481-74-3Relevant articles and documents
Eder,Hauser
, p. 321,448 (1925)
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.
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.
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.
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.
