The crude root-peel extract of Flemingia vestita, its active principle genistein and
the reference flukicide oxyclozanide were tested against Fasciolopsis buski, the giant
intestinal trematode. The amino acid composition of F. buski was demonstrated using
HPLC and it was observed that the free amino acid (FAA) pool of the control worm consisted
of aspartate, threonine, serine, glutamic acid, glutamine, proline, glycine, alanine,
valine, methionine, isoleucine, leucine, tyrosine, lysine, histidine, arginine, phosphoserine,
taurine, citrulline, ornithine, beta-alanine, and gamma-amino butyric acid (GABA).
Of the amino acids detected valine was found to be the maximum in quantitative analysis.
In qualitative analysis the FAA pool of the parasites under various treatments remained
same as that of the control; however, quantitatively the level of various FAAs in
the parasite was significantly affected. The treated parasites showed a marked decrease
in the levels of arginine, ornithine, tyrosine, leucine, isoleucine, valine, alanine,
glycine, proline, serine, threonine, and taurine following treatment with 20 mg/ml
of crude peel extract, 0.5 mg/ml of genistein and 20 mg/ml of the reference drug,
though an increase in the levels of glutamic acid, glutamine, phosphoserine, citrulline
and GABA was noticeable. Enhanced levels of GABA and citrulline under the influence
of genistein may be implicated in alterations of nitric oxide release and consequent
neurological change (e.g. paralysis) in the parasite. Ammonia in the tissue homogenate
as well as in the incubation medium showed a quantitative increase compared to the
controls after treatment with the various test materials. The ammonia level increased
by 40.7%, 66.4% and 18.16% in treatments with F. vestita, genistein and oxyclozanide,
respectively, at the mentioned dosages. The changes in the levels of the amino acids
and nitrogen components post treatment suggest that the amino acid metabolism in the
parasite may have been altered under the influence of the test materials.