Cholesterol-lowering properties of defatted kenaf seed meal and its phenolics-saponins-rich extract in a rat model

Kenaf (Hibiscus cannabinus L.) is an important commercial fiber crop and defatted kenaf seed meal (DKSM) is a secondary by-product from the kenaf industry. The present study focused on the investigation of cholesterol-lowering properties of DKSM and its phenolics-saponins-rich extract (PSRE) in a rat model. Proximate analysis revealed that DKSM was high in protein, carbohydrate and crude fibre; while magnesium, potassium and phosphorus were the major minerals found in DKSM. The absence of acute oral toxicity in DKSM was observed through brine shrimp and rat models. In addition, DKSM exhibited higher phenolic content and antioxidant activity as compared to the selected edible flours (p 0.05), but significantly upregulated by PSRE (p < 0.05). The combined results showed that hypercholesterolemia and atherogenic risk in rats were effectively attenuated by DKSM and PSRE supplementation, possibly via modulations of multiple vital processes in hepatic cholesterol metabolism. In addition, serum total antioxidant capacity and hepatic expression of antioxidant genes of hypercholesterolemic rats were significantly enhanced by DKSM and PSRE supplementation, accompanied with marked suppression against the levels of circulating oxidized low-density lipoprotein and pro-inflammatory biomarkers (p < 0.05). Apart from the potential beneficiary effects of alleviated hypercholesterolemia, DKSM and PSRE may attenuate hypercholesterolemiaassociated oxidative stress and systemic inflammation in rats by enhancing the serum total antioxidant capacity as well as the endogenous antioxidant defense via activation of hepatic Nrf2-ARE pathway. In conclusion, DKSM and itsderived PSRE are effective functional food ingredients in ameliorating hypercholesterolemia and its-associated oxidative stress and systemic inflammation in the rat model. Phenolics and saponins may be the bioactives conferring DKSM and PSRE with their cholesterol-lowering, antioxidative and anti-inflammatory properties