Bioactive assessment of selected marine red algae against Leishmania major and chemical constituents of Osmundea pinnatifida

The antileishmanial activities of the seven different species of red algal extracts were evaluated against the promastigote form of leishmania major. the ethanol extracts of osmundea pinnatifida scored the highest activity with ic50 value 6.25 μg/ml comparable to other algae such as scinaia hatei with ic50 value 14.10 μg/ml,melanothamnus afaqhusainii with ic50 value 32.6 μg/ml and gracilaria corticata with ic50 value 37.5 μg/ml,which exhibited significant inhibitory effect on the viability of leishmania major. while other few species,like scinaia fascicularis,centroceras clavulatum and botryocladia leptopoda were found to show good activity and gave lethal effect in vitro,as conducted for the first time using the pakistani seaweeds. current report describes the isolation and structural elucidation of flavone scutellarein 4'-methyl ether (1) being a second report on the presence of flavone in algae and 4-methoxy pyran (2) from o. pinnatifida as reported for the first time from the genus osmundea.