Antimicrobial and antibiofilm activities of secondary metabolites from Vinca minor L.

The aim of study was to investigate the antimicrobial and antibiofilm activities as well as chemical analysis of aquatic, acetone and ethyl acetate extracts Vinca minor L. collected in Balkan mountains (Dinaric Alps, Serbia). Antimicrobial testing was performed by microdilution method. Minimum inhibitory concentration and minimal microbicidal concentration were determined for 26 species of microorganisms. Strong antimicrobial activity was detected against Gram-positive bacteria, especially from genus Bacillus. Gramnegative bacteria were not sensitive within the tested extracts concentrations. Ethyl acetate extract from V. minor caused some antifungal effect on Rhodotorula and Candida. Trichoderma viride was sensitive to aquatic extract of the plant. Antibiofilm activity was tested by crystal violet assay. Only ethyl acetate extract was effective against formation of biofilm by Proteus mirabilis and biofilm inhibitory concentration (BIC50) was at 22.8 mg/mL. Phytochemical analysis involved determining the amount of total phenols, flavonoids and tannins as well as antioxidant activity monitoring capability to neutralize 2.2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and reduction potential. Total phenolic content, DPPH and reduction potential of the aquatic extract of V. minor was significantly stronger compared to the acetone and ethyl acetate extracts.