- First chemical synthesis of antioxidative metabolites of sesamin
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The first chemical synthesis of two metabolites ((1R,2S,5R,6S)-6-(3,4- dihydroxyphenyl)-2-(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo[3,3,0]octane (SC-1) and (1R,2S,5R,6S)-2,6-bis(3,4-dihydroxyphenyl)-3,7-dioxabicyclo[3,3,0] octane (SC-2)) of sesamin was achieved by a simple two-step approach from sesamin. The approach consists of acetoxylation of the methylenedioxy moiety(ies) with lead(IV) tetraacetate and acid hydrolysis of the resulting hemiorthoester to SC-1 and SC-2.
- Urata, Hidehito,Nishioka, Yuka,Tobashi, Takafumi,Matsumura, Yasuo,Tomimori, Namino,Ono, Yoshiko,Kiso, Yoshinobu,Wada, Shun-Ichi
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- Phenolic compounds from the fresh leaves of eucalyptus maideni
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Four new phenolic compounds, 7-O-methylcatechin 5-O-β-D- glucopyranoside (1), 6-O-feruloyl-D-glucopyranose (2), demethylpiperitol 4-O-β-D-glucopyranoside (3), and 2-episesaminol 2-O-β-D- glucopyranoside (4) were isolated from the fresh leaves of Eucalyptus maideni, together with six hydrolyzable tannins, 5-10, a flavonol glycoside, 11, three simple phenolics, 12-14, a monoterpene glucoside, 15, and a rosenoside, 16. Their structures were determined on the basis of detailed spectroscopic analysis, acidic hydrolysis, and enzymatic hydrolysis. The known compounds 10 and 13 were obtained from the genus Eucalyptus for the first time. Copyright 2010 Verlag Helvetica Chimica Acta AG, Zuerich, Switzerland.
- Tian, Li-Wen,Yang, Chong-Ren,Zhang, Ying-Jun
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- Furofuran lignans as a new series of antidiabetic agents exerting α-glucosidase inhibition and radical scarvenging: Semisynthesis, kinetic study and molecular modeling
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A new series of furofuran lignans containing catechol moiety were prepared from the reactions between lignans and a variety of phenolics. All 22 products obtained were evaluated against three different α-glucosidases (maltase, sucrase and Baker's yeast glucosidase) and DPPH radical. Of furofuran lignans evaluated, β-14, having two catechol moieties and one acetoxy group, was the most potent inhibitor against Baker's yeast, maltase, and sucrase with IC50 values of 5.3, 25.7, and 12.9 μM, respectively. Of interest, its inhibitory potency toward Baker's yeast was 28 times greater than standard drug, acarbose and its DPPH radical scavenging (SC50 11.2 μM) was 130 times higher than commercial antioxidant BHT. Subsequent investigation on mechanism underlying the inhibitory effect of β-14 revealed that it blocked Baker's yeast and sucrase functions by mixed-type inhibition while it exerted non-competitive inhibition toward maltase. Molecular dynamics simulation of the most potent furofuran lignans (4, α-8b, α-14, and β-14) with the homology rat intestinal maltase at the binding site revealed that the hydrogen bond interactions from catechol, acetoxy, and quinone moieties of furofuran lignans were the key interaction to bind tightly to α-glucosidase. The results indicated that β-14 possessed promising antidiabetic activity through simultaneously inhibiting α-glucosidases and free radicals.
- Worawalai, Wisuttaya,Doungwichitrkul, Titiruetai,Rangubpit, Warin,Taweechat, Panyakorn,Sompornpisut, Pornthep,Phuwapraisirisan, Preecha
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- Discovery of a sesamin-metabolizing microorganism and a new enzyme
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Sesamin is one of the major lignans found in sesame oil. Although some microbial metabolites of sesamin have been identified, sesamin-metabolic pathways remain uncharacterized at both the enzyme and gene levels. Here, we isolated microorganisms growing on sesamin as a sole-carbon source. One microorganism showing significant sesamin-degrading activity was identified as Sinomonas sp. no. 22. A sesamin-metabolizing enzyme named SesA was purified from this strain and characterized. SesA catalyzed methylene group transfer from sesamin or sesamin monocatechol to tetrahydrofolate (THF) with ring cleavage, yielding sesamin mono- or di-catechol and 5,10-methylenetetrahydrofolate. The kinetic parameters of SesA were determined to be as follows: Km for sesamin = 0.032 ± 0.005 mM, Vmax = 9.3 ± 0.4 (μmol?min-1), and kcat = 7.9 ± 0.3 s-1 . Next, we investigated the substrate specificity. SesA also showed enzymatic activity toward (+)-episesamin, (-)-asarinin, sesaminol, (+)-sesamolin, and piperine. Growth studies with strain no. 22, and Western blot analysis revealed that SesA formation is inducible by sesamin. The deduced amino acid sequence of sesA exhibited weak overall sequence similarity to that of the protein family of glycine cleavage T-proteins (GcvTs), which catalyze glycine degradation in most bacteria, archaea, and all eukaryotes. Only SesA catalyzes C1 transfer to THF with ring cleavage reaction among GcvT family proteins. Moreover, SesA homolog genes are found in both Gram-positive and Gram-negative bacteria. Our findings provide new insights into microbial sesamin metabolism and the function of GcvT family proteins.
- Kumano, Takuto,Fujiki, Etsuko,Hashimoto, Yoshiteru,Kobayashi, Michihiko
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p. 9087 - 9092
(2016/08/12)
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- Identification of the metabolites of episesamin in rat bile and human liver microsomes
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Episesamin is an isomer of sesamin, resulting from the refining process of non-roasted sesame seed oil. Episesamin has two methylendioxyphenyl groups on exo and endo faces of the bicyclic skeleton. The side methylendioxyphenyl group was metabolized by cyt
- Tomimori, Namino,Nakai, Masaaki,Ono, Yoshiko,Kitagawa, Yoshinori,Kiso, Yoshinobu,Shibata, Hiroshi
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experimental part
p. 709 - 716
(2012/09/22)
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