Hypotensive and Vasorelaxant Effects of Sericin-Derived Oligopeptides in Rats

Abstract

Sericin-derived oligopeptides obtained from silk cocoons were investigated for the in vivo hypotensive effect and investigated for the underlying mechanism involved in vasodilation in isolated rat thoracic aorta. In normotensive anesthetized rats, oligopeptides induced an immediate and transient hypotensive activity. In rat aortic rings, oligopeptides induced a concentration-dependent vasorelaxation in vessels precontracted with both KCl and phenylephrine (PE) with endothelium-intact or endothelium-denuded rings. In endothelium-intact rings, pretreatment with Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME, 100 µM), an inhibitor of the NO synthase (NOS) or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 1 µM), a selective inhibitor of the guanylyl cyclase enzyme, significantly reduced the relaxant effect of oligopeptides. However, indomethacin, an inhibitor of the cyclooxygenase, had no effect on oligopeptides-induced relaxation. In addition, pretreatment with tetraethylammonium (TEA, 5 mM) reduced the maximal relaxant effect induced by oligopeptides. By contrast, relaxation was not affected by 4-aminopyridine (4-AP, 1 mM), glibenclamide (10 µM), or barium chloride (BaCl2, 1 mM). In depolarization Ca2+-free solution, oligopeptides inhibited calcium chloride- (CaCl2-) induced contraction in endothelium-denuded rings in a concentration-dependent manner. Nevertheless, oligopeptides attenuated transient contractions in Ca2+-free medium containing EGTA (1 mM) induced by 1 µM PE, but they were not affected by 20 mM caffeine. It is obvious that potent vasodilation effect of oligopeptides is mediated through both the endothelium and the vascular smooth muscle.

Silkworm Sericin: Properties and Biomedical Applications

“…Enzyme extraction is also used by other authors [52–55]. The use of enzyme to extract sericin from cocoon can be attributed to the discovery of cocoonase, a group of proteinases, which can attack the sericin bindings.…”

“…Bioactive peptides derived from dietary proteins are important in modulating physiological functions [143], and Onsa-ard et al [55] demonstrated that sericin, particularly oligopeptides with less than 5 kDa, has hypotensive potential, promoting vasodilation and relaxation of smooth muscle of the artery wall, whose temporary effect is dose-dependent. The authors believe that the oligopeptides of the sericin can have an antagonistic action on calcium channels by blocking them, leading to muscle relaxation.…”

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).…”

Silk‐Based Biomaterials for Cardiac Tissue Engineering

“…[ 128 ] Moreover, we confirmed that SS inhibited the activation of caspase‐3 to protect ECs and CMs from apoptosis. [ 125 ] Apart from these bioactivities, SS has been reported to possess beneficial effects including resisting oxidation, [ 129 ] anticoagulating activity, [ 130 ] antibacterial effect, [ 131 ] and lowering blood pressure, [ 132 ] thereby reducing the adverse factors of CVDs.…”