Ulcer preventive and antioxidative properties of astaxanthin from Haematococcus pluvialis

The anti-ulcer properties of astaxanthin fractions such as total carotenoid and astaxanthin esters from Haematococcus pluvialis were evaluated in ethanol-induced gastric ulcers in rats. Since oxygen radical release is a pathogenic factor of ethanol-induced gastric damage, astaxanthin - a free radical scavenger, was investigated as a potential ulcer preventive agent. Astaxanthin fractions - total carotenoid and astaxanthin esters were orally administered to experimental rats at 100, 250 and 500 mu g/kg b.w. prior to ulcer induction. Alcian blue binding assay indicates that, total carotenoid and astaxanthin esters at 500 mu g/kg b.w could protect gastric mucin similar to 40% and 67% respectively. Pre-treatment with astaxanthin esters, also resulted in significant increase in antioxidant enzyme levels - catalase, superoxide dismutase, and glutathione peroxidase in stomach homogenate. Histopathological examination substantiated the protective effect of astaxanthin in pre-treated rats. The increased antioxidant potencies such as free radical scavenging activity with all IC50 of similar to 8 mu g/ml and reducing power abilities (59 x 10(3) U/g) in vitro, reveal that H. pluvialis astaxanthin may protect gastric mucosal injury by antioxidative mechanism. In addition, similar to 23 fold increased lipoxygenase-inhibitory property, in comparison with standard astaxanthin and significant H+, K+-ATPase-inhibitory activity of astaxanthin esters, in comparison with known proton pump blocking anti-ulcer drug omeprazole, may envisage the potential gastroprotective effect by regulating the gastric mucosal injury and acid secretion by the gastric cell during ulcer disease. (C) 2008 Elsevier B.V. All rights reserved.