Abstract:
Dichapetalum crassifolium Chodat (Dichapetalaceae) is widely distributed in Africa, Tropical Asia and Latin
America. As part of our quest for potential bioactive lead compounds for various neglected tropical diseases, we
report the anti-schistosomal potential of the crude extracts and chemical constituents of the stems and roots of
Dichapetalum crassifolium. Column chromatography of extracts of the stems and roots led to the isolation and
identification of three oleanane-type triterpenoids, friedelan-3β-ol (1), friedelan-3-one (2), and maslinic acid (3);
the ursane-type tritepenoid, pomolic acid (4) and the dammarane-type tetracyclic triterpenoids, dichapetalin A
(5) and dichapetalin M (6). Dichapetalin A was isolated from only the roots. Isolated compounds were identified
by comparison of their physico-chemical and spectral data with published data. The highest in vitro antischistosomal activity (IC50) of the crude extracts against clinical isolates of Schistosoma haematobium (Bilharz
1852) was 248.6 μg/ml for the ethyl acetate extract of the root while dichapetalin A gave the highest activity at
151.1 μg/ml among the compounds compared with the 15.5 μg/ml for the standard drug, praziquantel. The rest of
the compounds showed activities in the order 177.9, 191.0, and 378.1 μg/ml respectively for mixture of
β-sitosterol/stigmasterol, dichapetalin M and friedelan-3-one. The least active extract was the methanol extract of
the stem (893.7 μg/ml). The constituents of D. crassifolium showed activity against the S. haematobium that are
below praziquantel. It is envisaged that the presence of multiple layers and the minute sizes of pores in the egg
shells, may preclude penetration of eggs by the compounds
