Antiproliferative activity of methanolic extracts from two green algae, Enteromorpha intestinalis and Rizoclonium riparium on HeLa cells

Background: Natural compounds can be alternative sources for finding new lead anti-cancer molecules. Marine algae have been a traditional source for bioactive compounds. Enteromorpha intestinalis and Rhizoclonium riparium are two well distributed saline/brackish water algae from Sundarbans. There's no previous report of these two for their anti-proliferative activities. Methods: Cytotoxicity of the algal methanolic extracts (AMEs) on HeLa cells were assayed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay. Morphological examinations were done by Haematoxylin, Hoechst 33258 and Acridine orange staining. DNA fragmentation was checked. Gene expressions of Cysteine aspartate protease (Caspase) 3, Tumor protein (TP) 53, Bcl-2 associated protein X (Bax) were studied by Reverse transcription-polymerase chain reaction (RT-PCR) keeping Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as internal control. Protein expressions were studied for Caspase 3, phospho-p53, Bax, Microtubule associated proteins-1/light chain B (MAP1/LC3B) by western blot. Results: The AMEs were found to be cytotoxic with Inhibitory concentration 50 (IC50) values 309.048 +/- 3.083 mu g/ml and 506.081 +/- 3.714 mu g/ml for E. intestinalis and R. riparium extracts respectively. Treated cells became round with blebbings with condensed nuclei. Acidic lysosomal vacuoles formation occurred in treated cells. Expression of apoptotic genes in both mRNA and protein level was lowered. Expression of LC3B-II suggested occurrence of autophagy in treated cells. Conclusions: These two algae can be potent candidates for isolating new lead anticancer molecules. So they need further characterization at both molecular and structural levels.