Chebulagic acid

Chebulagic acid (140), Eugeniin (141), Agrimoniin, Cas-uarictin, Coriariin, Geraniin (142), Galloylgeraniin, pemagalloytgtucose,... 

Other tannins of this type (Fig. 12.6) contain modified acids such as chebulagic acid (18) andpedunculagin (19), and the brevilagins 1 (20) and 2 (21) which are normally considered ellagitannins (Haslam, 1979). When the galloyl groups are in the diaxial position, radical coupling can occur to produce compounds such as chebulinic acid (22) (Fig. 12.7). 

Yoshida, T, Fujii, R. Okuda, T. (1980). Revised structure of chebulinic acid and chebulagic acid. Chemical and Pharmaceutical Bulletin, 28, 3713-3715. 

No evidence has yet been obtained to show that dimeric products are formed by oxidative coupling of the monomeric species such as was noted in Class 2B (vide supra). However, brief comment should be made on two phenolic metabolites, isolated early in the studies of the ellagitannins chebulinic acid (91,140) and chebulagic acid (91) (Table 7.2.9). It is clear from biogenetic considerations that these are phenolic metabolites very probably derived by further oxidative ring fission of one aryl ring in a precursor such as geraniin (51). 

Chebulagic acid T. chebula yff-galloyl (/ )-hexahydroxydiphenic acid linked 3,6 chebulic acid (24) linked 2,4 to D-glucopyranose 91, 140... 

Okuda T, Fuji R, Yoshida T 1980 Revised structures of chebulinic and chebulagic acid. Chem Pharm Bull 28 3713-3715... 

Okuda T, Yoshida T, Koga T, Toh N 1982 Absolute configurations of chebulic, chebulinic and chebulagic acids. Chem Pharm Bull 30 2655-2658... 

Scheme 14. Proposed pathways of biosynthesis of chebulinic acid (56) and chebulagic acid (57) from P-penta-o-galloyl-D-glucose (11), 81). Hydrolysis of (56 and 57) to give...

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