Ethnobotanical study, toxicity and phytochemical screening of selected medicinal plants of Tinderet district, Nandi county, Kenya

Abstract

Most indigenous communities depend on plants for medicine. Plants contain active principles that ensure the well being of local communities. The purpose of this study was to identify and document the medicinal plants of the Nandi people of Tinderet District, Rift Valley Province, Kenya. Selected plants were also tested for toxicity using brine shrimp (Artemia salina) and also screened for major secondary metabolites. Information on medicinal plants was gathered through key informant interviews with the aid of an interview guide in fifteen locations. Forty two (42) herbalists (24 males and 18 females) between the age of 18 and 92 were purposively selected and interviewed. They provided the local plant names, parts of the plant used, mode of preparation, administration and medicinal use. The study identified ninety five (95) medicinal plants distributed among eighty four (84) genera and forty two (42) families. The most commonly used plant families included Asteraceae (12.63%), Euphorbiaceae (8.42%), Lamiaceae (5.26%) and Mimosaceae (5.26%). Five popularly used medicinal plants; Albizia coriaria (Mimosaceae), Clutia abyssinica (Euphorbiaceae), Dovyalis abyssinica (Flacourtiaceae), Ehretia cymosa (Boraginaceae) and Rhamnus prinoides (Rhamnaceae) were selected, collected, extracted in ethanol and used for toxicity using brine shrimp (Artemia salina). They were also screened to determine presence or absence of Alkaloids, Flavonoids, Saponins, Sesquiterpene lactones and Steroids using Thin Layer Chromatography (TLC). Pearson correlation coefficient was used to determine the degree of correlation between age of informants and the number of medicinal plant citations. LD50 was determined by analysis of toxicity assay data using Finney’s Probit analysis. Factor of informant consensus (Fic) was used to determine the level of consensus between the herbalists. v There was a high correlation (r= 0.83) between age of informants and number of medicinal plant citations. The commonly treated ailments gave a mean Fic of 0.72 depicting high consensus in plant use. Albizia coriaria was toxic to brine shrimp while Dovyalis abyssinica, Clutia abyssinica, Ehretia cymosa and Rhamnus prinoides were non toxic to brine shrimp. Ethanolic extracts of the five species tested positive for alkaloids, flavonoids, sesquiterpene lactones, saponins and steroids except steroids were lacking in Ehretia cymosa ethanol extract. Key words: Albizia coriaria, Clutia abyssinica, Dovyalis abyssinica, Ehretia cymosa, Rhamnus prinoides, Ethnobotany, Traditional medicine, Toxicity and phytochemical screening