Anti-diabetic activity of field cricket glycosaminoglycan by ameliorating oxidative stress

Field cricket (Gryllus bimaculatus) is newly emerged as an edible insect in several countries. Anti-inflammatory effect of glycosaminoglycan derived from this cricket on chronic disease animal model such as diabetic mouse has not been fully investigated yet. Thus, the objective of this study was to determine the anti-oxidative effect of such glycosaminoglycan on diabetic mouse.

To discover potential therapeutic agents, field cricket glycosaminoglycan (GbG) was tested in the present study. Its anti-oxidative activities in diabetic mice were determined based on its abilities to reduce glucose, ALT, AST, ALP, LDL-cholesterol and BUN levels. Dung beetle (C. molossus) glycosaminoglycan (CaG) was used as a positive control. Db mice were intraperitoneally administered for 1 month according to their group assignments: 1) normal (DB-Hetero); 2) control (DB-Homo); 3) 5 mg/kg treatment of CaG (CaG5); 4) 5 mg/kg treatment of GbG (GbG5); and 5) 10 mg/kg treatment of metformin (Metformin 10).

Blood glucose level decreased after 1st week of treatment with GbG. LDL-cholesterol and alkaline phosphatase levels were also inhibited by GbG. Markers of oxidative damage, such as protein carbonyl content and levels of hepatocellular biomarkers, were reduced in db mice treated with GbG. Especially anti-oxidative activities of catalase, superoxide dismutase and glutathione peroxidase were significantly increased in GbG treated group compared to those in the control (Db Homo). GbG was composed of heparin disaccharides. Its main N-glycan was identified as Hex₉GlcNAc₂ (m/z 1905.7) with neutral mono-sugar mainly comprising of hexose and L (+) rhamnose by mass spectroscopy.

Sero-biochemical and hepatocellular anti-oxidant assay results in db mice suggest that cricket (G. bimaculatus) glycosaminoglycan might possess anti-oxidative effect in diabetic state.