Abstract

ASSESSMENT OF ANTISPASMODIC EFFECTS OF POLYPHENOL AND COMPLEX CATECHIC TANNIN EXTRACTS FROM SOME MEDICINAL PLANTS USED TO TREAT DIARRHOEA IN TRADITIONAL MEDICINE IN KINSHASA-DEMOCRATIC REPUBLIC OF CONGO

Cimanga Kanyanga R.*, Kimbuira L., Tona L.G., Kambu K.O., Vlietinck A.J., Pieters L.

ABSTRACT

Polyphenol and complex catechic tannin extracts from some medicinal plants used as antidiarrheal remedies in traditional medicine in Kinshasa-Democratic Republic of Congo were submitted to the evaluation of their capacity to inhibit contractions induced by acetylcholine (ACh) and depolarizing solution rich in KCl (DSR-KCl) on isolated guinea-pig ileum. Against ACh effects, results revealed that five polyphenol extracts including those from Maprounea africana and Mangifera indica stem bark, Morinda morinodoides, Psidium guajava and Tithonia diversifolia leaves, inhibited contractions induced by this agonist by 80% < % inhibition < 90%. Seven polyphenol extracts from Alchornea cordifolia, Cajan cajan, Nauclea latifolia and Morinda lucida leaves, Bridelia ferruginea and Garcinia kola stem bark, and Harugana madagascariensis root bark produced an inhibition of contractions induced by ACh between 70 and 80% on isolated guinea-pig ileum. Two polyphenol extracts from Paropsia brazzeana root bark and Pentaclethra macrophylla stem bark produced less than 55% inhibition of ACh effects. Among tannins extracts, those from B. ferruginea and M. africana stem bark, H. madagascariensis root bark and M. morindoides leaves produced more than 70% inhibition induced by ACh on isolated organ and other complex catechic tannin extracts from C. cajan, N. latifolia, M. lucida leaves, B. ferruginea and G. kola stem bark, and H. madagascariensis reached 60% % inhibition < 70% of contractions induced this agonist. Regarding their effects on DSR-KCl, results indicated that polyphenol extracts from four medicinal plants including M. morinodoides and P. guajava leaves, M. africana and M. indica stem bark caused an inhibition of contractions induced by this agonist ranging from 80 to 89% while those from A. cordifolia, C. cajan, M. lucida leaves, G. kola and H. madagascariensis and M. africana stem bark produced 70% < inhibition < 80% of its effects. In conclusion, these tested phytochemical groups including polyphenols and complex catechic tannins were found able to inhibit significantly contractions induced by both agonists showing their antispasmodic effect and can be in part, considered as responsible for the antidiarrhrrhoeal properties attributed to these medicinal plants by different practioners in traditional medicine in Democratic Republic of Congo.

Keywords: Medicinal plants, polyphenols, tannins, antispasmodic activity.