Phytochemistry and antifungal potential of Datura inoxia Mill. on soil phytopathogen control

Abstract

The application of chemical pesticides for the control of fungal diseases results in impacts on the environment and human health. The use of vegetal extracts with antifungal properties for the proper management of crops becomes a viable alternative, mainly for organic and family farming. The objective of this study was to carry out the phytochemical evaluation of Datura inoxia, evaluating its antifungal potential against the mycelial growth of Fusarium solani and Sclerotinia sclerotiorum. The extracts, aqueous and ethanolic, obtained from the leaves of the plant collected in areas of the municipality of Campo Grande, Mato Grosso do Sul, were submitted to phytochemical prospecting and quantification of flavonoids and total phenols. It was evaluated its antifungal activity at concentrations of 800, 1200, 1600, 2000, and 2400 μg 100 mL^-1. Each concentration was separately incorporated into BDA agar, poured into Petri dishes, and inoculated with the mycelial disc of the fungus. The diameter of the colonies were measured daily. Two solutions were prepared as control, one containing the solvent added to PDA medium (ethanol solution), and another with only PDA medium (without D. inoxia extract, control). In both extracts were found the same diversity of secondary metabolites (nine classes). The ethanolic extract, a solvent of lower polarity than water, was more efficient in the extraction of these constituents. Alkaloids and phenolic compounds were the most frequent compounds (100%). In relation to antifungal activity, the ethanolic extract provided 100% inhibition of mycelial growth of Sclerotinia sclerotitorum in all concentrations, relative to the control. On the other hand, the growth of Fusarium solani was only negatively affected at the highest concentrations of 800 and 1200 μmL^-1 100 mL^-1. The antifungal potential of Datura inoxia was probably related to the abundance of alkaloids and phenolic compounds in its chemical constitution that negatively effects the development of the vegetative mycelium.