Phytochemical composition of Avicennia marina leaf extract, its antioxidant, antimicrobial potentials and inhibitory properties on Pseudomonas fluorescens biofilm

Abstract

Mangroves are widely used for the extraction of natural compounds for the purpose to be used in traditional medicine and the pharmaceutical sector. In this study, Avicennia marina leaves (gathered in Safaga, Red Sea, Egypt) were dried and extracted by ethanol, acetone and ethyl acetate. The antimicrobial activity of the three organic extracts was examined against different fish and human pathogens. The mangrove ethyl acetate extract (MEE) which gave the highest antimicrobial activity was further evaluated, as it exhibited a promising antioxidant activity determined by the DPPH test with IC50 of 50.3 µg/ml. Its total phenolic and flavonoid contents were determined to be 109 and 23 mg/g, respectively. In addition, MEE antibiofilm activity was assessed by total biomass quantification using microplate assay and observed under light microscope. MEE showed a highly promising antibiofilm activity, where it succeeded not only in preventing initial cell attachment and biofilm formation by the fish pathogen Pseudomonas fluorescens, but also in disrupting the preformed biofilm with IC50 of 42.0 and 45.8 mg/ml, respectively. Furthermore, its chemical composition was determined by GC–MS analysis demonstrating that its major constituents are alcohol, fatty acids and their derivatives. Overall, the current study confirms the promising antimicrobial, antioxidant activities of MEE and reports biofilm inhibition and eradication activities of A. marina ethyl acetate extract against Pseudomonas fluorescens.