Cassia sieberiana root bark used in traditional medicine in Togo: Anthelmintic property against Haemonchus contortus and tannins composition

Helminth infections of livestock result in economic losses around the globe. The majority of the people in West Africa treats such infections with medicinal plants related to the local traditional medicine. In a previous ethnomedicinal survey carried out in the north of Togo, traditional healers frequently cited Cassia sieberiana DC to treat helminth infections. The aim of the present study was to validate the traditional application of C. sieberiana root bark as a dewormer and to analyse the metabolite composition in preparations with this activity. Two tannin-rich fractions (FrE14 and FrE15) obtained from ethyl acetate extract were submitted to UPLC-MS analysis. The anthelmintic activity of C. sieberiana extracts and tannins-rich fractions was investigated on the small ruminant parasite Haemonchus contortus using Larval Migration Inhibition tests. The ethyl acetate, butanol and aqueous extracts significantly disrupted larval migration of Haemonchus contortus L3 with inhibition of 30.3%, 22.2% and 26.5% respectively at 2.5 mg/mL, as compared to negative control. The two tannin-rich fractions, FrE14 and FrE15 presented larval migration inhibition of 6.5% and 20.7% respectively at the same concentration. From these two fractions, 28 flavan-3-ols were identified including 3 monomers (catechin, epicatechin and epiafzelechin), 22 dimers (7 homodimers and 15 heterodimers) as well as 3 newly described trimers consisting of (epi)afzelechin, (ent)cassiaflavan or (epi)guibourtidinol subunits.