Bioassay-guided isolation of glycolipids from the seaweed Gracilaria corticata

Background and purpose: In some countries, seaweeds are famous traditional food which contain different types of secondary metabolites. These marine organisms have several bioactive secondary metabolites. The aim of this study was to perform bioassay-guided isolation of glycolipids from a Persian Gulf seaweed Gracilaria corticata J.Agardh. Experimental approach: G. corticata was collected from the Persian Gulf. The plant was extracted by maceration with methanol-ethyl acetate solvent. The extract was partitioned by the Kupchan method to yield n-hexane, dichloromethane, butanol, and water partitions. The most active partition found in the cytotoxicity assay was further fractionated using medium pressure liquid chromatography and high-performance liquid chromatography (HPLC) methods to yield two pure compounds. The structures of the isolated compounds were elucidated using various spectroscopic methods. The cytotoxic activities of all fractions were also tested. Findings/Results: n-hexane and dichloromethane partitions exhibited higher and significant cytotoxicity against the HeLa cell line with IC50s of 117.41 and 291.38 µg/mL, respectively. The cytotoxic effects of nine fractions of the n-hexane partition against HeLa and HUVEC cells were also ranging from 96.33 to 243.56 µg/mL and 85.38 to 290.5 µg/mL, respectively. Two sulfoquinovosyldiacylglycerides were isolated and their structures were elucidated. Conclusion and implications: From the spectral characteristics, the isolated compound from the extract was confirmed to be α-D-glucopyranosyl-1,2-O-diacyl-glycerols with moderate cytotoxic activity.