Antitumor and antioxidant activity of the freshwater macroalga Cladophora surera

Macroalgae are currently being explored as novel and sustainable sources of bioactive compounds for both pharmaceutical and nutraceutical applications arising from their antioxidant, anticancer, and antimicrobial activity. In the present study, the antitumoral and antioxidant activities of crude methanolic extracts of the freshwater macroalga Cladophora surera Parodi & Caceres, harvested from Naposta Creek (Argentina), were investigated in vitro. The antioxidant activity was assessed by DPPH method and polyphenol content using Folin-Ciocalteu phenol reagent. Antitumoral activity was evaluated on the human breast adenocarcinoma cell line MCF-7 by measuring proliferation, migration, and cell adhesion. The algal extract (AE) showed a total phenol content of 1.62 +/- 0.17g GAEmg(-1) dry alga and DPPH scavenging activity of 25.03 +/- 1.99% (10mg)(-1) dry alga. The trypan blue assay after 48h of treatment indicated that the AE significantly inhibits proliferation in a dose-dependent manner (1-100gmL(-1)), being more effective the highest dose employed, with a concomitant increment in dead cells. However, the colorimetric MTS assay only showed a significant decrease in cell viability at 100gmL(-1) AE. Using the wound healing assay, we demonstrated that AE inhibits cell migration. Through a cell adhesion assay, we found that AE affects considerably the cell adhesion capacity at all doses probed. Analysis of cell spreading indicated that cell morphology was also affected by AE treatment. These results indicate that C. surera could be a source of valuable bioactive compounds usable as antitumoral preventive therapy for their effects on the regulation of processes involved in metastasis in cells derived from human mammary cancer.