Ovicidal and larvicidal activity of Cassia alata leaf acetone extract and fractions on Haemonchus contortus: In vitro studies

Abstract

Context: The failure of modern anthelmintics to control nematode parasites of sheep and goats is a reality on many farms in the tropical/subtropical regions of the world. This necessitates chemotherapeutic control alternatives and plant secondary metabolite with activity is one of those potential solutions.

Objective: This study was design to evaluate the efficacy of solvent: solvent fractions of Cassia alata Gelenggang Besar (Leguminosae) leaf acetone extract against Heamonchus contortus Rudolphi (Trichostrongylidae).

Materials and methods: C. alata leaf was extracted with 70% acetone and fractions were obtained by solvent: solvent group separation procedures. The acetone extract and the fractions were tested by egg hatch assay (EHA) and larval development and viability assay to assess relative bioactivity against H. contortus eggs and larvae.

Results: The extracts inhibited egg hatchability and killed infective larvae of H. contortus in a concentration-dependent manner. The best-fit LC₅₀ values were 0.562, 0.243, 0.490, 0.314, and 0.119 mg/mL for the acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against nematode eggs. The best-fit LC₅₀ values were 0.191, 0.505, 1.444, 0.306, and 0.040 mg/mL for acetone extract, chloroform, hexane, butanol and 35% water in methanol fractions, respectively, when tested against larvae. The 35% water in methanol fraction was the most active against the larvae and eggs of H. contortus demonstrating the lowest LC₅₀ values

Discussion and conclusion: This study demonstrates that the leaf extracts of C. alata have anthelmintic activity; therefore it could find application in the control of helminths in livestock.

Keywords::

• Cassia alata
• egg hatch assay
• Haemonchus contortus
• larval development assay
• solvent:solvent fractions

Acknowledgement

The authors wish to express gratitude to the National Research Foundation South Africa for providing the funds for this study. Onderstepoort Veterinary research Institute, South Africa and Dr A.F Vatta are thanked for the provision of facility and technical assistance. The authors would like to thank Dr. F. van Schalkwyk, Biozetica Agri-source (Pty) Ltd., South Africa for supplying the H. contortus larvae.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.