In vivo growth-inhibition of Sarcoma 180 tumor by alginates from brown seaweed Sargassum vulgare

Previous studies had demonstrated that alginates from Sargassum sp. (Phaeophyta) showed a considerable activity against various murine tumors. The aim present study is to investigate the in vivo antitumor activity of two alginates (SVHV and SVLV) with different viscosity extracted from brown seaweed Sargassum vulgare C. Agardh against Sarcoma 180 cells transplanted in mice. Both alginates inhibited growth of sarcoma 180. The oral route of administration was more effective for both alginates, leading to an inhibition of 51.8 and 74.8% for SVLV at the doses of 50 and 100 mg/m2/day, respectively, and of 66.2 and 88.8% for SVHV at the same doses. SVLV was 2.04 times more active after oral administration, while SVHV was 1.89, both at the dose of 100 mg/m2/day. Alginates-antitumor activity was related to the tumor proliferation rate inhibition, as observed by reduction of Ki67 staining in tumor of the treated-animals. The histopathological analysis of liver and kidney showed that both organs were affected by SVHV and SVLV treatment. However, only SVLV led to acute tubular necrosis. Alginates cause the enlargement of the white pulp of the spleen of treated animals, suggesting that the observed antitumor activity could be related to alginates immunomodulatory properties.