INHIBITORY EFFECT OF Vitex mollis Kunth EXTRACTS AGAINST BACTERIA AND Fusarium SPECIES OF HUMAN AND AGRICULTURAL IMPORTANCE

Abstract

Currently, antibiotic resistance and indiscriminate use of chemical fungicides in agriculture need to be addressed. This research evaluated the inhibitory effect of aqueous, methanolic, acetonic and hexanic extracts from leaf and stem of Vitex mollis Kunth (Lamiaceae) against several bacteria (Escherichia coli, Micrococcus luteus, Salmonella enterica and Staphylococcus aureus) and species of Fusarium fungus (F. verticillioides, F. oxysporum, F. tapsinum and F. oxysporum f. sp. lycopersici), and determined their general chemical composition. The minimum inhibitory concentration (MIC) was determined by the micro-dilution technique for all extracts, except for the hexanic extract which did not show inhibition on the bacteria studied. S. enterica was the bacterium that showed the highest sensitivity to the methanolic extracts from stem (MIC = 28 μg mL^-1), followed by M. luteus (MIC = 32 μg mL^-1), S. aureus (MIC = 75 μg mL^-1) and E. coli (MIC = 80 μg mL^-1). The methanolic and aqueous extracts from the stem presented higher percentage of inhibition against different types of Fusarium evaluated by the agar dilution method. Extracts of V. mollis inhibited F. verticillioides between 62 and 91 % with 120 μg mL^-1 of extract. The order of fungi species as inhibited by the extracts was F. verticillioides > F. oxysporum > F. tapsinum > F. oxysporum f. sp. lycopersici. The chemical composition of the species was determined by tests for phenols, tannins, flavonoids, triterpenes, alkaloids, coumarins and saponins. None of the extracts presented alkaloids and saponins.Phenols (37.1 mg EAG/g dry sample) and flavonoids (26.8 mg EQ/g drysample) were the major compounds in the methanolic and aqueous extracts. In conclusion, small amounts of extracts are required to inhibit bacteria andFusarium; hence, V. mollis can be considered a source of metabolites forthis purpose and in agriculture as an alternative control within an integrated management of diseases.