1 8 Dihydroxyanthraquinone Derivatives

A. rubroviolacea A. perryi

Schmidt etal., 2001

Table 3-3 Derivatives of 8-C-glucosylaloediol (aloesindiol).

Acyl group

7- Hydroxy-

7- Methoxy-

7-Glucosyl

Unsubstituted

2'-Cinnamoyl

7-O-Methylaloesindiol

A. vera

Okamura et al, 1997

2' - O -Cinnamoyl-7- O -methyl-aloesindiol A 2' - O -Cinnamoyl-7 - O -methyl-aloesindiol B

A. vera

Okamura etal., 1998

A. rubroviolacea A. perryi

Schmidt etal., 2001

Dihydroxyanthraquinone
Figure 3-4 Chrysophanol (3-methyl,1,8-dihydroxy-anthraquinone) and its derivatives.
Aloe Vera Dihydroxyanthraquinone

Figure 3.5 Derivatives of 1-methyl-3,8-dihydroxy-anthraquinone.

Laccaic acid D methyl ester Deoxyerythrolaccin

Figure 3.5 Derivatives of 1-methyl-3,8-dihydroxy-anthraquinone.

may be because anthraquinones are a minor component of leaf exudates and tend to be overlooked in analyses. Early observations, usually by paper chromatography, showed it in Cape aloes drug (A. ferox) (Awe etal, 1958; Horhammer etal, 1965) and it was then isolated from this product (Koyama etal., 1994). It was demonstrated in the leaves of A. africana Mill., A. marlothii Berger and A. pretoriensis Pole Evans (Rheede van Oudtshoorn, 1964) and also in A. elgonica Bullock (Conner etal, 1990b) and in A. arborescens Mill. (Constantinescu etal, 1969; Hirata and Suga, 1977; Kodym, 1991; Yamamoto etal, 1991). There are also records of it being found in A. vera leaves (Choi etal, 1996; Saleem etal, 1997b; Strickland etal, 2000; Pecere etal, 2000), but not in the roots of any species.

The first record of helminthosporin and isoxanthorin in aloes was in underground stems of A. saponaria (Yagi etal, 1977a). Helminthosporin was then found in the roots of 27 species (Dagne etal, 1994). The anthraquinone aglycone of the other common anthrone-C-glucoside, homonataloin, is the 8-0-methyl ether of nataloe-emodin and has been reported from A. lateritia Engl. (Rauwald and Niyonzima, 1991a), while nataloe-emodin itself was isolated from A. nyeriensis var. kedongensis (Reynolds) S. Carter leaves (Conner etal, 1987).

Aloesaponarin II, an isomer of chrysophanol, where the position of the groups on carbon atoms 1 and 3 is reversed, was reported from A. saponaria (Yagi etal, 1974) and then in the roots of 97 Aloe species (Van Wyk etal, 1995a).

It was also found in five species of Lomatophyllum (Van Wyk etal, 1995c). Its 6-hydroxy derivative, deoxyerythrolaccin was also found in A. saponaria and then in A. ferox (as Cape aloes) (Koyama etal, 1994). Aloesaponarin I and laccaic acic D methyl ester, the methyl esters of derivatives of these compounds containing a carboxyl group on carbon atom 2, were first found in A. saponaria (Yagi etal, 1974), and were subsequently observed in the roots of over 100 species (Van Wyk etal., 1995a) including some in Lomatophyllum.

Both chrysophanolanthrone and aloe-emodinanthrone occur in aloe flowers (Rauwald and Beil, 1993; Sigler and Rauwald, 1994b). The first occurs in A. bakeri Scott-Elliot, A. vaombe Decorse and Poiss., A. khamiesensis Pillans and A. dawei A.Berger and the second in A. bakeri, A. vaombe, A. ballyi Reynolds and A. dawei. It is noteworthy that no trace was found in the leaf exudates.

Tetrahydroanthracenones

The compounds in which the C-ring is reduced are typical of the subterranean stems and roots of aloes and mirror in some of their substitution patterns the leaf anthraquinones (Figure 3.6). In fact it was postulated that the conversion of aloesaponol I to aloesapon-

Math Fraction Puzzles

Aloebarbendol

Figure 3.6 Tetrahydroanthracenes.

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