CHEMICAL CONSTITUENTS AND ANTIFUNGAL POTENTIAL OF THE Richardia brasiliensis (Gomes) ETHANOLIC EXTRACT

Abstract

The objective of this work was to evaluate the fungicide potential of the Richardia brasiliensis plant extract or its fractions on Lasiodiplodia theobromae and Colletotrichum gloeosporioides, as well as the isolation and identification of substances present in these fractions. For both the crude and ethanolic extracts, the plants’ aerial part was fractionated and the hexane fractions and ethyl acetate were separately subjected to columns of silica-gel leading to isolation of steroids and triterpene acids respectively. One- and two-dimensional 1H-NMR and 13C-NMR spectral analyses were used for structural elucidation.  Concentrations of 10; 20; 40; 80; 160 µg 100mL-1 ethanolic extract, hexane fractions and a pure isolated substance (oleanolic acid) with 5 µL of DMSO were utilized for antifungal activity evaluation. Spectral analysis allowed identification and isolation of β-sitosterol and a mixture of β-sitosterol and stigmasterol. For fungicide action, the hexane and acetate or pure fractions provided reduction of the mycelial growth of C. gloesporioides, at the 160 μg100 mL-1 concentration. For L. theobromae, the acetate or pure fraction and the ethanolic extract were highlighted in the concentrations of 80 and 160 μg100 mL-1. From the results of the evaluation of fungicide potential of the R. brasiliensis extract and its fraction against the fungi C. gloeosporioides and L. Theobromae, as well as the chemical insulation of the substances involved, it can be noted that this weed contains potential fungicidal substances and especially the isolated triterpenes are promising for use in formulations in the control of these pathogens.