kobayashi, Jyumpei,Shimizu, Yasuhiro,Mutaguchi, Yuta,Doi, Katsumi,Ohshima, Toshihisa
p. 15 - 22
(2013/10/22)

Two new compounds from the metabolites of a marine-derived actinomycete Streptomyces cavourensis YY01-17
Our current marine natural product program investigated the second metabolites of an actinomycete Streptomyces cavourensis YY01-17 originating from the Antarctic ecological niche to discover potential antitumor chemical entities. Two new compounds, along with a known compound, were isolated from the ethyl acetate extract of the fermentation broth of the marine-derived actinomycete, and their structures were elucidated, respectively, as 2(S)-3′-hydroxybutan-2′-yl 2-hydroxypropanoate (1), (E)-3-hydroxy-2,4-dimethylhept-4-enamide (2), and 2-hydroxy-3-methylbutanoic acid (3) on the basis of spectroscopic data interpretation.
Su, Shan-Shan,Tian, Li,Chen, Gang,Li, Zhan-Qiang,Xu, Wen-Feng,Pei, Yue-Hu
p. 265 - 269
(2013/07/05)

RECOVERY METHOD OF HIGHLY PURE LACTIC ACID AND ALKYL LACTATE
A method for recovery of highly pure alkyl lactate and lactic acid is provided, which includes a step 1 for producing source liquid comprising lactic acid or ammonium lactate; a step 2 for dehydrating the source liquid product of step 1; a step 3 for producing liquid mixture by sequentially adding and stirring alcohol and acid solution to the dehydrated source liquid; a step 4 for separating and removing ammonium salt precipitation from the liquid mixture of step 3; a step 5 for producing alkyl lactate from ammonium salt-free liquid mixture by esterification reaction; and a step 6 for separating alcohol and alkyl lactate by distillation from the mixture of step 5.
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(2012/06/16)

Transforming polylactide into value-added materials
The production of chemical building blocks and polymer precursors from biorenewable and sustainable resources is an attractive method to bypass traditional fossil fuel derived materials. Accordingly, we report the organocatalytic recycling of postconsumer polylactide (PLA) into value-added small molecules. This strategy, using the highly active transesterification catalyst triazabicyclodecene, is shown to completely depolymerize PLA in the presence of various alcohols into valuable lactate esters. Using previously used PLA packaging material, the depolymerization is complete in minutes at room temperature and fully retains the stereochemistry of the lactate species. Further, the modularity and utility of this methodology with respect to polyester substrate is detailed by using a variety of functional alcohols to depolymerize both PLA and polyglycolide, with the corresponding ester small-molecules being used to make new polymeric materials. The opportunities to transform waste streams into value-added chemicals and new materials through simple and versatile chemistry hold significant potential to extend the lifecycle of renewable chemical feedstocks.
Leibfarth, Frank A.,Moreno, Nicholas,Hawker, Alex P.,Shand, Justin D.
p. 4814 - 4822
(2013/01/15)

Total syntheses of the gregatins A-D and aspertetronin A: Structure revisions of these compounds and of aspertetronin B, together with plausible structure revisions of gregatin E, cyclogregatin, graminin A, the penicilliols A and B, and the huaspenones A and B
Comprehensive comparisons of 1H and 13C NMR chemical shift values in the furanone cores a, b, and c provide plausible support for a reassessment of the furanone nuclei of the title compounds from b to c. Total syntheses via enantiomerically pure lactic esters were based on the Seebach-Frater "self-reproduction of stereocenters" methodology. Attachment of the hexadienyl side-chain in a trans,trans-selective manner was achieved by addition of the Seebach-Frater enolate to trans-hex-4-en-1-al rather than to trans-hex-3-en-1-al. The type-c furanone cores of the synthetic materials were reached by single or double acylation of a model γ-hydroxy-β-oxo ester (compound 50) and its hexadiene-containing counterpart 29. Our syntheses confirmed the novel connectivities in six compounds. In addition, they required revision of the configuration of a quaternary carbon atom in five cases. Moreover, they allowed elucidation of the configurations of four previously unassigned stereocenters. Hindsight analyses of why the furanone cores of the title compounds had been misinterpreted as a and/or b instead of c are given. Why the stereocenters in the heterocycles had been incorrectly configured, on the bases (a) of relay studies in the 1960s, and (b) of a 1984 total synthesis of gregatin B, is also discussed.
Burghart-Stoll, Heike,Brueckner, Reinhard
scheme or table
p. 3978 - 4017
(2012/10/18)

Extraction and separation of (D,L)-lactic acid in simulated fermentation broth
The recovery of lactic acid from fermentation broth plays an important part in production of lactic acid. In this case, the extraction of lactic acid from simulated fermentation broth was processed by tri-n-octylamine dissolved in oleyl alcohol. The extraction efficiency was investigated with several variables, and the optimal condition of extraction of lactic acid (10 mg/mL) from aqueous solution was tri-n-octylamine/oleyl alcohol (30/70, v/v) and solvent phase/fermentation (1/2, v/v) stirring for 60 min under room temperature. The optimal back extraction of lactic acid was obtained by hot water (～90°C) with solvent phase/water (1/4, v/v). The back extracted racemic lactic acid was direct enantiomeric analyzed and separated by chiral ligand chromatography due to strict requirement of absolute configuration in pharmaceutical field and food science. The effect of various parameters on enantioselectivity was discussed and the (L)-phenylalaninamide·HCl (6.0 mmol/L) and CuSO4·5H2O (3.0 mmol/L) dissolved in methanol/water (5/95, v/v) at pH 6.0 was the suitable mobile phase for chiral ligand exchange separation of (D,L)-lactic acids. By the investigations, a convenient systemic method was established for extraction and separation of (D,L)-lactic acid.
Zhou, Jun,Bi, Wentao,Row, Kyung-Ho
p. 631 - 636
(2012/10/30)

Continuous multiple liquid-liquid separation: Diazotization of amino acids in flow
A second-generation laboratory-scale, modular liquid-liquid separation device based on computer-controlled high-pressure pumps and a high-resolution digital camera has been invented. The diazotization of amino acids to produce valuable chiral hydroxyacids is demonstrated in flow for the first time. The use of a triple-separator system in conjuction with the developed diazotization process allows the safe and efficient production and automated isolation of multigram quantities of valuable chiral hydroxyacids.
Hu, Dennis X.,O'Brien, Matthew,Ley, Steven V.
supporting information; experimental part
p. 4246 - 4249
(2012/10/08)

The direct conversion of xylan to lactic acid by Lactobacillus brevis transformed with a xylanase gene
A xylanase gene (xynR8), obtained from the DNA of a pool of uncultured rumen microbes, was introduced via a plasmid into Lactobacillus brevis. The recombinant xylanase, with an estimated molecular weight of 32 KDa, was expressed in the transformants and showed obvious xylanase activity (0.412 U ml-1) against oat-spelt xylan in broth when compared to the wild-type Lactobacillus brevis ATCC367. The transformants all shared a similar ability to utilize and metabolize xylooligosaccharides. When a selected transformant was inoculated into modified MRS medium containing xylan as the main carbon source, the cell density reached 2.20 × 109 CFU ml-1 on day 4, while the wild-type strain without the plasmid containing the recombinant xylanase did not grow at all under the same conditions. After fermentation, 1.70 g l-1 of lactic acid and 0.44 g l-1 of ethanol were present in the culture supernatant of the strain containing the recombinant xylanase. These results indicate that Lactobacillus brevis containing the xylanase gene is capable of directly saccharifying and fermenting xylan to produce lactic acid in one step. This strain will enable the development of a feasible and economical approach to the production of lactic acid directly from xylan.
Hu, Chun-Yi,Chi, Da-Jun,Chen, Shih-Syuan,Chen, Yo-Chia
experimental part
p. 1729 - 1734
(2011/10/08)

A chemoenzymatic synthesis of 5a-carba-α-D-mannose-6-phosphate
An efficient chemical synthesis of 5a-carba-α-D-mannose and its enzymatic elaboration to 5a-carba-α-D-mannose-6-phosphate, using yeast hexokinase, is described.
Williams, Paula M.,Sheldrake, Gary N.,Macdonald, Simon J.F.,Hamilton, Chris J.
experimental part
p. 1257 - 1261
(2011/07/09)

Degradation of 1-deoxy-d-erythro-hexo-2,3-diulose in the presence of lysine leads to formation of carboxylic acid amides
A novel species of amides formed from degradation of one of the most important key intermediates in Maillard hexose chemistry-1-deoxyhexo-2,3- diulose-was investigated. In 1-deoxyhexo-2,3-diulose/Nα-t-BOC- lysine reaction mixtures four amides, Nε-acetyl lysine, N ε-formyl lysine, Nε-lactoyl lysine and N ε-glycerinyl lysine, were identified and their structures verified by authentic reference standards. Amides and corresponding carboxylic acids (acetic acid, formic acid, lactic acid and glyceric acid) accumulated over time. Both Nε-lysine amides and carboxylic acids were thus determined as stable Maillard end products. Results of model incubations suggested the synthesis of amides to be mechanistically closely related to the formation of their corresponding carboxylic acids by β-dicarbonyl cleavage. Due to the different chemical properties of all the compounds monitored, various analytical strategies had to be carried out (LC-MS2, GC-MS, GC-FID, enzymatic determination).
Smuda, Mareen,Voigt, Michael,Glomb, Marcus A.
experimental part
p. 6458 - 6464
(2011/08/09)

Lipase-catalyzed oligomerization and hydrolysis of alkyl lactates: Direct evidence in the catalysis mechanism that enantioselection is governed by a deacylation step
Lipase-catalyzed oligomerization of alkyl d-and l-lactate monomers (RDLa and RLLa, respectively) was studied for the first time. It has been found that the oligomerization occurs enantioselectively only for d-lactates to give oligomers up to heptamers of lactic acid (LA) in good to high yields by using primary C1 to C8 alkyl groups and sec-butyl group for d-lactate monomers. No reaction happened for all l-lactates in similar conditions. Lipase-catalyzed hydrolysis of alkyl d-and l-lactates was also examined, revealing that the hydrolysis took place for both d-and l-lactates, although l-lactates proceeded a couple of times slower. The hydrolysis results clearly demonstrate that the lipase catalysis mechanism involves an acyl-enzyme intermediate (EM) formation via the acylation step from both d-and l-lactates as a rate-determining step, and the subsequent deacylation step, a nucleophilic attack of water to the EM, takes place to produce free LA. On the other hand, in the oligomerization of d-lactates, the deacylation step, in which a sec-alcohol group of the monomer or of the propagating chain-end attacks to the EM, is only allowed for the sec-d-alcohol group to give a one-LA-unit-elongated oligomer. l-Lactates form the EM; however, the subsequent deacylation reaction with both the sec-l-and sec-d-alcohol groups does not take place, failing in the oligomerization to occur. These results provide with the first direct evidence in the lipase catalysis that the enantioselection is governed by the deacylation step. In the co-oligomerization between l-and d-lactates, the l-isomer retarded the reaction rate of the d-isomer, which was found due to the function of the former as a competitive inhibitor in the acylation step toward the latter.
Ohara, Hitomi,Onogi, Akihisa,Yamamoto, Masafumi,Kobayashi, Shiro
experimental part
p. 2008 - 2015
(2011/03/22)

Genetic engineering of candida utilis yeast for efficient production of L-lactic acid
Polylactic acid is receiving increasing attention as a renewable alternative for conventional petroleum-based plastics. In the present study, we constructed a meta-bolically-engineered Candida utilis strain that produces L-lactic acid with the highest efficiency yet reported in yeasts. Initially, the gene encoding pyruvate decarbox-ylase (CuPDCl) was identified, followed by four CuPDCl disruption events in order to obtain a null mutant that produced little ethanol (a by-product of L-lactic acid). Two copies of the L-lactate dehydrogenase (l-LDH) gene derived from Bos taurus under the control of the CuPDCl promoter were then integrated into the genome of the CuPdcl -null deletant. The resulting strain produced 103.3 g/1 of L-lactic acid from 108.7 g/1 of glucose in 33 h, representing a 95.1% conversion. The maximum production rate of L-lactic acid was 4.9 g/l/h. The optical purity of the L-lactic acid was found to be more than 99.9% e.e.
Ikushima, Shigehito,Fujii, Toshio,Kobayashi, Osamu,Yoshida, Satoshi,Yoshida, Aruto
body text
p. 1818 - 1824
(2010/03/24)

Resolution of Racemic Organic Acids with (1S, 4S)-4[3,4-Dichlorophenyl]-1,2,3,4-Tetrahydro-N-Methyl-1-Naphthaloneamine
The present invention relates to novel chiral resolving agents and a process for resolution of racemic organic acids and their derivatives of the formula (+, ?)—R1R2CHCOOR3 with Cis-(1S,4S)-4[3,4-dichlorophenyl]-1,2,3,4-tetrahydro-N-methyl-1-naphthaloneamine and its Cis-(1R,4R)-isomer as well as Trans-(1S,4R)-4[3,4-dichlorophenyl]-1,2,3,4-tetrahydro-N-methyl-1-naphthaloneamine and its Trans-(1R,4S)-isomer.
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(2009/10/18)

Natural products chemistry and taxonomy of the marine cyanobacterium Blennothrix cantharidosmum
A Papua New Guinea field collection of the marine cyanobacterium Blennothrix cantharidosmum was investigated for its cytotoxic constituents. Bioassay-guided isolation defined the cytotoxic components as the known compounds lyngbyastatins 1 and 3. However, six new acyl proline derivatives, tumonoic acids D-I, plus the known tumonoic acid A were also isolated. Their planar structures were defined from NMR and MS data, while their stereostructures followed from a series of chiral chromatographies, degradation sequences, and synthetic approaches. The new compounds were tested in an array of assays, but showed only modest antimalarial and inhibition of quorum sensing activities. Nevertheless, these are the first natural products to be reported from this genus, and this inspired a detailed morphologic and 16S rDNA-based phylogenetic analysis of the producing organism.
Clark, Benjamin R.,Engene, Niclas,Teasdale, Margaret E.,Rowley, David C.,Matainaho, Teatulohi,Valeriote, Frederick A.,Gerwick, William H.
experimental part
p. 1530 - 1537
(2009/09/06)

Comparison of sucrose-hydrolyzing enzymes produced by Rhizopus oryzae and Amylomyces rouxii
Rhizopus oryzae produces lactic acid from glucose but not efficiently from sucrose, while Amylomyces rouxii, a species closely related to R. oryzae, ferments these sugars equally. The properties of two sucrose-hydrolyzing enzymes purified from culture filtrates of R. oryzae NBRC 4785 and A. rouxii CBS 438.76 were compared to assess lactic acid fermentation by the two fungi. The substrate specificity of the enzymes showed that the enzymes from strains NBRC 4785 and CBS 438.76 are to be classified as glucoamylase and invertase respectively. The entity of the enzyme from strain NBRC 4785 might be a glucoamylase, because eight residues of the N-terminal amino acid sequence coincided with those of the deduced protein from the amyB gene of R. oryzae. The enzyme from NBRC 4785 was more unstable than that from strain CBS 438.76 under conditions of lower pH and higher temperature. These observations mean that the culture conditions of R. oryzae for lactic acid production from sucrose should be strictly controlled to prevent inactivation of the glucoamylase hydrolyzing sucrose.
Watanabe, Tsuyoshi,Oda, Yuji
body text
p. 3167 - 3173
(2009/04/07)

Chiral mono boronic acid as fluorescent enantioselective sensor for mono α-hydroxyl carboxylic acids
(Graph Presented) New mono boronic acid was found to be an enantioselective fluorescent chemosensor for mono α-hydroxyl carboxylic acids, such as mandelic acid and lactic acid. The chiral sensor shows lower background fluorescence, higher fluorescence enh
Chi, Lina,Zhao, Jianzhang,James, Tony D.
p. 4684 - 4687
(2008/09/21)

PROCESS FOR PREPARING L- ( + ) -LACTIC ACID
The present invention provides a commercially viable process for the preparation of highly pure and optically active L-(+)-lactic acid and S-(-)-methyl lactate, in high yield, obtained from esterification of aqueous crude lactic acid solution produced by sugar cane juice fermentation broth and methanol in continuous counter current trickle phase approach or in continuous counter current bubble column manner, using stabilizers and the methyl lactate so obtained is recovered and followed by purification of reasonably pure methyl lactate using reagent mixture such as sodium bi-carbonate, mono-ethanolamine or di-ethanolamine, urea or sodium-bicarbonate, mono-ethanolamine or di-ethanolamine, thiourea to reduce the impurity of dimethyl ester of dicarboxylic such as dimethyl oxalate or di-methyl succinate or methyl ester of mono-carboxylic acid such as methyl pyruvate present as an impurity, so as to get highly pure S-(-)-methyl lactate followed by hydrolyzing highly pure S-(-)-methyl lactate using highly pure lactic acid as a catalyst, using highly pure water as the hydrolysis media and by using pre-treated activated carbon with dilute L-(+)-lactic acid, in batch or continuous mode. This very high pure S-(-)-methyl lactate constitutes an important product having interesting possibilities of application at an industrial level, in pharmaceuticals. Highly pure L-(+)-lactic acid thus obtained is used as an acidulant, as a food additive, for pharmaceutical applications ,a monomer for making poly-lactic acid ,as a monomer to prepare biodegradable polymer which are useful for manufacturing bags, application films, in the field of sanitary field, and has medical applications.
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(2008/06/13)

Asymmetric hydrolysis of 2-hydroxy-carboxylic esters using recombinant Escherichia coli
Optically active 2-hydroxy-carboxylates are important compounds for their use as intermediates in the synthesis of pharmaceuticals and stereoblock polymers. Enterobacter sp. DS-S-75 and the recombinant Escherichia coli harbouring the 4-chloro-3-hydroxybutyrate (CHB) hydrolase gene from the strain DS-S-75 showed asymmetric hydrolytic activity towards 2-hydroxy-carboxylates, as well as towards CHB. It was discussed that the hydroxyl group in the substrate was particularly important for the asymmetric hydrolytic activity of the CHB hydrolase, and as such, it was re-designated to EnHCH (hydroxy-carboxylic ester hydrolase derived from Enterobacter sp.). Using the recombinant cell, both the reaction rate and the concentration of the substrates were significantly improved upon when compared to that of DS-S-75. Optically active 2-hydroxy-carboxylates could be synthesized on a practical basis for industrial production in this report.
Nakagawa, Atsushi,Kato, Ko,Shinmyo, Atsuhiko,Suzuki, Toshio
p. 2394 - 2398
(2008/03/13)

Quinazolinone-based fungal efflux pump inhibitors. Part 1: Discovery of an (N-methylpiperazine)-containing derivative with activity in clinically relevant Candida spp.
The discovery of a series of quinazolinone-based fungal efflux pump inhibitors by high-throughput screening for potentiation of fluconazole in C. albicans is described. Attempts to improve the aqueous solubility of screening hits led to the discovery of an analog with greatly improved physical properties and activity against clinically-relevant Candida spp.
Lemoine, Rémy C.,Glinka, Tomasz W.,Watkins, William J.,Cho, Aesop,Yang, Jessie,Iqbal, Nadeem,Singh, Rajeshwar,Madsen, Deidre,Lolans, Karen,Lomovskaya, Olga,Oza, Uma,Dudley, Michael N.
p. 5127 - 5131
(2007/10/03)

PROCESS FOR PRODUCING LACTIDE AND PROCESS FOR PRODUCING POLYLACTIC ACID STARTING WITH FERMENTED LACTIC ACID
According to the present invention, a process for consistently producing lactide from ammonium lactate obtained by lactic fermentation, and a process for consistently producing polylactic acid from ammonium lactate obtained by lactic fermentation, are provided. A process for producing lactide, which comprises the steps of: (1) synthesizing lactate ester from ammonium lactate obtained by lactic fermentation; (2) polycondensing the lactate ester in the presence of a catalyst other than monobutyltin, whereby polylactic acid with a weight-average molecular weight of less than 15,000 (lactic acid prepolymer) is synthesized; and (3) depolymerizing the polylactic, whereby lactide is produced. A process for producing polylactic acid, which comprises the additional step of (4) ring-opening polymerizing said lactide, whereby polylactic acid is obtained. A process for producing lactate ester from ammonium lactate obtained by lactic fermentation.
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(2010/01/31)

Degradation mechanism and kinetics of thermosensitive polyacrylamides containing lactic acid side chains
Diblock copolymers of poly(N-isopropylacrylamide-co-N-(2-hydroxypropyl)methacrylamide lactate) (poly(NIPAAm-co-HPMAm-lactate)) as a thermosensitive block and poly(ethylene glycol) (PEG) as a hydrophilic block form polymeric micelles above the cloud point (CP) of the temperature-sensitive block. Destabilization of these micelles occurs upon hydrolysis of the lactate side chains. Here we report on the degradation kinetics of the HPMAm-mono(di)lactate monomers and their copolymers with NIPAAm. The degradation of the monomers and polymers in their soluble state (thus below their CP) followed normal ester hydrolysis behavior: the degradation rate increased with temperature, pH (from pH 7.5 to 11), and dielectric constant of the medium. Above the CP, where the polymers are in a precipitated state, a significant retardation of the polymer degradation occurred due to a decrease of dielectric constant of the local environment of the precipitated polymer. This study shows that it is possible to predict the rate of formation of HPMAm in NIPAAm-co-HPMAm-lactate copolymers with results in an increase of the overall hydrophilicity of the polymers and destabilization of polymeric micelles based on poly(NIPAAm-co-HPMAm-lactate).
Neradovic,Van Steenbergen,Vansteelant,Meijer,Van Nostrum,Hennink
p. 7491 - 7498
(2007/10/03)

Vapor Liquid Equilibria of the Mixtures Involved in the Esterification of Lactic Acid with Methanol
Isobaric vapor liquid equilibrium (VLE) data of the reactive quaternary system methanol (1) + water (2) + methyl lactate (3) + lactic acid (4) are presented in this paper. The experimental data were correlated using the UNIQUAC model to describe the chemical and phase equilibrium. The UNIQUAC parameters for some of the binary, nonreactive systems involved in the quaternary mixture were obtained from published VLE data and, in the case of the system water + lactic acid, from experimental VLE data reported in this paper. The rest of the binary UNIQUAC parameters were obtained by an optimization of the correlation of the experimental quaternary VLE data. The results obtained from the correlation were found to be in good agreement with experimental data. The reaction equilibrium constant was also calculated for each experimental data point. A three-dimensional phase diagram was constructed for the quaternary reactive system by using transformed composition variables. No reactive azeotrope was found.
Sanz, Maria Teresa,Beltran, Sagrario,Calvo, Beatriz,Cabezas, Jose Luis,Coca, Jose
p. 1446 - 1452
(2007/10/03)