Hypocholesterolemic effect of sericin-derived oligopeptides in high-cholesterol fed rats

Abstract

The beneficial effect of cholesterol-lowering proteins and/or peptides derived from various dietary sources is continuously reported. A non-dietary protein from silk cocoon, sericin, has also demonstrated cholesterol-lowering activity. A sericin hydrolysate prepared by enzymatic hydrolysis was also expected to posses this effect. The present study was aimed at investigating the cholesterol-lowering effect of sericin peptides, so called "sericin-derived oligopeptides" (SDO) both in vivo and in vitro. The results showed that SDO at all three doses tested (10 mg kg day, 50 mg kg day, and 200 mg kg day) suppressed serum total and non-HDL cholesterol levels in rats fed a high-cholesterol diet. Triglyceride and HDL-cholesterol levels were not significantly changed among all groups. The fecal contents of bile acids and cholesterol did not differ among high-cholesterol fed rats. SDO dose-dependently reduced cholesterol solubility in lipid micelles, and inhibited cholesterol uptake in monolayer Caco-2 cells. SDO also effectively bound to all three types of bile salts including taurocholate, deoxytaurocholate, and glycodeoxycholate. Direct interaction with bile acids of SDO may disrupt micellar cholesterol solubility, and subsequently reduce the absorption of dietary cholesterol in intestines. Taking all data together, SDO or sericin peptides exhibit a beneficial effect on blood cholesterol levels and could be potentially used as a health-promoting dietary supplement or nutraceutical product.

Purification and Identification of Cholesterol Micelle Formation Inhibitory Peptides of Hydrolysate from High Hydrostatic Pressure-Assisted Protease Hydrolysis of Fermented Seabass Byproduct

“…Marques et al [ 39 ] noted that the bioactive peptides produced in the hydrolysis of plant and animal proteins can reduce the absorption of exogenous cholesterol by destroying micelle formation in the intestine. Protein hydrolysates derived from animal sources including freshwater clam ( Corbicula fluminea ) (10 mg/mL), sericin (10 mg/mL), and milk protein (10 mg/mL) had CMF inhibitory percentages of 26% [ 15 ], 58% [ 3 ], and 37% [ 6 ], respectively. Peptides can inhibit CMF because their amino acid sequence is rich in hydrophobic amino acids, which can competitively bind with bile acid and can arrange cholesterol into a new structure, thereby destroying CMF and reducing the absorption of exogenous cholesterol content [ 40 , 41 ].…”

“…A high cholesterol concentration can easily lead to hypercholesterolemia, a risk factor for coronary occlusion [ 1 , 2 ]. It is also associated with various cardiovascular diseases [ 3 ]. To prevent and slow hypercholesterolemia, cholesterol content should be reduced.…”

Bioactive Peptides

“…The peptides reduced cholesterol solubility in lipid micelles, and inhibited cholesterol uptake in monolayer Caco-2 cells. They also bound tightly to taurocholate, deoxytaurocholate, and glycodeoxycholate which could lead to a reduced cholesterol absorption in the gut [106]. Soybean peptides LPYP, IAVPGEVA and IAVPTGVA have been reported to effectively activate the LDLR-SREBP 2 pathway and improve LDL uptake.…”

Unlocking the biological potential of proteins from edible insects through enzymatic hydrolysis: A review

“…Inhibition of -glucosidase may currently be used to reduce intestinal uptake of glucose and subsequently lower post-prandial hyperglycemia in type 2 diabetics (Umpierrez et al, 2017). Animal studies describing the antihypertensive (Onsa-ard et al, 2013;Yuan, Wang, & Zhou, 2012), antioxidant (Sangwong, Sumida, & Sutthikhum, 2016;Yuan et al, 2012), antidiabetic (Han, Lee, Lee, Suh, & Park, 2016;Jung et al, 2010), memory enhancement (Kang, Lee, Kang, & Kang, 2013) and hypocholesterolemic (Lapphanichayakool, Sutheerawattananonda, & Limpeanchob, 2017) properties of silk protein hydrolysates have been reported. However, it appears that, to date, BAPs and protein hydrolysates derived from edible insects (other than B. mori), having bioactive properties in vitro and in small animals, have not been extensively studied in comparison to silk protein-derived peptides (Xia et al, 2013).…”