Anticancer and Cisplatin Sensitizing Activities against Oesophageal Squamous Cell Carcinoma KYSE-150 Cells and Antioxidant Activity of Ethanolic and Methanolic Ulva sp. Extracts

Introduction: Green macroalgae have exhibited potent anticancer and antioxidant properties against oesophageal squamous cell carcinoma (ESCC). While cisplatin is used widely for ESSC treatment, it has low efficacy and induces chemoresistance. Methods: This study aimed to investigate the anticancer and cisplatin chemosensitising potentials of two polar Ulva sp. extracts in chemoresistant ESCC KYSE-150 cells and their antioxidant activity. Following phytochemical screening, cell viability, apoptosis, reactive oxygen species (ROS) assays were performed on Ulva sp. treated KYSE-150 along with chemosensitising effects and in silico molecular docking of phytochemicals against tumour-related protein targets. Results: Screening indicated the presence of glycosides (G-glycoside), tannins, terpenoids, carbohydrates, lipids, proteins and flavonoids, while absence of alkaloids. Both ethanolic (IC50 = 237.2 μg/ml) and methanolic (IC50=165.6 μg/ml) extracts induced higher cytotoxicity through caspase 3/7 activation of apoptosis. Besides, both extracts demonstrated potent antioxidant properties with methanolic extract showing better scavenging activity compared to ethanolic extract. In silico molecular docking revealed the ligands have high binding affinity towards B-cell lymphoma-extra-large with the predicted binding energies (-5.1 to -11.1 kcal/mol), where β-carotene displayed the highest binding affinity (-11.1 kcal/mol). Conclusion: While both extracts did not enhance the cisplatin-sensitivity of KYSE-150 cells, they exhibited significant antioxidant properties, signifying their potential as a treatment for ESSC.