Alleviation of high fat diet-induced obesity in mice by Samia ricini pupae protein ​

Obesity is a multifactorial metabolic disorder associated with aberrant lipid metabolism, dyslipidemia, oxidative stress and chronic low-grade inflammation. Edible insects are an underexplored source of nutrition and functional foods. The pupae of the eri silkworm, Samia ricini, have been traditionally consumed by several tribes of North-East India for their nutritive and therapeutic properties. We evaluated the potential of protein extracted from Samia ricini pupae (PESRP) to alleviate obesity induced in mice by high-fat diet (HFD). PESRP did not induce acute toxicity and was established to have an LD50 greater than 1000 mg/ kg body weight (bw). PESRP significantly decreased body weight and adipocyte hypertrophy, and normalized serum lipid profile of HFD-fed obese mice in a dose-dependent manner, with the 100 mg/kg bw dose producing effects similar to the standard anti-obesity drug, orlistat (20 mg/kg bw). It also ameliorated hepatic steatosis and normalized the levels of liver function markers in HFD fed obese mice. Mechanistically, PESRP activated AMPK signaling by increasing the ratio of pAMPK (Thr 172)/AMPK and pACC (Ser-79)/ACC and downregulating the expression of lipogenic enzymes FASN and HMGCR in both liver and epididymal white adipose tissue (eWAT). Moreover PESRP reduced obesity associated inflammation in both liver and eWAT by reducing expression of TNF-α and NF-ķβ, reduced oxidative stress and restored reduced glutathione levels in these tissues. Altogether, this study suggests that PESRP potentially attenuates obesity induced by HFD and holds promise as a novel edible insect-derived nutraceutical for obesity management.