Anti-Obesity and Anti-Dyslipidemic Effects of Salicornia arabica Decocted Extract in Tunisian Psammomys obesus Fed a High-Calorie Diet.

Salicornia is a halophyte plant that has been used in traditional medicine for the treatment of scurvy, goiter, and hypertension. It is commercialized in Europe and Asia as fresh salads, pickled vegetables, green salt, or tea powder. This work is the first to assess the potential anti-obesity and anti-dyslipidemic effects of Salicornia arabica decocted extract (SADE). SADE was characterized by its significant in vitro radical scavenging activity (using DPPH and ABTS assays). The effect of SADE on food intake, weight loss, serum biochemical parameters, liver and kidney weights, adiposity index and on liver histology was investigated in the Tunisian gerbil Psammomys obesus (P. obesus), which is recognized as a relevant animal model of human obesity and diabetes. P. obesus animals were firstly randomly divided into two groups: the first received a natural low-calorie chow diet (LCD), and the second group received a high-calorie diet (HCD) over 12 weeks. On day 90, animals were divided into four groups receiving or not receiving SADE (LCD, LCD + SADE, HCD, and HCD + SADE). If compared to the HCD group, SADE oral administration (300 mg/kg per day during 4 weeks) in HCD + SADE group showed on day 120 a significant decrease in body weight (-34%), blood glucose (-47.85%), serum levels of total cholesterol (-54.92%), LDL cholesterol (-60%), triglycerides (-48.03%), and of the levels of hepatic enzymes: ASAT (-66.28%) and ALAT (-31.87%). Oral administration of SADE restored the relative liver weight and adiposity index and significantly limited HCD-induced hepatic injury in P. obesus. SADE seems to have promising in vivo anti-obesity and anti-dyslipidemic effects.

Neuroprotective effects of oleuropein on retina photoreceptors cells primary culture and olive leaf extract and oleuropein inhibitory effects on aldose reductase in a diabetic model: Meriones shawi.

Aldose reductase (AR) is an enzyme implicated in the development of diabetes complications among them diabetic retinopathy. Erythrocyte AR activity was measured in control and diabetic Meriones shawi, a type-2 diabetic model. We noticed an increase of AR activity in diabetic Meriones by comparison to controls. Olive leaf aqueous extract and oleuropein were tested for their inhibitory potential on AR activity. Both exerted a partial in-vitro inhibition effect which was higher with the olive leaf extract. The ex-vivo protective effect of oleuropein was tested in photoreceptors rod and Mcône retinal cells of Meriones shawi in hyperglycaemic conditions. Mixed retinal cells were cultured at 25 mM glucose for 5 days and treated with oleuropein. Cell viability was assessed using MTT test and trypan blue exclusion dye. Rod and Mcône Photoreceptors were characterised by immuno-cytochemistry. Oleuropein protected retinal cells against the toxic effect of glucose by improving the viability of photoreceptors.

Hepatoprotective Effect of Oleuropein-Rich Extract from Olive Leaves against Cadmium-Induced Toxicity in Mice.

Cadmium (Cd) is a harmful pollutant which mainly affects the liver and kidney. In this work, we investigated the hepatoprotective effects of olive leaf extract based on oleuropein against hepatic cadmium toxicity in mice. Three groups of animals were used: the first one served as the control (C); the second one received intraperitoneal injection of cadmium 2 mg/kg b.w. (CD), administered five times during two weeks; and the third group received the same doses of Cd and simultaneously 16 mg/kg b.w. of oleuropein. Results showed that Cd induced a significant increase in liver injury biomarkers coupled with enhanced lipid peroxidation (MDA) and significant depletion of antioxidants (CAT and SOD). Histological and immunohistochemical analysis confirmed these findings. In fact, we observed a severe central lobular apoptosis and inflammation around central veins. Cotreatment with oleuropein significantly reduced the oxidative damage induced by cadmium. Our findings suggest that oleuropein could be used in the prevention of Cd hepatotoxicity.

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

BACKGROUND: Rose-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. METHODS: The 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.). RESULTS: After 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. CONCLUSIONS: It 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.

Effects of zinc pre-treatment on blood glutathione, serum zinc and kidney histological organisation in male rats exposed to cadmium.

The effects of sub-chronic exposure to cadmium (Cd) on the blood glutathione, serum zinc and on the kidney histological organisation in rats as well as the possible protective role of zinc (Zn) are the object of this study. For this purpose, 60 male Wistar rats (8 weeks old) were divided into three groups: the first group was exposed to Cd in the form of CdCl(2), administered in five doses (each of 0.4 mg Cd/kg b.w.) on days 5, 10, 15, 20 and 25, giving a total dose of 2mg Cd/kg b.w., i.p.; the second group was simultaneously exposed to Zn and Cd with the same timeline and the same doses of Cd as the first group but with, in addition, injections of Zn in the form of ZnCl(2), administered in doses of 0.8 mg Zn/kg b.w., giving a total dose of 4 mg Zn/kg b w, i.p.; a control group received 0.5 mL of physiological saline in an identical manner. Intoxication with Cd was followed by a significant decrease in blood glutathione, increase in oxidized glutathione as well as histological damage in kidneys. Pre-treatment with Zn exhibited a protective role against Cd toxicity with a significant decrease in serum zinc content. This fact may be explained by an excessive use of zinc in metallothionein synthesis as a cadmium detoxification agent.

Oil content, phenolic profiling and antioxidant potential of Tunisian olive drupes.

BACKGROUND: The aim of this work was to investigate the effect of the maturation process of the olive fruit on oil content, phenolic profile and antioxidant activity of four Tunisian cultivars (Zelmati, Chemchali, Chemlali and Chétoui). RESULTS: The average oil content of the studied varieties ranged between 17.50% and 20.25% at the first stage of maturation and from 30.20% to 35% in the last harvest. Qualitative and quantitative analysis of phenolic compounds were carried out using HPLC and LC-MS/MS. Twenty-six biophenolic compounds were identified. In all samples, hydroxytyrosol and oleuropein were the major compounds identified while rutin and luteolin 7-O-glucoside were the two main flavonoids. The total phenolic content varied from 3.46 to 4.30 g kg(-1) at the first stage of maturation and from 8.71 to 11.52 g kg(-1) of fruit fresh weight at the last maturation phase. Total flavonoid content reached 432.80 mg kg(-1). The antioxidant activity of the extract was evaluated by DPPH and ABTS assays. The IC(50) values of the olive extracts ranged from 2.69 to 10.96 microg L(-1) and from 2.15 to 3.03 mmol L(-1) trolox equivalent at the last stage of maturation. CONCLUSION: A relationship between the changes in phenolic content and the physicochemical changes in Tunisian olive fruit during maturation was established. These findings could be used for controlling the production processes and correlating the oil sensorial characteristics to the polyphenolic pattern.

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.

Phenolic composition, sugar contents and antioxidant activity of Tunisian sweet olive cultivar with regard to fruit ripening.

Dhokar olive cultivar growing in the south of Tunisia is an unusual olive tree which is characterized by the sweet taste of its fruit. We were particularly interested in the phenolic compounds of this cultivar in comparison to Chemlali cv. During the different maturation stages of olive fruits, the phenolic composition, sugar content, antioxidant activity and enzymatic change were examined. The phenolic composition was studied by using reverse-phase high-performance liquid chromatography followed by LC-MS and GC-MS analysis. Oleuropein, the major olive fruit biophenolic compound, decreased significantly during all the ripeness stages, and its level decreased from 3.29 g/kg fresh olive (July) to 0.16 g/kg (October) in Dhokar cv. and from 5.7 g/kg (July) to 3.75 g/kg (October) in Chemlali cv. This decrease inversely correlated with hydroxytyrosol concentrations until September. DPPH and ABTS assays show that the more important antioxidant capacity of olive extracts was found at the last stage of maturation. beta-Glucosidase and esterase activities were evaluated during the ripening stage. The data obtained during the ripening indicate that polyphenol content and composition, in particular the oleuropein concentration, were in correlation with the measured enzymatic activities. Glucosidase and esterase showed their maximum values in September reaching 179.75 and 39.03 U/g of olive pulp, respectively. In addition, sugar content was quantified using colorimetric and chromatographic methods and was compared to its concentration in Chemlali olive fruit cultivar. Glucose and mannitol were the main sugars; they reached their highest level at the last stage of ripening: 8.3 and 79.8 g/kg respectively.

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.

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.

Protective effect of zinc supplementation on blood antioxidant defense system in rats exposed to cadmium.

The aim of this study was to assess the effects of subchronic exposure to cadmium (Cd) on the antioxidant defense system of red blood cells (RBCs) and lipid peroxide concentration in the plasma, as well as the possible protective role of zinc (Zn). For this purpose, 60 male Wistar rats (8 weeks old) were divided into three groups: the first group was exposed to Cd in the form of CdCl(2), administered in five doses (each of 0.4mg Cd/kg BW) on days 5, 10, 15, 20 and 25, giving a total dose of 2mg Cd/kg BW, i.p.; the second group was simultaneously exposed to Zn and Cd with the same timeline and the same doses of Cd as the first group but with, in addition, injections of Zn in the form of ZnCl(2), administered in doses of 0.8mg Zn/kg BW, giving a total dose of 4mg Zn/kg BW, i.p.; a control group received 0.5mL of physiological saline in an identical manner. It was shown that exposure to Cd induced a significant decrease (p<0.05) in superoxide dismutase (Zn/Cu SOD) and catalase (CAT) activities in RBCs. Increased lipid peroxide concentration, measured by thiobarbituric acid reactive substances (TBARS), was also observed in the plasma of cadmium-exposed rats. Cd had no effect on glutathione peroxidase (GSH-Px) activity. Zn administration had a beneficial effect on the Cd-induced decrease in Zn/Cu SOD activity (p<0.05) but not on CAT activity. Animals receiving Cd and Zn simultaneously had significantly (p<0.05) lower concentrations of lipid peroxides than rats exposed to Cd alone. Our results indicate that Cd causes oxidative stress and that Zn supply in conditions of exposure to Cd can partially protect against Cd-induced oxidative stress.