Characterization of antidiabetic and antihypertensive properties of canary seed (Phalaris canariensis L.) peptides.

Canary grass is used as traditional food for diabetes and hypertension treatment. The aim of this work is to characterize the biological activity of encrypted peptides released after gastrointestinal digestion of canary seed proteins. Canary peptides showed 43.5% inhibition of dipeptidyl peptidase IV (DPPIV) and 73.5% inhibition of angiotensin-converting enzyme (ACE) activity. An isolated perfused rat heart system was used to evaluate the canary seed vasoactive effect. Nitric oxide (NO), a major vasodilator agent, was evaluated in the venous effluent from isolated perfused rat heart. Canary seed peptides (1 µg/mL) were able to induce the production of NO (12.24 µM) in amounts similar to those induced by captopril (CPT) and bradykinin (BK). These results show that encrypted peptides in canary seed have inhibitory activity against DPPIV and ACE, enzymes that are targets for diabetes and hypertension treatments.

Effect of 45 nm silver nanoparticles (AgNPs) upon the smooth muscle of rat trachea: role of nitric oxide.

AgNPs have been used to manufacture nanomaterials with new biophysical properties and functions. However, few experimental approaches have been used to assess their potential toxic or beneficial effects on human health, in association with the size, concentration, and biological target. The aim of this work was to evaluate the effects of the AgNPs on the smooth muscle of rat trachea. A single administration of AgNPs did not modify the smooth muscle tone, but, when the trachea rings were pre-treated with acetylcholine (ACh), AgNPs produced a contractile effect. Simultaneous administration of AgNPs and ACh resulted in a slight increase of smooth muscle contractility induced by ACh. AgNPs pretreatment followed by ACh administration showed that AgNPs exerted an important contraction effect induced by ACh after which muscle tone did not return to the basal level. This effect was associated with an increase in the production of nitric oxide (NO). The contractile response of the AgNPs induced by ACh was completely blocked when the rings were incubated, after the ACh but before the AgNPs administration, with 1400 W (NO blocker). The contractile effect was also abolished by atropine, which suggests that AgNPs alter ACh muscarinic receptor signaling. These data also show that AgNPs modify the contractile action of ACh through NO production and possibly induce hyper-reactivity of tracheal smooth muscle.

Effects of 45-nm silver nanoparticles on coronary endothelial cells and isolated rat aortic rings.

This study was undertaken to determine whether silver nanoparticles (Ag-45 nm NPs) induce selective and specific biological effects, such as induction of proliferation and nitric oxide (NO) production, and cytotoxicity in coronary endothelial cells (CECs), and regulation of vascular tone in isolated rat aortic rings. Physical characterization of Ag-45 nm NPs by transmission electron microscopy (TEM) demonstrated that nanoparticles ranging in size from 10 to 90 nm had biological effects on CECs. Increasing concentrations of Ag-45 nm NPs exerted a dual effect on cell proliferation whereby proliferation was inhibited at low concentrations of NPs and stimulated at high concentrations. The effects of high, but not low, concentrations of Ag-45 nm NPs were dependent on NO because the effects were partially blocked by N(G)-nitro-L-arginine methyl ester (L-NAME). We have also shown that high, but not low, concentrations of Ag-45 nm NPs induce NO-dependent proliferation through activation of endothelial nitric oxide synthase (eNOS) by phosphorylation of Serine 1177. Moreover, the antiproliferative and proliferative effects of Ag-45 nm NPs were concentration-dependent and inversely correlated with cellular toxicity. In isolated rat aortic rings, a low concentration of NPs induced vasoconstriction and a high concentration stimulated vasodilation. The physiologic effects induced by a low concentration of Ag-45 nm NPs inhibited acetylcholine- (ACh-) induced NO-mediated relaxation. Vasodilation induced by a high concentration of NPs was partially abolished by L-NAME pretreatment. When the endothelium was removed from the rings, all physiologic responses were blocked. These results clearly demonstrate that the NPs have selective and specific effects on the vascular endothelium in a concentration-dependent manner and suggest that opposite effects could be associated with NPs of different sizes.