S-1-Propenylcysteine promotes the differentiation of B cells into IgA-producing cells by the induction of Erk1/2-dependent Xbp1 expression in Peyer's patches

S-1-Propenylcysteine Enhances Endurance Capacity of Mice by Stimulating Fatty Acid Metabolism via Muscle Isoform of Carnitine Acyltransferase-1

BACKGROUND

Endurance is an important capacity to sustain healthy lifestyles. Aged garlic extract (AGE) has been reported to exert an endurance-enhancing effect in clinical and animal studies, although little is known about its active ingredients and mechanism of action.

OBJECTIVES

This study investigated the potential effect of S-1-propenylcysteine (S1PC), a characteristic sulfur amino acid in AGE, on the swimming endurance of mice, and examined its mechanism of action by a metabolomics-based approach.

METHODS

Male Institute of Cancer Research (ICR) mice (6 wk old) were orally administered either water (control) or S1PC (6.5 mg/kg/d) for 2 wk. The swimming duration to exhaustion was measured at 24 h after the final administration. Nontargeted metabolomic analysis was conducted on the plasma samples obtained from mice after 40-min submaximal swimming bouts. Subsequently, the enzyme activity of carnitine acyltransferase-1 (CPT-1) and the content of malonyl-coenzyme A (CoA), acetyl-CoA, and adenosine triphosphate (ATP) were quantified in heart, skeletal muscles, and liver of mice.

RESULTS

The duration time of swimming was substantially increased in the S1PC-treated mice as compared with the control group. Metabolomic analysis revealed significant alterations in the plasma concentration of the metabolites involved in fatty acid metabolism, in particular medium- or long-chain acylcarnitines in the mice treated with S1PC. Moreover, the administration of S1PC significantly enhanced the CPT-1 activity with the concomitant decrease in the malonyl-CoA content in the heart and skeletal muscles. These effects of S1PC were accompanied by the elevation of the acetyl-CoA and ATP levels to enhance the energy production in those tissues.

CONCLUSIONS

S1PC is a key constituent responsible for the endurance-enhancing effect of AGE. This study suggests that S1PC helps provide energy during endurance exercise by increasing fatty acid metabolism via CPT-1 activation in the heart and skeletal muscles.

Therapeutic effect of aged garlic extract on gingivitis in dogs

Periodontal disease is one of the most common dental health problems in dogs. Clinical studies in humans have shown that aged garlic extract (AGE), which contains stable and water-soluble sulfur-containing bioactive compounds, improves the symptoms of periodontal diseases. Our previous study demonstrated that oral administration of AGE in healthy Beagle dogs at 90 mg/kg/day for 12 weeks had no adverse effects such as hemolytic anemia, which is well known to occur as a result of ingestion of Allium species, including onions and garlic, in dogs. However, the therapeutic potential of AGE in canine periodontal disease remains unclear. Accordingly, we investigated the therapeutic effects of AGE in Beagle dogs with mild gingivitis. Feeding 18 mg/kg/day of AGE for 8 weeks resulted in the improvement of gingival index score, level of volatile sulfur compounds in exhaled air, and enzyme activity of periodontal pathogens without any adverse effects on clinical signs and hematological and serum biochemical parameters. Moreover, AGE increased the concentration of salivary cathelicidin, an antimicrobial peptide that contributes to the oral innate immune response. These results suggest that AGE could be a potential therapeutic agent for canine gingivitis.

S-1-propenyl-L-cysteine suppresses lipopolysaccharide-induced expression of matrix metalloproteinase-1 through inhibition of tumor necrosis factor-α converting enzyme-epidermal growth factor receptor axis in human gingival fibroblasts

Periodontal disease is the most common dental health problem characterized by the destruction of connective tissue and the resorption of alveolar bone resulting from a chronic infection associated with pathogenic bacteria in the gingiva. Aged garlic extract has been reported to improve gingival bleeding index and probing pocket depth score in patients with mild to moderate periodontitis. Although our previous study found that aged garlic extract and its constituents suppressed the tumor necrosis factor-α-induced inflammatory responses in a human gingival epithelial cell line, the mechanism underlying the effect of aged garlic extract on the destruction of the gingiva remains unclear. The present study investigated the effect of S-1-propenyl-L-cysteine, one of the major sulfur bioactive compounds in aged garlic extract, on the lipopolysaccharide-induced expression of matrix metalloproteinases in human gingival fibroblasts HGF-1 cells. Matrix metalloproteinases are well known to be closely related to the destruction of the gingiva. We found that S-1-propenyl-L-cysteine suppressed the lipopolysaccharide-induced expression and secretion of matrix metalloproteinase-1 in HGF-1 cells. In addition, S-1-propenyl-L-cysteine inhibited the lipopolysaccharide-induced phosphorylation of epidermal growth factor receptor and expression of the active form of tumor necrosis factor-α converting enzyme. Furthermore, the inhibitors of epidermal growth factor receptor tyrosine kinase and tumor necrosis factor-α converting enzyme, AG-1478 and TAPI-1, respectively, reduced the lipopolysaccharide-induced protein level of matrix metalloproteinase-1, as did S-1-propenyl-L-cysteine. Taken together, these results suggested that S-1-propenyl-L-cysteine suppresses the lipopolysaccharide-induced expression of matrix metalloproteinase-1 through the blockade of the tumor necrosis factor-α converting enzyme-epidermal growth factor receptor axis in gingival fibroblasts.

Assessment of standardization of domestic commercial black garlic extract for S-allyl-l-cysteine and S-1-propenyl-l-cysteine

Aged garlic extract (AGE) contains a significant amount of bioactive compounds, including S-allyl-l-cysteine (SAC), which is associated with various health benefits. Among different AGE products, black garlic extract (BGE) is widely consumed and a common product in the Korean market. BGE products do however contain different levels of SAC and S1PC. Here, the SAC contents in commercial BGE products were found to be in the range of 0.31-27.22 mg/100 mL, while the SAC contents of commercial black garlic (BG) cloves were in the range of 22.28-63.71 mg/100 g. Recently, S-1-propenyl-l-cysteine (S1PC) has emerged as a new bioactive compound of interest in AGE products. Analysis of BG and BGE indicated that their S1PC contents were 2.24-16.58 mg/100 g and ND-3.68 mg/100 mL, respectively. Based on the significance of these compounds, standardization of the SAC and S1PC content in commercial BGE products is required.

Beneficial effect of aged garlic extract on periodontitis: a randomized controlled double-blind clinical study

The purpose of this study is to assess the long-term efficacy of aged garlic extract to improve periodontitis. Two hundred and one participants were randomly stratified and assigned equally to the regimen group or the control group. At the start, 12 month, and 18 month subjects received dental examination and periodontal evaluation. Probing Pocket Depth and Gingival Recession were examined. For each efficacy parameter, the mean value of examination was calculated and assessed using paired-difference t tests. Statistical tests were two-sided using a 5% significance level. The mean value of pocket depth for the aged garlic extract group at 18 month was 1.06 ± 0.49 as compared to the baseline value of 1.89 ± 0.74 (p<0.001) and the corresponding value of 1.50 ± 0.46 for the placebo group (p<0.001), indicating the beneficial effect of aged garlic extract on periodontitis. According to a Multiple linear regression analysis the only three variables which reached statistical significance as predictors of PPD level were the baseline PPD scores (p<0.001), smoking (p = 0.020), and consumption of daily dose of aged garlic extract (p<0.001). These results demonstrated that aged garlic extract is an effective supplement for preventing or improving periodontal disease. The well demonstrated benefits of aged garlic extract for the oral disease may also be used as a means to improve general health because of the close relationship between periodontitis and some systemic diseases such as diabetes, hypertension, atherosclerosis, and others.

-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

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.

Chemistry of aged garlic: Diversity of constituents in aged garlic extract and their production mechanisms via the combination of chemical and enzymatic reactions

Raw garlic contains characteristic compounds, such as S-alk(en)ylcysteine sulfoxides, γ-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 γ-glutamyl tripeptides [γ-glutamyl-γ-glutamyl-S-methylcysteine, γ-glutamyl-γ-gluta-myl-S-allylcysteine (GGSAC), γ-glutamyl-γ-glutamyl-S-1-propenylcysteine], γ-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 γ-glutamyltranspeptidase (GGT), and two other tripeptides could be produced in similar reactions. GSAMC was produced by the reaction between γ-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.

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

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-α (TNF-α) 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-α possibly through post-translational levels without affecting the TNF-α-induced mRNA expression. However, SAC and SAMC had no effect. It was also confirmed the inhibitory effect of an antimicrobial peptide [human-β defensin-3 (hβD3)] and found that the inhibitory effects of hbD3 and S1PC were synergistic. On the other hand, the TNF-α-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 κ-light-chain-enhancer of activated B cells (NF-κB), 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-κB. 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.

Regulation of immune response by S-1-propenylcysteine through autophagy-mediated protein degradation

Autophagy is a key event in cellular recycling processes due to its involvement in the intracellular degradation of proteins. It has been demonstrated that S−1-propenylcysteine (S1PC), a characteristic sulfur compound in aged garlic extract, induces the activation of autophagy. S1PC degrades the adaptor protein myeloid differentiation response protein 88 (MyD88) of downstream of Toll-like receptor (TLR) by activating autophagy in vitro and in vivo. The degradation of MyD88 inhibits the TLR signaling pathway, including the phosphorylation of interleukin 1 receptor associated kinase 4 (IRAK4) and nuclear factor (NF)-κB p65 in vitro, and eventually leads to the inhibition of interleukin (IL)-6 production in vitro and C-C motif chemokine ligand 2 (Ccl2) mRNA expression in vivo. S1PC also increases the level of intestinal immunoglobulin A (IgA) and the number of IgA-producing cells in Peyer's patches in vivo. In addition, S1PC triggers the mRNA expression of X-box binding protein 1 (Xbp1), an inducer of IgA-producing cell differentiation via the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 and the degradation of paired box protein 5 (Pax5), a suppressor of Xbp1 mRNA expression. The present review summarizes the mechanisms through which the activation of autophagy by S1PC modulates the immune response.

Effect of Topical Garlic on Wound Healing and Scarring: A Clinical Trial

BACKGROUND

Historically, garlic containing compounds have been used on wounds to improve healing and ward off infection. Researchers have tested many of these ancient ointments, discovering that garlic is a common ingredient in those that are effective.

OBJECTIVE

To determine the efficacy of topical garlic on surgical wounds compared with Vaseline by analysis of visual analog scales and digital photograph analysis.

MATERIALS AND METHODS

Seventeen patients with 2 skin excisions applied a 30% garlic ointment to one surgical wound and Vaseline to the other surgical wound twice daily. They were followed up at 2 weeks and 4 weeks post-op. Digital photographs were taken of the sites, and wound visual analog scales were filled out by the patient and the physician.

RESULTS

Patients and the onsite physician stated the garlic site healed better in 59% and 65% of the wounds, respectively, at 2 weeks. At 4 weeks, the patients and the onsite physician stated the garlic site healed better in 76% and 88% of wounds, respectively. Digital photograph analysis revealed less erythema at the garlic sites (p-value = .02).

CONCLUSION

Surgical wounds treated with 30% garlic ointment healed with more cosmetically appealing scars than the Vaseline-treated sites.

S-Alk(en)ylcysteine sulfoxides in the genus Allium: proposed biosynthesis, chemical conversion, and bioactivities

S-Alk(en)ylcysteine sulfoxides are sulfur-containing natural products characteristic of the genus Allium. Both the flavor and medicinal properties of Allium plants are attributed to a wide variety of sulfur-containing compounds that are generated from S-alk(en)ylcysteine sulfoxides. Previous radiotracer experiments proposed that S-alk(en)ylcysteine sulfoxides are biosynthesized from glutathione. The recent identification of γ-glutamyl transpeptidases and a flavin-containing S-oxygenase involved in the biosynthesis of S-allylcysteine sulfoxide (alliin) in garlic (Allium sativum) provided insights into the reaction order of deglutamylation and S-oxygenation together with the localization of the biosynthesis, although the rest of the enzymes in the pathway still await discovery. In intact plants, S-alk(en)ylcysteine sulfoxides are stored in the cytosol of storage mesophyll cells. During tissue damage, the vacuolar enzyme alliinase contacts and hydrolyzes S-alk(en)ylcysteine sulfoxides to produce the corresponding sulfenic acids, which are further converted into various sulfur-containing bioactive compounds mainly via spontaneous reactions. The formed sulfur-containing compounds exhibit bioactivities related to pathogen defense, the prevention and alleviation of cancer and cardiovascular diseases, and neuroprotection. This review summarizes the current understanding of the occurrence, biosynthesis, and alliinase-triggered chemical conversion of S-alk(en)ylcysteine sulfoxides in Allium plants as well as the impact of S-alk(en)ylcysteine sulfoxides and their derivatives on medicinal, food, and agricultural sciences.

Safety and efficacy of aged garlic extract in dogs: upregulation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and Nrf2-regulated phase II antioxidant enzymes

Background

Plants of Allium spp., including garlic (A. sativum) and onions (A. cepa), are known to be oxidatively toxic to canine erythrocytes resulting in Heinz body hemolytic anemia in dogs. In humans, these plants have been used as medicinal agents for multiple diseases since ancient times. Especially, fresh garlic extracted over a prolonged period produces less irritative and odorless aged garlic extract (AGE), containing unique and beneficial organosulfur compounds that can help prevent many kinds of diseases. In this study, the safety and efficacy of long-term oral administration of AGE is evaluated in dogs. The objectives are to confirm the safe dosage for long-term use and beneficial functions of AGE for dogs and to plan and design a canine health supplement or a preventive agent for multiple diseases based on the data of this study.

Results

Beagles were orally administered AGE (45 or 90 mg/kg body weight once a day) or an equivalent amount of water as control for 12 weeks. In AGE-treated groups, at 12 weeks post-administration at a dose of 90 mg/kg, there were no observable changes in the clinical signs, complete blood count, and serum biochemical parameters. Heinz bodies and eccentrocytes, the markers of oxidative damage in erythrocytes, did not appear in blood smear examination. In order to further evaluate the beneficial effects of AGE on health of dogs, the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) gene (NFE2L2) and Nrf2-regulated phase II antioxidant enzyme genes (NQO1, GCLM, HMOX1, and SOD2) were determined in whole blood between pre- and post-AGE administration. The expression of NFE2L2 gene was significantly upregulated in the AGE-treated groups [45 (p < 0.05) and 90 mg/kg (p < 0.01), 8 weeks] as compared to in the control group. Among the Nrf2-regulated enzymes examined, the expressions of NQO1 [45 (p < 0.05) and 90 mg/kg (p < 0.01), 8 weeks] and GCLM [45 (p < 0.05) and 90 mg/kg (p < 0.01), 12 weeks] genes were significantly upregulated.

Conclusion

The long-term oral administration of AGE at a dose of 90 mg/kg/day for 12 weeks did not show any adverse effects in dogs. Furthermore, the administration of AGE upregulated the gene expressions of canine Nrf2 and Nrf2-regulated phase II antioxidant enzymes. These results suggest that AGE might safely contribute to the health of dogs provided that the appropriate dosage is used.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1699-2) contains supplementary material, which is available to authorized users.

Anti-inflammatory action of cysteine derivative S-1-propenylcysteine by inducing MyD88 degradation

The degradation of target proteins by small molecules utilizing the cellular proteolytic system is featured as a treatment strategy of several diseases. We found that S-1-propenylcysteine (S1PC) among several cysteine derivatives in aged garlic extract inhibited TLR-mediated IL-6 production by inducing the degradation of adaptor protein MyD88. We showed that S1PC directly denatured MyD88 and induced the formation of protein aggregates. Consequently, MyD88 was degraded by aggresome-autophagy pathway. On the other hand, S-allylcysteine, a structural analog of S1PC, failed to induce the degradation of MyD88 because of its inability to denature MyD88 although it also activated autophagy. Our findings suggest that S1PC induces MyD88 degradation through the denaturation of MyD88 and the activation of autophagy. Thus, S1PC may serve as the base to develop a therapeutic means for immune diseases associated with aberrant TLR signaling pathways.

Isolation and Identification of Three γ-Glutamyl Tripeptides and Their Putative Production Mechanism in Aged Garlic Extract

We analyzed aged garlic extract (AGE) to understand its complex sulfur chemistry using post-column high-performance liquid chromatography with an iodoplatinate reagent and liquid chromatography high resolution mass spectrometry (LC-MS). We observed unidentified peaks of putative sulfur compounds. Three compounds were isolated and identified as γ-glutamyl-γ-glutamyl- S-methylcysteine, γ-glutamyl-γ-glutamyl- S-allylcysteine (GGSAC) and γ-glutamyl-γ-glutamyl- S-1-propenyl-cysteine (GGS1PC) by nuclear magnetic resonance and LC-MS analysis based on comparisons with chemically synthesized reference compounds. GGSAC and GGS1PC were novel compounds. Trace amounts of these compounds were detected in raw garlic, but the contents of these compounds increased during the aging process. Production of these compounds was inhibited using a γ-glutamyl transpeptidase (GGT) inhibitor in the model reaction mixtures. These findings suggest that γ-glutamyl tripeptides in AGE are produced by GGT during the aging process.

Effects of S-1-propenylcysteine, a sulfur compound in aged garlic extract, on blood pressure and peripheral circulation in spontaneously hypertensive rats

OBJECTIVES

This study was designed to investigate the antihypertensive effect of S-1-propenylcysteine, a characteristic sulfur compound in aged garlic extract, using a hypertensive rat model.

METHODS

The blood pressure and tail blood flow of both spontaneously hypertensive rats and control Wistar Kyoto rats were measured by the tail-cuff method and the noncontact laser Doppler method, respectively, at various times after single oral administration of a test compound for 24 h.

KEY FINDINGS

Treatment with S-1-propenylcysteine (6.5 mg/kg BW) significantly decreased the systolic blood pressure of spontaneously hypertensive rat approximately 10% at 3 h after administration, and thereafter, the systolic blood pressure gradually returned to the baseline level in 24 h. The effect of S-1-propenylcysteine was dose-dependent and was maximal at the dose of 6.5 mg/kg BW at 3 h. However, the other compounds such as S-allylcysteine and S-allylmercaptocysteine in aged garlic extract were ineffective. In addition, S-1-propenylcysteine had no effect on systolic blood pressure of control Wistar Kyoto rats. Furthermore, S-1-propenylcysteine significantly increased the blood flow at 3 h after administration at the dose of 6.5 mg/kg BW.

CONCLUSIONS

S-1-propenylcysteine is a key constituent of aged garlic extract responsible for its antihypertensive effect, and the effect of S-1-propenylcysteine involves the improvement in peripheral circulation.

Chemical and Biological Properties of S-1-Propenyl-l-Cysteine in Aged Garlic Extract

S-1-Propenyl-l-cysteine (S1PC) is a stereoisomer of S-1-Propenyl-l-cysteine (SAC), an important sulfur-containing amino acid that plays a role for the beneficial pharmacological effects of aged garlic extract (AGE). The existence of S1PC in garlic preparations has been known since the 1960's. However, there was no report regarding the biological and/or pharmacological activity of S1PC until 2016. Recently, we performed a series of studies to examine the chemical, biological, pharmacological and pharmacokinetic properties of S1PC, and obtained some interesting results. S1PC existed only in trace amounts in raw garlic, but its concentration increased almost up to the level similar of SAC through aging process of AGE. S1PC showed immunomodulatory effects in vitro and in vivo, and reduced blood pressure in a hypertensive animal model. A pharmacokinetic study revealed that S1PC was readily absorbed after oral administration in rats and dogs with bioavailability of 88-100%. Additionally, S1PC had little inhibitory influence on human cytochrome P450 activities, even at a concentration of 1 mM. Based on these findings, S1PC was suggested to be another important, pharmacologically active and safe component of AGE similar to SAC. In this review, we highlight some results from recent studies on S1PC and discuss the potential medicinal value of S1PC.

Metabolomic study on the antihypertensive effect of S-1-propenylcysteine in spontaneously hypertensive rats using liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry

Aged garlic extract (AGE) has been shown to improve hypertension in both clinical trials and experimental animal models. However, the active ingredient of AGE remains unknown. In the present study, we investigated the antihypertensive effects of AGE and its major constituents including S-1-propenylcysteine (S1PC) and S-allylcysteine (SAC) using spontaneously hypertensive rats (SHR) and found that S1PC is an active substance to lower blood pressure in SHR. In addition, the metabolomics approach was used to investigate the potential mechanism of the antihypertensive action of S1PC in SHR. Treatment with AGE (2g/kg body weight) or S1PC (6.5mg/kg body weight; equivalent to AGE 2g/kg body weight) significantly decreased the systolic blood pressure (SBP) of SHR after the repeated administration for 10 weeks, whereas treatment with SAC (7.9mg/kg body weight; equivalent to AGE 2g/kg body weight) did not decrease the SBP. After the treatment for 10 weeks, the plasma samples obtained from Wistar Kyoto (WKY) rats and SHR were analyzed by means of ultra high performance liquid chromatography coupled with high-resolution quadrupole-Orbitrap mass spectrometry. Multivariate statistical analysis of LC-MS data showed a clear difference in the metabolite profiles between WKY rats and SHR. The results indicated that 30 endogenous metabolites significantly contributed to the difference and 7 of 30 metabolites were changed by the S1PC treatment. Furthermore, regression analysis showed correlation between SBP and the plasma levels of betaine, tryptophan and 3 LysoPCs. This metabolomics approach suggested that S1PC could exert its antihypertensive effect by affecting glycine, serine and threonine metabolism, tryptophan metabolism and glycerophospholipid metabolism.

Evaluation of the Effects of S-Allyl-L-cysteine, S-Methyl-L-cysteine, trans-S-1-Propenyl-L-cysteine, and Their N-Acetylated and S-Oxidized Metabolites on Human CYP Activities

Three major organosulfur compounds of aged garlic extract, S-allyl-L-cysteine (SAC), S-methyl-L-cysteine (SMC), and trans-S-1-propenyl-L-cysteine (S1PC), were examined for their effects on the activities of five major isoforms of human CYP enzymes: CYP1A2, 2C9, 2C19, 2D6, and 3A4. The metabolite formation from probe substrates for the CYP isoforms was examined in human liver microsomes in the presence of organosulfur compounds at 0.01-1 mM by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Allicin, a major component of garlic, inhibited CYP1A2 and CYP3A4 activity by 21-45% at 0.03 mM. In contrast, a CYP2C9-catalyzed reaction was enhanced by up to 1.9 times in the presence of allicin at 0.003-0.3 mM. SAC, SMC, and S1PC had no effect on the activities of the five isoforms, except that S1PC inhibited CYP3A4-catalyzed midazolam 1'-hydroxylation by 31% at 1 mM. The N-acetylated metabolites of the three compounds inhibited the activities of several isoforms to a varying degree at 1 mM. N-Acetyl-S-allyl-L-cysteine and N-acetyl-S-methyl-L-cysteine inhibited the reactions catalyzed by CYP2D6 and CYP1A2, by 19 and 26%, respectively, whereas trans-N-acetyl-S-1-propenyl-L-cysteine showed weak to moderate inhibition (19-49%) of CYP1A2, 2C19, 2D6, and 3A4 activities. On the other hand, both the N-acetylated and S-oxidized metabolites of SAC, SMC, and S1PC had little effect on the reactions catalyzed by the five isoforms. These results indicated that SAC, SMC, and S1PC have little potential to cause drug-drug interaction due to CYP inhibition or activation in vivo, as judged by their minimal effects (IC₅₀>1 mM) on the activities of five major isoforms of human CYP in vitro.

Aged garlic extract suppresses platelet aggregation by changing the functional property of platelets

Aged garlic extract (AGE), a garlic preparation rich in water-soluble cysteinyl moieties, has been reported to have multiple beneficial effects on cardiovascular disease including inhibition of platelet aggregation. However, the mode of AGE action on platelets has not been clear. In this study, we examined the effect of AGE on the functional property of platelet by administering AGE to rats and evaluating the platelet aggregation in response to collagen in vitro. We found that AGE treatment significantly reduced the ability of platelet to aggregate and this effect of AGE was manifested on the 14 day, but not 7 day of treatment. In addition, AGE treatment produced platelets that responded to collagen by significantly increasing the amount of both the extracellular ATP and the extra- and intracellular TXB₂. AGE treatment also dose-dependently suppressed the phosphorylation of collagen-induced ERK, p38 and JNK. However, AGE administration did not affect the bleeding time. These findings suggest that AGE treatment results in suppression of platelet aggregation by changing the functional property of platelets to respond to collagen.