Allylcysteine

S-allylcysteine induces cytotoxic effects in two human lung cancer cell lines via induction of oxidative damage, downregulation of Nrf2 and NF-kappaB, and apoptosis.[Pubmed:33136700]

Anticancer Drugs. 2020 Oct 28.

In this study, we investigated the putative cytotoxic effect elicited by the garlic-derived compound S-Allylcysteine (SAC) in two human cancer cell lines (HCC827 and NCI-H1975) in order to develop an experimental approach to the therapeutic potential of this molecule for lung cancer. Cells were incubated for 24, 48 and 72 h in the presence of SAC (10 or 20 mM), which resulted in a concentration- and time-dependent decrease in cell viability and culture confluence in both cell lines. These effects were contrasted with - and validated through - those observed in an immortalized but nontumorigenic epithelial cell line from human bronchial epithelium (BEAS-2B, negative control) and an adenocarcinoma human alveolar basal epithelial cell line (A549, positive control). SAC (20 mM at 72 h) also increased the oxidative damage to lipids, augmented apoptosis, and decreased the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) and the nuclear factor kappa B (NF-kappaB) proteins in HCC827 and NCI-H1975 cells. Our results establish the efficacy of SAC in reducing malignant growth and proliferation of lung tumor cells. This effect is mediated by the induction of oxidative damage associated with the downregulation of Nrf2 and NF-kappaB and their corresponding signaling pathways.

The Enhancing Effects of S-Allylcysteine on Liver Regeneration Are Associated with Increased Expression of mRNAs Encoding IGF-1 and Its Receptor in Two-Thirds Partially Hepatectomized Rats.[Pubmed:33132323]

Biol Pharm Bull. 2020;43(11):1776-1784.

Two-thirds partial hepatectomy (PHx) was performed in rats, and the differences in effects between S-Allylcysteine (SAC) and other sulfur-containing compounds on regeneration of the remaining liver and restoration of the injury were examined. Three days after two-thirds PHx, rats treated with 300 mg/kg/d, per os (p.o.) SAC showed a 1.2-fold increase in liver weight per 100 g body weight compared with saline-treated controls. In contrast, S-methylcysteine (SMC) (300 mg/kg/d, p.o.) or cysteine (Cys) (300 mg/kg/d, p.o.) did not have a regeneration-promoting effect. In the comparison with control rats, the regenerating liver of SAC-treated rats showed a significantly higher 5-bromo-2'-deoxyuridine labeling index on day 1. In contrast, serum alanine aminotransferase activity, which increases following PHx, was significantly inhibited by SAC and SMC (but not Cys) on day 1 after two-thirds PHx. In addition, SAC induced increases in insulin-like growth factor (IGF)-1 and its receptor mRNA expressions at 1 h after two-thirds PHx, and it increased phosphorylation of extracellular signal-regulated kinase (ERK)2 and Akt at 3 h after two-thirds PHx without affecting serum growth hormone levels. These results demonstrate that SAC is a mitogenic effector of normal remnant liver and promotes recuperation of liver function after two-thirds PHx. Moreover, SAC-induced proliferative effects are mediated via increased mRNA expressions of IGF-1 and its receptor and subsequent phosphorylation of ERK2 and Akt.

Prevailing Knowledge on the Bioavailability and Biological Activities of Sulphur Compounds from Alliums: A Potential Drug Candidate.[Pubmed:32916777]

Molecules. 2020 Sep 9;25(18). pii: molecules25184111.

Allium sativum (garlic) is widely known and is consumed as a natural prophylactic worldwide. It produces more than 200 identified chemical compounds, with more than 20 different kinds of sulfide compounds. The sulfide compounds particularly are proven to contribute to its various biological roles and pharmacological properties such as antimicrobial, antithrombotic, hypoglycemic, antitumour, and hypolipidemic. Therefore, it is often referred as disease-preventive food. Sulphur-containing compounds from A. sativum are derivatives of S-alkenyl-l-cysteine sulfoxides, ajoene molecules, thiosulfinates, sulfides, and S-Allylcysteine. This review presents an overview of the water-soluble and oil-soluble sulphur based phytochemical compounds present in garlic, highlighting their mechanism of action in treating various health conditions. However, its role as a therapeutic agent should be extensively studied as it depends on factors such as the effective dosage and the suitable method of preparation.

Effect of S-allylcysteine against diabetic nephropathy via inhibition of MEK1/2-ERK1/2-RSK2 signalling pathway in streptozotocin-nicotinamide-induced diabetic rats.[Pubmed:32862702]

Arch Physiol Biochem. 2020 Aug 29:1-9.

OBJECTIVE: In the current study, we evaluated the ameliorative effect of S-Allylcysteine (SAC) against streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic nephropathy (DN) in rats and also an attempt was made to establish the molecular mechanism of SAC. METHODS: DN rats were orally supplemented with SAC (150 mg/kg body weight) for a period of 45 days and the effect of SAC on urinary albumin excretion, metabolic parameters, and tubular injury biomarkers by ELISA, total levels and phosphorylation of MEK1/2, ERK1/2, and RSK2 by western blotting analysis in control and experimental rats were assessed. RESULTS: From this study, we observed that SAC considerably decreased polydipsia, poly urea, polyphagia, albuminuria and the levels of urinary N-acetyl-beta-D-glucosaminidase, neutrophil gelatinase-associated lipocalin, transforming growth factor-beta1 and SAC effectively altered the pathological changes in DN rats. SAC also reserved renal cortical phosphorylation of MEK1/2, ERK1/2 and RSK2. CONCLUSION: Hence this study recommended that SAC can successfully protect the DN through regulation of MEK1/2-ERK1/2-RSK2 signalling.

S-Allylcysteine Protects Against Excitotoxic Damage in Rat Cortical Slices Via Reduction of Oxidative Damage, Activation of Nrf2/ARE Binding, and BDNF Preservation.[Pubmed:32813208]

Neurotox Res. 2020 Dec;38(4):929-940.

Neuroprotective approaches comprising different mechanisms to counteract the noxious effects of excitotoxicity and oxidative stress need validation and detailed characterization. Although S-Allylcysteine (SAC) is a natural compound exhibiting a broad spectrum of protective effects characterized by antioxidant, anti-inflammatory, and neuromodulatory actions, the mechanisms underlying its protective role on neuronal cell damage triggered by early excitotoxic insults remain elusive. In this study, we evaluated if the preconditioning or the post-treatment of isolated rat cortical slices with SAC (100 muM) can ameliorate the toxic effects induced by the excitotoxic metabolite quinolinic acid (QUIN, 100 muM), and whether this protective response involves the early display of specific antioxidant and neuroprotective signals. For this purpose, cell viability/mitochondrial reductive capacity, lipid peroxidation, levels of reduced and oxidized glutathione (GSH and GSSG, respectively), the rate of cell damage, the NF-E2-related factor 2/antioxidant response element (Nrf2/ARE) binding activity, heme oxygenase 1 (HO-1) regulation, extracellular signal-regulated kinase (ERK1/2) phosphorylation, and the levels of tumor necrosis factor-alpha (TNF-alpha) and the neurotrophin brain-derived neurotrophic factor (BDNF) were all estimated in tissue slices exposed to SAC and/or QUIN. The incubation of slices with QUIN augmented all toxic endpoints, whereas the addition of SAC prevented and/or recovered all toxic effects of QUIN, exhibiting better results when administered 60 min before the toxin and demonstrating protective and antioxidant properties. The early stimulation of Nrf2/ARE binding activity, the upregulation of HO-1, the ERK1/2 phosphorylation and the preservation of BDNF tissue levels by SAC demonstrate that this molecule displays a wide range of early protective signals by triggering orchestrated antioxidant responses and neuroprotective strategies. The relevance of the characterization of these mechanisms lies in the confirmation that the protective potential exerted by SAC begins at the early stages of excitotoxicity and neurodegeneration and supports the design of integral prophylactic/therapeutic strategies to reduce the deleterious effects observed in neurodegenerative disorders with inherent excitotoxic events.

S -1-Propenylcysteine, a sulfur compound in aged garlic extract, alleviates cold-induced reduction in peripheral blood flow in rat via activation of the AMPK/eNOS/NO pathway.[Pubmed:32765777]

Exp Ther Med. 2020 Sep;20(3):2815-2821.

Aged garlic extract (AGE) has been shown to improve peripheral circulatory disturbances in both clinical trials and experimental animal models. To investigate the effect of S-1-propenylcysteine (S1PC), a characteristic sulfur compound in AGE, on cold-induced reduction in tail blood flow of rat, Wistar rats were individually placed in a restraint cage and given the treatment with cold water (15 C) after the oral administration of AGE or its constituents S1PC, S-Allylcysteine (SAC) and S-allylmercaptocysteine (SAMC). After the cold-treatment the tail blood flow of rats was measured at the indicated times. The pretreatment with AGE (2 g/kg BW) and S1PC (6.5 mg/kg BW) significantly alleviated the reduction of rat tail blood flow induced by cold treatment. The effect of S1PC was dose-dependent and maximal at the dose of 6.5 mg/kg BW, whereas SAC and SAMC were ineffective. To gain insight into the mechanism of S1PC action, the concentration of nitrogen oxide metabolites (NOx) in the plasma and the levels of phosphorylated endothelial nitric oxide synthase (eNOS) and 5'-AMP-activated protein kinase (AMPK) in the aorta were measured. The pretreatment with S1PC significantly increased the plasma concentration of NOx as well as the level of phosphorylated form of AMPK and eNOS in the aorta after cold-treatment. The present findings suggest that S1PC is a major constituent responsible for the effect of AGE to alleviate the cold-induced reduction of peripheral blood flow in rat by acting on the AMPK/eNOS/NO pathway in the aorta.

Elucidation of S-Allylcysteine Role in Inducing Apoptosis by Inhibiting PD-L1 Expression in Human Lung Cancer Cells.[Pubmed:32723260]

Anticancer Agents Med Chem. 2020 Jul 28. pii: ACAMC-EPUB-108556.

AIM: The aim of this study is to explore the therapeutic potential of S-Allylcysteine (SAC) organosulphur compound as potent immune checkpoint inhibitor PD-L1. BACKGROUND: Natural compounds have been showing tremendous anticancerous potential via suppressing the expression of genes involved in development and progression of several carcinomas. This has further motivated us to explore the therapeutic potential of organosulphur compounds as potent immune checkpoint inhibitors. OBJECTIVE: Our study was designed to elucidate the potential of S-Allylcysteine (SAC) as significant PD-L1 (immune checkpoint) inhibitor in human lung cancer A549 cancer cell line by using both the in vitro and in silico approaches. METHODS: Anticancerous effect of the SAC on lung cancer cells was determined by using the MTT cell viability. Apoptotic induction was confirmed by Hoechst staining, percent caspase-3 activity as well as gene expression analysis by real time PCR. Reactive Oxygen Species (ROS) was estimated by DCFDA method. Additionally, ligand-target protein interaction was analysed by molecular docking. RESULT: Cell growth and proliferation was significantly reduced in SAC treated A549 cells in a concentration and timedependent manner. Effect of SAC on apoptotic induction was analyzed by enhanced nuclear condensation, increased percent caspase-3 activity as well as modulation of apoptotic genes. Furthermore, SAC treatment also resulted in reduced expression of PD-L1 and HIF-1alpha. Additionally in silico analysis also supported the in vitro findings by showing efficient docking with PD-L1 immune checkpoint target. CONCLUSION: Therefore our results clearly suggested that SAC could serve as a novel chemotherapeutic candidate for the treatment of lung cancer by inhibiting immune checkpoint target PD-L1 in human lung cancer cells. Additionally, our study also explained a novel molecular mechanism of its antitumor activity.

Improvement of Learning and Memory in Senescence-Accelerated Mice by S-Allylcysteine in Mature Garlic Extract.[Pubmed:32575593]

Nutrients. 2020 Jun 19;12(6). pii: nu12061834.

S-Allylcysteine (SAC), a major thioallyl compound contained in mature garlic extract (MGE), is known to be a neuroactive compound. This study was designed to investigate the effects of SAC on primary cultured hippocampal neurons and cognitively impaired senescence-accelerated mice prone 10 (SAMP10). Treatment of these neurons with MGE or SAC significantly increased the total neurite length and number of dendrites. SAMP10 mice fed MGE or SAC showed a significant improvement in memory dysfunction in pharmacological behavioral analyses. The decrease of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, N-methyl-d-aspartate (NMDA) receptor, and phosphorylated alpha-calcium/calmodulin-dependent protein kinase II (CaMKII) in the hippocampal tissue of SAMP10 mice fed MGE or SAC was significantly suppressed, especially in the MGE-fed group. These findings suggest that SAC positively contributes to learning and memory formation, having a beneficial effect on brain function. In addition, multiple components (aside from SAC) contained in MGE could be useful for improving cognitive function by acting as neurotrophic factors.

Thallium Toxicity in Caenorhabditis elegans: Involvement of the SKN-1 Pathway and Protection by S-Allylcysteine.[Pubmed:32468422]

Neurotox Res. 2020 Aug;38(2):287-298.

Monovalent thallium (Tl(+)) is a cation that can exert complex neurotoxic patterns in the brain by mechanisms that have yet to be completely characterized. To learn more about Tl(+) toxicity, it is necessary to investigate its major effects in vivo and its ability to trigger specific signaling pathways (such as the antioxidant SKN-1 pathway) in different biological models. Caenorhabditis elegans (C. elegans) is a nematode constituting a simple in vivo biological model with a well-characterized nervous system, and high genetic homology to mammalian systems. In this study, both wild-type (N2) and skn-1 knockout (KO) mutant C. elegans strains subjected to acute and chronic exposures to Tl(+) [2.5-35 muM] were evaluated for physiological stress (survival, longevity, and worm size), motor alterations (body bends), and biochemical changes (glutathione S-transferase regulation in a gst-4 fluorescence strain). While survival was affected by Tl(+) in N2 and skn-1 KO (worms lacking the orthologue of mammalian Nrf2) strains in a similar manner, the longevity was more prominently decreased in the skn-1 KO strain compared with the wild-type strain. Moreover, chronic exposure led to a greater compromise in the longevity in both strains compared with acute exposure. Tl(+) also induced motor alterations in both skn-1 KO and wild-type strains, as well as changes in worm size in wild-type worms. In addition, preconditioning nematodes with the well-known antioxidant S-Allylcysteine (SAC) reversed the Tl(+)-induced decrease in survival in the N2 strain. GST fluorescent expression was also decreased by the metal in the nematode, and recovered by SAC. Our results describe and validate, for the first time, features of the toxic pattern induced by Tl(+) in an in vivo biological model established with C. elegans, supporting an altered redox component in Tl(+) toxicity, as previously described in mammal models. We demonstrate that the presence of the orthologous SKN-1 pathway is required for worms in evoking an efficient antioxidant defense. Therefore, the nematode represents an optimal model to reproduce mammalian Tl(+) toxicity, where toxic mechanisms and novel therapeutic approaches of clinical value may be successfully pursued.

Sulfur-containing amino acids in aged garlic extract inhibit inflammation in human gingival epithelial cells by suppressing intercellular adhesion molecule-1 expression and IL-6 secretion.[Pubmed:32042418]

Biomed Rep. 2020 Mar;12(3):99-108.

Aged garlic extract (AGE) contains various biologically active sulfur-containing amino acids, such as S-Allylcysteine (SAC), S-1-propenylcysteine (S1PC) and S-allylmercaptocysteine (SAMC). These amino acids have been demonstrated to lower hypertension, improve atherosclerosis and enhance immunity through their anti-inflammatory and antioxidant activities. It was recently reported that the administration of AGE alleviated gingivitis in a clinical trial. In this study, to gain insight into this effect of AGE, the authors examined whether AGE and the three above-mentioned sulfur compounds influence the effects of tumor necrosis factor-alpha (TNF-alpha) in inducing intercellular adhesion molecule-1 (ICAM-1) expression and interleukin-6 (IL-6) secretion in Ca9-22 human gingival epithelial cells. It was found that S1PC reduced the level of ICAM-1 protein induced by TNF-alpha possibly through post-translational levels without affecting the TNF-alpha-induced mRNA expression. However, SAC and SAMC had no effect. It was also confirmed the inhibitory effect of an antimicrobial peptide [human-beta defensin-3 (hbetaD3)] and found that the inhibitory effects of hbD3 and S1PC were synergistic. On the other hand, the TNF-alpha-induced IL-6 secretion was attenuated by SAC and SAMC in a dose-dependent manner, whereas S1PC was ineffective. In addition, SAC and SAMC, but not S1PC inhibited the phosphorylation of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB), which is involved in the expression of inflammatory molecules, suggesting that the anti-inflammatory effects of SAC and SAMC are mediated, at least partly, by NF-kappaB. On the whole, the findings of this study suggest that the three sulfur amino acids in AGE function synergistically in alleviating inflammation in human gingival epithelial cells.

Chemistry of aged garlic: Diversity of constituents in aged garlic extract and their production mechanisms via the combination of chemical and enzymatic reactions.[Pubmed:32010342]

Exp Ther Med. 2020 Feb;19(2):1574-1584.

Raw garlic contains characteristic compounds, such as S-alk(en)ylcysteine sulfoxides, gamma-glutamyl-S-alk(en)-ylcysteines and polysaccharides. These compounds undergo various transformation processes during the aging process. Among these compounds, the change of sulfur-containing molecules is diverse and time-dependent. Previously, by means of the liquid chromatography (LC)/LC-mass spectrometry (MS) method, a number of unidentified peaks corresponding to candidates of sulfur-containing molecules were detected in the chromatogram of aged garlic extract (AGE), and identified using MS and nuclear magnetic resonance (NMR). The production mechanisms of these compounds were then examined by model reactions and laboratory experiments mimicking the aging process. Three gamma-glutamyl tripeptides [gamma-glutamyl-gamma-glutamyl-S-methylcysteine, gamma-glutamyl-gamma-gluta-myl-S-Allylcysteine (GGSAC), gamma-glutamyl-gamma-glutamyl-S-1-propenylcysteine], gamma-glutamyl-S-allylmercaptocysteine (GSAMC) and cis-S-1-propenylcysteine (cis-S1PC) were isolated and identified. GGSAC was produced from GSAC through the enzymatic reaction catalyzed by gamma-glutamyltranspeptidase (GGT), and two other tripeptides could be produced in similar reactions. GSAMC was produced by the reaction between gamma-glutamyl dipeptides and allicin. Furthermore, GSAMC was a precursor compound of S-allyl-mercaptocysteine (SAMC), and thus it was produced from GSAMC by GGT. cis-S1PC was produced from trans-S1PC by the isomerization reaction. A number of other compounds were also identified, including Maillard reaction products; however, their production mechanisms have not been elucidated. In this review, we present the changes in characteristic constituents in raw garlic and garlic extract during the aging process and discuss their production mechanisms involving the various chemical and enzymatic reactions.

Bioactive components from garlic on brain resiliency against neuroinflammation and neurodegeneration.[Pubmed:32010338]

Exp Ther Med. 2020 Feb;19(2):1554-1559.

Garlic (Allium sativum) has been widely used for culinary and medicinal purposes. Aged garlic extract (AGE) and sulfur-containing compounds, including S-Allylcysteine (SAC) are well documented botanical active components of garlic. AGE is prepared by the prolonged extraction of fresh garlic with aqueous ethanol and is considered a nutritional supplement with potential to promote human health. SAC is a water-soluble organosulfur compound and the most abundant component of AGE. Studies have demonstrated that both AGE and SAC can exert neuroprotective effects against neuroinflammation and neurodegeneration. Another bioactive component in AGE is N-alpha-(1-deoxy-D-fructos-1-yl)-L-arginine (FruArg) although less is known about the metabolic activity of this compound. The main aim of this review was to provide an undated overview of the neuroprotective perspectives of these active garlic components (AGE, SAC and FruArg). Of interest, our studies and those of others indicate that both AGE and FruArg are involved in the regulation of gene transcription and protein expression. AGE has been shown to reverse 67% of the transcriptome alteration induced by endotoxins-lipopolysaccharide (LPS), and FruArg has been shown to account for the protective effects by reversing 55% of genes altered in a cell-based neuroinflammation paradigm stimulated by LPS in murine BV-2 microglial cells. AGE and FruArg can alleviate neuroinflammatory responses through a variety of signaling pathways, such as Toll-like receptor and interleukin (IL)-6 signaling, as well as by upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated oxidative stress pathways known to promote microglial resiliency against neuroinflammation and neurodegeneration. The capability of FruArg to pass through the blood-brain barrier further supports its potential as a therapeutic compound. In summary, these experimental results provide new insight into the understanding of the neuroprotective effects of garlic components in promoting brain resiliency for health benefits.

BACH1 mediates the antioxidant properties of aged garlic extract.[Pubmed:32010329]

Exp Ther Med. 2020 Feb;19(2):1500-1503.

In clinical studies, aged garlic extract (AGE) has been shown to improve endothelial dysfunction. The activation of nuclear factor erythroid 2 like 2 (Nrf2)-dependent gene expression is a proposed mechanism for maintaining vascular homeostasis. S-1-propenylcysteine (S1PC) and S-Allylcysteine (SAC) are two predominant sulfur-containing amino acids present in AGE. However, it remains unclear as to whether the two sulfur amino acids activate Nrf2 in cells. Nitric oxide (NO) is an important signaling molecule and one of the activators of the Nrf2 pathway. In a previous study, we examined the effects of the two sulfur amino acids on NO signaling for modulating the Nrf2-dependent antioxidant response. Neither S1PC nor SAC were found to affect the expression of Nrf2-regulated genes, such as heme oxygenase-1 (HMOX1) in human umbilical vein endothelial cells. However, S1PC was found to augment HMOX1 expression, induced by NO donors, such as NOR3. NOR3 was found to induce the nuclear accumulation of NRF2 protein and concomitantly enhance the degradation of BTB domain and CNC homolog 1 (BACH1), a transcriptional repressor that competes with NRF2. Notably, on our previous study, S1PC enhanced the NOR3-induced downregulation of BACH1, but did not further enhance the NOR3-induced accumulation of NRF2. The findings of that study indicated that the S1PC-induced degradation of BACH1 may provide a basis for the antioxidant effects of AGE. Thus, in this review, we aimed to provide a current overview of the antioxidant effects of AGE and sulfur-containing amino acids.

Aged garlic extract and S-allylcysteine increase the GLUT3 and GCLC expression levels in cerebral ischemia.[Pubmed:31851788]

Adv Clin Exp Med. 2019 Dec;28(12):1609-1614.

BACKGROUND: During cerebral ischemia, energy restoration through the regulation of glucose transporters and antioxidant defense mechanisms is essential to maintain cell viability. Antioxidant therapy has been considered effective to attenuate brain damage; moreover, the regulation of transcription factors that positively regulate the expression of glucose transporters is associated with this therapy. Recently, it has been reported that the use of antioxidants such as S-Allylcysteine (SAC), a component of aged garlic extract (AGE), improves survival in experimental models of cerebral ischemia. OBJECTIVES: The aim of this study was to determine the effect of AGE and SAC on the level of mRNA expression of the main neuronal glucose transporter (GLUT3) and the glutamate cysteine ligase catalytic subunit (GCLC) in rats with transient focal cerebral ischemia. MATERIAL AND METHODS: Cerebral ischemia was induced in male Wistar rats by middle cerebral artery occlusion (MCAO) for 2 h. The animals were sacrificed after different reperfusion times (0-48 h). Animals injected with AGE (360 mg/kg, intraperitoneally (i.p.)) and SAC (300 mg/kg, i.p.) at the beginning of reperfusion were sacrificed after 2 h. The mRNA expression level was analyzed in the fronto-parietal cortex using quantitative polymerase chain reaction (qPCR). RESULTS: Two major increases in GLUT3 expression at 1 h and 24 h of reperfusion were found. Both treatments increased GLUT3 and GCLC mRNA levels in control and under ischemic/reperfusion injury animals. CONCLUSIONS: This data suggests that SAC and AGE might induce neuroprotection, while controlling reactive oxygen species (ROS) levels, as indicated by the increase in GCLC expression, and regulating the energy content of the cell by increasing glucose transport mediated by GLUT3.