4. Chemotaxonomic significanceThe d

4. Chemotaxonomic significanceThe dried leaves, fronds, aerial parts and rhizome of Pteris cretica contain pterosins and ent-kauranoids, which are thechemical markers of the family Pteridaceae. Pterosin B (23) derived from the carcinogenic compound 1 and since 23 has beendetected in all species of Pteris investigated, it would suggest that 1 must be present in all species of Pteris. If this is the casethen all samples of Pteris used medicinally should be processed so that the end product is free of any carcinogenic compounds.The two flavonoids (8 and 27) were isolated from the leaves of P. cretica in high amount during the present study. Interestingly, our previous phytochemical investigation on one species of Pteris (P. multifida) demonstrated the presence ofpterosins, caffeate and/or coumarate derivatives of quinic acid, flavonoids and sucrose in the plant (Harinantenaina et al.,2008). So far, P. multifida is the only Pteris species which has been proved to contain a large amount of quinic acid derivatives.The phytochemical investigation of six species of Pteris has been carried out and the results are summarized in Table 2. Theent-kauranoids found in Pteris are C-2 and/or C-6, and/or C-15, and/or C-16 and/or C-17 and/or C-18 hydroxylated. Mainlyglucopyranosyl and/or allopyranosyl are the sugar moieties attached at the C-2 and/or C-6 hydroxyl group of ent-kauranoidsof P. cretica. Recently Ge et al. (2008) have isolated a tetrahydroxylated (at C-2, C-14, C-15, and C-18) ent-kaurene from P.multifida. Although C-15 hydroxylated kaurene has been isolated from P. cretica, this is the first report on the isolation of anent-kaurene with a b-oriented C-15-hydroxyl group from Pteris species.