Phytotoxic, antifungal activities and acute toxicity studies of the crude extract and compounds from Diospyros canaliculata.

In vitro biological activities including phytotoxic, antifungal activities as well as acute toxicity of the methanol extract, fractions and/or isolated compounds from the stem bark of Diospyros canaliculata were investigated. Well agar diffusion and macrodilution assays were used for investigating the antifungal activity. A phytotoxicity assay was performed against Lemna minor while an acute toxicity assay was performed in mice via oral administration. As a result, plumbagin (5-hydroxy-2-methyl-1,4-naphtoquinone) and two known pentacyclic triterpenes (lupeol and lupenone) were isolated from the extract. With regards the antifungal activities, the inhibition zones varied from 16.51 to 24.86 mm and from 20.50 to 25.10 mm for the extract and plumbagin, respectively. The minimum inhibitory concentrations of the extract and plumbagin ranged between 12.5-25 and 0.78-1.56 µg mL(-1), respectively. At 50 µg mL(-1), the hexane fraction showed phytotoxic activities similar to paraquat, the standard phytotoxic inhibitor. The extract was found to be non-toxic to mice after administration per os. Based on the current findings, we can conclude that this extract is non toxic, with significant phytotoxic and antifungal properties due to the presence of plumbagin.