Evaluation of the Toxicity and Anthelminthic Effect of Methanol Extract of Duranta Erecta Fruits

Abstract

The chemotherapy of gastrointestinal helminthosis relies mainly on the use of anthelminthics. However, concerns over drug resistance have encouraged the search for new drug leads. This project report focused on evaluating the toxicity and anthelminthic effect produced in vitro and in vivo by the methanol extract of Duranta erecta fruits. From the study, the plant extract was found to contain several chemical components including flavonoids, tannins, polyuronides, saponins, glycosides and terpenes. Acute toxicity evaluation of the plant extract showed that the extract had an LD50 greater than 5000mg/kg BW and therefore was not acutely toxic for oral use. The in vitro assay showed that the plant extract had a poor anthelminthic effect (LC50 Extract= 0.796mg/ml) when compared with Albedazole, a standard anthelminthic (LC50 Albendazole= 0.193µg/ml). Thirty (30) male albino mice randomly distributed into six experimental groups of five animals each were used for the in vivo experiment. Twenty-five mice were infected with the murine nematode Heligmosomoides bakeri and constituted the Infected Groups (A-E) while five mice were uninfected with the parasite and served as Uninfected Control Group (F) for the experiment. Graded ascending doses (250mg/kg BW, 500mg/kg BW and 1000mg/kg BW) of the plant extract and Albendazole (25mg/kg BW) were orally administered to the mice in the infected groups respectively. Corprological and haematological parameters including Faecal Egg Counts (FEC), Packed Cell Volume (PCV), Haemoglobin Concentration (Hb), Total Red Blood Cell Counts (RBC), Total White Blood Cell Counts (WBC) were evaluated and recorded during the study period. The Body Weight (BW) and Red blood cell indices including Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH) and Mean Corpuscular Haemoglobin Concentration (MCHC) were also estimated and recorded. Twenty-eight (28) days post infection, the infected mice were humanely sacrificed and the Post Mortem Adult Worm Burdens (WB) were estimated and recorded. The results showed that the plant extract was unable to eliminate faecal egg counts or adult worms in the gastrointestinal tract of infected animals even at the high doses used, reflected by increasing FEC in treated mice throughout the study. This is in contrast to the anthelminthic effect produced by Albendazole which significantly (p<0.05) reduced faecal egg counts and worm burdens by 71% and 92% respectively in treated mice. There was a significant (p<0.05) decline in all erythrocytic parameters (PCV, HB, RBC) in all infected groups, suggestive of anaemia. Treatment with the plant extract, regardless of the dose, was unable to reverse the effect of parasite infection on erythrocytic parameters. However, treatment with Albendazole positively reversed the anemia, restoring the mice to pre-infection values by the end of the experiment. The results showed a significant (p<0.05) increase in White blood cell counts following infection with the parasite. Treatment with the plant extract and Albendazole significantly (p<0.05) reduced the WBC counts to pre-infection values in almost all treatment groups. There were no significant (p<0.05) decreases in the body weights of the mice post infection and post treatment with the plant extracts. This is in contrast to the decrease in body weight observed in mice in the Untreated Control group. As a result of the poor anthelminthic effects recorded in the study, it was therefore recommended that the methanol extract of Duranta erecta fruits be explored for its other useful effects rather than as an anthelminthic.