Anthraquinone Biosynthesis

Anthraquinone Biosynthesis.—In the absence of any biosynthetic experiments to report, it is worth mentioning that a biogenetically interesting new dihydro- 

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Secondly, the deacetylated form of chitin, chitosan, does not induce phytoalexin formation in the rice system but is active in other plant culture systems [99]. Glucan elicitors induce phytoalexins in legumes (soybean, chickpea, bean, alfalfa, pea) and solanaceous sp. (potato, sweet pepper) [100]. However, anthraquinone biosynthesis was stimulated in Morinda citrifolia by both chitin and chitosan. The degree of acetylation was found to be important in inducing defense responses. During the first few days of incubation after adding elicitor,... 

Ramosvaldivia, A.C., Vanderheijden, R. and Verpoorte, R. (1997a) Elicitor-mediated induction of anthraquinone biosynthesis and regulation of isopentenyl diphosphate isomerase and famesyl diphosphate synthase activities in cell suspension cultures of Cinchona robusta How. Planta, 203, 155-61. 

DETROY, R.W., FREER, S., CIEGLER, A., Aflatoxin and anthraquinone biosynthesis by nitrosoquanidine-derived mutants of Aspergillus parasiticus. Can. J. Microbiol., 1973,19,1373-1378. 

Why the cells are capable of expressing the anthraquinone biosynthesis in in-vitro cell suspension cultures and not the alkaloid biosynthesis has still to be answered. Further studies on the genetic regulation of the secondary metabolism in Cinchona are needed to answer this question and to eventually open the way for a biotechnological production method. 

Gstraunthaler, G.J.A. The Effect of Cerulenin on Fatty Acid and Anthraquinone Biosynthesis in Vegetative Mycelia of Cortinarius orichalceus Fr. Biochim. Biophys. Acta 750, 424 (1983). 

In contrast to many other naphthoquinones (D 8.1) plumbagin is a polyketide Its formation resembles anthraquinone biosynthesis (D 3.3.5) ... 

The fact that phylloquinone and anthraquinone biosynthesis share a common biosynthetic pathway in the initial steps raises two questions how is the metabolic shift... 

One of the open questions in anthraquinone biosynthesis is the nature of the branching compound X (Fig. 4). In vitamin K2 biosynthesis 1,4-dihydroxy-2 naphthoic acid (V) is involved (vide supra). It may also be an intermediate in phylloquinone s and anthraquinone biosynthesis. Feeding experiments established that anthraquinones in Rubia, Morinda and Galium >28,2 9 derived from shikimic acid, a-ketoglutaric acid and mevalonic acid with -succinylben-zoic acid being a key intermediate. Incorpo-... 

WILSON, M.H. ZENK. 1979. Site of prenylation in anthraquinone biosynthesis in cell suspension of Galium mollugo. J. Chem. Soc., Chem. Commun., 957-959. 

Inoue, K., Y. Shiobara, H. Nayeshiro, H. Inouye, G. Wilson, and M.H. Zenk Site of Prenylation in Anthraquinone Biosynthesis in Cell Cultures of Galium mol-lugo. J. Chem. Soc. Chem. Commun. 1979, 957. 

Wilson, G., and P. Marron Growth and Anthraquinone Biosynthesis by Galium mollugo L. Cells in Batch and Chemostat Culture. J. Exp. Botany 29, 837 (1978). 

The anthraquinone biosynthesis by microorganisms is closely related to the in vivo formation of fatty acids, e.g., palmitic acid (14). One molecule of acetyl-coenzyme A (acetyl-CoA) as a starting unit condenses with seven molecules of malonyl-coenzyme A (malonyl-CoA), whereby the formed carbonyl group is reduced after each reaction step. If these reductions fail... 

It is not known if the formation of the polyketide chain and its cyclization proceed successively or as one process. The incorporation of smaller ketide units or of partly cyclized, possible intermediates of anthraquinone biosynthesis, e.g., 21 or 22, has not yet been investigated successfully. Furthermore, no information is available on the mechanism of the conformationally controlled enzymatic cyclization of the polyketide chain to give either endocrocin (17) or emodin (19) via 15, or to give the benzochromone eleutherin (20) via 16. 

Money (1963) discussed another chemical approach for oxidative cleavage, in connection with biogenetic hypotheses, which involved starting from anthrones, the intermediates in anthraquinone biosynthesis from acetate units. The anthrone might be autoxidized to the hydroperoxide (101, R = H) and then rearranged by acid catalysis to the benzophenone (103, R = H). On the basis of this speculation, it was possible to perform the oxidative cleavage for the first time by converting 10-methylanthrone hydroperoxide (101, R = CH3) in 4.5% yield into (103, R - CH3) (Franck et aL, 1967). 

This latter result contrasts somewhat with studies on anthraquinone biosynthesis in Peniclllium islandicum.The syn-14... 

This would appear to be the first detection of hicyclic intermediates in anthraquinone biosynthesis in microorganisms. 

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