Aged garlic extract reduces low attenuation plaque in coronary arteries of patients with diabetes: A randomized, double-blind, placebo-controlled study

Anti?atherosclerotic effect of aged garlic extract: Mode of action and therapeutic benefits (Review)

Atherosclerosis, a chronic inflammatory disease characterized by plaque buildup within the arteries that obstructs blood flow and significantly increases the morbidity and mortality rates associated with cardiovascular diseases caused by impaired blood flow due to vascular stenosis or occlusion, such as angina and myocardial infarction. The development of atherosclerosis involves a complex interplay of endothelial dysfunction, accumulation of oxidized low-density lipoprotein and macrophage-driven inflammation. The risk factors for atherosclerosis include chronic inflammation, hyperlipidemia and hypertension. Effective management of these risk factors can prevent and delay the onset and progression of atherosclerosis. Garlic and its processed preparations have previously been utilized to mitigate cardiovascular risk factors and continue to be used in traditional medicine in several countries. Among these preparations, aged garlic extract (AGE) has been shown to improve atherosclerosis in clinical trials and animal studies. AGE contains various compounds with potential anti-atherosclerotic properties, such as S-1-propenylcysteine, S-allylcysteine and other sulfur-containing constituents, which may help prevent the development and progression of atherosclerosis. The present manuscript reviewed and discussed the anti-atherogenic effect of AGE and its constituents by highlighting their mode of action and potential benefits for prevention and therapy in the management of atherosclerosis.

WITHDRAWN: Coronary atherosclerotic plaque regression strategies

Ahead of Print article withdrawn by publisher.

Genes encoding γ‑glutamyl‑transpeptidases in the allicin biosynthetic pathway in garlic (Allium sativum)

Allicin is a thiosulphate molecule produced in garlic (Allium sativum) and has a wide range of biological actions and pharmaceutical applications. Its precursor molecule is the non-proteinogenic amino acid alliin (S-allylcysteine sulphoxide). The alliin biosynthetic pathway in garlic involves a group of enzymes, members of which are the γ-glutamyl-transpeptidase isoenzymes, Allium sativum γ-glutamyl-transpeptidase AsGGT1, AsGGT2 and AsGGT3, which catalyze the removal of the γ-glutamyl group from γ-glutamyl-S-allyl-L-cysteine to produce S-allyl-L-cysteine. This removal is followed by an S-oxygenation, which leads to the biosynthesis of alliin. The aim of the present study is to annotate previously discovered genes of garlic γ-glutamyl-transpeptidases, as well as a fourth candidate gene (AsGGT4) that has yet not been described. The annotation includes identifying the loci of the genes in the garlic genome, revealing the overall structure and conserved regions of these genes, and elucidating the evolutionary history of these enzymes through their phylogenetic analysis. The genomic structure of γ-glutamyl-transpeptidase genes is conserved; each gene consists of seven exons, and these genes are located on different chromosomes. AsGGT3 and AsGGT4 enzymes contain a signal peptide. To that end, the AsGGT3 protein sequence was corrected; four indel events occurring in AsGGT3 coding regions suggested that at least in the garlic variety Ershuizao, AsGGT3 may be a pseudogene. Finally, the use of protein structure prediction tools allowed the visualization of the tertiary structure of the candidate peptide.

Interventions to Attenuate Cardiovascular Calcification Progression: A Systematic Review of Randomized Clinical Trials

BACKGROUND

Cardiovascular calcification, characterized by deposition of calcium phosphate in the arterial wall and heart valves, is associated with cardiovascular morbidity and mortality and is commonly seen in aging, diabetes, and chronic kidney disease. Whether evidence-based interventions could significantly attenuate cardiovascular calcification progression remains uncertain.

METHODS AND RESULTS

We conducted a systematic review of randomized controlled trials involving interventions, compared with placebo, another comparator, or standard of care, to attenuate cardiovascular calcification. Included clinical trials involved participants without chronic kidney disease, and the outcome was cardiovascular calcification measured using radiological methods. Quality of evidence was determined by the Cochrane risk of bias and Grading of Recommendations, Assessment, Development, and Evaluations assessment. Forty-nine randomized controlled trials involving 9901 participants (median participants 104, median duration 12 months) were eligible for inclusion. Trials involving aged garlic extract (n=6 studies) consistently showed attenuation of cardiovascular calcification. Trials involving 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (n=14), other lipid-lowering agents (n=2), hormone replacement therapies (n=3), vitamin K (n=5), lifestyle measures (n=4), and omega-3 fatty acids (n=2) consistently showed no attenuation of cardiovascular calcification with these therapies. Trials involving antiresorptive (n=2), antihypertensive (n=2), antithrombotic (n=4), and hypoglycemic agents (n=3) showed mixed results. Singleton studies involving salsalate, folate with vitamin B6 and 12, and dalcetrapib showed no attenuation of cardiovascular calcification. Overall, Cochrane risk of bias was moderate, and the Grading of Recommendations, Assessment, Development, and Evaluations assessment for a majority of analyses was moderate certainty of evidence.

CONCLUSIONS

Currently, there are insufficient or conflicting data for interventions evaluated in clinical trials for mitigation of cardiovascular calcification. Therapy involving aged garlic extract appears most promising, but evaluable studies were small and of short duration.

Achieving coronary plaque regression: a decades-long battle against coronary artery disease

INTRODUCTION

Traditionally atherosclerosis was thought to be progressive and medical treatment solely focused on delaying the progression of atherosclerosis rather than treating the disease itself. Multiple recent studies, however, have demonstrated a significant decrease in cardiovascular mortality with the use of additional anti-atherosclerotic therapies beyond statins. Consistent with these observations, mechanistic studies indicate that these additional anti-atherosclerotic therapies have a positive effect on both halting and reversing the course of atherosclerosis.

AREAS COVERED

We examine the progression of atherosclerosis and the efficacy of various anti-atherosclerotic treatment classes in this review utilizing multimodality imaging techniques. Searches were conducted in electronic databases: PubMed and EMBASE for all peer reviewed publications that examined coronary plaque progression, regression and stabilization using different imaging modalities and antiatherosclerosis therapies. The keywords coronary plaque, coronary angiography, IVUS, intravascular OCT, CCTA in conjunction with the various therapies included in this review were searched in different combinations. All relevant published articles on this topic were identified and their reference lists were screened for relevance.

EXPERT COMMENTARY

Though lipoprotein levels have traditionally been the target for antiatherosclerosis medication, several newer strategies have emerged creating novel targets in the treatment of coronary atherosclerosis. Using a combination of antiatherosclerosis therapies in conjunction with noninvasive imaging modalities like CCTA to directly visualize the plaque, is currently the focus of the future, with the aim of preventing and reversing atherosclerosis.

In Vitro Colonic Fermentation of (Poly)phenols and Organosulfur Compounds of Fresh and Black Garlic

The beneficial properties associated with garlic consumption have been related to the presence of bioactive compounds including (poly)phenols and organosulfur compounds (OSCs). This study aims to assess the effect of in vitro colonic fermentation on fresh and black garlic by determining the transformation of these compounds through ultrahigh-performance liquid chromatography coupled to mass spectrometry with a linear ion trap (uHPLC-LIT-MS). Colonic fermentation had a similar influence on the phenolic content of fresh and black garlic, with total respective decreases of 43.8% and 41.7%. Meanwhile, fermentation resulted in a significant decrease (33%) in OSCs in black garlic. Compounds such as 4-hydroxybenzoic acid, S-allylcysteine (SAC), and methionine sulfoxide were the phenolic compounds and OSCs with the highest concentration in fresh and black garlic after the in vitro fermentation. These compounds, potentially present at the colonic level, might be responsible for the systemic health benefits associated with the consumption of black and fresh garlic.

The Evolving Role of Omega 3 Fatty Acids in Cardiovascular Disease: Is Icosapent Ethyl the Answer?

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of morbidity and mortality globally. Despite significant advances in pharmacotherapies and the beneficial effects of statin therapy on ASCVD outcomes and progression of atherosclerosis, residual cardiovascular (CV) risk remains. Extensive evidence has identified the contribution of atherogenic dyslipidaemia, which is particularly characterised by elevated triglycerides (TGL) as a key driver of CV risk, even if low-density lipoprotein cholesterol levels are well controlled. Epidemiologic and genetic/Mendelian randomisation studies have demonstrated that elevated TGL levels serve as an independent marker for an increased risk of ischaemic events, highlighting TGLs as a suitable therapeutic target. Clinical studies have shown that omega 3 fatty acids (OM3FA) are effective in lowering TGLs; however, to date, trials and meta-analyses of combined OM3FA products have not demonstrated any clinical CV outcome benefit in patients receiving statins. However, icosapent ethyl (IPE) - a highly purified, stable ethyl ester of eicosapentaenoic acid (EPA) - has been rigorously demonstrated in multiple studies to be a useful adjunctive therapy to address residual CV risk. EPA is an omega-3 polyunsaturated fatty acid that is incorporated into membrane phospholipid bilayers and is reported to exert multiple beneficial effects along the pathway of coronary atherosclerosis. In this brief review, we will provide an overview of the mode of action of IPE in coronary atherosclerosis, the robust clinical evidence and trial data supporting its use, and expert consensus/recommendations on its use in specific populations, as an adjunct to existing anti-atherosclerotic therapies.

S-1-propenylcysteine improves TNF-α-induced vascular endothelial barrier dysfunction by suppressing the GEF-H1/RhoA/Rac pathway

Background

Vascular endothelial barrier function is maintained by cell-to-cell junctional proteins and contributes to vascular homeostasis. Various risk factors such as inflammation disrupt barrier function through down-regulation of these proteins and promote vascular diseases such as atherosclerosis. Previous studies have demonstrated that aged garlic extract (AGE) and its sulfur-containing constituents exert the protective effects against several vascular diseases such as atherosclerosis. In this study, we examined whether AGE and its sulfur-containing constituents improve the endothelial barrier dysfunction elicited by a pro-inflammatory cytokine, Tumor-necrosis factor-α (TNF-α), and explored their mode of action on TNF-α signaling pathway.

Methods

Human umbilical vein endothelial cells (HUVECs) were treated with test substances in the presence of TNF-α for various time periods. The endothelial permeability was measured by using a transwell permeability assay. The localization of cell-to-cell junctional proteins and actin cytoskeletons were visualized by immunostaining. RhoA and Rac activities were assessed by using GTP-binding protein pulldown assay. Gene and protein expression levels of signaling molecules were analyzed by real-time PCR and western blotting, respectively.

Results

We found that AGE and its major sulfur-containing constituent, S-1-propenylcysteine (S1PC), reduced hyperpermeability elicited by TNF-α in HUVECs. In addition, S1PC inhibited TNF-α-induced production of myosin light chain (MLC) kinase and inactivation of MLC phosphatase through the suppression of the Rac and RhoA signaling pathways, respectively, which resulted in the dephosphorylation of MLC2, a key factor of actin remodeling. Moreover, S1PC inhibited the phosphorylation and activation of guanine nucleotide exchange factor-H1 (GEF-H1), a common upstream key molecule and activator of Rac and RhoA. These effects of S1PC were accompanied by its ability to prevent the disruption of junctional proteins on the cell–cell contact regions and the increase of actin stress fibers induced by TNF-α.

Conclusions

The present study suggested that AGE and its major constituent, S1PC, improve endothelial barrier disruption through the protection of junctional proteins on plasma membrane.

Bioaccessibility of Bioactive Compounds of 'Fresh Garlic' and 'Black Garlic' through In Vitro Gastrointestinal Digestion

Numerous studies have reported health benefits associated with the consumption of fresh and black garlic, which are characterized by the presence of polyphenols and organosulfur compounds (OS). This study aims to analyze the bioaccessibility of the bioactive compounds in fresh and black garlic after in vitro gastrointestinal digestion by monitoring the individual profile of these compounds by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). Polyphenols decreased from the beginning of the digestive process, is mainly affected during intestinal digestion. Regarding the OS, the S-alk(en)yl-L-cysteine (SACs) derivatives were more influenced by the acidic conditions of the gastric digestion, while the γ-glutamyl-S-alk(en)yl-L-cysteine (GSAk) derivatives were more susceptible to intestinal digestion conditions in both the fresh and black garlic samples. In conclusion, after in vitro gastrointestinal digestion, the compounds with the highest bioaccessibility were vanillic acid (69%), caffeic acid (52%), γ-glutamyl-S-methyl-L-cysteine sulfoxide (GSMCS) (77%), and S-allylmercapto-L-cysteine (SAMC) (329%) in fresh garlic. Meanwhile, in black garlic, the main bioaccessible compounds were caffeic acid (65%), GSMCS (89%), methionine sulfoxide (262%), trans-S-(1-propenyl)-L-cysteine (151%), and SAMC (106%). The treatment (heating + humidity) to obtain black garlic exerted a positive effect on the bioaccessibility of OS compounds, 55.3% of them remaining available in black garlic, but only 15% in fresh garlic. Polyphenols showed different behavior regarding bioaccessibility.