Allicin relaxes isolated mesenteric arteries through activation of PKA-KATP channel in rat

Advances in the study of vascular related protective effect of garlic (Allium sativum) extract and compounds

Garlic (Allium sativum) is a functional food containing multiple bioactive compounds that find widespread applications in culinary and medicinal practices. It consists of multiple chemical components, including allicin and alliin. This article offers a comprehensive review of the protective effects of garlic extracts and their active constituents on the vascular system. In vitro and in vivo experiments have shown that garlic extracts and their active ingredients possess various bioactive properties. These substances demonstrate beneficial effects on blood vessels by demonstrating anti-inflammatory and antioxidant activities, inhibiting lipid accumulation and migration, preventing lipid peroxidation, promoting angiogenesis, reducing platelet aggregation, enhancing endothelial function, and inhibiting endothelial cell apoptosis. In clinical studies, garlic and its extracts have demonstrated their efficacy in managing vascular system diseases, including atherosclerosis, diabetes, and high cholesterol levels. In summary, these studies highlight the potential therapeutic roles and underlying mechanisms of garlic and its constituents in managing conditions like diabetes, atherosclerosis, ischemic diseases, and other vascular disorders.

Regulation of blood pressure by natural sulfur compounds: Focus on their mechanisms of action

Natural sulfur compounds are emerging as therapeutic options for the management of hypertension and prehypertension. They are mainly represented by polysulfides from Alliaceae (i.e., garlic) and isothiocyanates from Brassicaceae (or crucifers). The beneficial cardiovascular effects of these compounds, especially garlic polysulfides, are well known and widely reported both in preclinical and clinical studies. However, only a few authors have linked the ability of natural sulfur compounds to induce vasorelaxation and subsequent antihypertensive effects with their ability to release hydrogen sulfide (H₂S) in biological tissue. H₂S is an endogenous gasotransmitter involved in vascular tone regulation. Some cardiovascular diseases, such as hypertension, are associated with lower plasma H₂S levels. Consequently, exogenous sources of H₂S (H₂S donors) have been designed and synthesized or identified among secondary plant metabolites as potential therapeutic options. In addition to antioxidant effects due to its chemical properties as a reducing agent, H₂S induces vasorelaxation by interacting with a range of molecular targets. The mechanisms of action accounting for H₂S-induced vasodilation include opening of vascular potassium channels (such as ATP-sensitive (K_ATP) and voltage-operated (Kv7) channels), inhibition of 5-phosphodiesterase (5-PDE), and activation of vascular endothelial growth factor receptor-2 (VEGFR-2). These effects may be attributed to H₂S-induced S-persulfidation (or S-sulfhydration), which is a posttranslational modification of cysteine residues of many types of proteins resulting in structural and functional alterations (activation/inhibition). Thus, H₂S donors, such as natural sulfur compounds, are promising antihypertensive agents with novel mechanisms of action.

Current studies and potential future research directions on biological effects and related mechanisms of allicin

Allicin, a thiosulfonate extract from freshly minced garlic, has been reported to have various biological effects on different organs and systems of animals and human. It can reduce oxidative stress, inhibit inflammatory response, resist pathogen infection and regulate intestinal flora. In addition, dozens of studies also demonstrated allicin could reduce blood glucose level, protect cardiovascular system and nervous system, and fight against cancers. Allicin was widely used in disease prevention and health care. However, more investigations on human cohort study are needed to verify the biological or clinical effects of allicin in the future. In this review, we summarized the biological effects of allicin from previous outstanding and valuable studies and provided useful information for future studies on the health effects of allicin.

Protective Effects of Allicin on Acute Myocardial Infarction in Rats via Hydrogen Sulfide-mediated Regulation of Coronary Arterial Vasomotor Function and Myocardial Calcium Transport

Acute myocardial infarction (AMI) is a condition with high morbidity and mortality, for which effective treatments are lacking. Allicin has been reported to exert therapeutic effects on AMI, but the underlying mechanisms of its action have not been fully elucidated. To investigate this, a rat model of AMI was generated by ligating the left anterior descending branch of the coronary artery. DL-propargylglycine (PAG), a specific hydrogen sulfide (H₂S) synthetase inhibitor, was used to examine the effects of allicin on H₂S production. Isolated coronary arteries and cardiomyocytes were assessed for vascular reactivity and cellular Ca²⁺ transport using a multiwire myography system and a cell-contraction-ion detection system, respectively. Allicin administration improved cardiac function and myocardial pathology, reduced myocardial enzyme levels, and increased H₂S and H₂S synthetase levels. Allicin administration resulted in concentration-dependent effects on coronary artery dilation, which were mediated by receptor-dependent Ca²⁺ channels, ATP-sensitive K⁺ channels, and sarcoplasmic reticulum (SR) Ca²⁺ release induced by the ryanodine receptor. Allicin administration improved Ca²⁺ homeostasis in cardiomyocytes by increasing cardiomyocyte contraction, Ca²⁺ transient amplitude, myofilament sensitivity, and SR Ca²⁺ content. Allicin also enhanced Ca²⁺ uptake via SR Ca²⁺-ATPase and Ca²⁺ removal via the Na⁺/Ca²⁺ exchanger, and it reduced SR Ca²⁺ leakage. Notably, the protective effects of allicin were partially attenuated by blockade of H₂S production with PAG. Our findings provide novel evidence that allicin-induced production of H₂S mediates coronary artery dilation and regulation of Ca²⁺ homeostasis in AMI. Our study presents a novel mechanistic insight into the anti-AMI effects of allicin and highlights the therapeutic potential of this compound.

Activation of Inward Rectifier K+ Channel 2.1 by PDGF-BB in Rat Vascular Smooth Muscle Cells through Protein Kinase A

Platelet-derived growth factor-BB (PDGF-BB) can induce the proliferation, migration, and phenotypic modulation of vascular smooth muscle cells (VSMCs). We used patch clamp methods to study the effects of PDGF-BB on inward rectifier K⁺ channel 2.1 (Kir2.1) channels in rat thoracic aorta VSMCs (RASMCs). PDGF-BB (25 ng/mL) increased Kir2.x currents (−11.81 ± 2.47 pA/pF, P < 0.05 vs. CON, n = 10). Ba²⁺(50 μM) decreased Kir2.x currents (−2.13 ± 0.23 pA/pF, P < 0.05 vs. CON, n = 10), which were promoted by PDGF-BB (−6.98 ± 1.03 pA/pF). PDGF-BB specifically activates Kir2.1 but not Kir2.2 and Kir2.3 channels in HEK-293 cells. The PDGF-BB-induced stimulation of Kir2.1 currents was blocked by the PDGF-BB receptor β (PDGF-BBRβ) inhibitor AG1295 and was not affected by the PDGF-BBRα inhibitor AG1296. The PDGF-BB-induced stimulation of Kir2.1 currents was blocked by the protein kinase A inhibitor Rp-8-CPT-cAMPs; however, the antagonist of protein kinase B (GSK690693) had marginal effects on current activity. The PDGF-BB-induced stimulation of Kir2.1 currents was enhanced by forskolin, an adenylyl cyclase (AC) activator, and was blocked by the AC inhibitor SQ22536. We conclude that PDGF-BB increases Kir2.1 currents via PDGF-BBRβ through activation of cAMP-PKA signaling in RASMCs.

BPA and Nutraceuticals, Simultaneous Effects on Endocrine Functions

Background

Bisphenol A (BPA) is worldwide diffused as a monomer of epoxy resins and polycarbonate plastics and has recognized activity as Endocrine Disruptor (ED). It is capable to interfere or compete with endogenous hormones in many physiological activities thus having adverse outcomes on health. Diet highly affects health status and in addition to macronutrients, provides a large number of substances with recognized pro-heath activity, and thus called nutraceuticals.

Objective

This mini-review aims at summarizing the possible opposite and simultaneous effects of BPA and nutraceuticals on endocrine functions. The possibility that diet may represent the first instrument to preserve health status against BPA damages has been discussed.

Methods

The screening of recent literature in the field has been carried out.

Results

The therapeutic and anti-oxidant properties of many nutraceuticals may reverse the adverse health effects of BPA.

Conclusion

In vitro and in vivo studies provided evidence that nutraceuticals can preserve the health. Thus, the use of nutraceuticals can be considered a support for clinical treatment. In conclusion, dietary remediation may represent a successful therapeutic approach to maintain and preserve health against BPA damage.

Allicin suppresses the migration and invasion in cervical cancer cells mainly by inhibiting NRF2

Emerging evidence has demonstrated the antitumor activity of allicin in various tumors. However, little study has been carried out on the functional role of allicin in cervical cancer. Our data showed that allicin suppressed cervical cancer cell viability in a time- and dose-dependent manner. Allicin treatment could reverse H₂O₂-induced reactive oxygen species accumulation. Meanwhile, levels of glutathione and superoxide dismutase were increased, but malondialdehyde was decreased after allicin incubation for 48 h. Furthermore, TUNEL staining showed that H₂O₂ treatment induced cell apoptosis, but allicin treatment could decrease cell apoptosis. Western blot assay showed that allicin could suppress the expression of nuclear factor erythroid 2-related factor 2 (NRF2) and heme oxygenase 1. We also showed that NRF2 prompted SiHa cell proliferation and reduced SiHa cell apoptosis. More importantly, allicin-inactivated phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) signaling could be partially reversed by overexpressing of NRF2. We also evaluated cell apoptosis in SiHa cells transfected with plasmid NRF2. Our data showed that allicin-induced cell apoptosis (43.5±3.8%) could largely be abolished by upregulation of NRF2 (12.3±2.08%). In summary, our data showed allicin was effective in suppressing the malignant phenotype of cervical cancer cells mainly by inhibiting the expression of NRF2, showing the potential clinical benefits of allicin in cervical cancer patients.

Diallyl trisulfide regulates rat colonic smooth muscle contractions by inhibiting L-type calcium channel currents

Diallyl trisulfide (DATS) is an active organosulfide component of allicin and has several beneficial effects, including antimicrobial, antioxidant, cardioprotective and anticancer effects. Few studies have shown the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle cells and colonic motility. To investigate the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle and colonic contraction, L-type calcium channel currents were recorded, and colonic contractility in longitudinal and circular smooth muscle strips was measured. DATS attenuated L-type calcium channel currents without affecting steady-state activation or inactivation kinetics and inhibited the spontaneous contractions of both longitudinal and circular smooth muscle strips dose-dependently. In conclusion, DATS has an inhibitory effect on the contractions of colonic muscle strips that is related to its regulation of L-type calcium channels.

Alterations of ATP-sensitive K+ channels in human umbilical arterial smooth muscle during gestational diabetes mellitus

We investigated the alterations of ATP-sensitive K⁺ (K_ATP) channels in human umbilical arterial smooth muscle cells during gestational diabetes mellitus (GDM). The amplitude of the K_ATP current induced by application of the K_ATP channel opener pinacidil (10 μM) was reduced in the GDM group than in the control group. Pinacidil-induced vasorelaxation was also predominant in the normal group compared with the GDM group. Reverse transcription polymerase chain reaction and Western blot analysis suggested that the expression of K_ATP channel subunits such as Kir6.1, Kir6.2, and SUR2B were decreased in the GDM group relative to the normal group. The application of forskolin and adenosine, which activates protein kinase A (PKA) and thereby K_ATP channels, elicited K_ATP current in both the normal and GDM groups. However, the current amplitudes were not different between the normal and GDM groups. In addition, the expression levels of PKA subunits were not altered between the two groups. These results suggest that the reduction of K_ATP current and K_ATP channel-induced vasorelaxation are due to the decreased expression of K_ATP channels, not to the impairment of K_ATP-related signaling pathways.

Neuroprotective effects of allicin on ischemia-reperfusion brain injury

BACKGROUND

Ischemia-reperfusion brain injury (IRBI) is an important cause for mortality and morbidity. Studies on humans and animals showed that oxidative stress (OS) plays a crucial role in ischemic stroke with or without reperfusion. Allicin is reported to be able to attenuate OS and has neuroprotective effects on rabbits' ischemia-reperfusion spinal cord injury.

AIM

To explore whether Allicin pretreatment has neuroprotective effects on IRBI in mice.

METHODS AND RESULTS

Transient middle cerebral artery occlusion (MCAO) was conducted to induce IRBI in mice. The mice were pretreated with either Allicin (MCAOA) or normal saline in the same volume (MCAONS). Sham-operated groups [Allicin group (SOA) and normal saline group (SONS)] were also set. Blood pressure and cerebral blood flow measurements revealed comparable hemodynamics. Via brain MRI and neuronal nuclear antigen (NeuN) immune-histochemical staining, MCAOA mice had a significantly reduced stroke size than MCAONS mice (P < 0.05, n = 15). Allicin pretreatment could attenuate the OS, the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, inflammation, dysfunction of mitochondrial respiratory chain, and apoptosis (all P < 0.05, n = 15). Furthermore, Allicin also increased the activities of endogenous antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), and glutathione S-transferase (GST), and promoted the angiogenesis in the peri-infarct zone (all P < 0.05, n = 15).

CONCLUSION

We showed that Allicin could protect mice from IRBI through a series of mechanisms. Allicin represents a new therapeutic direction of IRBI.