Abstract:
Haemonchus contortus is parasitic helminths of the sheep capable of causing acute
and high mortality. Control of gastrointestinal helminths infection in livestock relies
mainly on the use of synthetic anthelmintics. However, these broad spectrum drugs
are expensive, inaccessible or inadequately available to farmers in remote poor
settings. The problem with synthetic anthelmintics is further compounded by
development of anthelmintic resistance. The present study investigated the
phytochemistry and anthelmintic activity of aqueous and solvent extracts (hexane,
acetone and methanol) of root bark of Entada leptostachya (Harms) and stem bark of
Rapanea rhododendroides (L.) Mez. To achieve the objectives, brine shrimp lethality
test using brine shrimp (Artemia salina) larvae was used to determine the toxicity of
the aqueous and organic extracts with modifications. The worm motility inhibition
assay was utilized in order to investigate the direct effects of the plant extracts on the
survival of adult worms of H. contortus. Four concentrations (12.5, 25, 50 and100
mg/ml) of each extract were studied in the bioassay. The Extracts of E. leptostachya
exhibited higher toxicity and anthelmintic activity compared to those of R.
rhododendroides. Methanolic extracts for both E. leptostachya and R.
rhododendroides were more potent against H. contortus adult worms exhibiting 70
and 50 % mortality respectively. Hexane extracts of both E. leptostachya (20 %) and
R. rhododendroides (10 %) were the least potent.
Methanol and aqueous extracts of E. leptostachya showed brine shrimp lethality of
1.1 and 2.7 g/ml, respectively. E. leptostachya and R. rhododendroides methanolic
extracts have significant anthelmintic activity (70 and 50 %) and have potential for
development of new anthelmintic drugs. Saponins, tannins and flavonoids were some
of the phytochemicals identified in the extracts. Oleanolic acid was isolated from E.
leptostachya methanol extract using chromatographic techniques and characterized
using spectroscopic techniques (IR, UV and MS). The data revealed the dosedependent anthelmintic activity in the in vitro studies. There were notable
anthelmintic activities by all extracts. Methanol extract of Entada leptostachya
showed the highest anthelmintic activity and therefore it can be used as a lead
compound to prepare anthelmintic drugs
