Emodin structure

Compounds 1-5 are anthraquinones. Compounds 1 and 4 are structurally similar to emodin. Structures 3 and 5 are glucoside derivatives of 2 and 4. 

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... 

It is now appreciated that the assembly of the anthraquinone skeleton (and related polycyclic structures) is achieved in a step-wise sequence. After the polyketide chain is folded, the ring at the centre of the fold is formed first, followed in turn by the next two rings. The pathway outlined for the biosynthesis of endocrocin and emodin is shown in Figure 3.30. Mechanistically, there is little difference between this and... 

Structure of emodin with the substituted group noted (R ). 

Unlike the emodin analogues, rhodocladonic acid analogues exhibited different phytotoxic effects for similar substitutions. There was no dose-dependent bleaching associated with any of these compounds. In addition, there was no selectivity in phytotoxic activity between monocots and dicots. Despite the lack of bleaching, structure-activity relationships would suggest the potential for PS II inhibition. Both series of Rhodocladonic acid analogues, those with terminal -CH3 and those with a terminal - OH (Fig. 1.11 A B, respectively), caused an increase in PSII activity with regard to controls. 

Fig. 18.3 SERS spectra from silver nanoparticles decorated silica beads. Curve 1 silica beads only. Curve 2 silica beads decorated by silver nanoparticles. Curve 3 silver nanoparticles decorated silica beads with probe molecules. Left inset. SEM image of silver nanoparticles decorated silica bead. Right inset molecular structure of emodin...

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). 

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. 

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). 

During their work, Kogl and Postowsky 432) isolated emodin (288) together with a second pigment which they named dermocybin. Structural studies by Birkinshaw 102) established dermocybin as either the 6- or 7-O-methyl ether of l,5,6,7,8-pentahydroxy-3-methyl-9,10-anthraquinone ( nordermocybin ) which was synthesised, thus establishing the oxygenation pattern in dermocybin itself. 

Cortinarius elegantior contains among its neutral pigments a pale yellow compound, cortinarin, to which the unique dimeric structure (381) has been assigned from spectroscopic data (Table 32) and from its cleavage with dilute aqueous sodium hydroxide into physcion (290) and emodin-6,8-di-0-methyl ether (292) (387, 515, 617). 

According to Kofler [358], microsublimation is any sublimation procedure in which the sublimate is caught on a smooth plate-usually a small slide-for purposes of microscopic examination (melting point, refraction, crystal structure). Many substances can be directly sublimed in crystalline form from drugs containing them, e. g., caffeine coumarin umbelliferone benzoic, ferulic, salicylic and cinnamic acids emodin etc. 

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). 

The benzophenone 26 may arise from the structurally related anthraquinones endocrocin (17) or emodin (19), by an oxidative cleavage of the C(10)-C(10a) bond. However, this assumption appeared tenuous, as metabolism of anthraquinones had not previously been observed. Therefore,... 

---