The present study aims to (i) identify the therapeutic uses and traditional preparation techniques of anthelmintic phytotherapy remedies by Katangese herbalists, tradipraticians, caterers and veterinary doctors; (ii) characterize the chemical groups present in the root bark of Vitex thomasii De Wild; and (iii) evaluate its effects on Haemonchus contortus in vitro and in vivo on goats raised on pasture. An ethnomedicinal study carried out in Kamina (DR Congo) showed that 44 users of medicinal herbs to treat goats livestock essentially use 9 local herbs (including V. thomasii) to fight diseases they identify as gastro-intestinal parasitoses. The receipts, which are generally mono-species, require different traditional preparation modes (crushing, pulverization, infusion, decoction, maceration) and are always administered per os. Vitex thomasii is by far the most frequently quoted plant (65,5 %). A phytochemical screening carried out on the extracts of V. thomasii root bark (successive extractions with petroleum, dichloromethane, methanol, water) revealed the presence of terpenoids, flavonoids, tannins, saponosides, quinones and iridoids. The anthelmintic activity of aqueous and ethanol extracts of V. thomasii root bark was evaluated in vitro on eggs and third stage larvae of Haemonchus contortus, using albendazole as positive control (62.5 to 2000 µg/ml of extracts or albendazole), distilled water, supernatant of the egg suspension and ethanol as placebo, negative control and ethanol control, respectively. The ethanol and aqueous extracts were active on the third stage larvae of Haemonchus contortus (IC50 = 56.44 µg/ml and 106.7 µg/ml, respectively) and inhibited egg hatching (IC50 = 53.09 µg/ml and 88.62 µg/ml, respectively). The antiparasitic efficacy of the V. thomasii root bark powder was tested in vivo on gastrointestinal strongyles. Thirty-two goats were allocated to 4 groups (5 adults and 3 prepuberous each) as follows: an untreated control group, a control group treated with albendazole (dose, 5 mg/kg) and two groups treated by the V. thomasii root bark powder (compressed in 500 mg tablets; doses, 1 g/kg and 2 g/kg). The number of eggs per gram of faeces and the number of total leukocytes significantly dropped in the groups treated with the albendazole (- 90 %; p < 0.05) and V. thomasii (- 85 % for 1 g/kg and - 86 % for 2 g/kg; p < 0.05). The weight and serum creatinin and transaminases remained stable in the three treated groups whereas the total proteins, albumin and haematocrit significantly increased. The effectiveness of the two Vitex thomasii treatments was comparable to albendazole. These results constitute a basis for the development of a rational phytotherapeutic approach to livestock treatment.
Anthelmintic activity of Vitex thomasii De Wild (Verbenaceae) root bark powder on Haemonchus contortus in goats