Evaluation of qualitative phytochemicals and antifungal activity of aqueous leaf extract of <i>Senna tora</i> on downy mildew of cabbage

Abstract

This study was embarked upon to evaluate the efficacy of aqueous extracts of Senna tora leaf against Perenospora parasitica, causing downy mildew on cabbage. Phytochemical analysis of the leaf extracts revealed the presence of some secondary metabolites (Tannins, Saponins, Flavonoid, Glycosides, Alkaloids, Phenolic compounds and Carbohydrates) which have been reported to have antimicrobial effects. Assays were performed using extract concentrations of 1000, 500, 250, 125 mg/ml by agar well diffusion technique. Results obtained, revealed a significant difference in diameter of mycelial zone of inhibition between the concentrations. Highest zone of inhibition was recorded at 1000 and 500 mg/ml (20 and 15 mm) respectively. Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) were determined and recorded at 250 mg/ml. The antifungal screening revealed that the extract exhibited inhibitory activities at varying concentrations against the downy mildew pathogen. These activities observed could be attributed to the presence of active metabolites contained in the extract.

Keywords: Aqueous leaf extract, Downy mildew, Perenospora parasitica and Senna tora