Role of flavonoid-rich fraction from Persea americana (Mill.) in bacterial leakage of Staphylococcus aureus

This study aimed to determine the ability of Persea americana (Mill.) or avocado peels ethanolic extract and its fractions to cause bacterial cell leakage in Staphylococcus aureus. The interaction of antibacterial compound with bacterial cells induces several changes leading to the damage of membrane permeability, followed by intracellular bacterial cell leakage. The experiment started with the determination of minimum inhibitory concentration and minimum bactericidal concentration by micro dilution method. Following the determination of MIC and MBC values, the samples, at the concentrations of 1xMIC and 2xMIC, were tested and analyzed by UV-Vis spectrophotometer at 260 and 280 nm to determine the leakage of bacteria cells. The value of K+ ion leakage was determined using atomic absorption spectrophotometry while the value of electrical conductivity was measured by conducto meter to determine the leakage of the cell membrane. The recorded MIC and MBC values of samples were 10% w/v. At the concentrations of 10% and 20% w/v, the samples caused an increase in nucleic acid, protein and DNA levels as well as an increase in extra cellular electrical conductivity. Prolonged exposure of the extract increased the leakage of bacterial cell contents and the electrical conductivity, indicating the damage of bacterial cell membrane.