Aqueous infusions of Mediterranean herbs exhibit antioxidant activity towards iron promoted oxidation of phospholipids, linoleic acid, and deoxyribose

Screening of analgesic activity of Tunisian Urtica dioica and analysis of its major bioactive compounds by GCMS

The present study was aimed to evaluate the analgesic properties of Urtica dioica (UD) and to profile phytochemicals by gas chromatography-mass spectrometry (GC-MS). The ethanolic extracts were prepared by maceration method and extraction using rotary evaporator. The analgesic activity was analysed by hot plate method, formalin test, acetic acid-induced writhing test and the tail-flick test with different doses of the ethanolic extract. In all tests, the leaf's ethanolic extract exhibited significant analgesic activity (p < .001) at a dose of 400 mg/kg. Even with a low dose, we noticed an analgesic activity with many tests. The GC-MS analysis of the ethanol extract of leaf revealed many compounds; 2-methyltetradecane dodecane, 2,6,11-trimethyl-; 2,6,11-trimethyldodecane, and trimethylhexane which are pharmaceutically the most important. These findings justify that UD can be a valuable natural analgesic source which seemed to provide potential phototherapeutics against various ailments. The analysis of ethanolic extract of UD by GCMS revealed the presence of several compounds including polyphenols, flavonoids, triterpenes which can explain the analgesic effect of UD and its mechanism of action. Hence, UD could be another therapeutic alternative for relieving pain and for minimising the use of drugs that have long-term secondary effects.

Urtica spp.: Ordinary Plants with Extraordinary Properties

Nettles (genus Urtica, family Urticaceae) are of considerable interest as preservatives in foods for both human and animal consumption. They have also been used for centuries in traditional medicine. This paper reviews the properties of nettles that make them suitable for wider applications in the food and pharmaceutical industries. Nettles contain a significant number of biologically-active compounds. For example, the leaves are rich sources of terpenoids, carotenoids and fatty acids, as well as of various essential amino acids, chlorophyll, vitamins, tannins, carbohydrates, sterols, polysaccharides, isolectins and minerals. Extracts from the aerial parts of nettles are rich sources of polyphenols, while the roots contain oleanol acid, sterols and steryl glycosides. Due to the variety of phytochemicals and their proportions they contain, nettles show noticeable activity against both Gram-positive and Gram-negative bacteria. These properties make nettles suitable for a range of possible applications, including functional food, dietary supplements and pharmacological formulations. Despite these benefits, the nettle is still an underestimated plant source. This paper provides a unique overview of the latest research on nettle plants focusing on the possibilities for transforming a common weed into a commercial plant with a wide range of applications. Special attention is paid to the antimicrobial activity of the active compounds in nettles and to possible uses of these valuable plants in food and feed formulations.

Comparison of microwave and ultrasound-assisted extraction techniques for leaching of phenolic compounds from nettle

In this study, extraction of phenolic compounds from nettle by microwave and ultrasound was studied. In both microwave and ultrasound-assisted extractions, effects of extraction time (5-20 min for microwave; 5-30 min for ultrasound) and solid to solvent ratio (1:10, 1:20, and 1:30 g/mL) on total phenolic content (TPC) were investigated. Effects of different powers (50 % and 80 %) were also studied for ultrasound-assisted extraction. In microwave-assisted extraction, the optimum TPC of the extracts (24.64 ± 2.36 mg GAE/g dry material) was obtained in 10 min and at 1:30 solid to solvent ratio. For ultrasound-assisted extraction, the condition that gave the highest TPC (23.86 ± 1.92 mg GAE/g dry material) was 30 min, 1:30 solid to solvent ratio, and 80 % power. Extracts obtained at the optimum conditions of microwave and ultrasound were compared in terms of TPC, antioxidant activity (AA) and concentration of phenolic acids with conventional extraction and maceration, respectively. Microwave reduced extraction time by 67 %. AA of extracts varied between 2.95 ± 0.01 and 4.48 ± 0.03 mg DPPH/g dry material among four methods. Major phenolic compounds were determined as naringenin and chlorogenic acid in nettle.

Phenolic compounds in red wine digestedin vitroin the presence of iron and other dietary factors

Quantitative and qualitative changes in the phenolic composition of red wine may occur during digestion in the lumen, particularly when other dietary components are present. In this study, mixtures of red wine, iron, and ascorbic acid, meat or casein were subjected to a simulated gastrointestinal digestion. This process involves incubation of samples for 4.5 h at 37 degrees C, at different pH values, in the presence of peptic enzymes and fractionation of digests through a dialysis membrane with a molecular weight cut-off of 6000-8000. Selected phenolic compounds were determined in undigested samples and in their dialysable digests by reversed-phase high-performance liquid chromatography. A dramatic decrease in the concentration of the selected phenolic compounds was observed in all samples after they were digested in vitro. Moreover, when iron and/or protein were added to red wine samples, changes in the phenolic profile of the undigested and of the in vitro digested samples were detected. These results suggest that interactions between red wine phenolic compounds and iron, protein and/or digestion components are important determinants of the physicochemical properties and the concentration of these phenolic compounds in the lumen. The in vitro methodology employed herein offers a tool for the study of phenolic compounds under conditions of simulated gastrointestinal digestion, incorporating lumenal events that may affect phenolic compounds.

Antioxidant activity of flavonoids isolated from young green barley leaves toward biological lipid samples

Natural plant flavonoids, saponarin/lutonarin=4.5/1, isolated from young green barley leaves were examined for their antioxidant activity using cod liver oil, omega-3 fatty acids, phospholipids, and blood plasma. The saponarin/lutonarin (S/L) mixture inhibited malonaldehyde (MA) formation from cod liver oil by 76.47+/-0.11% at a level of 1 micromol and 85.88+/-0.12% at a level of 8 micromol. The S/L mixture inhibited MA formation from the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by 45.60+/-1.08 and 69.24+/-0.24%, respectively, at a level of 8 micromol. The S/L mixture inhibited MA formation from the phospholipids lecithin I and II by 43.08+/-0.72 and 69.16+/-2.92%, respectively, at a level of 8 micromol. It also inhibited MA formation from blood plasma by 62.20+/-0.11% at a level of 8 micromol. The antioxidant activities obtained from the S/L mixture were comparable to those obtained from alpha-tocopherol and butylated hydroxy toluene (BHT) in all lipids tested.

Supercritical CO2 extraction and purification of compounds with antioxidant activity

Supercritical fluid extraction (SCFE), based on the utilization of a fluid under supercritical conditions, is a technology suitable for extraction and purification of a variety of compounds, particularly those that have low volatility and/or are susceptible to thermal degradation. The interest in SCFE is promoted by legal limitations of conventional solvents for food and pharmaceutical uses. The physicochemical properties of supercritical CO2 (higher diffusivity, lower viscosity, and lower surface tension than conventional solvents) facilitate mass transfer and allow an environmentally friendly operation. This article presents a comprehensive compilation of data on the supercritical CO2 extraction of antioxidant compounds from vegetal materials, with particular attention to those of a phenolic nature. Aspects concerning the supercritical operation for extraction and fractionation of antioxidants compounds are considered, including equilibrium solubility of pure compounds and effects of the operational conditions on the antioxidant activity of isolated fractions. The data are compared to those reported for synthetic antioxidants and natural extracts obtained by conventional solvent extraction from vegetal matrices.

Antioxidant, antimicrobial, antiulcer and analgesic activities of nettle (Urtica dioica L.)

In this study, water extract of nettle (Urtica dioica L.) (WEN) was studied for antioxidant, antimicrobial, antiulcer and analgesic properties. The antioxidant properties of WEN were evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. WEN had powerful antioxidant activity. The 50, 100 and 250 microg amounts of WEN showed 39, 66 and 98% inhibition on peroxidation of linoleic acid emulsion, respectively, while 60 microg/ml of alpha-tocopherol, exhibited only 30% inhibition. Moreover, WEN had effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities at the same concentrations. Those various antioxidant activities were compared to standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), quercetin, and alpha-tocopherol. In addition, total phenolic compounds in the WEN were determined as pyrocatechol equivalent. WEN also showed antimicrobial activity against nine microorganisms, antiulcer activity against ethanol-induced ulcerogenesis and analgesic effect on acetic acid-induced stretching.

Antioxidant activity of organic extracts from aqueous infusions of sage

The antioxidant activity of aqueous infusions of sage emerges from specific components present in that herb. In an attempt to investigate the chemical nature and properties of these components, four organic solvent extracts from aqueous infusions of sage were examined. HPLC analyses of these extracts led to the separation of a number of components, of which four were identified and quantified through the use of standard compounds of known chromatographic HPLC profiles. These compounds are the diterpenes carnosic acid, carnosol, and rosmanol and the hydroxycinnamic acid caffeic acid. The antioxidant activity and polyphenol content were determined in the four organic solvent extracts and the left-over aqueous fraction. Both polyphenolic and nonpolyphenolic substances present in the extracts arise as significant contributors to the observed antioxidant activity of the derived extracts and thus sage itself. In this sense, they reflect the antioxidant potential of the aqueous infusions of sage toward reactive oxygen species generated through variable mechanisms of iron-promoted oxidative processes.

Free radical-scavenging activity of Taiwanese native plants

The 70% aqueous acetone extracts of ten Taiwanese native plants were evaluated by various antioxidant assays, including 1, 1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (.OH) radicals, and reducing power assay. In the present study, extracts of Acer buerferianum var. formosanum, Cleyera japonica var. morii, Cyclobalanopsis stenophylla var. stenophylloides, and Machilus zuihoensis exhibited stronger activity against DPPH radicals, and their IC50 values ranged from 5.4 to 8.3 microg/ml. The ten selected extracts effectively inhibited the formation of .OH generated in the Fenton reaction system. Among the extracts whose reducing power activities were determined, A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, Eriobotrya deflex, and M. zuihoensis showed high activity. The results indicate the 70% aqueous acetone extracts of A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, and M. zuihoensis with great potency in these assay systems and may be candidates for the development of natural antioxidants.