chemical constituents and biological activities of two iranian cystoseira species

the marine environment represents approximately half of the global biodiversity and could provide unlimited biological resources for the production of therapeutic drugs. marine seaweeds comprise few thousands of species representing a considerable part of the littoral biomass. extracts of the cystoseira indica and cystoseira merica were subjected to phytochemical and cytotoxicity evaluation. the amount of total phenol was determined with folin-ciocalteu reagent. cytotoxicity was characterized by ic 50 of human cancer cell lines including mcf-7 (human breast adenocarcinoma), hela (cervical carcinoma), and ht-29 (human colon adenocarcinoma) using sulforhodamin assay. antioxidant activities were evaluated using 2,2-diphenylpicrylhydrazyl (dpph) method. the analysis revealed that tannins, saponins, sterols and triterpenes were the most abundant constituents in these cystoseira species while cyanogenic and cardiac glycosides were the least ones. c. indica had the higher content of total phenolics and also showed  higher antioxidant activity. cytotoxic results showed that both species inhibited cell growth effectively, especially against mcf-7 cell line. the present findings suggest potential pharmacological applications of selected seaweeds but require further investigation and identification of their bioactive principles.