Mohamed Bouaziz

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.

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.

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.

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.

Anaerobic membrane bioreactor for the treatment of leachates from Jebel Chakir discharge in Tunisia

Landfill leachate (LFL) collected from the controlled discharge of Jebel Chakir in Tunisia was treated without any physical or chemical pretreatment in an anaerobic membrane bioreactor (AnMBR). The organic loading rate (OLR) in the AnMBR was gradually increased from 1 g COD l(-1)d(-1) to an average of 6.27 g COD l(-1)d(-1). At the highest OLR, the biogas production was more than 3 volumes of biogas per volume of the bioreactor. The volatile suspended solids (VSSs) reached a value of approximately 3 g l(-1) in the bioreactor. At stable conditions, the treatment efficiency was high with an average COD reduction of 90% and biogas yield of 0.46 l biogas per g COD removed.

Effect of olive fruit fly infestation on the quality of olive oil from Chemlali cultivar during ripening

Olive fruits are seriously deteriorated by pre and post harvest damage due to the attack of insects, such as Bactrocera olaea, which strongly alters the quality of olives. Olives from Chemlali cultivar were collected and divided into different groups according to the presence or absence of infestation (0%, 5%, 10%, 15% and 100%) by the olive fruit fly (B. olaea). The infestation of this pest has been studied to evaluate its influence on virgin olive oil quality (free acidity, K(232) and K(270), fatty acids composition, pigment concentration, organoleptic characteristics, phenolic content, and antioxidant power). Results showed that both attacks by B. oleae and maturity process affected the quantitative and qualitative composition of the oil. These analyses demonstrated that the degree of fly attack was positively correlated with free acidity, the values of this parameter increase from 0.6 to 1.5 and 3.4, at the infestation levels 10%, 15% and 100%, respectively (R(2)=0.7418, P<0.05), and negatively related to the phenolic content which was always lower at the 100% infestation level (R(2)=0.9155, P<0.05), and consequently, the organoleptic characteristics. In addition, the infestation by olive fly did not cause an important change in the fatty acid composition while it is clear that fatty acids levels change in relation to the fruit repining stage. The antioxidant activity decreased during maturation, it was correlated to the total phenol content and the fruit infestation level.

Disinfectant properties of essential oils from Salvia officinalis L. cultivated in Tunisia

The essential oils were obtained by hydro-distillation of the aerial part of Salvia officinalis L. cultivated in Sfax gardens, Tunisia. The obtained oils were analyzed by gas chromatography-mass spectrometry (GC-MS) and 44 compounds were identified. Strong bactericidal and fungicidal effects were shown using the NCCLS broth dilution, EN 1275 and EN 1276 standard methods. The minimal cidal concentrations (MCCs) values ranged from 0.031 to 0.25 microLmL(-1). The essential oils concentrations of 0.5% and 1% (v/v) resulted in a reduction in viability higher than 5 and 4 log units per mL for the standard bacteria and fungi, respectively, within a contact time of 5 min. Using an air sampler and an aroma dispenser, vaporisation of 0.25 mLm(-3) of S. officinalis essential oils resulted in (72%, 73% and 70%) and (54%, 55% and 55%) reduction of the total microbial count and the total count of yeasts and moulds, after a residence time of 1h, 6h and 24h in a selected testing room, respectively. S. officinalis essential oils showed a potent vapour activity against a panel of bacteria, yeasts and fungi. This supported their use as a natural eco-friendly disinfectant to manage airborne microbes.

Effect of the Maturation Process on the Phenolic Fractions, Fatty Acids, and Antioxidant Activity of the Chétoui Olive Fruit Cultivar

Maturity is one of the most important factors associated with the quality evaluation of fruit and vegetables. This work aims to investigate the effect of the maturation process of the olive fruit on the phenolic fraction and fatty acid of irrigated Chétoui cultivar. The phenolic composition was studied by using reverse-phase high-performance liquid chromatography followed by LC-MS and GC-MS analyses and fatty acids by GC. Oleuropein was the major phenolic compound at all stages of ripeness. Unexpectedly, both phenolic compounds hydroxytyrosol and oleuropein exhibited the same trends during maturation. Indeed, the oleuropein levels decreased during the ripening process and were not inversely correlated with the concentrations of hydroxytyrosol. The antioxidant capacity of olive extracts was evaluated by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl and the beta-carotene linoleate model system. The IC 50 and AAC values of the olive extracts decreased from 3.68 to 1.61 microg/mL and from 645 to 431, respectively. There was a correlation between the antioxidant activity and the oleuropein concentration. The fatty acid composition was quantified in olive fruit during maturation and showed that fatty acids were characterized by the highest level of oleic acid, which reached 65.2%.

Detection of Chemlali Extra-Virgin Olive Oil Adulteration Mixed with Soybean Oil, Corn Oil, and Sunflower Oil by Using GC and HPLC

Fatty acid composition as an indicator of purity suggests that linolenic acid content could be used as a parameter for the detection of extra/virgin olive oil fraud with 5% of soybean oil. The adulteration could also be detected by the increase of the trans-fatty acid contents with 3% of soybean oil, 2% of corn oil, and 4% of sunflower oil. The use of the ΔECN42 proved to be effective in Chemlali extra-virgin olive oil adulteration even at low levels: 1% of sunflower oil, 3% of soybean oil, and 3% of corn oil. The sterol profile is almost decisive in clarifying the adulteration of olive oils with other cheaper ones: 1% of sunflower oil could be detected by the increase of Δ7-stigmastenol and 4% of corn oil by the increase of campesterol. Linear discriminant analysis could represent a powerful tool for faster and cheaper evaluation of extra-virgin olive oil adulteration.