Antioxidant Activities of Solanum Nigrum L. Leaf Extracts Determined in in vitro Cellular Models.

Several medicinal foods abound in traditional medicine with antioxidant potentials that could be of importance for the management of several diseases but with little or no scientific justification to substantiate their use. Thus, the objective of this study was the assessment of the antioxidant effect of two leave extracts of Solanum nigrum L. (SN), which is a medicinal plant member of the Solanaceae family, mainly used for soup preparation in different parts of the world. Then methanolic/water (80:20) (SN1) and water (SN2) leaves extracts were prepared. The total polyphenolic content and the concentration of phenolic acids and flavones compounds were determined. In order to verify whether examined extracts were able to restore the oxidative status, modified by glutamate in primary cultures of astrocytes, the study evaluated the glutathione levels, the intracellular oxidative stress, and the cytotoxicity of SN1 and SN2 extracts. Both extracts were able to quench the radical in an in vitro free cellular system and restore the oxidative status in in vitro primary cultures of rat astroglial cells exposed to glutamate. These extracts prevented the increase in glutamate uptake and inhibited glutamate excitotoxicity, which leads to cell damage and shows a notable antioxidant property.

Antioxidant activity of oleuropein and semisynthetic acetyl-derivatives determined by measuring malondialdehyde in rat brain.

OBJECTIVES: The purpose of this study was the evaluation of the antioxidant activity of natural and semisynthetic polyphenol derivatives from Olea europea L., by assessing malondialdehyde (MDA), an important marker of oxidative stress. METHODS: Polyphenol as hydroxytyrosol, oleuropein, oleuropein aglycone as mix of four tautomeric forms and their respective acetyl-derivatives were obtained from olive leaves using semisynthetic protocols. These compounds were administered intraperitoneally to Wistar rats treated with paraquat, an herbicide which is able to cause oxidative stress after central administration. Malondialdehyde was derivatized with 2,4-dinitrophenylhydrazine to produce hydrazone that was purified by solid-phase extraction. Using high-performance liquid chromatography coupled with a diode array, free and total MDA was measured on homogenate rat brain as marker of lipid peroxidation. The analytical method was fully validated and showed linearity in the tested concentration range, with detection limit of 5 ng/ml. Recovery ranged from 94.1 to 105.8%. KEY FINDINGS: Both natural and semisynthetic polyphenol derivatives from a natural source as olive leaves were able to reduce MDA detection. The more lipophilic acetyl-derivatives showed an antioxidant activity greater than parent compounds. This potency seems to put in evidence a strict correlation between lipophilicity and bioavailability.

A rapid profiling of gallotannins and flavonoids of the aqueous extract of Rhus coriaria L. by flow injection analysis with high-resolution mass spectrometry assisted with database searching.

Hydrolysable tannins appear to have some extremely important biological roles including antioxidant, antibacterial, anti-inflammatory, anti-hypoglycemic, anti-angiogenic, and anticancer activities. The aim of this work was to set up a flow injection high-resolution mass spectrometric approach combined with database searching to obtain rapidly a profiling of gallotannins and other phenolics in a crude extract from plant tissue. The flow injection analysis (FIA) takes place in an electrospray ionization source of an hybrid orbitrap high resolution mass spectrometry system (ESI-HR-MS/MS(2), resolution 100,000, negative ion mode) and polyphenols are tentatively identified by matching the monoisotopic masses of the spectra with those of polyphenols databases. This leads to the most probable molecular formulas and to the possible structures among those reported in the database. The structures confirmation occurs by the compliance of MS(2) fragments with those of a prediction fragment commercial database. With this method we identified in the aqueous extract of sumac leaves, with a maximum error of 1.7 ppm, a group of ten gallotannins from mono- to deca-galloyl glycosides of the class of hydrolysable tannins and a set of coextracted flavonoid derivatives including myricetin, quercetin-3-O-rhamnoside, myricetin-3-O-glucoside, myricetin-3-O-glucuronide, and myricetin-3-O-rhamnoglucoside. The separation of isomers of gallotannins and flavonoids present in the same extract occurred by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (HPLC/ESI-HR-MS(2)); this approach allowed the structure resolution of the isobaric flavonoids quercetin-3-O-glucoside and myricetin-3-O-rhamnoside.

Anti-ischemic activity and endothelium-dependent vasorelaxant effect of hydrolysable tannins from the leaves of Rhus coriaria (Sumac) in isolated rabbit heart and thoracic aorta.

The aim of this work was to investigate the cardioprotective activity of hydrolysable gallotannins from Rhus coriaria L. leaves extract (RCLE) in isolated rabbit heart preparations, submitted to low-flow ischemia/reperfusion damage. RCLE induces a dose-dependent normalization of coronary perfusion pressure (CPP), reducing left ventricular contracture during ischemia, and improving left ventricular developed pressure and the maximum rate of rise and fall of left ventricular pressure at reperfusion. Creatinine kinase (CK) and lactate dehydrogenase (LDH) outflow were significantly reduced during reperfusion. In parallel there was a rise in the release of the cytoprotective 6-ketoprostaglandin F (1alpha) (6-keto-PGF (1alpha)) and a decrease of tumor necrosis factor-alpha (TNF-alpha), both significant only at the highest RCLE concentrations (150-500 microg/mL). The vasorelaxant activity of RCLE was studied in isolated rabbit aorta rings precontracted with norepinephrine (NE) with and without endothelium. The vasorelaxation induced by RCLE was predominantly endothelium-dependent as demonstrated by the loss of RCLE vasorelaxant ability in i) de-endothelized rings and ii) in intact aortic rings after pretreatment with NG-monomethyl- L-arginine (L-NMMA) and 1 H-[1.2.4]oxadiazolo[4.3- A]quinoxalin-1-one (ODQ). The inhibition of vasorelaxation in intact rings by indomethacin (INDO) demonstrates the ability of RCLE to modulate the coronary endothelium cyclooxygenase (COX) pathway. The K-ATP channel antagonist glibenclamide (GLIB) was ineffective. The antioxidant activity of RCLE, investigated in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) model and in living cell systems (rat erythrocytes), was stronger than that of gallic acid, ascorbic acid and trolox. The structure of its main bioactive constituents, profiled by HPLC-ESI-HR-S, comprised a mixture of polygalloylated D-glucopyranose with different degrees of galloylation and 3- O-methylgallic acid. The cardiovascular protective effect of RCLE seems to be due to an interplay of different factors: COX pathway activation, TNF-alpha inhibition, endothelial nitric oxide synthase (eNOS) activation, and free radical and ROS scavenging.

Simultaneous determination of catechins, rutin, and gallic acid in Cistus species extracts by HPLC with diode array detection.

A simple high-performance liquid chromatography method using a diode array detector (DAD) is developed for the simultaneous analysis of five major catechins: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GCT), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), and the phenolic plant metabolites gallic acid (GA) and rutin (RT) in lyophilized extracts of Cistus species. The optimal analytical conditions are investigated to obtain the best resolution and the highest UV sensitivity for the quantitative detection of catechins. The optimized conditions (acetonitrile-phosphate buffer 50 mM, pH 2.5, gradient elution system on a C18 reversed-phase column with a flow rate of 1 mL/min and UV absorbance at 210 nm) allowed a specific and repeatable separation of the studied analytes to be achieved. All compounds are successfully separated within 32 min. Calibration curves are linear in the 2-50 microg/mL range for GCT, C, and EGCG and in the 5-50 microg/mL range for GA, EGC, EC, and RT. The limit of detection values ranged from 0.24 to 0.74 microg/mL. The limit of quantitation limit values ranged from 0.77 to 1.94 microg/mL. The validated method is applied to the determination of the specific phytochemical markers GA, GCT, C, and RT in Cistus incanus and Cistus monspeliensis lyophilised extracts. The recovery values ranged between 78.7% and 98.2%. The described HPLC method appears suitable for the differentiation and determination of the most common catechins together with the glycoside rutin and the phenolic compound gallic acid and can be considered an effective and alternative procedure for the analyses of this important class of natural compounds.

Analysis of ecdysteroids by micellar electrokinetic chromatography with on-line preconcentration.

In order to enhance the UV detection sensitivity, an application study of an on-line preconcentration technique for micellar electrokinetic chromatographic (MEKC) was carried out. The simultaneous determination of four test ecdysteroids, 20-hydroxyecdysone, ajugasterone C, polypodine B and ponasterone A has been investigated by using the normal stacking mode in MEKC with UV detection. The effects of anionic surfactant composition and concentration, the applied voltage, the pH buffer, the kind and the amount of organic solvent and the injection time on the analyte resolution were evaluated. The optimised conditions for the separation involved the use of a 50 mM borate as the running buffer containing 50 mM of a mixture of sodium dodecyl sulphate (SDS) and sodium cholate (SC) in the ratio of 1:1 together with a concentration of 10% (v/v) of 2-PrOH at pH 9.0. Hydrodynamic injection of 12 s at 50 mbar and separation voltage of 20 kV at temperature of 20 degrees C were employed. These conditions allowed a repeatability separation within 21 min. Concentration detection limit for the neutral analytes studied improve about an order of magnitude. The method was also applied to the determination of ecdysteroids in a real sample.

In vitro percutaneous absorption studies and in vivo evaluation of anti-inflammatory activity of essential fatty acids (EFA) from fish oil extracts.

The aim of the present study was to evaluate the in vitro percutaneous absorption and the in vivo anti-inflammatory activity of EPA and DHA fatty acids from three oily extracts, obtained by acetonic extractions from the entrails of different varieties of Mediterranean fishes such as mackerel (Scomber scombrus), sardine (Sardina pilchardus) and horse mackerel (Trachurus mediterraneus). In the first part of our research, we focused our attention on the characterization of the oily extracts to determine their omega-3 polyunsaturated fatty acid content, then, we evaluated the in vitro percutaneous absorption through excised human skin (stratum corneum/epidermis membranes; SCE) of EPA and DHA contained in the extracts. In the second part, the fish oil which guaranteed the best in vitro permeation profile of these omega-3 fatty acids was studied in order to evaluate its inhibiting ability towards the in vivo UVB-induced skin erythema. From the results obtained, all the fish oils tested in this study presented significant amounts of omega-3 fatty acids EPA and DHA, and particularly sardine oil extract showed higher concentrations of these substances compared to the other two fish oils. The in vitro experiments revealed interesting fluxes of these compounds from sardine extract through the stratum corneum/epidermis membranes and an appreciable anti-inflammatory activity against UVB-induced erythema in human volunteers was also observed.