Antioxidative, cytotoxic, and anti-metastatic potentials of Laurencia obtusa and Ulva lactuca seaweeds

Objective: To investigate the antioxidant and cytotoxic properties of the most active extracts from Ulva lactuca and Laurencia obtusa against colon and cervical cancer cell lines. Methods: The antioxidant radical scavenging activity of the algal extracts was estimated using the 2,2-diphenyl-1-picrylhydrazyl colorimetric assay. Moreover, the cytotoxic potential of these bioactive extracts was studied against HCT-116 and HeLa cells by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay. Wound healing analysis was adopted to evaluate the anti-metastatic effects of protein extracts from both algae. Cell cycle analysis was performed by flow cytometry, and apoptotic bodies were detected using 4’,6-diamidino-2-phenylindole fluorescent staining. Amino acids of hydrolyzed protein extract were separated and identified chromatographically by high performance liquid chromatography. Results: The green algae Ulva lactuca had higher lipid content than Laurencia obtusa, whereas the latter had higher protein content with high antioxidant capacity. Protein extracts had significant dose- and time-dependent cytotoxicity and anti-metastatic activity against HCT-116 cells. Protein b extracts of both algae obtained from the chloroform:hexane solvent lipid-free residue caused morphological changes and induced apoptosis of HCT-116 cells. Further analysis revealed that apoptosis induced upon Laurencia obtusa protein b treatment was triggered via the ROS pathway, causing a significant increase in the sub-G1 population. Glycine and arginine (5.94 and 5.47 μM, respectively) were the most common amino acids in Laurencia obtusa protein b extract. Conclusions: Proteins of Laurencia obtusa and Ulva lactuca could be considered as an adjuvant nutraceutical source of pro-apoptotic and anti-metastatic biomolecules against colon cancer.