Allicin protects rat cardiomyoblasts (H9c2 cells) from hydrogen peroxide-induced oxidative injury through inhibiting the generation of intracellular reactive oxygen species

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.

A Review on Therapeutic Potential of Natural Phytocompounds for Stroke

Stroke is a serious condition that results from an occlusion of blood vessels that leads to brain damage. Globally, it is the second highest cause of death, and deaths from strokes are higher in older people than in the young. There is a higher rate of cases in urban areas compared to rural due to lifestyle, food, and pollution. There is no effective single medicine for the treatment of stroke due to the multiple causes of strokes. Thrombolytic agents, such as alteplase, are the main treatment for thrombolysis, while multiple types of surgeries, such ascraniotomy, thrombectomy, carotid endarterectomy, and hydrocephalus, can be performed for various forms of stroke. In this review, we discuss some promising phytocompounds, such as flavone C-glycoside (apigenin-8-C-β-D-glucopyranoside), eriodictyol, rosamirinic acid, 6″-O-succinylapigenin, and allicin, that show effectiveness against stroke. Future study paths are given, as well as suggestions for expanding the use of medicinal plants and their formulations for stroke prevention.

Cellular Mechanisms Underlying the Cardioprotective Role of Allicin on Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a group of diseases in which the common denominator is the affection of blood vessels, heart tissue, and heart rhythm. The genesis of CVD is complex and multifactorial; therefore, approaches are often based on multidisciplinary management and more than one drug is used to achieve the optimal control of risk factors (dyslipidemia, hypertension, hypertrophy, oxidative stress, endothelial dysfunction, inflammation). In this context, allicin, a sulfur compound naturally derived from garlic, has shown beneficial effects on several cardiovascular risk factors through the modulation of cellular mechanisms and signaling pathways. Effective pharmacological treatments for CVD or its risk factors have not been developed or are unknown in clinical practice. Thus, this work aimed to review the cellular mechanisms through which allicin exerts its therapeutic effects and to show why it could be a therapeutic option for the prevention or treatment of CVD and its risk factors.

Effects of Voghiera garlic extracts in neuronal human cell line against zearalenone's derivates and beauvericin

The Fusarium toxins constitute one of the largest groups of mycotoxins produced by Fusarium species, which are major pathogens of cereal plants. In the present study neuroprotection effect of Allium sativum L garlic extract which is known as Voghiera garlic, from a local garlic ecotype of Ferrara (Italy) was examined on an undifferentiated SH-SY5Y neuronal cells against ZEA's metabolites (α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL)) and beauvericin (BEA) mycotoxins which are considered as the most reported Fusarium mycotoxins, via MTT (3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, over 24 h and 48 h through direct treatment, simultaneous treatment and pre-treatment strategies. The results demonstrated remarkable improvement in cells viability in simultaneous and pre-treatment strategy with Voghiera garlic extract (VGE); specifically, for simultaneous treatment of VGE with β-ZEL which viability increased significantly up to 56%, and subsequently with α-ZEL and BEA by up to 38% and 37% respectively, compared to each mycotoxin tested alone for their highest concentrations assayed, while direct treatments for each mycotoxins individually decreased significantly (for α-ZEL up to 69%, for β-ZEL 82% and for BEA up to 43%). It is proposed by the present study that VGE extract found to be effective in reducing the cytotoxicity/neurotoxicity of α-ZEL, β-ZEL and BEA mycotoxins encountered in food and feed commodity.

Targeting Myeloperoxidase (MPO) Mediated Oxidative Stress and Inflammation for Reducing Brain Ischemia Injury: Potential Application of Natural Compounds

Oxidative stress and inflammation are two critical pathological processes of cerebral ischemia-reperfusion injury. Myeloperoxidase (MPO) is a critical inflammatory enzyme and therapeutic target triggering both oxidative stress and neuroinflammation in the pathological process of cerebral ischemia-reperfusion injury. MPO is presented in infiltrated neutrophils, activated microglial cells, neurons, and astrocytes in the ischemic brain. Activation of MPO can catalyze the reaction of chloride and H2O2 to produce HOCl. MPO also mediates oxidative stress by promoting the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), modulating the polarization and inflammation-related signaling pathways in microglia and neutrophils. MPO can be a therapeutic target for attenuating oxidative damage and neuroinflammation in ischemic stroke. Targeting MPO with inhibitors or gene deficiency significantly reduced brain infarction and improved neurological outcomes. This article discusses the important roles of MPO in mediating oxidative stress and neuroinflammation during cerebral ischemia-reperfusion injury and reviews the current understanding of the underlying mechanisms. Furthermore, we summarize the active compounds from medicinal herbs with potential as MPO inhibitors for anti-oxidative stress and anti-inflammation to attenuate cerebral ischemia-reperfusion injury, and as adjunct therapeutic agents for extending the window of thrombolytic treatment. We highlight that targeting MPO could be a promising strategy for alleviating ischemic brain injury, which merits further translational study.

Effect of Allicin against Ischemia/Hypoxia-Induced H9c2 Myoblast Apoptosis via eNOS/NO Pathway-Mediated Antioxidant Activity

Allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester, diallyl thiosulfinate) is the main biologically active ingredient in garlic. The present study investigated the protective effect of allicin against cardiomyocyte apoptosis that was induced by ischemia in vitro and the potential molecular mechanisms that were involved in this antiapoptotic effect. The results indicated that allicin increased H9c2 cell activity and attenuated the rate of apoptosis that was induced by ischemia/hypoxia. Intracellular calcium concentrations significantly decreased in the allicin-treated groups. Bax expression significantly decreased, and Bcl-2 expression increased in allicin-treated rats. Nitric oxide blockade significantly inhibited these effects. Allicin also increased the activity of SOD and NO release and decreased MDA levels. Allicin significantly increased the expression of eNOS, Nrf2, and HO-1 proteins. Collectively, these findings demonstrate that allicin protects H9c2 cells against apoptosis, and this protective effect appears to occur via eNOS/NO pathway-mediated antioxidant activity.

Allicin Alleviates Reticuloendotheliosis Virus-Induced Immunosuppression via ERK/Mitogen-Activated Protein Kinase Pathway in Specific Pathogen-Free Chickens

Reticuloendotheliosis virus (REV), a gammaretrovirus in the Retroviridae family, causes an immunosuppressive, oncogenic, and runting-stunting syndrome in multiple avian hosts. Allicin, the main effective component of garlic, has a broad spectrum of pharmacological properties. The hypothesis that allicin could relieve REV-induced immune dysfunction was investigated in vivo and in vitro in the present study. The results showed that dietary allicin supplementation ameliorated REV-induced dysplasia and immune dysfunction in REV-infected chickens. Compared with the control groups, REV infection promoted the expression of inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-10, interferon (IFN)-γ, and tumor necrosis factor-α (TNF-α), whereas, allicin reversed these changes induced by REV infection. The decreased levels of IFN-α, IFN-β, and IL-2 were observed in REV-infected chickens, which were significantly improved by allicin. Allicin suppressed the REV-induced high expression of toll-like receptors (TLRs) as well as melanoma differentiation-associated gene 5 (MDA5) and the activation of mitogen-activated protein kinase (MAPK) and the nuclear factor kappa B p65. REV stimulated the phosphorylation of JNK, ERK, and p38, the downstream key signaling molecules of MAPK pathway, while allicin retarded the augmented phosphorylation level induced by REV infection. The decreased phosphorylation level of ERK was associated with REV replication, suggesting that ERK signaling is involved in REV replication, and allicin can alleviate the REV-induced immune dysfunction by inhibiting the activation of ERK. In addition, REV infection induced oxidative damage in thymus and spleen, whereas allicin treatment significantly decreased the oxidative stress induced by REV infection, suggesting that the antioxidant effect of allicin should be at least partially responsible for the harmful effect of REV infection. In conclusion, the findings suggest that allicin alleviates the inflammation and oxidative damage caused by REV infection and exerts the potential anti-REV effect by blocking the ERK/MAPK pathway.

Allicin protects against H2O2-induced apoptosis of PC12 cells via the mitochondrial pathway

Allicin is a major bioactive ingredient of garlic and has a broad range of biological activities. Allicin has been reported to protect against cell apoptosis induced by H₂O₂ in human umbilical vein endothelial cells. The present study evaluated the neuroprotective effect of allicin on the H₂O₂-induced apoptosis of rat pheochromocytoma PC12 cells in vitro and explored the underlying mechanism involved. PC12 cells were incubated with increasing concentrations of allicin and the toxic effect of allicin was measured by MTT assay. The cells were pretreated for 24 h with low dose (L-), medium dose (M-) and high dose (H-) of allicin, followed by exposure to 200 µM H₂O₂ for 2 h, and the cell viability was examined by MTT assay. In addition, cell apoptosis rate was analyzed by Annexin V-FITC/PI assay, while intracellular reactive oxygen species (ROS) and mitochondrial transmembrane potential (∆ψm) were measured by flow cytometry. Bcl-2, Bax, cleaved-caspase-3 and cytochrome c (Cyt C) in the mitochondria were also examined by western blotting. The results demonstrated that 0.01 µg/ml (L-allicin), 0.1 µg/ml (M-allicin) and 1 µg/ml (H-allicin) were non-toxic doses of allicin. Furthermore, H₂O₂ reduced cell viability, promoted cell apoptosis, induced ROS production and decreased ∆ψm. However, allicin treatment reversed the effect of H₂O₂ in a dose-dependent manner. It was also observed that H₂O₂ exposure significantly decreased Bcl-2 and mitochondrial Cyt C, while it increased Bax and cleaved-caspase-3, which were attenuated by allicin pretreatment. The results revealed that allicin protected PC12 cells from H₂O₂-induced cell apoptosis via the mitochondrial pathway, suggesting the potential neuroprotective effect of allicin against neurological diseases.

Allicin protects traumatic spinal cord injury through regulating the HSP70/Akt/iNOS pathway in mice

Allicin is a major component of garlic, extracted as an oily liquid. The present study was designed to investigate the beneficial effects of allicin on traumatic spinal cord injury (TSCI) in mice, and whether the effects are mediated via regulation of the heat shock protein 70 (HSP70), v-akt murine thymoma viral oncogene homolog 1 (Akt) and inducible nitric oxide synthase (iNOS) pathways. Adult BALB/c mice (30–40 g) received a laminectomy at the T9 vertebral level as a model of TSCI. In the present study, treatment of the TSCI mice with allicin significantly increased their Basso, Beattie and Bresnahan (BBB) scores (P<0.01) and reduced the spinal cord water content (P<0.01). This protective effect was associated with the inhibition of oxidative stress and inflammatory responses in TSCI mice. Western blot analysis demonstrated that allicin increased the protein levels of HSP70, increased the phosphorylation of Akt and reduced the iNOS protein expression levels in TSCI mice. Additionally, treatment with allicin significantly reduced the levels of ROS and enhanced the NADH levels in TSCI mice. Collectively, these data demonstrate that the effects of allicin on TSCI are mediated via regulation of the HSP70, Akt and iNOS pathways in mice.

Allicin inhibits oxidative stress-induced mitochondrial dysfunction and apoptosis by promoting PI3K/AKT and CREB/ERK signaling in osteoblast cells

Osteoporosis is a disease of the skeleton that is characterized by the loss of bone mass and degeneration of bone microstructure, resulting in an increased risk of fracture. Oxidative stress, which is known to promote oxidative damage to mitochondrial function and also cell apoptosis, has been recently indicated to be implicated in osteoporosis. However, there are few agents that counteract oxidative stress in osteoporosis. In the present study, the protective effects of allicin against the oxidative stress-induced mitochondrial dysfunction and apoptosis were investigated in murine osteoblast-like MC3T3-E1 cells. The results demonstrated that allicin counteracted the reduction of cell viability and induction of apoptosis caused by hydrogen peroxide (H₂O₂) exposure. The inhibition of apoptosis by allicin was confirmed by the inhibition of H₂O₂-induced cytochrome c release and caspase-3 activation. Moreover, the inhibition of apoptosis by allicin was identified to be associated with the counteraction of H₂O₂-induced mitochondrial dysfunction. In addition, allicin was demonstrated to be able to significantly ameliorate the repressed phosphoinositide 3-kinase (PI3K)/AKT and cyclic adenosine monophosphate response element-binding protein (CREB)/extracellular-signal-regulated kinase (ERK) signaling pathways by H₂O₂, which may also be associated with the anti-oxidative stress effects of allicin. In conclusion, allicin protects osteoblasts from H₂O₂-induced oxidative stress and apoptosis in MC3T3-E1 cells by improving mitochondrial function and the activation of PI3K/AKT and CREB/ERK signaling. The present study implies a promising role of allicin in oxidative stress-associated osteoporosis.

Allicin improves endoplasmic reticulum stress-related cognitive deficits via PERK/Nrf2 antioxidative signaling pathway

Endoplasmic reticulum (ER) stress is involved in neurodegenerative diseases including Alzheimer's disease (AD), in which dysregulation of double-stranded RNA-dependent protein kinase (PKR)-like ER-resident kinase (PERK) is considered to play a critical role. Allicin, a garlic extract, has been demonstrated a protective role in AD model. The present study was designed to investigate the possible protective effect of allicin on ER stress-induced cognitive deficits and underlying mechanisms in rats. In this study, 72h of lateral ventricular infusion of tunicamycin (TM), an ER stress stimulator, induced significant cognitive deficits. TM increased tau phosphorylation, Aβ42 deposit, and oxidative stress, and reduced antioxidative enzymes activity in the hippocampus. TM moderately elevated the expression of PERK and its downstream substrate nuclear factor erythroid-derived 2-like 2 (Nrf2) in the hippocampus. All these impaired changes by TM were significantly improved by allicin pretreatment. Allicin markedly increased PERK and Nrf2 expression in the hippocampus. Thus, our data demonstrate the protective role of allicin in ER stress-related cognitive deficits, and suggest that PERK/Nrf2 antioxidative signaling pathway underlies the action mechanism.

Protective effects of allicin against ischemic stroke in a rat model of middle cerebral artery occlusion

Allicin, a molecule predominantly responsible for the pungent odor and the antibiotic function of garlic, exhibits various pharmacological activities and has been suggested to be beneficial in the treatment of various disorders. The present study aimed to elucidate the effect of allicin in cerebral ischemia/reperfusion (I/R) injury in rats. Rats were subjected to 1.5 h of transient middle cerebral artery occlusion (MCAO), followed by 24 h of reperfusion. Rats were randomly assigned to the sham surgery group, the MCAO group and the MCAO + allicin group. Neurological score, cerebral infarct size, brain water content, neuronal apoptosis, serum tumor necrosis factor (TNF)‑α and myeloperoxidase (MPO) activity were measured. The results suggested that allicin reduced cerebral infarction area, brain water content, neuronal apoptosis, TNF‑α levels and MPO activity in the serum. The results of the present study indicated that allicin protects the brain from cerebral I/R injury, which may be ascribed to its anti‑apoptotic and anti‑inflammatory effects.

Allicin Alleviates Dextran Sodium Sulfate- (DSS-) Induced Ulcerative Colitis in BALB/c Mice

The objective of this study is to evaluate the effect of allicin (10 mg/kg body weight, orally) in an experimental murine model of UC by administering 2.5% dextran sodium sulfate (DSS) in drinking water to BALB/c mice. DSS-induced mice presented reduced body weight, which was improved by allicin administration. We noted increases in CD68 expression, myeloperoxidase (MPO) activities, and Malonaldehyde (MDA) and mRNA levels of proinflammatory cytokines, such as tumor necrosis factor- (TNF-) α, interleukin- (IL-) 1β, IL-6, and IL-17, and decrease in the activities of enzymic antioxidants such as superoxide dismutase (SOD), Catalase (CAT), Glutathione reductase (GR), and Glutathione peroxidase (GPx) in DSS-induced mice. However, allicin treatment significantly decreased CD68, MPO, MDA, and proinflammatory cytokines and increased the enzymic antioxidants significantly (P < 0.05). In addition, allicin was capable of reducing the activation and nuclear accumulation of signal transducer and activator of transcription 3 (STAT3), thereby preventing degradation of the inhibitory protein IκB and inducing inhibition of the nuclear translocation of nuclear factor (NF)-κB-p65 in the colonic mucosa. These findings suggest that allicin exerts clinically useful anti-inflammatory effects mediated through the suppression of the NF-κB and IL-6/p-STAT3^Y705 pathways.