Emodin derivatives

Both direct and indirect covariance processing was appHed to H—C HMBC data, although the HMBC was described as a long-range HSQC with decoupling [88]. As model systems, an emodin derivative 5... 

In addition to emodins, rhubarb root also contains dimeric reduced forms of emodins derived from 10,10 -bianthronyl (9-167), which are called bianthrones (dianthraquinones). They can occur as homobianthrones, such as emodin bianthrone and parietin bianthrone, or as heterobianthrones (mixed dimers), such as pahnidin A (9-168), which is bianthrone of emodin and aloe-emodin. 

Emodins with both aromatic rings hydroxylated are synthesised exclusively by the polyketide pathway as octaketides. Biosynthesis of bianthrones and other condensed emodin derivatives occurs by one-electron oxidation of anthrone derivatives (anthranols) to radicals, which are joined to form bianthrones. 

Cassia angustifolia Vahl. Fan Xie Ye (leaflet) Sennosides, aloe-emodin, dianthrone glucoside, rhein monoglucoside, rhein, kaempferin, myricyl alcohol, anthraquinone derivative.33-510 Purgative, laxative, cathartic. 

N.A. Aloin isobarbaloin, aloeresin A, B, aloesin glycone, aloesone, emodin, chrysophanic acid, 1,8-dihydroxy-anthracene derivatives, barbaloin, anthaquinone glycosides.99-100 108 109 510-511 Purgative, eupeptic, and cholagogue effect. It is a laxative and cathartic. Juice from leaves used for cuts and other skin problems. 

Aromatic natural products of polyketide origin are less prevalent in plants compared with microorganisms. The majority of the plant constituents that contain aromatic stmctures are known to arise from the shikimate pathway (see below). Unlike those derived from the shikimate pathway, aromatic products of the polyketide pathway invariably contain a meta oxygenation pattern because of their origin from the cyclization of polyketides. Phenolic compounds such as chrysophanol-anthrone (Bl), and emodin-anthrone (B2), and the anthraquinones, aloe-emodin (B3) and emodin (B4) (Fig. 2), are products of the polyketide pathway and are found to occur in some plants of the genera Cassia (Leguminosae) (21), Rhamnus (Rhamnaceae) (22), and Aloe (Liliaceae) (23). The dimer of emodin-anthrone (B2), namely hypericin, (B5) is a constituent of the antidepressant herbal supplement, St. John s wort (Hypericumperforatum, Hy-pericaceae) (24). 

Several anthranoid derivatives (notably the aglycones aloe-emodin, chrysophanol, emodin, and physicon) are genotoxic in bacterial and/or mammalian test systems... 

Various organic reagents are used for direct determination of calcium, such as murexide (ammonium purpurate) (e = 1.4-10 at 500 nm) [2,49], Metalphthalein [50], Calcein [51,52], Chrome Azurol S (in the presence of 1,10-phenanthroline) [53], Alizarin S [54], 8-hydroxyquinoline (extraction into CHCI3 in the presence of n-butylamine or butoxyethanol) [55], and Emodine (l,3,8-trihydroxy-6-methylanthraquinone) [56]. Calcium has been determined as a complex with Emodine, in the presence of Be and Mg, by the derivative spectrophotometry technique. The anionic complexes of calcium with bromo-oxine [57] or HTTA [58] have been extracted into benzene as ion associates with Rhodamine B. Calcium was also determined as a complex with o-cresolphthalein [59-63], or thymolphthalein [64]. 

Some other organic reagents have been also proposed for determination of Mg, e.g., Eriochrome Cyanine R [45], Alizarin S [46], o-cresolphthalein [47] and its derivatives [48], 1,2,7-trihydroxyanthraquinone [49], 1,8-dihydroxyanthraquinone (e = 1.2-10 at 510 nm) [50], and leuco-quinizarin [51]. Mg has been determined also with the use of emodin... 

Little is known about the biosynthetic origin of hypericin(s) they are related to the anthranoid metabolism and emodin anthrone is possibly their precursor. Synthesis in vitro of hypericin following alkaline dimerization of emodin and oxidation of its reduction derivative, emodine anthrone, has in fact been demonstrated [35,36]. 

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