Bactericidal Effect of Bark Extract from Laguncularia racemosa L.

Aqueous and ethanolic extracts of stem bark from Laguncularia racemosa L were analyzed to determine their metabolites through phytochemical analysis and bactericidal activity using the agar dilution method. Phytochemical analysis mainly revealed the presence of tannins, but also detected saponins, among other compounds. Both extracts showed antibacterial activity against all Gram-positive and Gram-negative microorganisms included in the study, although ethanolic extract tended to be more active than aqueous extracts. Antimicrobial activity of aqueous extracts at pH 5.0, 6.0 7.0 or 8.0 was not affected, the best antibacterial activity being founded at pH 8.0. Each bacteria tested was inhibited by stem bark extracts, even if microorganism presented resistance to one or various commercial antibiotics, suggesting that bactericidal mechanism of bioactive metabolites contained in the extracts is independent of bacterial resistance.