Allicin Treatment Research Articles

Allicin Could Potentially Alleviate Oral Cancer Pain by Inhibiting "Pain Mediators" TNF-alpha, IL-8, and Endothelin.

To evaluate the effects of allicin on mediators of pain secreted by oral cancer cells in vitro, single-cell suspensions were prepared by enzymatic method from oral squamous cell carcinoma (OSCC). Cancer stem cells were isolated by the CD133+ selection method with magnetic cell sorting. Stemness markers were checked in both cancer cells and cancer stem cells by RT-PCR. Comparative analysis of pain mediators TNF-alpha, IL-8, and endothelin at both RNA and protein levels for normal epithelial cells, cancer cells, and cancer stem cells was carried out with and without allicin treatment. CD133 and CD44 expression levels were checked in cancer cells and cancer stem cells flow cytometrically. Allicin inhibited both gene and protein expression of TNF-alpha, IL-8, and endothelin in both cancer cells and cancer stem cells. Allicin is more likely to be a promising treatment in alleviating the levels of pain and inflammation in OSCCs.

Allicin attenuates myocardial apoptosis, inflammation and mitochondrial injury during hypoxia-reoxygenation: an in vitro study

BackgroundMyocardial ischemia–reperfusion (IR) injury is a damage due to an initial reduction in blood flow to the heart, preventing it from receiving enough oxygen, and subsequent restoration of blood flow through the opening of an occluded coronary artery producing paradoxical harmful effects. The finding of new therapies to prevent IR is of utmost importance. Allicin is a compound isolated from garlic having the ability to prevent and cure different diseases, and a protective effect on the myocardium was also demonstrated. Therefore, the aim of this study was to evaluate the in vitro protective effect of Allicin against myocardial IR injury on cardiomyocytes.MethodsWe established an in vitro hypoxia-reoxygenation (HR) model of primary porcine cardiomyocytes to simulate myocardial IR injury. Primary porcine cardiomyocytes were extracted from Mini-musk swines (1 day old). After a period of adaptation of at least 2–3 days, cardiomyocytes in good condition were selected and randomly divided into control group (normal oxygen for 5 h), HR group (2 h of hypoxia/3 h of reoxygenation), and HR + Allicin group (hypoxia/reoxygenation + Allicin treatment).ResultsAfter the induction of hypoxia/reoxygenation, Allicin treatment enhanced the cell viability. Moreover, Allicin treatment resulted in a reduction of apoptosis from 13.5 ± 1.2% to 6.11 ± 0.15% compared with the HR group (p < 0.05), and the apoptosis related proteins were regulated as well, with a decreased expression of Bax, cleaved caspase-3 and cytosolic cytochrome C and an increase in Bcl-2 expression in the HR + Allicin group (all p < 0.01). Pro-inflammatory cytokines, such as interleukin-6 and tumor necrosis factor alpha were down-regulated by the treatment with Allicin (both p < 0.01). In addition, it significantly decreased intracellular reactive oxygen species generation (p < 0.01) and reduced the loss of mitochondrial membrane potential (p < 0.01). Furthermore, the expression of PPARγ coactivator-1α and endothelial nitric oxide synthase was up-regulated (both p < 0.01), while the expression of Endothelin-1, hypoxia inducing factor-1α and transforming growth factor beta was down-regulated (all p < 0.01) by Allicin treatment.ConclusionsThese results suggested that Allicin protected the cardiomyocytes against HR damage by reducing apoptosis, inflammation and mitochondrial injury, thus providing a basis for its potential use in the treatment of myocardial IR.

Allicin regulates Treg/Th17 balance in mice with collagen-induced arthritis by increasing the expression of MEKK2 protein.

To study the role of Allicin in regulating Treg/Th17 ratio in splenic lymphocyte by increasing the expression of MEKK2 protein in MAPK signaling pathway, and to explore the mechanism of immune response in mice with collagen‐induced arthritis (CIA). Mouse CIA model was induced by chicken collagen type II, and experimental mice were randomly divided into NC group, Model group, and Allicin group. HE staining was used to compare the degree of joint pathological damage in mice of each group, and Masson staining to observe the proliferation of collagen tissue in each group. Flow cytometry detected Treg/Th17 ratio in splenic lymphocytes. Furthermore, RT‐PCR and WB were used to detect the mRNA and protein expression of related transcription factors and inflammatory factors Foxp3, ROR‐γt, and IL‐17A, as well as MEK2 protein expression in splenic lymphocytes. The results showed that Allicin treatment could reduce the severity of arthritis and the proliferation of collagen fibers on the surface of cartilage and bone joints in CIA mice. Compared with NC group, Treg decreased and Th17 increased in spleen lymphocyte of Model group (p < .01); after Allicin treatment, Treg increased while Th17 decreased significantly (p < .01). Meanwhile, MEKK2 protein expression in spleen lymphocyte of Model group decreased compared to that in NC group (p < .01), and MEK2 protein expression increased significantly after Allicin treatment (p < .01). To sum up, the present study suggests that MEKK2 protein plays an important role in the pathogenesis of CIA model. In terms of mechanism, Allicin may play a therapeutic role in rheumatoid arthritis (RA) by increasing the expression of MEKK2 protein and affecting Treg/Th17 ratio.

Effects of Allicin on Pathophysiological Mechanisms during the Progression of Nephropathy Associated to Diabetes.

This study aimed to assess the impact of allicin on the course of diabetic nephropathy. Study groups included control, diabetes, and diabetes-treated rats. Allicin treatment (16 mg/kg day/p.o.) started after 1 month of diabetes onset and was administered for 30 days. In the diabetes group, the systolic blood pressure (SBP) increased, also, the oxidative stress and hypoxia in the kidney cortex were evidenced by alterations in the total antioxidant capacity as well as the expression of nuclear factor (erythroid-derived 2)-like 2/Kelch ECH associating protein 1 (Nrf2/Keap1), hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF), erythropoietin (Epo) and its receptor (Epo-R). Moreover, diabetes increased nephrin, and kidney injury molecule-1 (KIM-1) expression that correlated with mesangial matrix, the fibrosis index and with the expression of connective tissue growth factor (CTGF), transforming growth factor-β1 (TGF-β1), and α-smooth muscle actin (α-SMA). The insulin levels and glucose transporter protein type-4 (GLUT4) expression were decreased; otherwise, insulin receptor substrates 1 and 2 (IRS-1 and IRS-2) expression was increased. Allicin increased Nrf2 expression and decreased SBP, Keap1, HIF-1α, and VEGF expression. Concurrently, nephrin, KIM-1, the mesangial matrix, fibrosis index, and the fibrotic proteins were decreased. Additionally, allicin decreased hyperglycemia, improved insulin levels, and prevented changes in (GLUT4) and IRSs expression induced by diabetes. In conclusion, our results demonstrate that allicin has the potential to help in the treatment of diabetic nephropathy. The cellular mechanisms underlying its effects mainly rely on the regulation of antioxidant, antifibrotic, and antidiabetic mechanisms, which can contribute towards delay in the progression of renal disease.

Allicin-induced host-gut microbe interactions improves energy homeostasis.

Allicin (diallylthiosulfinate) is a natural food compound with multiple biological and pharmacological functions. However, the mechanism of beneficial role of Allicin on energy homeostasis is not well studied. Gut microbiota (GM) profoundly affects host metabolism via microbiota-host interactions and coevolution. Here, we investigated the interventions of beneficial microbiome induced by Allicin on energy homeostasis, particularly obesity, and related complications. Interestingly, Allicin treatment significantly improved GM composition and induced the most significant alteration enrichment of Bifidobacterium and Lactobacillus. Importantly, transplantation of the Allicin-induced GM to HFD mice (AGMT) played a remarkable role in decreasing adiposity, maintaining glucose homeostasis, and ameliorating hepatic steatosis. Furthermore, AGMT was effective in modulating lipid metabolism, activated brown adipose tissues (BATs), induced browning in sWAT, reduced inflammation, and inhibited the degradation of intestinal villi. Mechanically, AGMT significantly increased Blautia [short-chain fatty acids (SCFAs)-producing microbiota] and Bifidobacterium in HFD mice, also increased the SCFAs in the cecum, which has been proved many beneficial effects on energy homeostasis. Our study highlights that Allicin-induced host-gut microbe interactions plays an important role in regulating energy homeostasis, which provides a promising potential therapy for obesity and metabolic disorders based on host-microbe interactions.

Thiosulfinate Tolerance Is a Virulence Strategy of an Atypical Bacterial Pathogen of Onion

Unlike most characterized bacterial plant pathogens, the broad-host-range plant pathogen Pantoea ananatis lacks both the virulence-associated type III and type II secretion systems. In the absence of these typical pathogenicity factors, P.ananatis induces necrotic symptoms and extensive cell death in onion tissue dependent on the HiVir proposed secondary metabolite synthesis gene cluster. Onion (Allium. cepa L), garlic (A.sativum L.), and other members of the Allium genus produce volatile antimicrobial thiosulfinates upon cellular damage. However, the roles of endogenous thiosulfinate production in host-bacterial pathogen interactions have not been described. We found a strong correlation between the genetic requirements for P.ananatis to colonize necrotized onion tissue and its capacity for tolerance to the thiosulfinate "allicin" based on the presence of an eleven-gene, plasmid-borne, virulence cluster of sulfur redox genes. We have designated them "alt" genes for allicin tolerance. We show that allicin and onion thiosulfinates restrict bacterial growth with similar kinetics. The alt gene cluster is sufficient to confer allicin tolerance and protects the glutathione pool during allicin treatment. Independent alt genes make partial phenotypic contributions indicating that they function as a collective cohort to manage thiol stress. Our work implicates endogenous onion thiosulfinates produced during cellular damage as major mediators of interactions with bacteria. The P.ananatis-onion pathosystem can be modeled as a chemical arms race of pathogen attack, host chemical counterattack, and pathogen defense.

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

BackgroundAllicin, 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. MethodsThe 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. ResultsIn 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. ConclusionAllicin 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.

Allicin suppressed bladder cancer cell biological activities via regulation of the miR-26b-5p/PTEN axis in an in vitro study

IntroductionThe aim of this study was to investigate the anti-tumour effects of allicin in bladder cancer and to elucidate the related mechanisms by performing an in vitro study.Material and methodsUsing the 5637 and T24 cell lines as model systems, the cell proliferation, apoptosis, cell invasion number and wound-healing rate were measured by MTT, flow cytometry, and Transwell and wound-healing assays. The expression of miR-26b-5p mRNA was evaluated by qRT-PCR assay, and relative protein expression (PTEN, PI3K and AKT) was evaluated by western blot assay. The correlation between miR-26b-5p and PTEN in 5637 and T24 cells was examined by the Dual Luciferase assay.ResultsCompared with the normal control (NC) group, cell proliferation was significantly depressed as apoptosis increased (p &lt; 0.05), the invasion cell number and wound-healing rate were significantly suppressed with allicin treatment, and miR-26b-5p was significantly down-regulated in a dose-dependent manner (p &lt; 0.05); PTEN was significantly up-regulated, and PI3K and AKT proteins were significantly down-regulated (p &lt; 0.05) in the allicin-treated groups. With miR-26b-5p transfection, the cell biological activities of 5367 and T24 were significantly restored compared with the allicin-treated group (p &lt; 0.05), with PTEN significantly depressed and PI3K and AKT significantly increasing in 5637 and T24 cells (p &lt; 0.05).ConclusionsAllicin has anti-tumour effects on bladder cancer cell biological activities, and the mechanism may involve regulation of the miR-26b-5p/PTEN axis in bladder cancer cells.

A (Speculative) View on Allicin and Primary Metabolism: An Additional Way to Affect Cell’s Physiology

Background:Allicin from garlic is known for different medical uses for centuries. One important explanation for these effects is the chemical reactivity of allicin as a thiosulfinate towards thiol-groups and the modification of thiol-groups by thioallylation.Objective:It has been shown that thioallylation can inhibit the enzymatic function of proteins. In different organisms, the thioallylated proteins upon allicin treatment have been examined. It was found, especially in human T-cell lymphocytes (Jurkat-cells), that the glycolysis is a major target for allicin. Here, we briefly discuss that affecting the primary metabolism is a possible part of allicin’s physiological functions and might be, both from therapeutic and nutraceutical view, of particular interest for the application of allicin as an active principle of freshly damaged garlic.Conclusion:This might, in summary, explain a possible further mode of action of allicin on cells by changing the metabolism as the central life process and thus influencing the overall structure of the physiological processes in the cell, which can lead to the multitude of consequences caused by allicin.

High Dose Allicin with Vitamin C Improves EPCs Migration from the Patient with Coronary Artery Disease

Endothelial Progenitor Cells (EPCs) have an important role in endothelial dysfunction repairment through neovasculogenesis and cardiac myocytes regeneration. However, EPCs migration is greatly reduced in the patient with Coronary Artery Disease (CAD). Allicin and Vitamin C are hypothesized to improve EPCs migration due to its antioxidant properties. Objective: To investigate the effect of Allicin and its combination with Vitamin C in EPCs migration of CAD patients. Material and Method: Mononuclear cells were isolated from CAD patients and cultured on fibronectin-coated plates with colony-forming unit Hill medium. The cells were divided into untreated (control), Allicin treatment (dose 100 mcg/ml, 200 mcg/ml, 400 mcg/ ml), and each dose of Allicin combined with 250 mcg/mL of Vitamin C. EPCs migration was assessed with Transwell Migration Assay Kit and evaluated by using statistical tests. Results: This research shows that EPC migration was significantly higher in the treatment. Allicin at all dose (dose 100 mcg/ml, 200 mcg/ml, 400 mcg/ml) and its combination with 250 mcg/mL of vitamin C compared to untreated group (p<0.05). Allicin increase EPCs migration in a dosedependent manner. However, the only combination of 400 mcg/ml Allicin with 250 mcg/mL of vitamin C which has significantly higher EPCs migration compared to Allicin treatment alone. Conclusion: Allicin improves EPCs migration in a dose-dependent manner. Improvement of the migration only observed on the Allicin dose 400 mcg/ml with Vitamin C.

Allicin alleviates inflammation of diabetic macroangiopathy via the Nrf2 and NF-kB pathway

As diabetic macroangiopathy is becoming increasingly prevalent, it is urgent to explore preventive and therapeutic drugs and study the mechanism. Diabetic mice were induced by intraperitoneal injection of streptozotocin (STZ)for five consecutive days. Diabetic mice were divided into diabetic and allicin groups. After sacrifice, frozen aortic root sections were immunohistochemically stained for nuclear factor erythroid 2-related factor 2 (Nrf2) and inflammation cytokine-tumor necrosis factor α (TNF-α), and the remaining aortic tissues were analyzed by Western blot for the expression of proinflammation genes. In vitro, Nrf2 and inflammatory relative protein expression levels in Human Umbilical Vein Endothelial Cells (HUVECs) were examined. HUVECs proliferation and apoptosis were measured. TNF-α expression was increased in diabetic group compared to that in control group; this effect was alleviated in allicin-treated mice. Inflammation relative protein expression of Vascular Cell Adhesion Molecule 1(VCAM-1), Matrix metalloproteinase 2 (MMP-2), Inducible Nitric Oxide Synthase (iNOS), and monocyte chemotactic protein 1 (MCP-1) was higher in the diabetic group than in the control group; however, allicin treatment inhibited these diabetes-induced increase. In vitro, allicin treatment reversed the hyperglycemia-induced reduction in proliferation, and decreased the apoptosis induced by high glucose. Inflammation relative protein expression was consistent with that in vivo. Additionally, the expression of nuclear factor kappa-B (NF-κB)and Nrf2 was increased in both DM mice and HUVECs; allicin treatment induced a significant reduction in NF-κB level and improvement in Nrf2 level. Allicin alleviates inflammation caused by diabetic macroangiopathy, and the mechanism may occur via increasing Nrf2 and decreasing NF-κB.

Overexpression miR-486-3p Promoted by Allicin Enhances Temozolomide Sensitivity in Glioblastoma Via Targeting MGMT

Glioblastoma is the most common primary tumor of the central nervous system that develops chemotherapy resistance. Previous studies showed that Allicin could inhibit multiple cancer cells including glioblastoma, but the function of Allicin in glioblastoma is still unclear. Our work aimed to investigate the underlying molecular mechanism. The results showed that miR-486-3p levels were greatly increased in glioblastoma during Allicin treatment. Overexpression of miR-486-3p increased chemosensitivity to temozolomide (TMZ) in vitro and in vivo. O6-methylguanine-DNA methyltransferase (MGMT) was identified as a direct target of miR-486-3p, and miR-486-3p overexpression prevented the protein translation of MGMT. Moreover, overexpression of MGMT restored miR-486-3p-induced chemosensitivity to TMZ. Taken together, our studies revealed that Allicin could upregulate miR-486-3p and enhance TMZ sensitivity in glioblastoma. The results suggested that in the future, Allicin can be used as an adjuvant therapy with TMZ to improve the prognosis of patients, and miR-486-3p may be a potential target for glioblastoma treatment to improve the curative effects.

Allicin suppresses human glioblastoma cell growth by inducing cell cycle arrest and apoptosis, and by promoting autophagy

Glioblastoma is the most aggressive cancer that occurs in the brain and spinal cord. In the present study, we investigated the effect of allicin, an organosulfur compound obtained from garlic (Allium sativum), on glioblastoma cell growth. When human glioblastoma DBTRG-05MG cells were incubated with different concentrations of allicin for 24 h, cell growth was suppressed in a dose-dependent manner. The results from image-based cytometer assays suggested that allicin caused S and G2/M phase cell cycle arrest and induced apoptosis. Autophagy detection studies showed that allicin also promoted this mechanism. Because cell migration is a key process during tumor formation, the effect of allicin on glioblastoma cell migration was also examined. After allicin treatment, the migration ability of cells decreased when compared with the control after 24 h. Taken together, the present results suggested that allicin inhibited human glioblastoma cell growth by inducing S and G2/M phase cell cycle arrest, apoptosis and autophagy. Our findings suggest that allicin suppressed glioblastoma cell growth through multiple target pathways. Therefore, allicin potentially serves as an alternative therapeutic candidate or could be synergistically used in combination with the standard drug for the treatment of glioblastoma multiforme.

Effect of thymoquinone and allicin on some antioxidant parameters in cancer prostate (PC3) and colon cancer (Caco2) cell lines

Background Thymoquinone (TQ) and allicin are two natural compounds separated from the seeds of Nigella sativa (black seeds) and garlic, respectively. These two compounds are known to have antioxidant properties. Aim The aim of this study was to investigate the antioxidant properties of both TQ and allicin in cancer prostate (PC3) and colon cancer (Caco2) cell lines using four cellular parameters, namely, reduced glutathione (GSH), lipid peroxide [malondialdehyde (MDA], catalase enzyme (CAT) and nitric oxide (NO). Materials and methods Two types of cancer cell lines, PC3 cells and Caco2 cells, were used for the investigation of four aforementioned antioxidant parameters before and after treatment with the two natural compounds (TQ and allicin). Viability assay was done first to determine the concentrations used. Results It was found that the concentration of reduced glutathione was highly significantly and significantly decreased in both PC3 cells and Caco2 cells, respectively, after treatment with TQ compared with control, whereas the change in the concentration of reduced glutathione was not significant after allicin treatment for both cell lines compared with control cells. Regarding the concentration of lipid peroxide (MDA), its concentration was highly significantly reduced in PC3 cells in both treatments, whereas it was significantly increased in Caco2 cells treated with TQ compared with control cells. Catalase activity was significantly reduced in PC3 cells after treatment with TQ, and highly significantly increased after treatment with allicin, whereas in Caco2 cells, catalase activity was highly significantly increased after treatment with TQ and allicin compared with control cells. NO concentration was not affected in PC3 cells after treatment with TQ, and highly significantly increased after treatment with allicin, while it was highly significantly increased in Caco2 cells in both treatments, compared to control cells.

Allicin Improve Myocardial Fibrosis by Regulation Mitogen-Activated Protein Kinase 1/3 and Matrix Metalloprotein-8 Expression

Objective: To explore the improvement of Allicin on myocardial fibrosis and expression of MAPK1/2 and MMP-8 in rats. Methods : Dividing 30 SD rats into 3 groups, normal control, model and Allicin treatment based on model (Allicin) groups. Using 40 mg/kg streptozotocin (STZ) to make diabetes model. The the NC and Model groups' rats received daily intraperitoneal injections of saline, and those in Allicin group was given Allicin (40 mg/kg) injections. After 8 weeks, the pathologies of cardiac fibrosis were examined with HE staining and Masson staining, the proteins expressions of collagen I, MAPK1/3 and MMP-8 were analyzed with WB and IHC assay. Results: Compared with NC group, the Model rats showed increased collagen content and obvious interstitial fibrosis in the myocardial tissue with significantly increased expression levels of collagen I, MAPK1/3 and MMP-8 (P &lt; 0 001, respectively); all the changes were obviously reversed by treatment with Allicin (P &lt; 0 001). Collagen I, MAPK1/3 and MMP-8 expression levels and the degree of myocardial fibrosis were comparable between Allicin group and NC group (P &gt; 0 05). Conclusion: Allicin could improve cardiac fibrosis in diabetic rats, and the mechanism might involve the inhibition of MAPK1/3/MMP-8 signal pathway.

Interspecies Comparison of the Bacterial Response to Allicin Reveals Species-Specific Defense Strategies.

Allicin, a broad-spectrum antimicrobial agent from garlic, disrupts thiol and redox homeostasis, proteostasis, and cell membrane integrity. Since medicine demands antimicrobials with so far unexploited mechanisms, allicin is a promising lead structure. While progress is being made in unraveling its mode of action, little is known on bacterial adaptation strategies. Some isolates of Pseudomonas aeruginosa and Escherichia coli withstand exposure to high allicin concentrations due to as yet unknown mechanisms. To elucidate resistance and sensitivity-conferring cellular processes, the acute proteomic responses of a resistant P. aeruginosa strain and the sensitive species Bacillus subtilis are compared to the published proteomic response of E. coli to allicin treatment. The cellular defense strategies share functional features: proteins involved in translation and maintenance of protein quality, redox homeostasis, and cell envelope modification are upregulated. In both Gram-negative species, protein synthesis of the majority of proteins is downregulated while the Gram-positive B. subtilis responded by upregulation of multiple regulons. A comparison of the B. subtilis proteomic response to a library of responses to antibiotic treatment reveals 30 proteins specifically upregulated by allicin. Upregulated oxidative stress proteins are shared with nitrofurantoin and diamide. Microscopy-based assays further indicate that in B. subtilis cell wall integrity is impaired.

Allicin, a natural antimicrobial defence substance from garlic, inhibits DNA gyrase activity in bacteria

Allicin (diallylthiosulfinate) is a potent antimicrobial substance, produced by garlic tissues upon wounding as a defence against pathogens and pests. Allicin is a reactive sulfur species (RSS) that oxidizes accessible cysteines in glutathione and proteins. We used a differential isotopic labelling method (OxICAT) to identify allicin targets in the bacterial proteome. We compared the proteomes of allicin-susceptible Pseudomonas fluorescens Pf0-1 and allicin-tolerant PfAR-1 after a sublethal allicin exposure. Before exposure to allicin, proteins were in a predominantly reduced state, with approximately 77% of proteins showing less than 20% cysteine oxidation. Protein oxidation increased after exposure to allicin, and only 50% of proteins from allicin-susceptible Pf0-1, but 65% from allicin-tolerant PfAR-1, remained less than 20% oxidised. DNA gyrase was identified as an allicin target. Cys433 in DNA gyrase subunit A (GyrA) was approximately 6% oxidized in untreated bacteria. After allicin treatment the degree of Cys433 oxidation increased to 55% in susceptible Pf0-1 but only to 10% in tolerant PfAR-1. Allicin inhibited E. coli DNA gyrase activity in vitro in the same concentration range as nalidixic acid. Purified PfAR-1 DNA gyrase was inhibited to greater extent by allicin in vitro than the Pf0-1 enzyme. Substituting PfAR-1 GyrA into Pf0-1 rendered the exchange mutants more susceptible to allicin than the Pf0-1 wild type. Taken together, these results suggest that GyrA was protected from oxidation in vivo in the allicin-tolerant PfAR-1 background, rather than the PfAR-1 GyrA subunit being intrinsically less susceptible to oxidation by allicin than the Pf0-1 GyrA subunit. DNA gyrase is a target for medicinally important antibiotics; thus, allicin and its analogues may have potential to be developed as gyrase inhibitors, either alone or in conjunction with other therapeutics.

Allicin protects porcine oocytes against damage during aging in vitro.

Allicin, a chemical component of garlic, has strong antioxidant activity and is thought to exert antiaging effects in vitro. We investigated whether allicin treatment would protect porcine oocytes and embryos from postovulatory aging mediated by apoptosis and autophagy. The rates of oocyte survival and polar body extrusion in samples treated with 1 µM allicin (1 AL) were significantly higher than in untreated samples (0 AL). In addition, 1 AL prevented defects in spindle formation and chromosome alignment, as well as decreases in the expression of maturation markers, during in vitro aging. In this study, we considered allicin to be a regulator of autophagy rather than an antioxidant or antiapoptotic agent. At the embryo level, although the cleavage rate after parthenogenetic activation was similar in all groups, the blastocyst formation rate was higher in the 1 AL group than in the 0 AL group. Our findings demonstrate that allicin effectively prevents the deterioration of porcine oocytes during aging in vitro, and could therefore be used to improve the quality of aged oocytes used in in vitro experiments.

Allicin alleviates lead-induced hematopoietic stem cell aging by up-regulating PKM2.

Hematopoietic stem cells (HSCs) aging is associated with hematopoietic dysfunction and diseases. Our previous study showed that lead exposure induced a functional decline in HSCs. Allicin, a chemical extracted from the garlic (Allium sativum L.), has been reported to have antioxidative and anti-inflammatory effects. However, the biological activities of allicin on lead-induced toxicity, especially in the hematopoietic system, remain unclear. Here, we found that lead exposure elicited aging phenotypes in HSCs, including perturbed cell quiescence, disabled self-renewal function and colony-forming ability, and myeloid-biased differentiation, all of which contributed to significant hematopoietic disorders in mice. Intragastric administration of allicin substantially ameliorated lead-induced HSCs aging phenotypes in vivo. Lead exposure induced a peroxide condition in HSCs leading to DNA damage, which reduced expression of the glycolytic enzyme pyruvate kinase M2 isoform (PKM2), a phenotype which was significantly ameliorated by allicin treatment. These findings suggested that allicin alleviated lead-induced HSCs aging by up-regulating PKM2 expression; thus, it could be a natural herb for preventing lead toxicity.

Staphylococcus aureus responds to allicin by global S-thioallylation – Role of the Brx/BSH/YpdA pathway and the disulfide reductase MerA to overcome allicin stress

The prevalence of methicillin-resitant Staphylococcus aureus (MRSA) in hospitals and the community poses an increasing health burden, which requires the discovery of alternative antimicrobials. Allicin (diallyl thiosulfinate) from garlic exhibits broad-spectrum antimicrobial activity against many multidrug resistant bacteria. The thiol-reactive mode of action of allicin involves its S-thioallylations of low molecular weight (LMW) thiols and protein thiols. To investigate the mode of action and stress response caused by allicin in S. aureus, we analyzed the transcriptome signature, the targets for S-thioallylation in the proteome and the changes in the bacillithiol (BSH) redox potential (EBSH) under allicin stress. Allicin caused a strong thiol-specific oxidative and sulfur stress response and protein damage as revealed by the induction of the PerR, HypR, QsrR, MhqR, CstR, CtsR, HrcA and CymR regulons in the RNA-seq transcriptome. Allicin also interfered with metal and cell wall homeostasis and caused induction of the Zur, CsoR and GraRS regulons. Brx-roGFP2 biosensor measurements revealed a strongly increased EBSH under allicin stress. In the proteome, 57 proteins were identified with S-thioallylations under allicin treatment, including translation factors (EF-Tu, EF-Ts), metabolic and redox enzymes (AldA, GuaB, Tpx, KatA, BrxA, MsrB) as well as redox-sensitive MarR/SarA-family regulators (MgrA, SarA, SarH1, SarS). Phenotype and biochemical analyses revealed that BSH and the HypR-controlled disulfide reductase MerA are involved in allicin detoxification in S. aureus. The reversal of protein S-thioallylation was catalyzed by the Brx/BSH/YpdA pathway. Finally, the BSSB reductase YpdA was shown to use S-allylmercaptobacillithiol (BSSA) as substrate to regenerate BSH in S. aureus. In conclusion, allicin results in an oxidative shift of EBSH and protein S-thioallylation, which can be reversed by YpdA and the Brx/BSH/YpdA electron pathways in S. aureus to regenerate thiol homeostasis.