Antioxidant and in-vitro anthelminthic potentials of methanol extracts of barks and leaves of Voacanga africana and Rauwolfia vomitoria

Voacanga africana (Stapf) and Rauwolfia vomitoria (Afzel) (Apocynaceae) are traditional plants widely used in folkloric medicine. Methanol extracts of V. africana bark (VAB) and leaves (VAL), and R. vomitoria bark (RVB) and leaves (RVL) were evaluated for antioxidant and anthelmintic potentials. The antioxidant properties of the extracts were determined by the DPPH free radical scavenging method using ascorbic acid as reference antioxidant. The IC50 values were then determined. Four concentrations (20, 30, 40 and 50 mg/mL) of extracts were evaluated for in-vitro anthelmintic activity by determining the effects of the extracts on the paralytic and death time of Pheretima posthuma using albendazole (ABZ) (10 mg/mL) as reference standard. Results reveal that, all the extracts exhibited some level of antioxidant activity with IC50 values of 187, 43, 610 and 967 µg/mL for VAL, RVB, VAB and RVL, respectively. VAB and RVB demonstrated significant anthelmintic activity. RVB at a concentration of 50 mg/mL had a paralytic time of 11.17 ± 0.088 min (p < 0.001) with reference to ABZ. It also demonstrated a concentration dependent reduction in death time of the worms at all concentrations tested. VAB demonstrated a concentration dependent effect on the worms with decreasing paralytic and death times upon an increase in extract concentration. It also showed significant paralytic and death times (p < 0.001) at concentrations of 30, 40 and 50 mg/mL with reference to albendazole.