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−1 day−1, 50 mg kg−1 day−1, and 200 mg kg−1 day−1) 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.
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The authors thank Dr. Norman Scholfield for manuscript preparation. This research project was supported by Agricultural Research Development Agency (ARDA), and the Center of Excellence for Innovation in Chemistry (PERCH-CIC).
Conflict of interest
Phakhamon Lapphanichayakool declares no conflict of interest. The sponsor (ARDA), Manote Sutheerawattananonda, and Nanteetip Limpeanchob hold a patent WO2013/032411A1 in title silk-based bioactive oligopeptide compositions and manufacturing process thereof.
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Lapphanichayakool, P., Sutheerawattananonda, M. & Limpeanchob, N. Hypocholesterolemic effect of sericin-derived oligopeptides in high-cholesterol fed rats. J Nat Med 71, 208–215 (2017). https://doi.org/10.1007/s11418-016-1050-9
- Hypocholesterolemic effect
- Protein hydrolysate
- Bile acid binding
- Micellar solubility