Aloe-emodin structure

One hydroxyl is missing, and a new hydroxyl has been incorporated adjacent to the methyl. Without any evidence for the sequence of such reactions, the structure of intermediate 2 shows the result of three aldol condensations and reduction of a carbonyl. A dehydration reaction, two oxidations, and a decarboxylation are necessary to attain the islandicin structure. In chrysophanol, aloe-emodin, and rhein, the same oxygen function is lost by reduction as in islandicin, and decarboxylation also occurs. The three compounds... 

Cahn Simon sen. J. Chetn. Soc. 1932, 2573 Rosen thaler. Arch. Pharm. 270, 214 (1932) Miihlc-mann Pharm. Acta Helv. 27, 17 (1952) Bohme Bertram. Arch. Pharmr 288, 510 (1955). The molecule is built from aloe-emodin, q.v., and from glucose. Structure Hay. 

Barbaloin was first isolated in 1851, but an acceptable structure was not proposed until 1952, when Miihlemann showed that condensation of aloe-emodin anthrone Ql,8-dihydroxy-3-(hydroxymethyl)anthrone, 7, R = CH2OH] with tetra-O-acetyl-a-D-glucopyranosyl bromide in acetone in... 

Isobarbaloin appears to be an isomer of barbaloin, and degradative experiments give the same results as with barbaloin thus, Ldger - has shown that, on prolonged, acid treatment, isobarbaloin gives aloe-emodin and D-arabinose. It yields aloe-emodin anthrone on treatment with aqueous borax, and consumes 2 moles of periodic acid per mole. The ultraviolet spectrum of isobarbaloin is identical with that of barbaloin, showing that it, too, has an anthrone structure. The infrared spectrum of isobarbaloin shows only minor differences from that of barbaloin. From these data, it seems likely that isobarbaloin and barbaloin differ only in their stereochemistry. 

Four structurally-related anthraquinones - rhein, 1,8-dihydroxyanlhraquinone, etnodin (3-methyl-l,6,8-trihydroxyanlhraquinone) and aloe-emodin were also tested for activity against poliovirus type 3 (Semple et al. 2001). None of the four compounds was as active as chrysophanic add against the virus. The results suggested that two hydrophobic positions on the chrysophanic acid molecule (C-6 and the methyl group attached to C-3) were important for the compound s activity against poliovirus (Semple et al. 2001). 

Miller,. 4Joe vera Linne) Or Cape Aloe (,Aloe ferox Miller and hybrids), family Litiaeeae. Habit. Curasao in Dutch West Indies Cape, in Southern Africa. Constii. Curasao IS-25% a loin (curagaloin), Cape 4.5-9% aloin (cap-alojn) all the aloes, moreover, contain resin, emodin and volatile oil. Aloe yields not less than 50% of water-sol extractive. Structure Of aloerestn A, a major constituent of Cape Aloe P. Gramatica et al, Tetrahedron Letters 23, 2423 (1932). Review Chem. Week. 78(1). 44 (Jan. 7. 1956). 

Re-examination i of Natal aloes gave only the product corresponding to Lager s homonataloin. It had m. p. 202-204°, [aln —111-5° (ethanol), and was shown to have the formula C22H24O9 when rigorously dried. Oxidation with aqueous ferric chloride gave D-arabinose and nataloe-emodin monomethyl ether, which was shown to have the structure (15). 

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