Vasodilation and hypotension of a novel 3-benzylquinazolin- 4(3H)-one derivative via the inhibition of calcium flux

Therapeutic potentials of allicin in cardiovascular disease: advances and future directions

Cardiovascular disease (CVD) remains the predominant cause of mortality and disability worldwide. Against this backdrop, finding effective drugs for the pharmacological treatment of CVD has become one of the most urgent and challenging issues in medical research. Garlic (Allium sativum L.) is one of the oldest plants and is world-renowned for its dietary and medicinal values. Allicin (diallyl thiosulfinate) is one of the primary natural active ingredients in garlic, which has been proven to have powerful cardioprotective effects and mediate various pathological processes related to CVD, such as inflammatory factor secretion, myocardial cell apoptosis, oxidative stress, and more. Therefore, allicin holds a promising application prospect in the treatment of CVD. This review summarized the biological functions of allicin and its potential mechanisms in CVD, including antioxidation, anti-inflammation, and anti-apoptosis effects. Reckoning with these, we delved into recent studies on allicin's cardioprotective effects concerning various CVDs, such as atherosclerosis, hypertension, myocardial infarction, arrhythmia, cardiac hypertrophy, heart failure, and cardiotoxicity. Further, considering the tremendous advancement in nanomedicine, nanotechnology-based drug delivery systems show promise in addressing limitations of allicin's clinical applications, including improving its solubility, stability, and bioavailability. Through this review, we hope to provide a reference for further research on allicin in cardioprotection and drug development.

The Antiplatelet Action of S-Nitroso Human Serum Albumin in Whole Blood

Nitric oxide donors (NO-donors) have been shown to have therapeutic potential (e.g., ischemia/reperfusion injury). However, due to their release rate/antiplatelet properties, they may cause bleeding in patients. We therefore studied the antiplatelet effects of the two different NO-donors, i.e., S-NO-Human Serum Albumin (S-NO-HSA) and Diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate) in whole blood (WB) samples. WB samples were spiked with S-NO-HSA or DEA-NONOate (100 µmol/L or 200 µmol/L), and the NO release rate (nitrite/nitrate levels via HPLC) and antiplatelet efficacy (impedance aggregometry, platelet function analyzer, Cone-and-platelet analyzer, thrombelastometry) were assessed. S-NO-HSA had a significantly lower NO release compared to equimolar concentrations of DEA-NONOate. Virtually no antiplatelet action of S-NO-HSA was observed in WB samples, whereas DEA-NONOate significantly attenuated platelet function in WB. Impedance aggregometry measurements revealed that Amplitudes (slope: −0.04022 ± 0.01045 ohm/µmol/L, p = 0.008) and Lag times (slope: 0.6389 ± 0.2075 s/µmol/L, p = 0.0051) were dose-dependently decreased and prolonged by DEA-NONOate. Closure times (Cone-and-platelet analyzer) were dose-dependently prolonged (slope: 0.3738 ± 0.1403 s/µmol/L, p = 0.0174 with collagen/ADP coating; slope: −0.5340 ± 0.1473 s/µmol/L, p = 0.0019 with collagen/epinephrine coating) by DEA-NONOate. These results in WB further support the pharmacological potential of S-NO-HSA as an NO-donor due to its ability to presumably prevent bleeding events even at high concentrations up to 200 µmol/L.

Antihypertensive effects of allicin on spontaneously hypertensive rats via vasorelaxation and hydrogen sulfide mechanisms

BACKGROUND

Allicin, the principle active constituent in garlic, has been reported to have antihypertensive effects on drug-induced hypertension or renal hypertension in rats, but reports on spontaneously hypertensive rats (SHRs) are rare. Allicin is comprised of a variety of sulfur-containing compounds, and hydrogen sulfide (H₂S) has been shown to have specific vasomotor effects. We therefore hypothesize that allicin may exert a vasorelaxant activity by inducing H₂S production, and this eventually result in a reduction in blood pressure in SHRs.

METHODS

The in vivo antihypertensive effect of allicin was assessed using a tail-cuff method on SHRs. The in vitro vasorelaxant effect and in-depth mechanisms of allicin were explored on rat mesenteric arterial rings (RMARs) isolated from SD rats.

RESULTS

In the in vivo study, administration of allicin (7 mg/kg and 14 mg/kg, 4 weeks, i.g) dramatically decreased the blood pressure in SHRs, which was also shown to be attenuated by H₂S synthase inhibitor (PAG, 32 mg/kg, i.g). In in vitro studies, allicin (2.50-15.77 mM) produced a concentration-dependent vasorelaxation on RMARs, which was obviously reduced by preincubation with PAG. The removal of endothelium led to a decline in allicin's vasorelaxation, which was almost completely mitigated when treatment was followed with PAG. Inhibitors of nitric oxide (NO) and prostaglandin (PGI₂) pathways separately suppressed the vasorelaxation induced by allicin to a certain degree. When the RMARs incubated with PAG were treated with or without the above inhibitors in separate groups, the relaxations caused by allicin were almost identical under both these conditions. Moreover, allicin treatment increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) levels (downstream products of NO and PGI₂ pathways), which was decreased by PAG. Additionally, allicin increased the acetylcholine-induced endothelium-derived hyperpolarizing factor (EDHF) -mediated relaxation, which was unaffected by PAG.

CONCLUSION

Allicin exhibits a potent antihypertensive effect through vasodilatory properties and H₂S mechanisms. Moreover, the vasodilation of allicin is partially dependent on endothelium. The endothelium-dependent vasodilation of allicin is mediated by the NO-sGC-cGMP, PGI₂-AC-cAMP and EDHF pathways, of which H₂S participates in the first two but not the third one. The endothelium independent vasodilation can be predominantly attributed to H₂S production.