1.8- dihydroxy-anthracene derivatives

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. 

PET is the key feature of many other photo-oxidations involving aromatic substrates. It has been shown, for example, that pyrene and anthracene which are covalently attached to silica, gold or indium-doped tin oxide (ITO), undergo a photo-oxidation forming dihydroxy/dione derivatives. The reaction involves 02, formed by ET between excited pyrene, or anthracene, and O2, and it is suggested that the implications of such a photodegradation need to be considered when polycyclic aromatic hydrocarbons (PAHs) are used as spectroscopic probes in surface adlayers. The redox photosensitized amination of 1,2-benzo-1,3-cycloalkadienes, arylcyclopropanes, and quadricyclane with ammonia and primary amines, using 1,2,4-triphenylbenzene (1,2,4-TPB) or 2,2 -methylenedioxy-1,1 -binaphthalene in the presence of m- or p-dicyano-benzene (DCB), has been described (Scheme 51). The process involves the formation of the radical cation of 1,2,4-TPB, for example, by PET to the DCB, followed by hole transfer from the radical cation to the substrate, the latter... 

These findings indicate that PGH synthase in the presence of arachidonate can catalyze the terminal activation step in BP carcinogenesis and that the reaction may be general for dihydrodiol metabolites of polycyclic hydrocarbons. Guthrie et. al. have shown that PGH synthase catalyzes the activation of chrysene and benzanthracene dihydrodiols to potent mutagens (33). As in the case with BP, only the dihydrodiol that is a precursor to bay region diol epoxides is activated. We have recently shown that 3,4-dihydroxy-3,4-dihydro-benzo(a)anthracene is oxidized by PGH synthase to tetrahydrotetraols derived from the anti-diol epoxide (Equation 4) (34). 

The major isolated mammalian liver metabolite of benz[a]anthracene, the (— )-8,9-dihydroxy-8,9-dihydroderivative, has an 81 ,91 configuration and is enzymatically derived from (+)-(8/ ,9S)-benz[a] anthracene 8,9-oxide. It may be converted to trans-(%R,9S )-dihydroxy-( 10S, 11R )-epoxy-8,9,10,11 -tetrahydrobenz [a] anthracene prior to being covalently bonded to cellular nucleic acids. 

Fuchs J, MIcoch J, Oesch F, et al. 1993b. Characterization of highly polar DNA adducts derived from dibenz[a,h]anthracene (DBA), 3,4-dihydroxy-3.4-dihydroxy-3.4-dihydro-DBA. and 3,4.10,11-tetrahydroxy-3,4,10,11-tetrahydro-DBA. Toxicol Ind Health 9(3) 503-509. 

Benz(a)anthracene-3,4-diol-1,2-epoxide (BADE) is a potent carcinogen [74-76] that metabolizes stereochemically and results in enantioselec-tive toxicities. The tumorigenic activities of benz(a)anthracene (BA), the (-1-)- and (—)-enantiomers of fra s-3,4-dihydroxy-3,4-dihydrobenz(a)anth-racene (BA-3,4-dihydrodiol) and the racemic diastereomers of the BA-3,4-diol-1,2-epoxides - that is, either or both of the diastereomeric 1,2-epoxides derived from BA-3,4-dihydrodiol, in which the epoxide oxygen is cis-(diol epoxide-1) or trans- (diol epoxide-2) to the benzylic 4-hydroxyl group-were examined in newborn Swiss-Webster mice by Wislocki etal. [77]. The mice were administered a total dose of 280 nmoles of compound, in divided doses consisting of 40 nmoles within 24 h of birth, 80 nmoles at 8 days of age, and 160 nmoles at 15 days of age. The experiment was terminated when the animals were 26 weeks of age. BA-3,4-diol-l,2-epoxide-2 was the most potent compound tested. All of... 

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