Antioxidant properties, total phenols and pollen analysis of propolis samples from Portugal.

Pollen analysis, total phenols content and antioxidant activity were studied for the first time in Portuguese propolis samples from Bornes and Fundão regions. Total phenols content was determined by colorimetric assay and their amount was of 329 mg/g of GAE in Bornes sample and 151 mg/g of GAE in Fundão propolis. The antioxidant capacity of propolis extracts was assessed through the scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) and reducing power of iron (III)/ ferricyanide complex assays. A concentration-dependent antioxidative capacity was verified in DPPH and reducing power assays. Low values of EC50 on DPPH scavenging assay were obtained for Bornes and Fundão propolis (of 6.22 microg/mL and 52.00 microg/mL, respectively). For reducing power the values were 9.00 microg/mL, for Bornes propolis, and 55.00 microg/mL, for Fundão propolis. The high activity of propolis from Bornes could be related with their different pollen composition. The results obtained indicate that Portuguese propolis is an important source of total phenols showing antioxidant properties that could be beneficial for human health.

Antioxidant activity and total phenols in different extracts of four Staphylea L. Species.

Staphylea L. is a deciduous ornamental shrub that possesses significant cytotoxic and antibacterial activity, although the chemical composition of its extracts and the identity of the structures responsible for these biological activities are not yet known. In this study we have determined the total phenolic content in chloroform and ethyl acetate extracts of four Staphylea species: Staphylea colchica Stev., S. elegans Zab., S. holocarpa Hemsl. and S. pinnata L.. The antioxidant potential (DPPH radical and peroxynitrite scavenging activity) of these extracts was also determined and a correlation between the phenolic content and antioxidant activities of the ethyl acetate extracts has been found. Ethyl acetate extracts were more active and one of them, obtained from S. colchica Stev., possessed the highest activity.

Antioxidant properties of Glossogyne tenuifolia.

Glossogyne tenuifolia (Labill) Cass. (Compositae) is a special medicinal plant in the Pescadores Islands. Ethanolic, cold and hot water extracts were prepared from the dried herb and their antioxidant properties and components were studied. Ascorbic acid, alpha-tocopherol, butylated hydroxyanisole, citric and ethylenediaminetetraacetic acids were used in assays for comparison. With regard to EC(50) values in antioxidant activity, ethanolic and hot water extracts (0.08 and 0.09 mg/ml) were much more effective than the cold water extract (0.76 mg/ml). At 1.0 mg/ml, reducing capacities were 1.57, 0.31 and 1.04 for ethanolic, cold water and hot water extracts, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were in descending order: ethanolic > cold water > hot water extracts. At 20 mg/ml, the hot water extract chelated all hydroxyl ions (100%) whereas the scavenging ability of the cold water extract was 68.86%. Chelating abilities on ferrous ions were in descending order: cold water > hot water > ethanolic extracts. Phenols were found to be the major antioxidant components. All EC(50) values were below 20 mg/ml, and some even below 0.1 mg/ml, indicating that all three extracts from G. tenuifolia were rich in antioxidant properties.

Prostaglandin inhibitory and antioxidant components of Cistus laurifolius, a Turkish medicinal plant.

As Cistus laurifolius has been used traditionally to treat inflammatory and rheumatic disorders, its leaves were tested for prostaglandin (PG) inhibitory and antioxidant activities. The leaf extract showed both activities, i.e., inhibitory effect at 300 microg/ml on PGE1- and E2-induced contractions in guinea pig ileum and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect. The separation guided by the activities shown by these dual assays provided sixteen compounds, 1-16. Known compounds 1-12 and 15 were identified as 3-O-methyl quercetin (1), 3,7-O-dimethyl quercetin (2), genkwanin (3), 3,7-O-dimethyl kaempferol (4), 3,4'-O-dimethyl quercetin (5), apigenin (6), 3,4'-O-dimethyl kaempferol (7), ellagic acid (8), beta-sitosterol-3-O-beta-glucoside (9), quercetin 3-O-alpha-rhamnoside (10), 5-O-p-coumaroyl quinic acid methyl ester (11), 1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-alpha-l-rhamnopyranoxypropyl)-2-methoxyphenoxy]-1,3-propanediol (12) and 2,3-dihydro-2-(4'-alpha-l-rhamnopyranosyloxy-3'-methoxyphenyl)-3-hydroxymethyl-7-methoxy-5-benzofuranpropanol (15). New lignan glycosides 13 and 14 were determined to be olivil 9-O-beta-D-xyloside and berchemol 9-O-rhamnoside, respectively. Compound 16 was isolated as a 2:1 mixture of two diastereomers, the major one of which was determined to be (7S,8R)-dihydrodehydrodiconiferyl alcohol 9'-O-alpha-L-rhamnoside. The structures were determined by detailed 2D NMR analysis together with NOEDF and CD. PG inhibitory effect was observed in 1, 5, 10, 12 and 16 at 30 microg/ml and antioxidant activity, in 1, 2, 8, 10, 12-14 and 16.

Comparison of free radical scavenging activity of Siamese neem tree (Azadirachta indica A. Juss var. siamensis Valeton) leaf extracts prepared by different methods of extraction.

OBJECTIVE: The aim of this study was to investigate the antioxidant activity of the aqueous extracts of leaves of Siamese neem tree (Azadirachta indica A. Juss var. siamensis Valeton) from several extracting and drying methods using 2,2-diphenyl-1-picrylhydrazyl (DPPH)-scavenging assay. MATERIALS AND METHODS: The leaves of Siamese neem tree were extracted using percolation, decoction, maceration, soxhlet extraction, freeze drying or spray drying methods. The extract was tested for antioxidant activity using DPPH-scavenging assay. Thin-layer chromatography of the extract from decoction was also investigated. RESULTS: The freeze drying method gave the highest yield (51.50%, w/w) of crude extract, while decoction gave the most effective DPPH-scavenging activity (EC(50): 31.4 microg/ml). Thin-layer chromatography analysis was used to screen the leaf extract obtained using decoction, and the chromatogram showed spots corresponding to quercetin and rutin flavonoids which exhibited antioxidant activities (EC(50): 2.29 and 34.67 microg/ml, respectively). CONCLUSION: Siamese neem tree leaf extracts possessed free radical scavenging activity against the DPPH radical. The most active extract was obtained with the leaf decoction method. It showed antioxidant activity with EC(50) of 31.4 microg/ml.

Radical-scavenging activity of hot water extract of Japanese rice bran--association with phenolic acids.

A strong radical-scavenging activity against a stable radical compound, 1,1-diphenyl-2-picrylhydrazyl (DPPH) was found in the hot water extract of Japanese rice bran. When the extract was treated with ethanol, a dominant radical-scavenging activity was observed in the ethanol-soluble (ES) fraction in a dose-dependent manner, but a weak radical-scavenging activity was detected in the ethanol-precipitable (EP) fraction. Their activities were proportional to the amounts of phenolic substances in each fraction. The phenolic substances in the ES fraction were efficiently separated by Amberlite XAD column chromatography and high performance liquid chromatography using an ODS column. The four major phenolic acids (ferulic, para-coumaric, para-hydroxybenzoic and vanillic acids) and four minor phenolic acids (caffeic, gentisic, protocatechuic and syringic acids) were detected in the HPLC system. Among these phenolic acids, protocatechuic, caffeic, ferulic and gentisic acids showed relatively strong radical scavenging activities (EC50: 8, 9, 29 and 75 microM, respectively) compared with the control antioxidants such as ascorbic acid and alpha-tocopherol (EC50: 93 and 134 microM). Para-coumaric, syringic and vanillic acids exhibited weak but significant radical-scavenging activities (EC50: 780, 2640 and 3250 microM). However, para-hydroxybenzoic acid did not show any significant effects even at 5 mM. Furthermore, a simulated mixture combined with these phenolic acids in comparable amounts in the ES fraction showed slightly weak radical-scavenging activity compared with that of rice bran extract. However, all the phenolic acids detected in the ES fraction did not show significant antioxidant activities against hydroperoxide generation in lipid peroxidation compared with that of a typical antioxidant such as ascorbic acid, which was estimated by the alminum chloride method. These results suggest that Japanese rice bran has a potent radical-scavenging activity against DPPH radical and this activity is associated with some phenolic acids in the ES fraction. The significance of this finding is discussed from the viewpoint of the protective role of rice bran against oxygen radical-induced chronic diseases.

Cytisus scoparius link--a natural antioxidant.

BACKGROUND: Recent investigations have shown that the antioxidant properties of plants could be correlated with oxidative stress defense and different human diseases. In this respect flavonoids and other polyphenolic compounds have gained the greatest attention. The plant Cytisus scoparius contains the main constituent of flavone and flavonals. The present study was undertaken to evaluate the in vitro antioxidant activities of extract of aerial part of Cytisus scoparius. METHODS: The plant extract was tested for DPPH (1, 1-diphenyl, 2-picryl hydrazyl) radical scavenging, nitric oxide radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, antilipid peroxidation assay, reducing power and total phenol content. RESULTS: The extract exhibited scavenging potential with IC50 value of 1.5 microg/ml, 116.0 microg/ml and 4.7 microg/ml for DPPH, nitric oxide and superoxide anion radicals. The values were found to lesser than those of vitamin C, rutin, and curcumin, as standards. The extract showed 50% protection at the dose of 104.0 microg/ml in lipid peroxidation induced by Fe2+/ ascorbate system in rat liver microsomal preparation. There is decrease in hydroxyl radical generation with IC50 value of 27.0 microg/ml when compared with standard vitamin E. The reducing power of the extract depends on the amount of extract. A significant amount of polyphenols could be detected by the equivalent to 0.0589 microg of pyrocatechol from 1 mg of extract. CONCLUSION: The results obtained in the present study indicate that hydro alcoholic extract of aerial part of Cytisus scoparius is a potential source of natural antioxidants.

Antioxidant activity of polyphenols from solid olive residues of c.v. Coratina.

The antioxidant profile of extracts from solid olive residue (SOR) of c.v. Coratina, a cultivar widely diffused in the south of Italy, using both cell-free and cell-based experimental models, was investigated. A total hydroalcoholic extract (polyphenols content 19.7%) and a purified extract (Oleaselecttrade mark) (polyphenols content 35.1%) were tested for their ability to quench the stable free radical DPPH, the peroxyl radicals (ORAC assay), by monitoring the loss in fluorescence of R-phycoerythrin induced by the peroxyl radical generator AAPH and their ability to inhibit the cumene hydroperoxide-induced lysis of rat red blood cells (RBC). The total hydroalcoholic extract showed IC(50) 26.96+/-1.53 microg/ml in the DPPH assay, that 10 microg/ml were equivalent to 2.11+/-0.12 microg/ml Trolox (ORAC assay) and IC(50) 1.7+/-0.20 microg/ml in the RBC hemolysis. The Oleaselect extract was 4 to 5 folds more active than the hydroalcoholic extract in all the experimental models, with IC(50) values of 7.36+/-0.38 microg/ml in the DPPH test and of 0.38+/-0.03 microg/ml in RBC; the antioxidant activity in the ORAC assay was slightly greater than that of Trolox (10 microg/ml equivalent to 11.45+/-0.40 microg/ml). The scavenging effect of the extract in the ORAC assay was compared to that of verbascoside (the main polyphenol component) and of caffeic acid (the basic constituent of verbascoside): the results indicate that caffeic acid (10 microg/ml equivalent to 35.70+/-2.95 microg/ml Trolox) is more potent than verbascoside (10 microg/ml equivalent to 15.42+/-1.21 microg/ml Trolox) in entrapping peroxyl radicals. Finally the antioxidant activity of the Oleaselect extract was confirmed in human umbilical endothelial cells (EC) exposed to the site-specific peroxyl radical inducer AAPH, where a massive lipid peroxidation process (marker the fluorescence probe BODIPY) takes place, paralleled by a marked loss of cell viability (calcein assay). The purified extract (1-20 microg/ml) pre-incubated with EC for 1 h dose-dependently inhibited both the lipid-peroxidation damage and cell death. Taking into account the total polyphenol content, these results clearly indicate a greater antioxidant activity for the purified extract, due to a cooperative antioxidant interaction among its polyphenol constituents.

A new lavandulylated flavonoid with free radical and ONOO- scavenging activities from Sophora flavescens.

A new lavandulylated flavonoid, 8-lavandulylkaempferol (1), was isolated from the roots of Sophora flavescens AITON (Leguminosae). The structure of this compound was determined via spectroscopic analysis. Compound 1 was determined to be a scavenger on both 1,1-diphenyl-2-picrylhydrazyl radicals and ONOO-.

Inhibitory activity of flavonoids from Prunus davidiana and other flavonoids on total ROS and hydroxyl radical generation.

Since reactive oxygen species (ROS) and hydroxyl radicals (*OH) play an important role in the pathogenesis of many human degenerative diseases, much attention has focused on the development of safe and effective antioxidants. Preliminary experiments have revealed that the methanol (MeOH) extract of the stem of Prunus davidiana exerts inhibitory/scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, total ROS and peroxynitrites (ONOO-). In the present study, the antioxidant activities of this MeOH extract and the organic solvent-soluble fractions, dichloromethane (CH2Cl2), ethyl acetate (EtOAc), and n-butanol (n-BuOH), and the water layer of P. davidiana stem were evaluated for the potential to inhibit *OH and total ROS generation in kidney homogenates using 2',7'-dichlorodihydrofluorescein diacetate (DCHF-DA), and for the potential to scavenge authentic ONOO-. We also evaluated the inhibitory activity of seven flavonoids isolated from P. davidiana stem, kaempferol, kaempferol 7-O-beta-D-glucoside, (+)-catechin, dihydrokaempferol, hesperetin 5-O-beta-D-glucoside, naringenin and its 7-O-beta-D-glucoside, on the total ROS, *OH and ONOO- systems. For the further elucidation of the structure-inhibitory activity relationship of flavonoids on total ROS and *OH generation, we measured the antioxidant activity of sixteen flavonoids available, including three active flavonoids isolated from P. davidiana, on the total ROS and *OH systems. We found that the inhibitory activity on total ROS generation increases in strength with more numerous hydroxyl groups on their structures. Also, the presence of an ortho-hydroxyl group, whether on the A-ring or B-ring, and a 3-hydroxyl group on the C-ring increased the inhibitory activity on both total ROS and *OH generation.

Inhibitory activity on lipid peroxidation of extracts from marine brown alga.

Several extracts from marine brown alga Sargassum micracanthum (Kuetzing) Endlicher were screened for their inhibitory activity on lipid peroxidation. In an in vitro study, methanol extract (Sm-M), chloroform/ methanol (3:1) extract and ethyl acetate fraction of Sm-M inhibited lipid peroxidation in rat liver homogenates. The IC(50) values were 0.70, 0.70 and 0.37 micro g/mL, respectively. These inhibitions were stronger than vitamin C and E. These extracts showed reductive activity on DPPH, the IC(50) values were 34, 37 and 11 micro g/mL, respectively. In an in vivo study, Sm-M had the effect on CCl4 induced liver injury in rats and Sm-M (120-1200 mg/kg, p.o.) lowered dose-dependently the level of lipid peroxidation in liver.