**3.8** *Rauwolfia vomitoria* **Afzel. (Apocynaceae)**

[Refer to Section 2.13 for plant description].

The root and stem bark of *Rauwolfia vomitoria* were evaluated for schistosomicidal effect on two different parasitic stages of *Schistosoma mansoni* i.e. cercariae and adult worms [84].

The ethanolic extract of the root and stem bark were both found to be active against the cercariae and adult worms. At a concentration range of 62.5–1000 g/ mL the stem bark extract exhibited significant anti-cercarial activity (*p* < 0.05) with an LC50 of 207.4 and 61.18 g/mL after 1 and 2 h of exposure respectively. At the highest concentration (1000 g/mL), there was 100% mortality of cercariae within 90 min of exposure. The roots were less active than the stem bark showing activity at a higher concentration range of 250–1000 g/mL. The schistomicidal activity of the stem bark and roots were further determined against adult worms. All adult worms exposed to the concentrations range of 250–1000 g/mL for both plant parts died within 120 h of incubation [84].

## **3.9** *Vernonia amygdalina* **Del. (Asteraceae)**

[Refer to Section 2.15 for plant description].

In a previous study, the evaluation of the cercaricidal and schistosomicidal activities of the methanol extract of the leaves of *V. amygdalina* revealed significant potency response. At 250 μg/mL, the extract exhibited cercaricidal activity with an IC50 of 35.84 μg/mL within 180 min of exposure. Further, the extract was found to reduce the viability of adult schistosome worms *in vitro* at 250–1000 μg/mL.

The ability of the leaf extract (500 mg/kg *p.o.*) to reduce the worm recovery and worm burden in *S. mansoni* infected mice was further investigated in an *in vivo* study. After a two-week period of treatment, the mean number of worms recovered from *V. amygdalina-*treated mice was 12.00 ± 1.549, indicating 48.9%, worm burden which was significantly lower than that of the untreated group (40.20 ± 3.072). While there was significant increase in the weight of the liver and spleen of the untreated infected mice with marked formation of granuloma, *V. amygdalina*-treat infected mice showed no increase in liver or spleen size and had few granulomas which were smaller in diameter with relatively less severe inflammatory cell infiltration compared [73].
