481-74-3Relevant articles and documents
CONVERSION OF EMODIN TO CHRYSOPHANOL IN A CELL-FREE SYSTEM FROM PYRENOCHAETA TERRESTRIS
Anderson, John A.
, p. 103 - 106 (1986)
Incubation of a cell-free extract from Pyrenochaeta terrestris with emodin gave a single major product which was purified and identified as chrysophanol by mass spectrometry.Maximum conversion of emodin to chrysophanol was obtained with anaerobic conditions and NADPH, ATP, mercaptoethanol, iron(II) and glycerol.The apparent Km for emodin in the crude extract was 1.0 +/- 0.2 μM.At 4.2 μM, the conversion of emodin was 17 times the conversion of emodinanthrone to chrysophanol plus chrysophanolanthrone.It is proposed that chrysophanol is synthesized in plant and fungal species primarily by dehydroxylation of emodin.Key Word Index-Pyrenochaeta terrestris; Sphaeropsidaceae; cell-free system; biosynthesis; emodin; chrysophanol
In vitro formation of the anthranoid scaffold by cell-free extracts from yeast-extract-treated Cassia bicapsularis cell cultures
Abdel-Rahman, Iman A.M.,Beuerle, Till,Ernst, Ludger,Abdel-Baky, Afaf M.,Desoky, Ezz El-Din K.,Ahmed, Amany S.,Beerhues, Ludger
, p. 15 - 24 (2013)
The anthranoid skeleton is believed to be formed by octaketide synthase (OKS), a member of the type III polyketide synthase (PKS) superfamily. Recombinant OKSs catalyze stepwise condensation of eight acetyl units to form a linear octaketide intermediate which, however, is incorrectly folded and cyclized to give the shunt products SEK4 and SEK4b. Here we report in vitro formation of the anthranoid scaffold by cell-free extracts from yeast-extract-treated Cassia bicapsularis cell cultures. Unlike field- and in vitro-grown shoots which accumulate anthraquinones, cell cultures mainly contained tetrahydroanthracenes, formation of which was increased 2.5-fold by the addition of yeast extract. The elicitor-stimulated accumulation of tetrahydroanthracenes was preceded by an approx. 35-fold increase in OKS activity. Incubation of cell-free extracts from yeast-extract-treated cell cultures with acetyl-CoA and [2-14C]malonyl-CoA led to formation of torosachrysone (tetrahydroanthracene) and emodin anthrone, beside two yet unidentified products. No product formation occurred in the absence of acetyl-CoA as starter substrate. To confirm the identities of the enzymatic products, cell-free extracts were incubated with acetyl-CoA and [U- 13C3]malonyl-CoA and 13C incorporation was analyzed by ESI-MS/MS. Detection of anthranoid biosynthesis in cell-free extracts indicates in vitro cooperation of OKS with a yet unidentified factor or enzyme for octaketide cyclization.
A Biomimetic Synthesis of Racemic Dihydroanthracen-1(2H)-ones Using Sodium Borohydride in Water
Mondal, Amit,Singh, Shailesh Kumar,Saha, Nirmal,Husain, Syed Masood
, p. 2425 - 2430 (2020)
Herein, we report a single step synthesis of racemic dihydroanthracenones by the reduction of anthraquinones using NaBH4 and Na2S2O4 in water. The racemic mixture is utilized to determine the enantiomeric excess for the chiral dihydroanthracenones reportedly synthesized by the chemoenzymatic reduction of anthraquinones. The results show > 99percent ee for the putative biosynthetic intermediates, (R)-configured dihydroanthracenones obtained through chemoenzymatic reduction of emodin, lunatin, and citreorosein using MdpC of Aspergillus nidulans or PHAR of Cochliobolus lunatus. This also implied for the confirmation about the optical purity of the natural products which are synthesized using chiral dihydroanthracenones.
PURIFICATION AND PROPERTIES OF EMODIN DEOXYGENASE FROM PYRENOCHAETA TERRESTRIS
Anderson, John A.,Lin, Bor-Kang,Wang, Shan Shue
, p. 2415 - 2418 (1990)
Emodin deoxygenase, which catalyses the reduction of emodin to chrysophanol, was purified 17-fold from crude extracts of Pyrenochaeta terrestris.The Mr of the enzyme was 103000.Upward curvature was exhibited by the plot of rate vs concentration of the crude extract.The protein fraction obtained from gel filtration with Sephadex G-75 was activated by ATP plus a low Mr fraction; ATP alone or low Mr fraction alone did not increase its activity.The Km for NADPH of the crude extract was 3 μM, that after NADPH gel filtration of the crude extract was 1.5 mM.It is proposed that ATP plus an unidentified factor increase emodin deoxygenase activity by lowering the Km for NADPH.Iron II, which increased activity of the crude extract, inhibited activity of the partially purified enzyme by 95 percent.Sulphydryl reagents inhibited activity by 90 percent.Partially purified emodin deoxygenase activity was low in the absence of mercaptans and was increased eight-fold by the addition of dithiothreitol.It is proposed that a pair of thiol groups is required for activity and that they occur in the disulphide form in the absence of mercaptans.
NADPD ISOTOPE EFFECT ON ACTIVITY OF EMODIN DEOXYGENASE
Anderson, John A.,Lin, Bor-Kang
, p. 811 - 812 (1993)
Thermoanaerobium brokii alcohol dehydrogenase catalysed the transfer of the pro 4H, hydrogen of NADPH.The effect of 4-deuteration of NADPH on the initial rate of conversion of emodin to chrysophanol catalysed by emodin deoxygenase was determined.The deuterium isotope effects on V/Km and Vmax with NADPH were 1.20 +/- 0.36 and 1.10 +/- 0.11, respectively.The deuterium isotope effects on V/Km and Vmax with NADPH were 4.08 +/- 1.55 and 6.90 +/- 0.74, respectively.Emodin deoxygenase, therefore, transfers the 4S hydrogen of NADPD in the rate-determining step.Key word index - Pyrenochaeta terrestris; Sphaeropsidaceae; emodin; chrysophanol; deoxygenase; 2>NADPH; kinetics.
Predomination of dimers over naturally occurring anthraquinones in soil
Fujitake, Nobuhide,Suzuki, Takeshi,Fukumoto, Mariko,Oji, Yoshikiyo
, p. 189 - 192 (1998)
Four bianthraquinones and two monoanthraquinones were isolated as the major soil anthraquinones from a volcanic ash soil in Japan. They were identified as a new natural product 5,5'-biphyscion (named hinakurin) (3) and five known compounds, chrysotalunin (1), (-)-7,7'-biphyscion (2), microcarpin (4), chrysophanol (5), and physcion (6) using MS, 1D NMR, and 2D NMR techniques. Although the dimers (1-4) are rarely found as natural products, they, along with 5 and 6, were ubiquitous and predominant over other anthraquinones in various soils from Japan and Nepal.
(R)-PRECHRYSOPHANOL FROM ALOE GRAMINICOLA
Yenesew, Abiy,Ogur, J. A.,Duddeck, H.
, p. 1442 - 1444 (1993)
From the subterranean stem of Aloe graminicola, a new pre-anthraquinone named prechrysophanol was isolated.Chrysophanol, helminthosporin, (R)-aloesaponol II, aloesaponarin I, aloesaponarin II and laccaic acid D methyl ester were also identified.
Synthetic Studies of the Rubellin Natural Products: Development of a Stereoselective Strategy and Total Synthesis of (+)-Rubellin C
Gartman, Jackson A.,Tambar, Uttam K.
, p. 11237 - 11262 (2021/08/16)
This manuscript describes our studies of the class of natural products known as the rubellins, culminating in the total synthesis of (+)-rubellin C. These anthraquinone-based natural products contain a variety of stereochemical and architectural motifs, including a 6-5-6-fused ring system, 5 stereogenic centers, and a central quaternary center. Herein, we report our development of a strategy to target the stereochemically dense core and anthraquinone nucleus, including approaches such as a bifunctional allylboron and vinyl triflate reagent, an anthraquinone benzylic metalation strategy, and a late-stage anthraquinone introduction strategy. Our studies culminate in a successful route to highly functionalized anthraquinone-based natural product scaffolds and a stereoselective total synthesis of (+)-rubellin C. These strategies and outcomes will aid in synthetic planning toward anthraquinone-based natural products of high interest.
Promiscuity of an unrelated anthrol reductase ofTalaromyces islandicusWF-38-12
Singh, Shailesh Kumar,Rajput, Anshul,De, Arijit,Chakraborti, Tapati,Husain, Syed Masood
, p. 474 - 478 (2021/02/09)
An anthrol reductase ofTalaromyces islandicusWF-38-12 (ARti-2) from an unrelated biosynthetic gene cluster (BGC) has been identified and characterized. It catalyses the NADPH-dependent reduction of anthrols (hydroanthraquinones), estrone and a naphthol with high stereo- and regioselectivity. The role of ARti-2, theCRG89872.1gene of the same BGC and non-enzymatic oxidation in the biosynthesis of (?)-flavoskyrin has been proposed.
Synthesis of (-)-Flavoskyrins by Catalyst-Free Oxidation of (R)-Configured Dihydroanthracenones in Aqueous Media and Its (Bio)synthetic Implications
Mondal, Amit,De, Arijit,Husain, Syed Masood
supporting information, p. 8511 - 8515 (2020/11/12)
A catalyst-free method for the synthesis of dimeric (-)-flavoskyrins has been developed. It involves the autoxidation of chemoenzymatically synthesized (R)-configured dihydroanthracenones in the presence of molecular oxygen in buffer of pH 6.0 followed by spontaneous [4 + 2] cycloaddition in stereocontrolled exo-anti fashion to form (-)-flavoskyrins. The method is applied to obtain several homo- A s well as heterodimerized flavoskyrins (nine examples) in 27-72% yield and implies the involvement of a similar pathway in the (bio)synthesis of modified bisanthraquinones and their analogues.
