Abdelfattah El Feki

Antidiabetic and Antioxidant Effects of Hydroxytyrosol and Oleuropein from Olive Leaves in Alloxan-Diabetic Rats

This study was designed to test the antidiabetic and antioxidative activities of olive leaf oleuropein and hydroxytyrosol. Diabetes in Wistar rats was induced by intraperitoneal injections of alloxan. The serum glucose and cholesterol, hepatic glycogen, the thiobarbituric acid-reactive substances (TBARS), and the components of hepatic and serum antioxidant system were examined. Diabetic rats showed hyperglycemia, hypercholesterolemia, increased lipid peroxidation, and depletion in the antioxidant enzymes activities. The administration, for 4 weeks, of oleuropein and hydroxytyrosol rich extracts, leading to 8 and 16 mg/kg body weight of each compound, significantly decreased the serum glucose and cholesterols levels and restored the antioxidant perturbations. These results suggested that the antidiabetic effect of oleuropein and hydroxytyrosol might be due to their antioxidant activities restraining the oxidative stress which is widely associated with diabetes pathologies and complications.

Hypolipidimic and antioxidant activities of oleuropein and its hydrolysis derivative-rich extracts from Chemlali olive leaves.

Oleuropein-rich extracts from olive leaves and their enzymatic and acid hydrolysates, respectively rich in oleuropein aglycone and hydroxytyrosol, were prepared under optimal conditions. The antioxidant activities of these extracts were examined by a series of models in vitro. In this study the lipid-lowering and the antioxidative activities of oleuropein, oleuropein aglycone and hydroxytyrosol-rich extracts in rats fed a cholesterol-rich diet were tested. Wistar rats fed a standard laboratory diet or cholesterol-rich diets for 16 weeks were used. The serum lipid levels, the thiobarbituric acid reactive substances (TBARS) level, as indicator of lipid peroxidation, and the activities of liver antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) were examined. The cholesterol-rich diet induced hyperlipidemia resulting in the elevation of total cholesterol (TC), triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C). Administration of polyphenol-rich olive leaf extracts significantly lowered the serum levels of TC, TG and LDL-C and increased the serum level of high-density lipoprotein cholesterol (HDL-C). Furthermore, the content of TBARS in liver, heart, kidneys and aorta decreased significantly after oral administration of polyphenol-rich olive leaf extracts compared with those of rats fed a cholesterol-rich diet. In addition, these extracts increased the serum antioxidant potential and the hepatic CAT and SOD activities. These results suggested that the hypocholesterolemic effect of oleuropein, oleuropein aglycone and hydroxytyrosol-rich extracts might be due to their abilities to lower serum TC, TG and LDL-C levels as well as slowing the lipid peroxidation process and enhancing antioxidant enzyme activity.

Influence of thyroid dysfunction on liver lipid peroxidation and antioxidant status in experimental rats.

The purpose of this study was to evaluate the effects of dysthyroidism on lipid peroxidation, antioxidants status, liver, and serum dysfunction parameters in the hypo-/hyperthyroidism-induced rats. Hypothyroidism and hyperthyroidism conditions were induced for 5 weeks by administration of 0.05% benzythiouracile (BTU) and l-thyroxine sodium salt (0.0012%), in drinking water, respectively. The enzymatic activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and the lipid peroxidation product; thiobarbituric acid reacting substances (TBARS) were measured in liver as indicators of oxidative damage. However, liver dysfunction parameters represented by the activities of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma glutamyl transferase (GGT), were measured in serum. In hyperthyroidism rats, the TBARS contents of liver have significantly increased compared to those in hypothyroid rats and the controls (p<0.001), associated with a fall of the total antioxidant status (TAS) in the serum of the hyperthyroid rats. The SOD, CAT, and GPx activities in liver of hyperthyroid rats have significantly increased compared to hypothyroid rats and the controls (p<0.001). The AST, ALT, LDH, GGT, and ALP activities increased in the hyperthyroidism rats (p<0.05). We conclude that thyroid dysfunction induces oxidative stress and modifies some biochemical parameters of liver. Our results show the occurrence of a state of oxidizing stress in relation to hyperthyroidism.

Lipid-lowering and antioxidant effects of hydroxytyrosol and its triacetylated derivative recovered from olive tree leaves in cholesterol-fed rats.

This study was designed to test the lipid-lowering and antioxidative activities of triacetylated hydroxytyrosol compared with its native compound, hydroxytyrosol, purified from olive tree leaves. Wistar rats fed a standard laboratory diet or a cholesterol-rich diet for 16 weeks were used. The serum lipid levels, the thiobarbituric acid-reactive substances (TBARS) level, as an indicator of lipid peroxidation, and the activity of superoxide dismutase (SOD) as well as that of catalase (CAT) were examined. The cholesterol-rich diet induced hypercholesterolemia that was manifested in the elevation of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C). Administration of hydroxytyrosol and triacetylated hydroxytyrosol (3 mg/kg of body weight) decreased the serum levels of TC, TG, and LDL-C significantly and increased the serum level of high-density lipoprotein cholesterol (HDL-C). Furthermore, the content of TBARS in liver, heart, kidney, and aorta decreased significantly when hydroxytyrosol and its triacetylated derivatives were orally administered to rats compared with those fed a cholesterol-rich diet. In addition, triacetylated hydroxytyrosol and hydroxytyrosol increased CAT and SOD activities in the liver. These results suggested that the hypolipidemic effect of triacetylated hydroxytyrosol and hydroxytyrosol might be due to their abilities to lower serum TC, TG, and LDL-C levels as well as to their antioxidant activities preventing the lipid peroxidation process.

Hepatoprotective role and antioxidant capacity of selenium on arsenic-induced liver injury in rats

The present study was undertaken to evaluate the protective effect of selenium against arsenic-induced oxidative damage in experimental rats. Males were randomly divided into four groups where the first was served as a control, whereas the remaining groups were respectively treated with sodium selenite (3 mg/kg b.w.), sodium arsenite (5.55 mg/kg b.w.) and a combination of sodium arsenite and sodium selenite. Changes in liver enzyme activities, thiobarbituric acid reactive substances (TBARS) level, antioxidants and reduced glutathione (GSH) contents were determined after 3 weeks experimental period. Exposure of rats to As caused a significant increase in liver TBARS compared to control, but the co-administration of Se was effective in reducing its level. The activities of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) of As-treated group were found lower compared to the control and the Se-treated group. The co-administration of Se had an additive protective effect on liver enzyme activities compared to As-treated animals. On the other hand, a significant increase in plasmatic activities of AST, ALT and ALP was observed in As-treated group. The latter was also exhibited a decrease in body weight and an increase in liver weight compared to the control. The co-administration of Se has decreased the activities of AST, AST and ALP and improved the antioxidant status as well. Liver histological studies have confirmed the changes observed in biochemical parameters and proved the beneficial role of Se. To conclude, results suggest that As exposure enhanced an oxidative stress by disturbing the tissue antioxidant defense system, but the Se co-administration protected liver tissues against As intoxication probably owing to its antioxidant properties.

Testicular toxicity in mercuric chloride treated rats: association with oxidative stress.

Mercury has been recognized as an industrial hazard that adversely affects male reproductive systems of humans and animals. However, less information is available concerning the underlying mechanism in the pathogenesis of male reproductive dysfunction. The present study investigated the possible involvement of oxidative stress to induce oxidative deterioration of testicular functions in adult rats. Wistar male rats (n=132) were continuously exposed to HgCl(2) at 0, 50 and 100 ppm during 90 days through oral administration in the drinking water. Mercury exposure for 90 days resulted in an increase in the absolute and relative wet weight of the testis and a decrease in the absolute and relative wet weight of the accessory sex glands, with respect to the matched control. Marked perturbation in testosterone serum level was also detected during the treatment for the treated groups. Cauda epididymal sperm count/motility decreased significantly in the mercury-treated group and qualitative examination of testicular sections revealed a fewer mature luminal spermatozoa in comparison to the control. When the mercury-treated males were mated with normal cyclic females, mercury exposure resulted in a decline of the reproductive performance of male rats. These effects were associated with a significant increase in mercury content of testes and blood in time-dependent and dose-dependent fashion, respectively. The HgCl(2) treatment was associated with oxidative stress. Evidence of induction of oxidative stress was obtained in terms of perturbations in antioxidant defense and a significant dose-dependent increase in the testicular lipid peroxidation as a consequence of pro-oxidant exposure. Taken together, the results suggest that an increase in free radical formation relative to loss of antioxidant defense system after mercury exposure may render testis more susceptible to oxidative damage leading to their functional inactivation.

Lipid-Lowering and Antioxidant Effects of an Ethyl Acetate Extract of Fenugreek Seeds in High-Cholesterol-Fed Rats

The purpose of this study was to investigate the relationship between the lipid effects, the phenolic content, and the antioxidative effects of an ethyl acetate extract of fenugreek. Wistar rats fed a standard laboratory diet or cholesterol-rich diets for 16 weeks were used. The plasma lipid levels, total phenolics, and total flavonoid contents were measured, and the thiobarbituric acid reactive substances (TBARS) and antioxidant activities were examined. Administration of fenugreek ethyl acetate extract significantly lowered the plasma levels of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C), while increasing the plasma level of high-density lipoprotein cholesterol (HDL-C). Furthermore, the content of TBARS and catalase (CAT) and superoxide dismutase (SOD) activities in liver, heart and kidney decreased significantly after oral administration of the extract compared with those of rats fed a cholesterol-rich diet. These lipid effects and in vivo antioxidative effects were correlated with the in vitro phenolic content scavenging ability. In addition, three flavonoids (kaempferol 3-O-glycoside, apigenin-7-O-rutinoside, and naringenin) were identified by using an LC-MS/MS apparatus. Naringenin was the abundant flavonoid compound in the ethyl acetate extract, and its concentration reaches 7.23 +/- 0.09 mg/g of dry extract. These results revealed significant hypocholesterolemic effects and antioxidant activity in an ethyl acetate extract of fenugreek seed, which may be partly due to the presence of flavonoids, especially naringenin.

Hypoglycemic and antioxidant effects of leaf essential oil of Pelargonium graveolens L’Hér. in alloxan induced diabetic rats

BackgroundRose-scented geranium (Pelargonium graveolens L’Hér.), which is used in traditional Tunisian folk medicine for the treatment of hyperglycaemia, is widely known as one of the medicinal herbs with the highest antioxidant activity. The present paper is conducted to test the hypoglycemic and antioxidative activities of the leaf essential oil of P. graveolens.MethodsThe essential oil P. graveolens was administered daily and orally to the rats at two doses of 75 mg/kg and 150 mg/kg body weight (b.w.) for 30 days. The chemical composition of P. graveolens essential oil, body weight, serum glucose, hepatic glycogen, thiobarbituric acid-reactive substances (TBARS), the components of hepatic, and renal and serum antioxidant systems were evaluated. The hypoglycemic effect of rose-scented geranium was compared to that of the known anti-diabetic drug glibenclamide (600 μg/kg b.w.).ResultsAfter the administration of two doses of essential oil of Pelargonium graveolens L’Hér. together with glibenclamide which is known by its antidiabetic activities and used as reference (600 μg/kg b.w.), for four weeks, the serum glucose significantly decreased and antioxidant perturbations were restored. The hypoglycemic effect of P. graveolens at the dose of 150 mg/kg b.w. was significantly (p< 0.05) more effective than that of glibenclamide. It is through the histological findings in hepatic and renal tissues of diabetic rats that these beneficial effects of geranium oils were confirmed.ConclusionsIt suggests that administration of essential oil of P. graveolens may be helpful in the prevention of diabetic complications associated with oxidative stress. Our results, therefore, suggest that the rose-scented geranium could be used as a safe alternative antihyperglycemic drug for diabetic patients.

Inhibitory potential of omega-3 fatty and fenugreek essential oil on key enzymes of carbohydrate-digestion and hypertension in diabetes rats

Backgrounddiabetes is a serious health problem and a source of risk for numerous severe complications such as obesity and hypertension. Treatment of diabetes and its related diseases can be achieved by inhibiting key digestives enzymes-related to starch digestion secreted by pancreas.MethodsThe formulation omega-3 with fenugreek terpenenes was administrated to surviving diabetic rats. The inhibitory effects of this oil on rat pancreas α-amylase and maltase and plasma angiotensin-converting enzyme (ACE) were determined.Resultsthe findings revealed that administration of formulation omega-3 with fenugreek terpenenes (Om3/terp) considerably inhibited key enzymes-related to diabetes such as α-amylase activity by 46 and 52% and maltase activity by 37 and 35% respectively in pancreas and plasma. Moreover, the findings revealed that this supplement helped protect the β-Cells of the rats from death and damage. Interestingly, the formulation Om3/terp modulated key enzyme related to hypertension such as ACE by 37% in plasma and kidney. Moreover administration of fenugreek essential oil to surviving diabetic rats improved starch and glucose oral tolerance additively. Furthermore, the Om3/terp also decreased significantly the glucose, triglyceride (TG) and total-cholesterol (TC) and LDL-cholesterol (LDL-C) rates in the plasma and liver of diabetic rats and increased the HDL-Cholesterol (HDL-Ch) level, which helped maintain the homeostasis of blood lipid.Conclusionoverall, the findings of the current study indicate that this formulation Om3/terp exhibit attractive properties and can, therefore, be considered for future application in the development of anti-diabetic, anti-hypertensive and hypolipidemic foods.

Antidiabetic activity of levan polysaccharide in alloxan-induced diabetic rats.

This study aims to examine the effects of polysaccharide levan on oxidative stress and hyperglycemia in alloxan-induced diabetic rats. Levan, used in this study, was a microbial levan synthetisized by a non pathogenic bacteria recently isolated and identified as Bacillus licheniformis. Animals were allocated into four groups of six rats each: a control group (Control), diabetic group (Diab.), normal rats received levan (L) and diabetic rats fed with levan (DL). Treated diabetic rats were administrated with levan in drinking water through oral gavage for 60 days. The administration of polysaccharide levan in diabetic rats caused a significant increase in glycogen level by 52% and a decrease in glucose level in plasma by 52%. Similarly, the administration of polysaccharide levan in diabetic rats caused a decrease in the thiobarbituric acid-reactive substances (TBARS) by 31%, 41%, 39% and 25%, an increase in superoxide dismutase (SOD) by 40%, 50%, 44% and 34%, and in catalase (CAT) by 18%, 20%, 12% and 18% in liver, kidney, pancreas and heart, respectively. Furthermore, a significant decrease in hepatic and renal indices toxicity was observed, i.e. alkalines phosphatases (ALP), aspartate and lactate transaminases (AST and ALT) activities, total bilirubin, creatinine and urea levels by 19%, 31%, 32%, 36%, 37% and 23%, respectively. The results show that administration of polysaccharide levan can restore abnormal oxidative indice near normal levels. This study demonstrates, for the first time, that polysaccharide levan is efficient in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggests that levan supplemented to diet may be helpful in preventing diabetic complications in adult rats.