Water-soluble organosulfur compounds of garlic inhibit fatty acid and triglyceride syntheses in cultured rat hepatocytes

Traditional Chinese medicine and plant-derived natural products in regulating triglyceride metabolism: Mechanisms and therapeutic potential

The incidence of cardiometabolic disease is increasing globally, with a trend toward younger age of onset. Among these, atherosclerotic cardiovascular disease is a leading cause of mortality worldwide. Despite the efficacy of traditional lipid-lowering drugs, such as statins, in reducing low-density lipoprotein cholesterol levels, a significant residual risk of cardiovascular events remains, which is closely related to unmet triglyceride (TG) targets. The clinical application of current TG-lowering Western medicines has certain limitations, necessitating alternative or complementary therapeutic strategies. Traditional Chinese medicine (TCM) and plant-derived natural products, known for their safety owing to their natural origins and diverse biological activities, offer promising avenues for TG regulation with potentially fewer side effects. This review systematically summarises the mechanisms of TG metabolism and subsequently reviews the regulatory effects of TCM and plant-derived natural products on TG metabolism, including the inhibition of TG synthesis (via endogenous and exogenous pathways), promotion of TG catabolism, regulation of fatty acid absorption and transport, enhancement of lipophagy, modulation of the gut microbiota, and other mechanisms. In conclusion, through a comprehensive analysis of recent studies, this review consolidates the multifaceted regulatory roles of TCM and plant-derived natural products in TG metabolism and elucidates their potential as safer, multi-target therapeutic agents in managing hypertriglyceridemia and mitigating cardiovascular risk, thereby providing a basis for new drug development.

Randomized, double-blind clinical trial evaluating the impact of freeze-dried garlic extract capsules on blood pressure, lipid profile, and nitric oxide levels in individuals at risk for hypertension

OBJECTIVES

Hypertension, substantially heightens the risk of cardiovascular disease. This study aims to evaluate the effectiveness of freeze-dried garlic extract in blood pressure and lipid profiles in prehypertensive individuals.

METHODS

Participants (age of 30-70 years) were allocated to intervention (n=47) or control (n=49) groups. The intervention group received two capsules of freeze-dried garlic extract daily for eight weeks, while the control group received identical placebo capsules. Primary outcomes, SBP, DBP, PP, MAP, TC, TG, LDL and HDL levels, serum NO levels, were assessed at baseline, four weeks, and eight weeks.

RESULTS

At the end of study, results showed significant changes in the values of SBP, DBP, and MAP except for PP. In comparison to those who received the placebo, a significant drop in SBP, DBP (p<0.001), and MAP (p<0.001) was observed in the intervention group. Also, there were significant changes in TG, LDL, TC, and HDL levels in the interventional group. A noticeable decline was reported in TG (p<0.001), LDL (p<0.001), and TC (p<0.001), while HDL levels increased (p<0.001) in the intervention group compared to those receiving the placebo. Following garlic supplementation, a significant increase in blood NO levels was reported in the intervention group (p<0.001).

CONCLUSIONS

The study showed that garlic supplementation was effective in lowering blood pressure, improving lipid profile, and increasing nitric oxide levels in prehypertensive participants. These results indicate that garlic could be a valuable complementary therapy for managing prehypertension.

Garlic against Heart-related Ailments: Chemistry, Pharmacology, and Future Perspective

BACKGROUND

Allium sativum L. (Garlic) is a well-recognized plant of great nutraceutical value with pharmacological evidences. It is full of dietary as well as pharmaceutical properties and has been used in traditional medications for a long time. It is known for good antioxidant, antifungal, antibacterial, anti-diabetic, anti-inflammatory, anticancer, and antiviral effects, along with other therapeutic roles in cardiovascular diseases, anti-atherosclerotic, antihypertensive, anti-thrombotic, blood pressure, bone and skin related problems etc. Objective: Considering the potential of garlic in the treatment of cardiovascular/heart-related diseases, the main objective of this study was to prepare a subject-centric mini-review focusing on its chemistry and pharmacology in heart-related issues.

METHODS

In order to prepare this mini-review article, an extensive online literature search was performed to find out the most recent studies related to this topic. These studies were briefly reviewed, assessed, and discussed to explore the possible capability of garlic for the cure of cardiovascular problems.

RESULT

Several experiments on mice models, rat models as well as on humans show the effective role of various forms of garlic in cardiovascular or heart-related ailments. After reviewing the available publications on garlic in heart-related issues, authors found that garlic and its sulfur (S)-based organic constituents may have advantageous applications in the treatment of cardiovascular diseases.

Allicin and Capsaicin Ameliorated Hypercholesterolemia by Upregulating LDLR and Downregulating PCSK9 Expression in HepG2 Cells

Hypercholesterolemia is a common cause of cardiovascular diseases (CVDs). Although allicin and capsaicin possess hypolipidemic effects through several molecular mechanisms, their effects on LDLR and PCSK9 expression are still unknown. This study aimed to investigate the effects of allicin and capsaicin on LDLR and PCSK9 expression in HepG2 cells. The effects of allicin and capsaicin on cell viability were evaluated by MTT assay and trypan blue exclusion assay. Low-density lipoprotein receptor (LDLR) levels and LDL uptake were determined by flow cytometry and confocal laser scanning microscopy (CLSM), respectively. RT-qPCR and Western blot analyses were performed to evaluate the expression of PCSK9, LDLR, SREBP-2, and HNF1α. ELISA was used to measure PCSK9 levels in culture media. Allicin and capsaicin increased the protein expression levels of LDLR via activation of the transcription factor SREBP2. However, allicin and capsaicin decreased the expression of PCSK9 protein and the secretion of PCSK9 in culture media via the suppression of HNF1α. Moreover, allicin and capsaicin increased LDL uptake into HepG2 cells. The efficacies of the hypolipidemic effects of allicin (200 µM) and capsaicin (200 µM) were comparable to that of atorvastatin (10 µM) in this study. In conclusion, allicin and capsaicin possessed hypolipidemic effects via the upregulation of LDLR and downregulation of PCSK9 expression, thereby enhancing LDL uptake into HepG2 cells. This indicates that allicin and capsaicin should be used as potent supplements to ameliorate hypercholesterolemia.

Acute and subchronic 90-days toxicity assessment of propyl-propane-thiosulfinate (PTS) in rats

The organosulfur compounds (OSC) extracted from Allium spp. exhibit antibacterial, antifungal, and antioxidant properties. The agri-food industry is taking advantage of these properties by using them as natural feed and food additives. In the present work, an acute and a subchronic 90-days toxicity studies have been conducted for the first time to assess the safety of the OSC propyl-propane-thiosulfinate (PTS). Both studies were carried out following the Organization for Economic Co-operation and Development test guidelines (425 and 408, respectively). The acute study provided a maximum tolerated dose (MTD) of 175 mg/kg and the subchronic study established the Non Observed Adverse Effect Level (NOAEL) ≥ 55 mg/kg body weight (b.w.)/day in both sexes. In addition, the subchronic study performed on rats exposed to 14, 28 and 55 mg/kg b.w./day PTS, revealed no changes in any of the hematological parameters measured as well as no differences in body weight and water/food consumption. However, biochemical parameters were altered in some groups, although they were not biologically significant (Ca2+ in female rats, and the thyroids hormones T3 and T4 in rat males). Furthermore, the histopathological assessment evidenced no abnormality on the gastrointestinal, respiratory, lymphoid, urinary, circulatory, nervous, musculoskeletal, and reproductive systems.

Increased protein expression of ABCA1, HMG-CoA reductase, and CYP46A1 induced by garlic and allicin in the brain mouse and astrocytes-isolated from C57BL/6J

Objective:

Regulation of cholesterol level is essential for the brain optimal function. The beneficial effect of garlic consumption on cholesterol homeostasis is well known; however, the molecular mechanism to support its properties is unclear. Here, we investigated the beneficial effect of aqueous extract of garlic and allicin on lipid profile and the main players involved in brain cholesterol homeostasis including ABCA1, HMG-CoA reductase, and CYP46A1 in both C57BL/6J mice brain and astrocytes.

Materials and Methods:

Thirty mice were divided into control and garlic groups. Garlic group was fed with the aqueous extract of garlic. Serum lipids were measured and brain protein levels of ABCA1, HMGCR, and CYP46A1 were determined by western blotting. Changes in these proteins expression were also studied in the presence of allicin in cultured astrocytes.

Results:

A moderate decrease in serum total cholesterol and a significant increase in plasma HDL-C levels (p<0.05) were detected. A significant increase in ABCA1, HMGCR, and CYP46A1 protein levels was observed in the garlic group and in the cultured astrocytes treated with allicin by western blotting (p<0.05).

Conclusion:

Our findings indicated that the main players involved in cholesterol turnover including HMGCR that is involved in cholesterol synthesis, ABCA1 that is important in cholesterol efflux, and CYP46A1 that is necessary in cholesterol degradation, were up regulated by garlic/allicin in both animal and cell culture model. We concluded that increasing cholesterol turnover is a possible mechanism for the beneficial effects of garlic in cholesterol homeostasis.

The Influence of Plants from the Alliaceae Family on Morphological Parameters of the Intestine in Atherogenic Rats

Bulbs from the Alliaceae family have been well-known and valued spices for thousands of years, not only for their unique flavor and aroma features, but also for their high nutritional and health-promoting values. Long-term or excessive consumption of these vegetables, especially raw garlic, can have side effects in the body (including in the digestive tract), causing a number of pathological changes in the intestinal wall; these changes lead, in turn, to its damage, dysfunction, and disorder development. Therefore, the aim of this study was to investigate the effect of the addition of freeze-dried vegetables from the Alliaceae family, i.e., garlic (Allium sativum L.), white onion, and red onion (Allium cepa L.) on the morphometric parameters (intestinal villi length, crypt depth, thickness of tunica mucosa, and the thickness of tunica muscle) of the jejunum of rats fed a semi-synthetic atherogenic diet (1% dietary cholesterol). In freeze-dried vegetables administered to rats, the contents of selected bioactive ingredients and their antioxidant potentials were determined. The effect of the onion vegetable supplements on growth parameters, serum lipid profile, plasma antioxidant potential, and the intestinal morphological parameters of rats loaded with cholesterol was determined. In an animal experiment, 30 male Wistar rats were divided into 5 diet groups, diet consumption and FER were studied. Supplementation of the atherogenic diet with vegetables improved the blood plasma lipid profiles and atherogenic indices, in a manner that was dependent on the type of supplementation used, with the best hypolipidemic and anti-atherosclerotic effects found in garlic use. The atherogenic diet, as well as the supplementation of this diet with the tested vegetables from the Alliaceae family, influenced the histological changes in the epithelium of the jejunum of rats. The damage to the intestinal mucosa was the greatest in animals fed an atherogenic diet supplemented with garlic. Bearing in mind that the desired beneficial therapeutic or prophylactic effects of onion vegetables (in particular garlic) in the course of various metabolic ailments (including atherosclerosis) are achieved during long-term supplementation, it is important to remember their possible cytotoxic effects (e.g., on the digestive tract) in order to achieve real benefits related to the supplementation with vegetables from the Alliaceae family.

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

Phytotherapy for Cardiovascular Disease: A Bench-to-Bedside Approach

At present, cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, and global trends suggest that this panorama will persist or worsen in the near future. Thus, optimization of treatment strategies and the introduction of novel therapeutic alternatives for CVD represent key objectives in contemporary biomedical research. In recent years, phytotherapy-defined as the therapeutic use of whole or minimally modified plant components-has ignited large scientific interest, with a resurgence of abundant investigation on a wide array of medicinal herbs (MH) for CVD and other conditions. Numerous MH have been observed to intervene in the pathophysiology of CVD via a myriad of molecular mechanisms, including antiinflammatory, anti-oxidant, and other beneficial properties, which translate into the amelioration of three essential aspects of the pathogenesis of CVD: Dyslipidemia, atherosclerosis, and hypertension. Although the preclinical data in this scenario is very rich, the true clinical impact of MH and their purported mechanisms of action is less clear, as large-scale robust research in this regard is in relatively early stages and faces important methodological challenges. This review offers a comprehensive look at the most prominent preclinical and clinical evidence currently available concerning the use of MH in the treatment of CVD from a bench-to-bedside approach.

s-Ethyl cysteine, an amino acid derivative, attenuated cisplatin induced nephrotoxicity

Renal protection from s-ethyl cysteine (SEC) against cisplatin (CP)-induced inflammatory and oxidative injury was examined. Mice were divided into five groups: normal group, 0.25% SEC group, CP group, 0.125% SEC + CP group, 0.25% SEC + CP group. After 2 weeks supplementation, mice of CP and SEC + CP groups received CP treatment. H&E stain showed that CP caused infiltration of inflammatory cells and necrosis of tubular cells. SEC pre-treatments attenuated CP-induced inflammatory injury and degeneration. SEC pre-treatments limited CP-stimulated release of interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha and prostaglandin E₂ in kidney. CP raised the renal activity and mRNA expression of cyclooxygenase-2 and nuclear factor kappa B. SEC pre-treatments reversed these alterations. CP increased the production of reactive oxygen species and nitric oxide, and lowered glutathione content, glutathione peroxidase and glutathione reductase activities in kidney. SEC pre-treatments reversed these changes. CP up-regulated renal inducible nitric oxide synthase (iNOS) mRNA expression, and down-regulated nuclear factor E2-related factor (Nrf)-2 and heme oxygenase (HO)-1 mRNA expression. SEC pre-treatments suppressed iNOS mRNA expression; and enhanced renal Nrf2 and HO-1 mRNA expression. These novel findings suggest that dietary SEC via exerting its multiple bio-functions could be considered as a protective agent for kidney against CP.

Organosulfur Compounds: A Review of Their Anti-inflammatory Effects in Human Health

Phytonutrients are widely recognized for providing protective human health benefits. Among the phytonutrients, epidemiological and experimental studies show that dietary organosulfur compounds (OSC) play a significant role in preventing various human pathological progressions, including chronic inflammation, by decreasing inflammatory mediators such as nitric oxide (NO), prostaglandin (PG)E₂, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-17, which are all typical hallmarks of inflammation. Evidence supports OSC in reducing the expression of these markers, thereby attenuating chronic inflammatory processes. Nuclear factor-kappa B (NF-κB) is a key regulating factor during inflammation, and novel evidence shows that OSC downregulates this transcriptional factor, thus contributing to the anti-inflammatory response. In vitro and in vivo studies show that inflammation is mechanistically linked with acute and chronic pathological conditions including cancer, diabetes, obesity, neural dysfunction, etc. Furthermore, a considerable number of experiments have demonstrated that the anti-inflammatory properties of OSC occur in a dose-dependent manner. These experiments also highlight indirect mechanisms as well as potent co-functions for protective roles as antioxidants, and in providing chemoprotection and neuroprotection. In this brief review, we provided an overview of the anti-inflammatory effects of OSC and elucidated probable mechanisms that are associated with inflammation and chronic disorders.

Alliin, an Allium sativum Nutraceutical, ReducesMetaflammation Markers in DIO Mice

Obesity generates a chronic low-grade inflammatory state which promotes oxidative stress and triggers comorbidities. Alliin is the main organosulfur compound in garlic and has been shown to induce a decrease in the expression of proinflammatory cytokines; its systemic effect on metabolic parameters and adipose tissue is not yet known, however. After nine weeks of HFD and with obesity established in C57BL/6 mice, we observed that a daily treatment with alliin for 3.5 weeks (15 mg/kg) did not affect body weight, but significantly improved insulin sensitivity and glucose tolerance, both evaluated through a blood glucose monitoring system. Once alliin treatment was completed, serum, adipose tissue, and organs of interest related to metabolism were removed for further analysis. We observed that alliin significantly decreased the size of adipocytes from epididymal adipose tissue, evaluated via microscopy. A decrease in gene expression and serum protein levels of the adipocytokines leptin and resistin, as well as decreased serum IL-6 concentration, were detected by qRT-PCR and ELISA, respectively. It did not, however, affect mRNA expression of antioxidant enzymes in the liver. Taken altogether, these results indicate that treatment with alliin reduces metaflammation markers in DIO mice and improves some metabolic parameters without affecting others.

Medicinal plants in treatment of hypertriglyceridemia: A review based on their mechanisms and effectiveness

BACKGROUND

Hypertriglyceridemia (HTg) defines as high amounts of triglyceride (TG) in the blood which can lead to serious complications over time. HTg is usually a part of metabolic disorders such as diabetes mellitus, metabolic syndrome, and dyslipidemia. Different medications have been used to treat HTg but experimentally, many herbs have been recommended for treating HTg as an adjuvant therapy. In most cases, the recommendations are based on animal studies and limited evidences exist about their mechanisms and clinical usefulness.

PURPOSE

This review focused on the herbs which have been shown TG lowering effect.

METHOD

The search was done in PubMed, Science Direct, Scopus, Web of Science and Google Scholar databases a 20-year period between 1997 to 2017 with keywords search of medicinal plant, plant extract, hypertriglyceridemia, dyslipidemia, hyperlipidemia, lipoprotein lipase and apolipoprotein.

RESULTS

According to the results, many plants showed positive effects but Allium sativum, Nigella sativa, Curcuma longa, Anethum graveolens and Commiphora mukul had the best TG lowering effect with exact mechanisms of action.

CONCLUSION

It seems that use of these plants as complementary therapeutics or extraction of their active ingredients along with currently available drugs will improve the management of HTg in patients.

Anti-hyperlipidemia of garlic by reducing the level of total cholesterol and low-density lipoprotein: A meta-analysis

BACKGROUND

This study aimed to understand the impact of garlic on improving blood lipids using a meta-analysis.

METHODS

A literature search of the PubMed, EMBASE, and Cochrane Library databases was performed using keywords such as "garlic" and "hypercholesterolemia," and the deadline "July 14 (th), 2017." After extracting relevant details, each selected literature was evaluated for quality according to the quality evaluation criteria of bias risk recommended by Cochrane Collaboration recommendations and heterogeneity tests were performed. Standardized mean difference (SMD) and 95% confidence interval (CI) were evaluated using R 3.12 software. The publication bias was assessed using Egger method.

RESULTS

A total of 14 eligible papers published from 1981 to 2016 were included. The quality of the literatures was of moderate to high qualities. The values of TC (SMD = -1.26, 95% CI, -1.86 to -0.66), low-density lipoprotein (LDL) (SMD = -1.07, 95% CI, -1.67 to -0.47), and high-density lipoprotein (HDL) (SMD = 0.50, 95% CI, 0.06-0.94) after taking garlic in the experimental group and the control group have statistical significance, while there was no significant difference of TG in the 2 groups (SMD = -0.16, 95% CI, -0.87-0.55). However, the result of HDL was reversed when removed some of the literatures. No significant publication bias among the eligible studies with values of TC (P = .0625), LDL (P = .0770), HDL (P = .2293), and TG (P = .3436).

CONCLUSION

Garlic can reduce the level of TC and LDL instead of HDL and TG, indicating the ability of anti-hyperlipidemia.

Effect of Garlic and Lemon Juice Mixture on Lipid Profile and Some Cardiovascular Risk Factors in People 30-60 Years Old with Moderate Hyperlipidaemia: A Randomized Clinical Trial

BACKGROUND

This study was performed to effects of garlic and lemon juice mixture on lipid profile and some cardiovascular risk factors in people 30-60 years old with moderate hyperlipidemia.

METHODS

In a parallel-designed randomized controlled clinical trial, a total of 112 hyperlipidemic patients 30-60 years, were recruited from Isfahan Cardiovascular Research Center. People were selected and randomly divided into four groups. Control blood samples were taken and height, weight, and blood pressure were recorded. (1) Received 20 g of garlic daily, plus 1 tablespoon lemon juice, (2) received 20 g garlic daily, (3) received 1 tablespoon of lemon juice daily, and (4) did not receive garlic or lemon juice. A study technician was done the random allocations using a random numbers table. All participants presented 3 days of dietary records and 3 days of physical activity records during 8 weeks. Blood samples were obtained at study baseline and after 8 weeks of intervention.

RESULTS

Results showed a significant decrease in total cholesterol (changes from baseline: 40.8 ± 6.1, P < 0.001), low-density lipoprotein-cholesterol (29.8 ± 2.6, P < 0.001), and fibrinogen (111.4 ± 16.1, P < 0.001) in the Group 1, in comparison with other groups. A greater reduction in systolic and diastolic blood pressure was observed in Group 1 compared with the Groups 3 and 4 (37 ± 10, P = 0.01) (24 ± 1, P = 0.02); respectively. Furthermore, a great reduction in body mass index was observed in the mixed group compared with the lemon juice and control groups (1.6 ± 0.1, P = 0.04).

CONCLUSIONS

Administration of garlic plus lemon juice resulted in an improvement in lipid levels, fibrinogen and blood pressure of patients with hyperlipidemia.

Natural thioallyl compounds increase oxidative stress resistance and lifespan in Caenorhabditis elegans by modulating SKN-1/Nrf

Identification of biologically active natural compounds that promote health and longevity, and understanding how they act, will provide insights into aging and metabolism, and strategies for developing agents that prevent chronic disease. The garlic-derived thioallyl compounds S-allylcysteine (SAC) and S-allylmercaptocysteine (SAMC) have been shown to have multiple biological activities. Here we show that SAC and SAMC increase lifespan and stress resistance in Caenorhabditis elegans and reduce accumulation of reactive oxygen species (ROS). These compounds do not appear to activate DAF-16 (FOXO orthologue) or mimic dietary restriction (DR) effects, but selectively induce SKN-1 (Nrf1/2/3 orthologue) targets involved in oxidative stress defense. Interestingly, their treatments do not facilitate SKN-1 nuclear accumulation, but slightly increased intracellular SKN-1 levels. Our data also indicate that thioallyl structure and the number of sulfur atoms are important for SKN-1 target induction. Our results indicate that SAC and SAMC may serve as potential agents that slow aging.

The inhibitory effects of γ-glutamylcysteine derivatives from fresh garlic on glycation radical formation

The effects of three reactive peptides, γ-glutamylmethylcysteine (γ-GMC), γ-glutamylpropylcysteine (γ-GPC), and γ-glutamylbutylcysteine (γ-GBC) on the suppression of reactive radicals during the heating of l-lysine in the presence or absence of glucose was studied by electron spin resonance spectroscopy. γ-GMC and γ-GPC were extracted from fresh garlic, and γ-GBC was a synthetic peptide. The results showed that γ-GMC and γ-GPC effectively suppress formation of l-lysine radicals, but that γ-GBC exhibits low radical inhibition. The origin of the short peptides, and the length of their side chain, influenced their surface hydrophobicity and subsequent radical inhibition. In addition, the oxidation of l-lysine was inhibited by the peptides in a similar manner to their inhibition of the Maillard reaction (MR), and their radical inhibition was consistent with similar activity towards N(ε)-(carboxymethyl)lysine (CML).

Potential therapeutic effects of functionally active compounds isolated from garlic

The medicinal properties of functionally active organosulfur compounds such as allin, diallyl disulfide, S-allylmercaptocysteine, and S-trityl-L-cysteine isolated from garlic have received great attention from a large number of investigators who have studied their pharmacological effects for the treatment of various diseases. These organosulfur compounds are able to prevent for development of cancer, cardiovascular, neurological, and liver diseases as well as allergy and arthritis. There have been also many reports on toxicities and pharmacokinetics of these compounds. The aim of this study is to review a variety of experimental and clinical reports, and describe the effectiveness, toxicities and pharmacokinetics, and possible mechanisms of pharmaceutical actions of functionally active compounds isolated from garlic.

Dietary spices as beneficial modulators of lipid profile in conditions of metabolic disorders and diseases

Spices are valued for their medicinal properties besides their use as food adjuncts to enhance the sensory quality of food. Dietary garlic, onion, fenugreek, red pepper, turmeric, and ginger have been proven to be effective hypocholesterolemics in experimentally induced hypercholesterolemia. The hypolipidemic potential of fenugreek in diabetic subjects and of garlic and onion in humans with induced lipemia has been demonstrated. Capsaicin and curcumin - the bioactive compounds of red pepper and turmeric - are documented to be efficacious at doses comparable to usual human intake. Capsaicin and curcumin have been shown to be hypotriglyceridemic, thus preventing accumulation of fat in the liver under adverse situations by enhancing triglyceride transport out of the liver. Capsaicin, curcumin, fenugreek, ginger, and onion enhance secretion of bile acids into bile. These hypocholesterolemic spices/spice principles reduce blood and liver cholesterol by enhancing cholesterol conversion to bile acids through activation of hepatic cholesterol-7α-hydroxylase. Many human trials have been carried out with garlic, onion, and fenugreek. The mechanism underlying the hypocholesterolemic and hypotriglyceridemic influence of spices is fairly well understood. Health implications of the hypocholesterolemic effect of spices experimentally documented are cardio-protection, protection of the structural integrity of erythrocytes by restoration of membrane cholesterol/phospholipid profile and prevention of cholesterol gallstones by modulation of the cholesterol saturation index in bile.

Anti-obesity effects of onion extract in Zucker diabetic fatty rats

Anti-obesity effects of onion extract were determined in obesity and diabetes-prone Zucker diabetic fatty rats by measuring the efficacy of markers concerned with diabetes and obesity. Body and adipose tissue weights in 5% of onion extract-fed group were found to be significantly lower than the control group without onion extract. Fasting blood glucose and HOMA-IR levels were also improved, although the serum insulin and leptin levels did not show any remarkable difference. Serum triglyceride and free fatty acid levels in both the 3% and 5%-fed group were found to be reduced compared to the control group. Additionally the feeding of the onion extract increased the glucose tolerance. These results suggest that dietary onion extract is beneficial for improving diabetes by decreasing lipid levels. We also examined differentiation ability of rat white preadipocyte cells using the onion extract and its sulfur-containing components. Cycloalliin, S-methyl-L-cysteine, S-propyl-L-cysteine sulfoxide, dimethyl trisulfide, especially S-methyl-L-cysteine sulfoxide were reported to be effective in inhibiting formation of oil drop in the cells, suggesting that these compounds may be involved in the anti-obesity effect of the onion extract.

Diallyl trisulfide suppresses the adipogenesis of 3T3-L1 preadipocytes through ERK activation

Garlic and its organosulfur compounds display hypolipidemic effects by inhibiting fatty acid and cholesterol synthesis. We investigated the anti-adipogenic effect of diallyl trisulfide (DATS), the second most abundant organosulfide in garlic oil. We studied the effects of DATS in 3T3-L1 preadipocytes and the mechanism involved in its action. DATS (0-75 μM) inhibited CCAAT/enhancer-binding protein (C/EBP) α and β and peroxisome proliferator-activated receptor (PPAR) γ mRNA and protein levels in a dose- and time-dependent manner, leading to a decrease of fatty acid synthase (FAS) expression and lipid accumulation in 3T3-L1 cells. Insulin treatment induced a transient increase in ERK phosphorylation in 3T3-L1 preadipocytes, and maximal induction was observed at 5 min and then declined. DATS, however, sustained ERK phosphorylation up to 120 min. In the presence of PD98059, the phosphorylation of ERK and suppression of PPARγ expression and DNA binding activity of PPARγ by DATS were reversed, and lipid accumulation was restored. In conclusion, these results indicate that DATS inhibits the differentiation of 3T3-L1 preadipocytes into adipocytes. DATS is likely to act by prolonging ERK activation, which leads to the down-regulation of adipogenic transcription factor expression during adipogenesis. Our results suggest that garlic may have potential as an anti-obesity agent.

The effects of time-released garlic powder tablets on multifunctional cardiovascular risk in patients with coronary artery disease

The double-blinded placebo-controlled randomized study has been performed in 51 coronary heart disease (CHD) patients to estimate the effects of time-released garlic powder tablets Allicor on the values of 10-year prognostic risk of acute myocardial infarction (fatal and non-fatal) and sudden death, with the respect of secondary CHD prevention. It has been demonstrated that 12-month treatment with Allicor results in the significant decrease of cardiovascular risk by 1.5-fold in men (p < 0.05), and by 1.3-fold in women. The above results were equitable also in terms of relative risks. The main effect that played a role in cardiovascular risk reduction was the decrease in LDL cholesterol by 32.9 mg/dl in men (p < 0.05), and by 27.3 mg/dl in women. Thus, the most significant effects were observed in men, while in women the decrease of cardiovascular risk appeared as a trend that might be due presumably to the insufficient sample size. Since Allicor is the remedy of natural origin, it is safe with the respect to adverse effects and allows even perpetual administration that may be crucial for the secondary prevention of atherosclerotic diseases in CHD patients.

Protective effects of cysteine analogues on acute myocardial ischemia: novel modulators of endogenous H(2)S production

The current study was designed to evaluate the pharmacologic effects of three novel cysteine-containing compounds: S-propyl-l-cysteine (SPC), S-allyl-l-cysteine (SAC), and S-propargyl-l-cysteine (SPRC) on H(2)S production and antioxidant defenses in an acute myocardial infarction (MI) rat model. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as glutathione redox status and malonaldehyde (MDA) content, also were determined. All three compounds were found to preserve SOD and GPx activities and also tissue GSH levels while reducing the formation of the lipid peroxidation product MDA in ventricular tissues. With immunfluorescence assays, we observed the expression of CSE and Mn-SOD. The morphologic changes of the cardiac cells are seen with both light and electron microscopy. The corresponding pathologic alterations were characterized mainly as loss of adherence between cardiac myocytes and swollen or ruptured mitochondria at the ultrastructural level. Propargylglycine, a selective inhibitor of CSE, abolished the protective effects of each compound used in the current model. Our study provides novel evidence that SPC, SAC, and SPRC have cardioprotective effects in MI by reducing the deleterious effects of oxidative stress by modulating the endogenous levels of H(2)S and preserving the activities of antioxidant defensive enzymes like SOD.

An onion byproduct affects plasma lipids in healthy rats

Onion may contribute to the health effects associated with high fruit and vegetable consumption. A considerable amount of onion production ends up as waste that might find use in foods. Onion byproduct has not yet been explored for potential health benefits. The aim of this study is to elucidate the safety and potential role of onion byproducts in affecting risk markers of cardiovascular disease (CVD). For that purpose, the effects of an onion byproduct, Allium cepa L. cepa 'Recas' (OBP), and its two derived fractions, an ethanolic extract (OE) and a residue (OR), on the distribution of plasma lipids and on factors affecting cholesterol metabolism in healthy rats have been investigated. The OBP or its fractions did not significantly reduce cholesterol or down-regulate hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase (Hmgcr) gene expression. The OR even had the effect of increasing plasma triacylglycerides (TAG) and cholesterol in the very low density lipoprotein (VLDL-C) fraction. Neither total bile acids nor total primary or secondary bile acids were significantly affected by feeding rats the OBP or its fractions. Principal component analysis combining all markers revealed that the controls could be completely separated from OBP, OE, and OR groups in the scores plot and also that OE and OR groups were separated. Plasma lipids and bile acid excretion were the discriminating loading factors for separating OE and OR but also contributed to the separation of onion-fed animals and controls. It was concluded that the onion byproduct did not present significant beneficial effects on individual markers related to plasma lipid transport in this healthy rat model but that onion byproduct contains factors with the ability to modulate plasma lipids and lipoprotein levels.

Nutraceutical use of garlic sulfur-containing compounds

Garlic is one of the world's oldest medicines that has been employed not only for flavouring but also as a medical herb for its prophylactic and therapeutic actions. Most garlics' beneficial effects are due to the presence of the organosulphate molecule allicin. Allicin is a highly unstable molecule and, during processing, is rapidly transformed into a variety of organosulfur components. The enzyme alliinase, which is responsible for the conversion of alliin to allicin, is irreversibly destroyed at the acidic environment of stomach. This is the reason why most garlic supplements contain garlic powder or granules, but do not contain allicin itself. Garlic alliinase could be encapsulated and coated with materials which would protect it in the harsh conditions of the stomach. The objective of this chapter is to summarize the most important garlic health benefits and to discuss promising encapsulation/stabilization approaches.

Garlic: Empiricism or Science?

Garlic (Allium sativum L. fam. Alliaceae) is one of the best-researched, best-selling herbal remedies and is also commonly used as a food and a spice. Garlic constituents include enzymes (for example, alliinase) and sulfur-containing compounds, including alliin, and compounds produced enzymatically from alliin (for example, allicin). Traditionally, it has been employed to treat infections, wounds, diarrhea, rheumatism, heart disease, diabetes, and many other disorders. Experimentally, it has been shown to exert antilipidemic, antihypertensive, antineoplastic, antibacterial, immunostimulant and hypoglycemic actions. Clinically, garlic has been evaluated for a number of conditions, including hypertension, hypercholesterolemia, intermittent claudication, diabetes, rheumatoid arthritis, common cold, as an insect repellent, and for the prevention of arteriosclerosis and cancer. Systematic reviews are available for the possible antilipidemic, antihypertensive, antithrombotic and chemopreventive effects. However, the clinical evidence is far from compelling. Garlic appears to be generally safe although allergic reactions may occur.

Consumption of brown onions (Alliumcepavar.cavalierand var.destiny) moderately modulates blood lipids, haematological and haemostatic variables in healthy pigs

Although garlic and onions have long been associated with putative cardiovascular health benefits, the effects of different commercially available onions and level of intake have not been studied. Therefore, the aim of the present study was to evaluate the potential health benefits of raw onions using the pig as a biomedical model. Twenty-five female (Large White×Landrace) pigs were used in a (2×2)+1 factorial experiment. Pigs were fed a standard grower diet supplemented with 100 g tallow/kg with the addition ofAllium cepavar.cavalieror var.destinyat 0, 10 or 25 g/MJ digestible energy for 6 weeks. Overall, the consumption of onions resulted in significant reductions in plasma triacylglycerol; however, the reductions were most pronounced in pigs feddestinyonions (−26 %,P=0·042). Total plasma cholesterol and LDL:HDL ratios were not significantly different. Onion supplementation, regardless of the variety, resulted in dose-dependent reductions in erythrocyte counts and Hb levels, while the white blood cell concentrations, particularly lymphocytes, were increased in pigs that consumed onions. Furthermore, indices of blood clotting were largely unaffected by onion consumption. In conclusion, dietary supplementation with raw brown onions has moderate lipid-modulating and immunostimulatory properties. However, daily onion intake >25 g/MJ digestible energy could be detrimental to erythrocyte numbers.

Effects of water garlic extracts on cell cycle and viability of HepG2 hepatoma cells

Garlic extracts, either aqueous or oily, are commonly employed to prepare garlic derivative supplements used as nutraceuticals for the treatment of different pathologies. In this study, we investigated the effects of water garlic extracts from two different areas of Italy well known for garlic production, Latina (GEL) and Sulmona (GES), on cell cycle and death of HepG2 hepatoma cells. The effects of the treatments with GEL and GES were also compared with the oil-soluble sulfur compound of garlic, diallyl disulfide (DADS). GEL and GES induced a p53/p21-dependent cell cycle arrest in G2/M phase and apoptosis, although to a different extent, whereas DADS, under the experimental conditions used, was not detrimental to HepG2 cells. GEL and GES committed HepG2 cells to apoptosis by the activation of c-Jun-NH(2) terminal kinase (JNK)/c-Jun phosphorylative cascade without a detectable increase in the flux of reactive oxygen species. Moreover, differentiation of HepG2 cells induced by retinoic acid determined resistance to GEL and GES treatments without the activation of JNK signaling pathway. Overall, the results obtained indicate that water-soluble garlic extracts are more inhibitory of the growth of transformed hepatoma cells than the oil-soluble isolated compound DADS, and that their antiproliferative properties are different depending on the area of origin of the starting material.

Garlic and cardiovascular disease: a critical review

Epidemiologic studies show an inverse correlation between garlic consumption and progression of cardiovascular disease. Cardiovascular disease is associated with multiple factors such as raised serum total cholesterol, raised LDL and an increase in LDL oxidation, increased platelet aggregation, hypertension, and smoking. Numerous in vitro studies have confirmed the ability of garlic to reduce these parameters. Thus, garlic has been shown to inhibit enzymes involved in lipid synthesis, decrease platelet aggregation, prevent lipid peroxidation of oxidized erythrocytes and LDL, increase antioxidant status, and inhibit angiotension-converting enzyme. These findings have also been addressed in clinical trials. The studies point to the fact that garlic reduces cholesterol, inhibits platelet aggregation, reduces blood pressure, and increases antioxidant status. Since 1993, 44% of clinical trials have indicated a reduction in total cholesterol, and the most profound effect has been observed in garlic's ability to reduce the ability of platelets to aggregate. Mixed results have been obtained in the area of blood pressure and oxidative-stress reduction. The findings are limited because very few trials have addressed these issues. The negative results obtained in some clinical trials may also have resulted from usage of different garlic preparations, unknown active constituents and their bioavalability, inadequate randomization, selection of inappropriate subjects, and short duration of trials. This review analyzes in vitro and in vivo studies published since 1993 and concludes that although garlic appears to hold promise in reducing parameters associated with cardiovascular disease, more in-depth and appropriate studies are required.

Effect of five cysteine-containing compounds on three lipogenic enzymes in Balb/cA mice consuming a high saturated fat diet

The in vivo effects of N-acetyl cysteine (NAC), S-allyl cysteine, S-ethyl cysteine (SEC), S-methyl cysteine (SMC), and S-propyl cysteine (SPC) against hyperlipidemia development and oxidation stress in Balb/cA mice consuming a high saturated fat diet were examined. The influence of these agents on plasma levels of glucose, insulin, uric acid, TG, cholesterol, and the activity of three lipogenic enzymes--glucose-6-phosphate dehydrogenase, malic enzyme, and FA synthase--was determined. All mice consumed the coconut oil-basd, high saturated fat diet, water, and cysteine or one of the five cysteine-containing compounds for 4 wk. The diet with 18% saturated fat significantly elevated the activity of three lipogenic enzymes and significantly increased TG and cholesterol biosynthesis in plasma and liver (P < 0.05). When compared with the water and cysteine groups, the treatments from five cysteine-containing agents significantly reduced high saturated fat diet-increased malic enzyme and FA synthase activities, and significantly lowered TG levels in plasma and liver (P< 0.05); however, only NAC, SAC, and SMC treatments significantly reduced cholesterol levels in plasma and liver (P < 0.05). The five cysteine-containing agents significantly restored high saturated fat diet-decreased glutathione peroxidase (GPX) activity in liver (P< 0.05); however, only SMC and SPC significantly restored GPX activity in heart and kidney (P< 0.05). These agents also significantly improved high saturated fat diet-related hyperglycemia, hyperuricemia, and oxidation stress (P < 0.05). These data support the hypothesis that these compounds are potential multiply-protective agents for hyperlipidemia prevention or therapy.

Association of maximum voluntary dietary intake of freeze-dried garlic with Heinz body anemia in horses

OBJECTIVE

To characterize hematologic and clinical consequences of chronic dietary consumption of freeze-dried garlic at maximum voluntary intake in horses.

ANIMALS

4 healthy sex- and age-matched horses.

PROCEDURE

An initial garlic dose (0.05 g/kg, twice daily) was fed to 2 horses in a molasses carrier as part of their normal ration and was gradually increased to maximum voluntary intake (0.25 g/kg, twice daily) over 41 days. Dietary supplementation then continued for a total of 71 days. Two control horses were fed molasses with no garlic with their ration. Blood samples were collected weekly and analyzed for hematologic and biochemical changes, including the presence of Heinz bodies. Recovery of affected blood values was followed for 5 weeks after termination of dietary supplementation with garlic.

RESULTS

At a daily dose of > 0.2 g/kg, horses fed garlic developed hematologic and biochemical indications of Heinz body anemia, as characterized by increases in Heinz body score (HBS), mean corpuscular volume (MCV), mean corpuscular hemoglobin, platelet count, and serum unconjugated and total bilirubin concentrations and decreases in RBC count, blood hemoglobin concentration, mean corpuscular hemoglobin concentration, and serum haptoglobin concentration. Recovery from anemia was largely complete within 5 weeks after termination of dietary supplementation with garlic. Heinz body score and MCV remained high at the end of the 5-week recovery period.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses will voluntarily consume sufficient quantities of garlic to cause Heinz body anemia. The potential for garlic toxicosis exists when horses are chronically fed garlic. Further study is required to determine the safe dietary dose of garlic in horses.

Garlic and aging: new insights into an old remedy

There has been an impressive gain in individual life expectancy with parallel increases in age-related chronic diseases of the cardiovascular, brain and immune systems. These can cause loss of autonomy, dependence and high social costs for individuals and society. It is now accepted that aging and age-related diseases are in part caused by free radical reactions. The arrest of aging and stimulation of rejuvenation of the human body is also being sought. Over the last 20 years the use of herbs and natural products has gained popularity and these are being consumed backed by epidemiological evidence. One such herb is garlic, which has been used throughout the history of civilization for treating a wide variety of ailments associated with aging. The role of garlic in preventing age-related diseases has been investigated extensively over the last 10-15 years. Garlic has strong antioxidant properties and it has been suggested that garlic can prevent cardiovascular disease, inhibit platelet aggregation, thrombus formation, prevent cancer, diseases associated with cerebral aging, arthritis, cataract formation, and rejuvenate skin, improve blood circulation and energy levels. This review provides an insight in to garlic's antioxidant properties and presents evidence that it may either prevent or delay chronic diseases associated with aging.

S-propyl cysteine reduces the secretion of apolipoprotein B100 and triacylglycerol by HepG2 cells

A number of sulfur-containing amino acids and peptides are found in allium plants such as onion and garlic that have physiologic functions. In HepG2 cells, S-propyl cysteine decreased the secretion of apolipoprotein B100. The compound reduced the secretion of newly synthesized triacylglycerol and cholesterols from radiolabeled acetate. We associated the decrease of apolipoprotein B100 secretion to the length of the acyl-chain of the sulfur-containing amino acids. The present study suggests that foods containing S-propyl cysteine including onions have beneficial effects.