Phytochemical screening and acute toxicity studies of crude ethanolic extract and flavonoid fraction of <i>Carissa edulis</i> leaves

Abstract

Carissa edulis is used traditionally in Nigeria for the treatment of epilepsy, headache, syphilis, rheumatism and sickle cell anaemia. In this study, phytochemical screening was conducted to determine putative active components of Carissa edulis, as well as acute toxicity studies of the ethanolic extract and flavoniod fractions of the leaf. The phytochemical screening of the ethanolic extract of the leaves indicated the presence of carbohydrates, anthraquinones, saponins, tannins, flavonoids and alkaloids. Acute toxicity studies for the ethanolic extract and the flavonoid fraction were carried out using Lorke’s method. In the first part of the experiment (phase A), Three groups of mice (n=3 in each group) were intraperitoneally given 10 mg/kg, 100 mg/kg and 1000 mg/kg of body weight concentration of the ethanolic extract and the mice were observed for 24 hours. The same procedure was repeated for the flavonoid fraction. The results showed that administration of 1000 mg/Kg concentrations of the ethanolic extract was fatal, while no death was recorded at the same concentration of flavonoid fraction. On this basis, in the second part of the study (phase B), mice were intraperitoneally administered 600 mg/kg, 1000 mg/kg, 1600 mg/kg and 2900 mg/kg concentration of the ethanolic extract while those for the flavonoid fraction had 1200 mg/kg, 1600 mg/kg, 2900 mg/kg and 5000 mg/kg flavonoid fraction. All mice were observed for 24 hours. The LD₅₀ of the ethanolic extract and flavonoid fraction of the Carissa edulis leaves was 2154.1 mg/kg which is said to be slightly toxic. The maximum tolerated doses for both ethanolic extract and flavonoid fraction of Carissa edulis was 646.23mg/kg. The findings revealed that the leaves of Carissa edulis contain carbohydrates, anthraquinones, saponins, tannins, flavonoids and alkaloids that may contribute to its reported medicinal value. The acute toxicity studies suggest that the extract and fraction are slightly toxic. Thus further studies are necessary for full characterization of the active components in order to develop it further for safe medicinal use.

Keywords: Phytochemical Screening, Acute Toxicity, Carissa edulis, Herbal Medicines