Sahla Belhadj

Inhibitory activities of Ulva lactuca polysaccharides on digestive enzymes related to diabetes and obesity

Abstract The aim of this study was to evaluate the effect of alga Ulva lactuca polysaccharides (ULPS) on key enzymes related to diabetes and obesity. This marine natural product, ULPS, exerted potential inhibition on key enzymes related to starch digestion and absorption in both plasma and small intestine mainly α-amylase by 53% and 34% and maltase by 97 and 164% respectively, leading to a significant decrease in blood glucose rate by 297%. Moreover, ULPS potentially inhibited key enzymes of lipid metabolism and absorption as lipase activity in both plasma and small intestine by 235 and 287% respectively, which led to a notable decrease of blood LDL-cholesterol and triglycerides levels, and in the counterpart an increase in HDL-cholesterol level in surviving diabetic rats. Additively, ULPS significantly protected the liver-kidney functions, by decreasing of aspartate transaminase (AST), alanine transaminase (ALT) and gamma-glytamyl transpeptidase (GGT) activities and creatinine, urea and albumin rates in plasma.

LC-MS–MS and GC-MS analyses of biologically active extracts and fractions from Tunisian Juniperus phoenice leaves

Abstract Context: Despite some studies related to Juniperus phoenicea L. (Cupressaceae), phytochemical and biological investigations of this plant remain unexplored. Objective: This work is the first report dealing with the identification and characterization of volatile components and flavonoids in hexane and methanol extracts from J. phoenicea leaves Materials and methods: Antioxidant activity of hexane, and methanol extracts from J. phoenicea leaves were determined by DPPH-radical scavenging assay. α-Amylase inhibitory activity was evaluated by enzyme inhibition using in vitro assay (each extract was dissolved in DMSO to give concentrations of 50, 100 and 200 mg/mL). The chemical composition of fractions (Fr1-Fr3) from methanol extract was determined by high-performance liquid chromatography coupled with mass spectroscopy (HPLC-MS) analysis. Results and discussion: The hexane extract was analyzed by GC-MS technique which allowed the identification of 32 compounds. The main constituents were α-humulene (16.9%), pentadecane (10.2%) and α-cubebene (9.7%). Fraction Fr 2 exhibited a strong DPPH radical-scavenging activity (IC50 = 20.1 μg/mL) compared to that of BHT as well as the highest α-amylase inhibitory activity (IC50 = 28.4 μg/mL). Three flavonoids were identified in these fractions using HPLC-MS analysis: Quercetin 3-O-glucoside, isoscutellarein 7-O-pentoside and quercetin 3-O-pentoside. In addition, the more active fraction (Fr 2) was purified with semi-preparative HPLC affording one pure compound (amentoflavone) using 1H NMR analysis. This compound exhibited powerful DPPH radical-scavenging (IC50 = 14.1 μg/mL) and α-amylase inhibition (IC50 = 20.4 μg/mL) effects. Conclusion: This study provides scientific support to some medicinal uses of J. phoenicea found in North Africa.

Antioxidant and α-amylase inhibitory activities of extract and isolates from Zygogynum pancheri subsp. arrhantum

One new sesquiterpenoid (5R*,8R*,9R*,10R*)-cinnamolide (8), and seven known compounds, 5-hydroxy-7-methoxyflavonone (1), 8-hydroxy-3-(4′-hydroxyphenyl)-6,7-(2″,2″-dimethylchromene)-tetralone (2), 8-hydroxy-3-(3′,4′-dihydroxyphenyl)-6,7-(2″,2″-dimethylchromene)-tetralone (3), 1β-E-O-p-methoxycinnamoyl-bemadienolide (4), 1β-O-(E-cinnamoyl)-6α-hydroxy-9-epi-polygodial (5), 1β-O-(E-cinnamoyl)-6α-hydroxypolygodial (6), and 1β-O-E-cinnamoylpolygodial (7) were isolated from the ethyl acetate extract of barks of Zygogynum pancheri subsp. arrhantum (Winteraceae). The structures of these molecules were assigned predominantly based on spectral data. The structure of compound 8 was confirmed by X-ray crystallographic analysis. Compounds 2 and 3 exhibited significant antioxidant activity, whereas compounds 1 and 4–7 showed significant α-amylase inhibitory activity.

Beneficial Effect of Jojoba Seed Extracts on Hyperglycemia-Induced Oxidative Stress in RINm5f Beta Cells

Hyperglycemia occurs during diabetes and insulin resistance. It causes oxidative stress by increasing reactive oxygen species (ROS) levels, leading to cellular damage. Polyphenols play a central role in defense against oxidative stress. In our study, we investigated the antioxidant properties of simmondsin, a pure molecule present in jojoba seeds, and of the aqueous extract of jojoba seeds on fructose-induced oxidative stress in RINm5f beta cells. The exposure of RINm5f beta cells to fructose triggered the loss of cell viability (−48%, p < 0.001) and disruption of insulin secretion (p < 0.001) associated with of reactive oxygen species (ROS) production and a modulation of pro-oxidant and antioxidant signaling pathway. Cell pre-treatments with extracts considerably increased cell viability (+86% p < 0.001) for simmondsin and +74% (p < 0.001) for aqueous extract and insulin secretion. The extracts also markedly decreased ROS (−69% (p < 0.001) for simmondsin and −59% (p < 0.001) for aqueous extract) and caspase-3 activation and improved antioxidant defense, inhibiting p22phox and increasing nuclear factor (erythroid-derived 2)-like 2 (Nrf2) levels (+70%, p < 0.001) for aqueous extract. Simmondsin had no impact on Nrf2 levels. The richness and diversity of molecules present in jojoba seed extract makes jojoba a powerful agent to prevent the destruction of RINm5f beta cells induced by hyperglycemia.

Metabolic impairments and tissue disorders in alloxan-induced diabetic rats are alleviated by Salvia officinalis L. essential oil

The current research explored for the first time the effect of Salvia officinalis L. (Sage) essential oil (EO) on Alloxan-induced diabetes in male Wistar rats. Sage EO was extracted by a Clevenger apparatus and analyzed by GC-FID and GC-MS. The most important chemical families identified in this oil were oxygenated monoterpenes (56.32%), hydrocarbon monoterpenes (15.00%) and hydrocarbon sesquiterpenes (14.70%). All treatments were administered orally. In vitro investigation showed that the EO had α-amylase and lipase inhibitory activities with IC50 = 38 μg/mL and IC50 = 52 μg/mL, respectively. In vivo experiments highlighted that the activities of serum α-amylase and lipase were reduced by 46.6% and 32.1%, respectively. Sage EO reduced glycemia by 60% and the level of glycogen stored in the liver by 43.7%. Treatments of diabetes with Sage EO significantly protected the liver function by lowering serum AST (35%), ALT (79%) and LDH (43%) activities. Furthermore, Sage EO was efficient to preserve the kidney function in diabetes by reverting back serum creatinine (47%) and UA (62.5%) concentrations to control values. The obtained results altogether evidenced that Sage EO had hypoglycemic and anti-obesity effects and could be a valuable complement in future diabetes therapy.

Effect of Sardina pilchardus oil on alloxan-induced diabetic rats

Abstract The purpose of this study was to prevent or to delay the onset of diabetes-related complications, by using a natural marine resource, Sardina pilchardus oil, administrated to alloxan-induced diabetic rats showing hyperglycemia and hyperlipidemia. Gas chromatography–mass spectrometry analysis of the sardine oil detected 18 constituents. The major ones were n-3 highly unsaturated fatty acids among which are docosahexaenoic acid (25.09%) and eicosapentaenoic acid (19.61%). Sardine oil inhibited the α-amylase activity in rats’ sera (26.82%) and thus improved glycemia (54%). The supplement of this oil protected the β-cells from death and damage, significantly decreased total triglycerides, total cholesterol and LDL-cholesterol concentrations in diabetic rats’ sera and increased the HDL-cholesterol level. Gavage administration of this oil to rats protected the liver and kidney functions by reducing the aspartate transaminase, alanine transaminase and phosphatase alkaline activities, and by decreasing creatinine, urea and uric acid levels.