Mohamed Damak

Hypoglycemic and antioxidant effects of phenolic extracts and purified hydroxytyrosol from olive mill waste in vitro and in rats.

This study aimed to evaluate the effect of phenolic extract and purified hydroxytyrosol (HT) from olive mill waste (OMW) on oxidative stress and hyperglycemia in alloxan-induced diabetic rats. The OMW biophenols were extracted using ethyl acetate. The obtained extract was fractionated by solid phase extraction (SPE) experimentation to generate two fractions: (F1) and (F2). HPLC-UV and HPLC-MS analysis showed that (F1) was made of known OMW monomeric phenolics mainly hydroxytyrosol (HT) while (F2) contained oligomeric and polymeric phenols such as verbascosid and ligstrosid. (HT) was purified from (F1) using silica gel-column chromatography and silica gel-TLC techniques. In incubated pancreas, supplementation of OMW fractions enhanced insulin secretion. The administration of OMW extract fractions (F1) and (F2) as well as purified (HT) in diabetic rats caused a decrease in glucose level in plasma and an increase in renal superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities in liver and kidney. Furthermore, a protective action against hepatic and renal toxicity in diabetic rats was clearly observed. 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 and the thiobarbituric acid-reactive substances (TBARs), total and direct bilirubin, creatinine and urea levels. In addition, (F1), (F2) and especially (HT) decreased triglycerides (TG), total-cholesterol (T-Ch) and higher HDL-cholesterol (HDL-Ch) in serum. These beneficial effects of OMW biophenols were confirmed by histological findings in hepatic, renal and pancreatic tissues of diabetic rats. This study demonstrates for the first time that OMW polyphenols and especially (HT) are efficient in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggests that administration of HT may be helpful in the prevention of diabetic complications associated with oxidative stress.

In vitro study of the PLA2 inhibition and antioxidant activities of Aloe vera leaf skin extracts

BackgroundIn the present work we determined the total phenolic content of Aloe vera leaf skin (AVLS) extracts by using various solvents (hexane, chloroform-ethanol (1/1), ethyl acetate, butanol and water). We have also evaluated the antioxidant and the anti-PLA2 properties of these extracts by measuring their inhibition potency on the human pro-inflammatory phospholipase A2 (group IIA).ResultsThe water extract exhibits the highest inhibitory effect with an IC50 = 0.22 mg/ml and interestingly no effect was observed on the digestive phospholipase A2 (group IB) even at a concentration of 5 mg/ml. Antioxidant activities were also analyzed and the most active extracts were observed when using chloroform ethanol (1/1) and ethyl acetate (IC50 = 0.274 and 0.326 mg/ml, respectively). Analysis of the total phenolic content reveals that the water extract, with the best anti-PLA2 effect, was poor in phenolic molecules (2 mg GAE/g). This latter value has to be compared with the chloroform-ethanol and the ethyl acetate extracts (40 and 23.8 mg GAE/g, respectively), mostly responsible for the antioxidant activity.ConclusionA significant correlation was established between the total phenolic content and the antioxidant capacity but not with the anti PLA2 activity. Results from phytochemical screening suggest that the anti PLA2 molecules were probably catechin tannins compounds.

In vitro anti-diabetic, anti-obesity and antioxidant proprieties of Juniperus phoenicea L. leaves from Tunisia

ABSTRACT Objective To examine chemical composition and antioxidant activity as well as the in vitro α-amylase and pancreatic lipase inhibitory activities of the essential oil and various extracts of Juniperus phoenicea ( J. phoenicea ). Methods Essential oil obtained by steam distillation were analyzed by gas chromatography-mass spectrometry technique. The antioxidant activity of the essential oil and various extracts of J. phoenicea were determined by DPPH and β-carotene bleaching methods. Results Gas chromatography-mass spectrometry analysis of the J. phoenicea essential oil resulted in the identification of 37 compounds, representing 96.98% of the oil; α-Pinene (24.02%), limonene (7.94%), D-3-Carene (16.9%), Germacrene D (11.98%), Germacrene B (5.40%) and δ-cadinene (6.52%) were the major compounds. The IC 50 values of essential oil, hexane and methanol extracts against α-amylase were 35.44, 30.15 and 53.76 μg/mL respectively, and those against pancreatic lipase were 66.15, 68.47 and 60.22 μg/mL respectively, suggesting powerful anti-diabetic and anti-obesity effects. Antioxidant activity (IC 50 =2 μg/mL) and total phenolics content (265 mg as gallic acid equivalent/g extract) of the methanol extract were found to be the highest compared to the other extracts. Conclusions The findings showed that the extents of α-amylase and pancreatic lipase inhibitory activities of the J. phoenicea extracts as well as their antioxidant activity are in accordance with total phenolics contents. Leaves of J. phoenicea being rich in phenolics may provide a good source of natural products with interesting medicinal properties.

Structural determination and NMR characterization of a bacterial exopolysaccharide

A strain of Bacillus licheniformis with high exopolysaccharide (EPS) production ability was isolated and identified. A new type of EPS was isolated from the strain fermentation and its structural characteristics were investigated and elucidated by partial and total acid hydrolysis, Fourier transform infrared, and (1)H and (13)C NMR spectroscopy including 2D (1)H, COSY, NOESY, XHCOR and HMBC experiments. Based on obtained data, the EPS was found to be a levan composed of linear chains of (2→6)-linked β-d-fructofuranosyl residues with connections β (2→6).

Molluscicidal activity of various solvent extracts from Solanum nigrum var. villosum L. aerial parts against Galba truncatula

Molluscicidal activity of Solanum nigrum var. villosum (morelle velue) extracts and their fractions were tested against the mollusca gastropoda Galba truncatula intermediate host of Fasciola hepatica. The results indicated that the hydro-methanol (MeOH-H2O) immature fruit extract possess the highest molluscicidal activity (LC50 = 3.96 mg/L) against Galba truncatula compared with other tested compounds. After acido-basic treatment, the methanolic extract fraction isolated from the immature fruits and the richest in alkaloids was the most toxic (LC50 = 1.65 mg/L). The fractions richest in saponosides obtained from the hydromethanolic and methanolic extracts of immature fruits showed interesting molluscicidal activities (LC50 = 6.15 mg/L and LC50 = 7.91 mg/L, respectively). The observed molluscicide activity could be attributed to the presence of alkaloids or saponosides. So, the immature fruits of Solanum nigrum var. villosum could be substrates of choice for molluscicide activity. In addition, total alkaloids and saponosides present in this plant deserve further investigations in order to identify the active principles and demonstrate their activities on mollusks in their natural habitat. According to the World Health Organization’s guidelines on screening for plant molluscicides, use of these fractions may add to the arsenal of methods to control snail transmitting fasciolosis in tropical and Third World countries where fasciolosis is a common disease.

Stabilization of Sunflower Oil During Accelerated Storage: Use of Basil Extract as a Potential Alternative to Synthetic Antioxidants

The antioxidant efficacy of basil extracts was estimated in stabilization of sunflower oil. The basil essential oil was analyzed by gas chromatography–mass spectrometry. Twenty-two compounds were identified representing 93.74% of the total essential oil. Basil methanolic extract was thermally evaluated by heating at 185°C. At the 100 min heating time, the extract exhibited antioxidant activity higher than that of butylated hydroxytoluene. Different concentrations of methanolic extract were added to sunflower oil. Selected parameters (i.e., weight gain, induction period to primary oil oxidation, peroxide value, conjugated dienes, and conjugated trienes) were considered for evaluating the effectiveness of basil in stabilization of sunflower oil. Basil methanolic extract showed good antioxidant activity according to synthetic antioxidants. Basil may be used as a natural antioxidants to prevent vegetable oils oxidation.

A new triterpene from olea europea stem with antidiabetic activity

Purification of the ethyl acetate extract of the Olea europea stem led to the isolation and characterization of two triterpenes: the known compound oleanolic acid and the new triterpene oleanolic acid demethyl. Their structures were determined by various spectroscopic techniques (NMR 1H, 13C, DEPT, HMQC, HMBC, NOESY, COSY, MS, UV, and IR). The compounds exhibited potent inhibitory activities in in vitro assays against α-amylase and lipase.

N-(Hydroxymethyl)ibogaine

The title compound (systematic name: 16-hydroxymethyl-12-methoxyibogamine), C21H28N2O2, was prepared by reaction of ibogaine with a formaldehyde–acetic acid solution (pH = 4). The crystal structure of this new product, belonging to the iboga indole family, is stabilized by an intermolecular O—H⋯N hydrogen bond. The identity of the compound was confirmed by one- and two-dimensional NMR spectroscopic techniques.

Molluscicidal activity of Solanum elaeagnifolium seeds against Galba truncatula intermediate host of Fasciola hepatica: Identification of β-solamarine

Abstract Context: The persistence of fascioliasis in many developing countries urges the search for simple, cheap, and effective substances. In this view, plants provide interesting molluscicidal activities thanks to the secondary metabolites they produce. The genus Solanum is known for its potent effect on vector snails. Objective: The molluscicidal activity of Solanum elaeagnifolium Cav. (Solanaceae) seeds against Galba truncatula Müll. (Lymnaeidae), intermediate host of Fasciola hepatica L. (Fasciolidae), was evaluated. Materials and methods: Solanum elaeagnifolium seeds were powdered and successively extracted using n-hexane, methylene chloride, acetone, and methanol, for 20 h each. After filtration, solvents were evaporated. An acid–base treatment was conducted on seed methanolic extract to isolate total alkaloids and β-solamarine. Total saponins fraction was obtained after successive macerations and evaporations. The molluscicidal activity was evaluated by subjecting snails, in groups of 10, for 48 h to 500 mL of extracts, fractions, and pure product aqueous solutions, each containing amounts, ranging from 1 to 50 mg of plant material in 5 mg increments. Results: The methanolic extract of seeds, β-solamarine isolated for the first time from this plant and total saponins fraction showed very potent activities on snails, giving respective median lethal concentrations (LC50) of 1.18, 0.49, and 0.94 mg/L. Total alkaloids fraction obtained from the methanolic extract was less active giving an LC50 value of 14.67 mg/L. Discussion and conclusion: This study emphasizes that glycoalkaloids and saponins of Solanum elaeagnifolium are potent molluscicidal agents. Seed methanolic extract, β-solamarine, and total saponins fraction may be used as molluscicides.

Hepatoprotective activity of Peganum harmala against ethanol-induced liver damages in rats

Abstract In this study, we investigated the protective effects of Peganum harmala seeds extract (CPH) against chronic ethanol treatment. Hepatotoxicity was induced in male Wistar rats by administrating ethanol 35% (4 g/kg/day) for 6 weeks. CPH was co-administered with ethanol, by intraperitonial (IP) injection, at a dose of 10 mg/kg bw/day. Control rats were injected by saline solution (NaCl 9‰). Chronic ethanol administration intensified lipid peroxidation monitored by an increase of TBARS level in liver. Ethanol treatment caused also a drastic alteration in antioxidant defence system; hepatic superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. A co-administration of CPH during ethanol treatment inhibited lipid peroxidation and improved antioxidants activities. However, treatment with P. harmala extract protects efficiently the hepatic function of alcoholic rats by the considerable decrease of aminotransferase contents in serum of ethanol-treated rats.