In vitro screening of secondary metabolites and evaluationof antioxidant,antimicrobial and cytotoxic properties of Gelidium sesquipedale Thuret et Bornet red seaweed from Algeria

In vitro antioxidant,antimicrobial and cytotoxic activities of hydromethanolic extract of red seaweed gelidium sesquipedalethuret et bornet and its fraction were investigated. phytochemical screening,total phenolic and flavonoid contents were also investigated. for phytochemical screening,some common and available standard tests were done. phytochemical screening revealed the presence of alkaloids,anthocyane,saponins,flavonoids,tannins and c-heterosids. the maximum total phenol and flavonoid content was observed in the diethyl ether fraction (101 gae/g) and in the ether acetate (5.63 qe/g) respectively. the high dpph radical scavenging was observed in chloroform fraction. the diethyl ether and n-butanol fraction showed good reducing power. the extracts exhibited high antioxidant activity by β-carotene/linoleic acid bleaching assay during the incubation time. antimicrobial activity was examined against eight bacteria and one yeasts. only one bacterial strain (enterobacter cloacae) was not inhibited by seaweed extracts,and chloroform fraction was generally more active than others. hydromethanolic extract was subjected to brine shrimp lethality bioassay for possible cytotoxicity. concentration dependent increment of brine shrimp nauplii mortality caused by the extract was indicative of the presence of cytotoxic constituents in this extract.