Toxicological, phytochemical and anthelminthic properties of rich plant extracts on Clarias gariepinus

Abstract

This research aims to study the acute and sub-chronic effects of the plant extracts on fingerlings and juveniles of Clarias gariepinus as they are used as potential drugs against the parasites. Quantitative and qualitative analyses of the extracts of seven plants; Piper guineense, Aframomum melegueta, Moringa oleifera, Gongronema latifolium, Azadirachta indica, Garcinia kola and Xylopia aethiopica and their potencies against C. gariepinus, helminth parasites and microorganisms were investigated. The study revealed the presence of alkaloids, flavonoids, saponins, tannins, phlobatannins, cardiac glycosides, anthraquinones and terpenoids. A 96 h acute toxicity of the extracts on fish juveniles was determined. Parasites were recovered from 60 samples of C. gariepinus obtained from Lekki lagoon. The low observed effect concentration of the extracts was also tested against the parasites, Staphylococcus aureus, Shigella flexneri, and Pseudomonas aeruginosa using standard methods. Average Survival Time (AST) for the parasites was estimated. Relative Toxicity Factors (RTFs) of the extracts at Low Observed Effect Concentration (LOEC) – 96 h LC₅ mg/l occurred in this trend; X. aethiopica (RTF, 1.0) < G. latifolium (RTF, 2.0) < A. indica (RTF, 2.0) < G. kola (RTF, 2.0) < M. oleifera (RTF, 2.0) < P. guineense (RTF, 5.0) < A. melegueta (RTF, 8.0). Parasites recovered from C. gariepinus include cestode (Wenyonia minuta), and nematode (Procamallanus longus). It was observed that only A. melegueta and A. indica slightly inhibited the growth of S. flexneri and P. aeruginosa. The potency of the extracts and Average Survival Time (AST) of intestinal parasites occurred in this trend; X. aethiopica < G. latifolium < A. indica < G. kola < M. oleifera < P. guineense < A. melegueta. A 95 h LC_2.5 of A. melegueta (32 mg/l) being the most toxic extract was used to carry out histopathology on the fish gills. The gills exposed showed some pathological effects. This study confirms that the extracts of the seven plants exert anthelminthic property, but choice of extract and its toxicological risk on the fish host is highly essential.