PHYTOCHEMICAL ANALYSIS OF BEACH-CAST SEAWEED, ZOSTERA SPP. COLLECTED FROM IZMIR COASTS, TURKEY AND EVALUATION OF IN VITRO ANTIMICROBIAL ACTIVITY

摘要

The bioactive compounds of detrital leaves of seaweed, Zostera spp. found as beach-cast were investigated by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Extracts of methanol, ethyl acetate, and n-hexane of detrital Zostera spp. leaves collected from Coasts of Aegean Sea, Izmir (Turkey) were used to determine the major bioactive constituents. Major bioactive elements in detrital leaves of Zostera spp. were elucidated as apigenin-7-O-glucoside, luteolin-7-O-glucoside, rosmarinic acid and diosmetin-7-sulfate. Minor amounts of apigenin-7-O-glucoside, luteolin-7- O-glucoside and rosmarinic acid were identified in the detrital leaves. Diosmetin-7-sulfate was the major compound in quantity. The antimicrobial activities of the extracts and individual bioactive compounds were tested for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Candida albicans and Vibrio alginolyticus. The antimicrobial activity of solvent extracts and the isolated compunds exhibited different sensitivities to the microorganisms tested. Antimicrobial activity was higher in the ethyl acetate extract in comparison to n-hexane and methanol extracts. Diosmetin-7-sulfate had no antimicrobial activity. Apigenin-7-O-glucoside, luteolin-7-O-glucoside and rosmarinic acid inhibited antifungal growth. Apigenin-7-O-glucoside and luteolin-7-O-glucoside showed antibacterial activity with different sensitivity towards bacteria. Dead biomass of Zostera spp. in beach-cast form can be used as a source for bioactive constituents. The bioactive potential of 'detrital leaves' of Zostera spp. may be of importance in projecting towards various biological applications.