Anti-diabetic and anti-inflammatory activities of the edible red alga Gracilariopsis chorda

Abstract

Gracilariopsis chorda (Holmes) Ohmi is an edible perennial red alga in the family Gracilariaceae and is distributed in the coastal area of Gangneung, and Jeju islands in Korea [1]. Previous studies on G. chorda, have investigated anti-inflammatory activity and neuroprotective effects [2]. In continuation of our search for bioactive natural products, we have found that the EtOH extract of G. chorda has antihyperglycemic activity in the zebrafish model for type 1 diabetes, and anti-inflammatory activity. The zebrafish model for type 1 diabetes was induced by alloxan, which causes pancreatic β-cell necrosis [3]. The EtOH extract was consecutively partitioned with hexane, CH2Cl2, EtOAc and n-BuOH to give five fractions. Anti-diabetic activity of the solvent fractions was evaluated by using a zebrafish model. Following alloxan treatment, pancreatic islet size and fluorescence intensity were measured. Among the fractions, the CH2Cl2, n-BuOH and H2O fractions revealed potent anti-diabetic activity for type 1 at a concentration of100 µg/ml. We also evaluated the levels of inflammatory mediators in LPS-stimulated RAW 264.7 macrophages, and TNF-α-induced VCAM-1 expression in MOVAS-1 vascular smooth muscle cells. The hexane fraction and hexane and CH2Cl2 fractions significantly decreased IL-6 and TNF-α production, respectively. The VCAM-1 expression was inhibited significantly by hexane, CH2Cl2 and H2O fractions.