Effect of garlic supplementation on erythrocytes antioxidant parameters, lipid peroxidation, and atherosclerotic plaque formation process in oxidized oil-fed rabbits

Effects of garlic extract on lipid profile in patients with coronary artery disease: A systematic review and meta-analysis of randomised clinical trials

This meta-analysis was conducted to evaluate the effects of garlic extract on total cholesterol (TC), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-c) and high-density lipoprotein-cholesterol (HDL-c), among the patients with coronary artery disease (CAD). Literature searches were conducted in EMBASE, Scopus, PubMed, Web of Science and Cochrane Library until Sep18th, 2020. Inter-study heterogeneity was examined using Cochrane's Q and I² tests. The random-effect models were utilised to pool the weighted mean differences (WMDs) and the corresponding 95% confidence intervals (CIs). Six articles were enrolled in the current meta-analysis. Garlic consumption significantly reduced TC levels (WMD -16.32 mg/dL; 95% CI -31.22, -1.43; P = .032). We found no significant effects on TG (WMD -10.93 mg/dL; 95% CI -26.19, 4.32; P = .160), HDL-c (WMD 4.55 mg/dL; 95% CI -1.13, 10.23; P = .116) and LDL-c concentrations (WMD -3.65 mg/dL; 95% CI -13.21, 5.92; P = .455). Significant heterogeneity was observed for HDL-c (I²  = 76.8%). However, the findings of sensitivity analysis revealed that upon exclusion of the potential heterogeneity source, the pooled WMD on HDL-c levels were stable. Garlic supplementation may result in a decrease in TC, but will not affect TG, HDL-c and LDL-c levels among CAD patients.

Antioxidant Enzyme Activities in Rabbits Under Oxidative Stress Induced By High Fat Diet

INTRODUCTION

The aim of this study was to investigate whether the type and form of oil (raw/non-oxidised (N) or post-frying/oxidised (O)) consumed in high-fat diets affect the oxidative status of an organism, as observed by malondialdehyde (MDA) concentration as an oxidative factor and antioxidant enzyme activity.

MATERIAL AND METHODS

Fats in the diet came from rapeseed oil (R) and olive oil (O).

RESULTS

The applied diet caused a decrease in MDA concentration (μmol/L) in serum in group RN from 2.94 ± 0.87 to 1.76 ± 0.13, in group ON from 2.45 ± 0.62 to 1.50 ± 0.10, and in group OO from 2.70 ± 1.16 to 1.84 ± 0.36. Meanwhile, MDA concentration (mmol/L) increased in blood haemolysate in group RO from 0.15 ± 0.07 to 0.22 ± 0.03 and in group OO from 0.17 ± 0.02 to 0.22 ± 0.02. The observed changes caused a response of the enzymatic antioxidant system in both models, especially followed by an increase in activities of total superoxide dismutase and its mitochondrial isoenzyme in all experimental groups, while its cytosolic isoenzyme activity increased only in ON and OO groups. Increased activity of glutathione peroxidase (GPX) in groups RN and RO and of catalase (CAT) in groups ON and OO was observed. Significant differences in responses to the different types and forms of oils were probably caused by the different oxidative stability of the studied oils.

CONCLUSION

This diet disturbed the body's oxidative status; however, during the six-month study the enzymatic antioxidant system remained effective.

Does Garlic Supplementation Control Blood Pressure in Patients with Severe Coronary Artery Disease? A Clinical Trial Study

Background

Hypertension is one of the major risk factors for cardiovascular morbidities, including coronary artery disease (CAD).

Objectives

With interest on the important role of hypertension in the progression of CAD, this study was designed to estimate the effect of garlic powder tablets on the blood pressure (BP) in patients with severe CAD.

Methods

A randomized, placebo-controlled, clinical trial was conducted on 56 CAD patients, aged 25 - 75 years old. The patients were randomly divided into two groups: Galois groups (n = 27), receiving garlic powder tablet (400 mg garlic) twice daily and the placebo groups (n = 29), receiving placebo for 3 months. The BP was assessed at baseline and at the end of the study.

Results

During the 3 months study, in the placebo group, systolic BP (SBP) increased with 6.3 mmHg and diastolic BP (DBP) increased with 4.6 mmHg, changes which were significant. After the 3 months, the effect of garlic on SBP, after adjusting for baseline value, was significant, and this effect was more significant in hypertensive patients. Plasma lipids and lipoproteins did not change significantly in either the garlic or placebo groups, during the study. Tolerability, compliance and acceptability were high in all patients.

Conclusions

These results demonstrate that treatment with garlic-based drugs can be an effective treatment for controlling BP in CAD patients and has no interaction with other drugs that CAD patients take. Therefore, it may be considered as a safe adjunct treatment for this group of patients.

The Influence of α-Lipoic Acid and Garlic Administration on Biomarkers of Oxidative Stress and Inflammation in Rabbits Exposed to Oxidized Nutrition Oils

We hypothesized that addition of substances with antioxidant activity could decrease the concentrations of biomarkers of oxidative stress and inflammatory process, thus inhibiting nonalcoholic steatohepatitis development. We investigated the influence of α-lipoic acid (ALA) and garlic administration on the development of adverse changes in rabbit liver and serum under oxidative stress conditions induced with HFD from oxidized oils. We determined 8-hydroxy-2′-deoxyguanosine (8OHdG) and malondialdehyde (MDA) in liver homogenates, total oxidant status (TOS), lipid peroxides (LOO) and tumor necrosis factor alpha (TNFα) in blood serum, and TNFα and IL-1α genes expression in liver. The results indicate that the intake of dietary ALA and garlic was significantly associated with decreases of 8OHdG and MDA levels in rabbits' liver tissue as well as TOS and LOO levels in rabbits' serum. Similarly, TNFα and IL-1α gene expressions were suppressed due to ALA and garlic supplementation. The histopathological analysis confirmed that HFD results in liver disorder leading to steatosis. This adverse effect of HFD was ameliorated by the supplementation of ALA and garlic. The obtained results indicate a beneficial effect of ALA and garlic administration by reducing the oxidative stress intensity and the levels of some proinflammatory cytokines in rabbits fed HFD.

Effect of selected dietary compounds on extracellular superoxide dismutase in the vitreous of chinchillas

PURPOSE

The purpose of this study was to evaluate the effect of diet on the extracellular superoxide dismutase (EC-SOD) activity in the vitreous of chinchillas.

METHODS

Seventy-eight male chinchillas were randomly divided into 7 subgroups: controls, receiving a standard basal diet, and 6 experimental groups additionally receiving 10% nonoxidized and 10% oxidized olive oil, a garlic extract and lipoic acid in their diet. The activities of EC-SOD were measured.

RESULTS

The highest EC-SOD activity was similar in the controls [2.17 ± 0.27 nitric units (NU)/mg protein] and in rabbits fed oxidized olive oil (2.29 ± 0.31 NU/mg protein; p = 0.519). Nonoxidized olive oil appeared to be the strongest antioxidant component of diet (1.58 ± 0.20 NU/mg protein) as compared with the subgroups above (p = 0.008 and p = 0.012, respectively). Administration of garlic and lipoic acid decreased the SOD activity only in the groups fed oxidized olive oil (p = 0.014).

CONCLUSIONS

The SOD activity in laboratory animals is possibly modulated by diet. Work will be continued to extrapolate these results to humans.

Effects of oxidized cooking oil and α-lipoic acid on blood antioxidants: enzyme activities and lipid peroxidation in rats fed a high-fat diet

The effects of administration of oxidized rapeseed oil and α-lipoic acid on activities of blood antioxidant enzymes and malondialdehyde (MDA) concentration were studied in laboratory rats fed a high-fat diet. Addition of oxidized oil resulted in increased production of oxygen radicals, evidenced by elevated plasma MDA production. Such effect was counteracted by administration of α-lipoic acid. There was an increase of the activities of superoxide dismutase (total and Cu/Zn-SOD) and catalase in rats fed a high-fat diet to which 10% oxidized oil was added. Administration of α-lipoic acid resulted in a decrease of the activities of these enzymes.

Effects of a skullcap root supplement on haematology, serum parameters and antioxidant enzymes in rabbits on a high-cholesterol diet

We studied the effects of Scutellaria baicalensis root on blood parameters and antioxidant enzyme activities in rabbits fed a high-cholesterol diet. Thirty-two New Zealand White rabbits were divided into four groups of eight animals each. They were fed a standard diet (C group), a diet with a 1% pure cholesterol supplement (CH group), a diet with a 1% pure cholesterol supplement and a 9% skullcap root supplement (CH+SR group), or a diet with a 9% skullcap root supplement (SR group). After 6 weeks, the rabbits fed the high-cholesterol diet had significantly decreased RBC and Hb levels and significantly increased MCV, MCH and Fe levels (p≤ 0.05). The skullcap root supplement had no adverse effects on the haematological parameters. The values for RBC, Hb, HCT, MCV, MCH and MCHC were similar in the skullcap root-treated and control rabbits. We also observed a remarkable elevation in the serum TC, LDL and TG levels at the end of the 6-week period. The rabbits fed the cholesterol diet showed decreased activity of the erythrocyte GSH-Px compared with the rabbits fed the basal diet. The GSH-Px activity was significantly higher in the rabbits fed the CH+SR diet than in those on the CH diet. The erythrocyte SOD activity was also significantly decreased in the rabbits on the CH diet. However, the CH+SR group rabbits showed significantly enhanced erythrocyte SOD activity. The SOD level in the CH+SR rabbits was 34.91 U/ml, which was a 23% increase (p≤ 0.05) in relation to the results for the CH group and only 15% diminished in relation to the control group. These results suggest that the dietary supplementation of skullcap root may improve rabbit antioxidant systems and protect against the risks from a high-cholesterol diet.

Effects of oxidized cooking oil and α-lipoic acid on liver antioxidants: enzyme activities and lipid peroxidation in rats fed a high fat diet

The effects of administration of oxidized rapeseed oil and α-lipoic acid on activities of hepatic antioxidant enzymes and lipid peroxidation were studied in laboratory rats. There was an increase of the activities of superoxide dismutase, glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase in rats fed a high fat diet to which 10% oxidized oil was added. Administration of α-lipoic acid resulted in a decrease of the activities of these enzymes. Addition of oxidized oil also resulted in increased production of oxygen radicals, evidenced by elevated malondialdehyde production. Such effect was counteracted by administration of α-lipoic acid.

Garlic increases antioxidant levels in diabetic and hypertensive rats determined by a modified peroxidase method

Oxidative damage by free radicals has been implicated in the pathogenesis of vascular disease in diabetes and hypertension. In the present study, the total antioxidant status in diabetic and hypertensive rats before and after treatment with garlic (Allium sativum) was determined. The total serum antioxidants were measured by a modified method reported earlier by Miller and coworkers. The reproducibility of the assay was confirmed by determining standard curves for the known antioxidants: trolox (a stable analog of vitamin E), glutathione and vitamin C with interassay correlation coefficients (R(2), n = 10 in triplicate) of 0.9984, 0.9768 and 0.987, respectively, confirming the reliability and reproducibility of the assay. This assay was then used to determine total serum antioxidant levels of streptozotocin-induced diabetic rats and two-kidney one-clip hypertensive rats both before and after 3 weeks of treatment with an aqueous extract of garlic (500 mg/kg IP daily). The serum antioxidant levels of rats after 3 weeks of treatment were significantly higher (P < .001) than the pretreatment levels in both diabetic and hypertensive rats. The increased serum antioxidant levels were paralleled by a decrease in serum glucose in the garlic-treated diabetic rats and lowered systolic blood pressure in the garlic-treated hypertensive rats. We conclude from our study that (i) total antioxidants can be measured by a simple, reproducible, reliable assay and (ii) the total antioxidant status can be significantly improved by treatment with garlic.

The influence of fluoride ions upon selected enzymes of protein metabolism in blood plasma of rabbits with hypercholesterolemia

Three-month studies were performed on 18 adult rabbits of New Zealand breed divided into three groups, with six animals in each: a control group on standard diet, a cholesterol group receiving 500 mg of cholesterol/100 g of feed per rabbit per 24 h (CH group), and a cholesterol + fluorine group (CH + F group) receiving 500 mg of cholesterol/100 g of feed per rabbit per 24 h and 3 mg of F(-)/kg of body weight per 24 h. The conducted studies proved that cholesterol in the applied dosage (500 mg cholesterol per rabbit per 24 h) has an atherogenic action. Fluoride ions administered together with a 500-mg cholesterol atherogenic diet inhibit the atheromatosic changes in the aorta. The concentration of plasma cholesterol was elevated in both study groups when compared to the control group but decreased in the CH + F group when compare to the CH group. The influence of fluoride ions has been examined upon the activity of alanine aminotransferase, aspartate aminotransferase, and glutamate dehydrogenase (GLDH) in the plasma in the liver of rabbits in the course of experimental hypercholesterolemia. Increase in the activity of study enzymes has been observed in the blood plasma, which may be due to damage occurring to hepatocytes of the animals examined (a statistically significant increase in the activity of GLDH in the plasma). In the liver, the inhibition of activity for all examined enzymes has been observed in the group of rabbits with hypercholesterolemia, which testifies the disturbances in protein metabolism in examined animals. The addition of sodium fluoride to the diet rich in cholesterol results in "removing the block" on those activities, which increase. We suppose that the permeability of the hepatocyte membrane was elevated, so the activities of examined enzymes increased in the plasma ("escape" to plasma). On the one hand, fluoride ions result in probable lesion of hepatocytes membranes; on the other hand, they inhibit the atheromatosic changes in the aorta.