Anthelmintic activity of crude and separated extract of Aloe vera (Xanthorrhoeaceae) against bovine adults parasites of Onchocerca ochengi and infected larvae of drug resistant strains of the free-living nematode Caenorhabditis elegans

Abstract

Human onchocerciasis is caused by the filarial worm. Onchocerca volvulus is a parasite that forms nodules under the skin. The aim of this work was to assess the nematicidal activities of Aloe vera on Onchocerca ochengi and Caenorahbditis elegans and to determine the phytochemical compounds. Nodules were collected from the umbilical region of infected cattle, dissected and male worms were cultured in RPMI-1640. Worms were incubated with different concentrations of A. vera extracts in RPMI-1640 and M9-buffer. Polyphenol, tannin and flavonoid contents of extract were determined by using gallic acid and rutin as standards. The anthelmintic effect of A. vera extract against O. ochengi was concentration dependent with LC₅₀ of 20.71 µg/mL and 11.75 µg/mL after 48 and 72 h respectively. A. vera extract exerted concentration dependent lethal effects (LC₅₀ = 2747 and LC₅₀ = 31,937 µg/mL) against C. elegans (Wild Type). Methanolic-methylene chloride (MeOH-CH₂Cl₂) of A. vera extract exhibited high DPPH activity with an IC₅₀ value of 15 µg/mL and 9 µg/mL for ascorbic acid. The highest activity in adult worms was observed with the MeOH (100: 0) and AcOEtMeOH fractions with LC₅₀ values of 12.82 and 15.50 µg/mL respectively. EcOEtMeOH (8:2 v/v) was more effective (LC₅₀ = 250 µg/mL) on WT of C. elegans. A. vera contains polyphenols (1015.05 and AcOEtMeOH = 893.60), flavonoids (25.35 and MeOH = 225.76) and tannins (401.37 and Hex = 788.89). A. vera showed in vitro nematicidal activity against O. ochengi and C. elegans. A. vera could be used as an alternative anthelmintic for onchocerciasis treatment.

Keywords: Aloe vera; Anthelmintic activity; Caenorahbditis elegans; Nematicidal activity; Onchocerca ochengi; Traditional healers.