71013-35-9

Chemical examination of the methanolic extract of the roots of Cassia pudibunda led to isolation of the new rubrofusarin-6-O-beta-D-glucopyranoside, quinquangulin-6-O-beta- D-apiofuranosyl-(1----6)-O-beta-D-glucopyranoside, quinquangulin-6-O-beta-D-glucopyranoside and chrysophanol dimethyl ether. Moreover the known chrysophanol, physcion, cis-3,3',5,5'-tetrahydroxy-4-methoxystilbene, trans-3,3',5,5' -tetrahydroxy-4-methoxystilbene, and cassiaside B were identified. The antimicrobial activity of some of these compounds is also reported.

Hairy root cultures of three Cassia plants, Cassia torosa, C. occidentalis and C. obtusifolia were induced by infection with Agrobacterium rhizogenes and were established to investigate their production and biosynthesis of phenolic pigments of polyketide origin. The hairy root cultures produced pigments similar to those of the mother plants, however, the contents of each pigment was varied by growth conditions. Incorporation experiments using stable isotopes in C. torosa hairy root cultures revealed the high biosynthetic activity of germichrysone.

Fifty-one new C-methyl-modified derivatives of the anthraquinones chrysophanol and emodin or their various methyl ethers were prepared for structure-activity relationship studies of anticancer activity against mouse leukemia L1210 and human leukemia HL-60 cells. Representative compounds were spectrophotometrically studied for their capacity to interact with natural and denatured DNA. In general, those anthraquinones bearing an amino function interact with DNA. 1,8-Dimethoxyanthraquinones are incapable of intercalating into DNA. 1- or 8-Monohydroxymonomethoxyanthraquinones, however, interact with DNA to some extent. No straightforward correlation is apparent between the DNA-affinity data of the compounds studied spectrophotometrically and their cytotoxic effects. Cytotoxic potencies of these compounds on cell growth inhibition during a 72-h period are inversely correlated to their potencies when inhibiting [3H]TdR incorporation into DNA during the initial 30 min of exposure. Surprisingly, some compounds that showed more cytotoxicity did not inhibit initial TdR incorporation (0-30 min), while some others that strongly inhibited TdR incorporation initially did not exhibit cytotoxicity in 72 h. The results suggest that the cytotoxicity produced by these compounds is time dependent and is not a direct result of initial inhibition of DNA replication.

The invention relates to a synthetic process of rhein. The synthetic process comprises the steps of: adopting 2,3-dimethyl phenol as a raw material, performing methylation and oxidation to obtain 3-methoxy phthalic acid, performing dehydration by using acetic anhydride to obtain acid anhydride, then performing a Friedel-Crafts reaction between the obtained acid anhydride and excess methyl anisoleunder the action of aluminum trichloride to obtain the product, and then conducting cyclization by using sulfuric acid to obtain an intermediate chrysophanol, performing acetylation on the obtained chrysophanol, performing oxidation to obtain diacerein, and finally carrying out deacetylation to synthesize rhein.

The invention relates to a total synthesis process of rhein. The process includes: adopting methoxy phthalic anhydride and a Grignard reaction liquid as the raw materials, and carrying out condensation, dehydration cyclization, methoxylation, oxidation and demethylation reaction so as to obtain rhein.

Nepodin and chrysophanol, isolated from Rumex nepalensis roots, showed significant cyclooxygenase (COX) inhibitory activity. To further optimize these lead molecules and study structure activity relationship (SAR), eighteen derivatives of nepodin and nine

The efficient total synthesis of (-)-balanol, a potent inhibitor of the protein kinase C, is described (-)-Balanol consists of a chiral hexahydroazepine-containing fragment and a benzophenone fragment, both of which were prepared via novel synthetic routes. The hxahydroazepine fragment was prepared in racemic form through either Bu3SnH- or SmI2-promoted radical cyclization of oxime ethers 2ab intramolecularly connected with the formyl group. SmI2-promoted radical cyclization of 2b was found to be particularly successful in the selective synthesis of the seven-membered trans-amino alcohol 8b. Preparation of the enantiomerically pure hexahydroazepine-containing fragment was achieved through the enantioselective enzymatic acetylation of racemic alcohol 9, employing the immobilized lipase from Pseudomonas sp. The benzophenone fragment was prepared in short steps through a biomimetic oxidative anthraquinone ring cleavage starting from commercially available natural chrysophanic acid 15c. This reaction proceeded via [4 + 2]-cycloaddition of single of oxygen to anthracene derivative 17c, followed by Baeyer-Villiger-type rearrangement of the resulting hydroperoxide to afford the benzophenone derivatives 22 and 23.

The total synthesis of (-)-balanol, a potent protein kinase C inhibitor, is described. The synthesis includes a radical cyclization approach to the hexahydroazepine-containing fragment and a biomimetic route to the benzophenone fragment.

A general synthesis of anthraquinones which depends on the displacement of the methoxy group from an o-methoxyaryldihydro-oxazole by a methoxy substituted benzylmagnesium chloride, generated by using a magnesium-anthracene complex, has been developed.The masked benzylbenzoic acids which result from these reactions are deprotected and then ring-closed to anthrones which on oxidation yield anthraquinones.In this way, the followeing naturally occurring anthraquinones (or derivatives thereof have been synthesized): chrysophanol (9), islandicin (19), digitopurpone (21), tri-O-methylemodin (26), and di-O-methylsoranjidiol (29).

Methoxy substituted benzyl magnesium chlorides formed by the use of a magnesium anthracene complex smoothly displace the ortho-methoxy group from (o-methoxyaryl)dihydro-oxazoles (oxazolines); the resultant masked o-benzylbenzoic acids are easily converted into anthraquinones.

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A variety of substituted 9,10-antraquinones with acetates and trifluoroacetates leaving groups at the 2-methyl position were synthesized from 2-methyl-9,10-antraquinones containing 0-2 methoxy substituents.Cyclic voltammograms of the acetates in DMF containing LiClO4 as supporting electrolyte exhibited two reduction waves, the first resulting from the formation of Li(1+) ion pairs of their radical anions and the second from Li(1+) ion pairs of their dianions.Constant potential reduction of the acetates to their dianions followed by air oxidation gave high yields (78-88percent) of their reductive cleavage products, the 2-methyl-9,10-anthraquinones.In contrast, reduction of the acetates to their radical anions led to high yields of their alcohols (the 2-(hydroxymethyl)-9,10-anthraquinones) as a result of saponification.Reduction of the trifluoroacetates in DMF/LiClO4 produced comparable yields of their corresponding reductive cleavage products and alcohols via ion pairs of their radical anions or dianions.

α,β- and β,γ-unsaturated esters can be converted by strong base and chlorotrimethylsilane to the corresponding mixed vinylketene acetals which are shown to be particularly useful and generally applicable reagents for the regiospecific annulation of halogenoquinones.The reaction proceeds readily with a variety of substrates including benzoquinones.