Resumo

Marine organisms are potential sources of bioactive secondary metabolites with potential for use in the development of new pharmaceutical agents and many of these substances have been demonstrated to possess interesting biological activities. Seaweeds have been screened extensively to isolate lifesaving drugs or biologically active substances. In the present study we have focused our vision to investigate the potential ability of the green seaweed Penicillus capitatus extracted using different solvents against six bacterial pathogens and its phytochemical compostion. The green seaweed was collected by hand picking from the submerged marine rocks at Paiva Beach, Cabo de Santo Agostinho municipality, Pernambuco State, Brazil. Voucher specimen have been deposited at Instituto Agronômico de Pernambuco Herbarium (IPA). The powdered material (100 g) was successively extracted with n-Hexane, Chloroform, Ethyl acetate and Methanol by maceration with occasional shaking at room temperature for 72 h. The n-Hexane extract H, chloroform extract C, ethyl acetate extract E and methanol extract M were concentrated after combining the filtrate and kept in desiccator for further investigation. The extracts H, C, E and M of green alga P. capitatus obtained by maceration were analyzed by qualitative methods for the presence of alkaloids, carbohydrates, flavonoids, terpenoids, steroids, glycosides and tannins. Antibacterial efficacy of crude extracts were tested using disc diffusion method and minimum inhibitory concentration (MIC). A suitable positive control was also maintained. Among the solvents tested, ethyl acetate and methanol extracts exhibited maximum inhibition on the growth of the tested bacterial species, specially for S.aureus and E. coli with 23±0.00 mm and 20±0.00 mm, respectivily. A minimum value of MIC as 0.39 was observed for S. aureus to the crude ethyl acetate extract. Some studies performed in the extraction of seaweeds using chloroform and ethyl acetate also exhibited good antibacterial activity. It was reported that methanol extracts of seaweeds tested showed broad spectrum antibacterial activity against human pathogenic bacteria. All extracts showed flavonoids but only ethyl acetate and methanol shoew terpenoids. It can be concluded that the different extracts of P. capitatus show moderate to significant antimicrobial activity against the strains used. Active constituents responsible for antimicrobial activity were possibily flavonoids and terpenoids.