Antioxidant activity and hepatoprotective potential of Phyllanthus niruri

Antioxidant activity and hepatoprotective potential of Phyllanthus niruri, a widely used medicinal plant, were investigated. Methanolic and aqueous extract of leaves and fruits of P. niruri showed inhibition of membrane lipid peroxidation (LPO), scavenging of 1,1-diphenyl-2picrylhydrazyl (DPPH) radical and inhibition of reactive oxygen species (ROS) in vitro. Antioxidant activity of the extracts were also demonstrable in vivo by the inhibition of the carbon tetrachloride (CCl₄) – induced formation of lipid peroxides in the liver of rats by pretreatment with the extracts. CCl₄ – induced hepatotoxicity in rats, as judged by the raised serum enzymes, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), was prevented by pretreatment with the extracts, demonstrating the hepatoprotective action of P. niruri.     

Antioxidant activity of Lactobacillus plantarum strains isolated from traditional Chinese fermented foods

Eleven Lactobacillus plantarum strains isolated from traditional Chinese fermented foods were investigated for their in vitro scavenging activity against hydroxyl and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals, and their resistance to hydrogen peroxide. L. plantarum C88 at a dose of 10(10) CFU/ml showed the highest hydroxyl radical and DPPH scavenging activities, with inhibition rates of 44.31% and 53.05%, respectively. Resistance of intact cells to hydrogen peroxide was also found in all strains. L. plantarum C88 was the most resistant strain against hydrogen peroxide. When L. plantarum C88 was administered to senescent mice suffering oxidative stress induced by d-galactose, the serum superoxide dismutase activity, the glutathione peroxidase activity and the total antioxidant capacity in liver increased significantly, while the level of malondialdehyde in liver decreased significantly. L. plantarum C88 isolated from traditional Chinese fermented dairy tofu could be considered as a potential antioxidant to be applied in functional foods.     

Antioxidant properties of water extracts from Monascus fermented soybeans

Solid-state bioprocessing of soybean by Monascus is a biotechnological strategy to produce Monascus-fermented soybeans (MFS) with more beneficial components. The objective of this study was to evaluate the antioxidant properties of cold and hot water extracts from MFS as compared to uninoculated soybeans. With regard to the EC₅₀ values of antioxidant activities, the effectiveness of cold water extracts was in a descending order: soybeans > MFS-31527 > MFS-31499 whereas that of the hot water extracts: soybeans ∼ MFS-31499 > MFS31527. Cold water extracts showed higher reducing power and lower scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals than hot water extracts. For both extracts, MFS and soybeans showed comparable effective chelating abilities on ferrous ions. Total phenols were the major naturally occurring antioxidant components found. For both extracts, soybeans were more effective in antioxidant activity and scavenging ability on DPPH radicals whereas MFS-31499 and MFS-31527 were more effective in reducing power and scavenging ability on hydroxyl radicals. Based on the results obtained, MFS-31499, MFS-31527 and soybeans were relatively effective in the antioxidant properties assayed and might be potential antioxidants for application in food products.     

Antioxidant activity of Agaricus sp. mushrooms by chemical,biochemical and electrochemical assays

The antioxidant activity of five Agaricus sp. mushrooms was screened through chemical, biochemical and electrochemical techniques. The chemical assays allowed an evaluation of their reducing power and radical scavenging activity, while biochemical assays evaluated the lipid peroxidation inhibition capacity, using erythrocytes and brain cells as models; the electrochemical characterization of the mushrooms extracts were performed by cyclic voltammetry and differential pulse voltammetry. All the species proved to have antioxidant activity and particularly, by the electrochemical techniques, it has been shown that mushroom extracts revealed similar electrochemical responses, suggesting similar electroactive chemical composition, and oxidation potentials more positive than those of the standards (ascorbic and gallic acids). Agaricus silvaticus was the most efficient species presenting the lowest EC₅₀ values in the chemical and biochemical assays, and the highest “antioxidant power” in the electrochemical assays.     

Optimised ultrasonic-assisted extraction of flavonoids from Folium eucommiae and evaluation of antioxidant activity in multi-test systems in vitro

The central composite design combined with response surface methodology was used to optimise ultrasonic-assisted extraction for flavonoids-enriched extract from Folium eucommiae. The results indicate that the highest extraction ratio of flavonoids by ultrasonic-assisted extraction could arrive 17.2% using 40% ethanol as solvent and 1:60 solid to lipid ratio for 70 min extraction, which was more efficient than that by heating, microwaves-assisted and enzyme-assisted extractions. The crude extract was then purified by macroporous adsorption resin, the flavonoids content in the purified extract increased to 78.6%. The flavonoids-enriched extract exhibited quite strong reducing property as well as the total antioxidant capacity, and excellent inhibitions of hydroxyl radical, superoxide radical, the haemolysis of rat erythrocytes and the generation of MDA of rat organ tissue. Meanwhile, it was found that the bioactivities appeared to be dose-dependent of flavonoids.     

Antioxidant capacities of Gundelia tournefortii L. extracts and inhibition on glutathione-S-transferase activity

Gundelia tournefortii L. is an important food source and a well-known medicinal plant in Eastern Anatolia. Therapeutic effects of medicinal plants are known to be closely related to their antioxidant capacities. Antioxidant activities of G. tournefortii, both for the aerial parts and seeds, were investigated by using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition methods. The seeds were found to have higher antioxidant potential than the aerial, with IC₅₀ values of 0.073 mg/mL for DPPH scavenging and 0.146 mg/mL for lipid peroxidation inhibition capacities. In addition, total phenolic contents of the Gundelia tournefortii L. extracts, especially the seed extracts correlates to its high antioxidant activity with 105.1 ± 8.7 μg gallic acid equivalents (GAEs) per mg of seed extract. Plant extracts with high phenolics content are known to have important effects on various enzymes, as well as glutathione-S-transferases, which are important detoxification enzymes in phase II systems with an important role in developing multi-drug resistance to chemotherapy in tumour cells. Consequently, the effects of G. tournefortii extracts on crude cytosolic glutathione-S-transferase was also studied and the seed extracts have shown effective inhibition of cytosolic GST activity, with an IC₅₀ of 97.51 μg/mL.     

Effects of Amelanchier fruit isolates on cyclooxygenase enzymes and lipid peroxidation

Bioassay-directed isolation and purification of the ethyl acetate and methanol extracts of Amelanchier canadensis resulted in 1,3-dilinoleoyl 2-olein (1), 1,3-dioleoyl 2-linolein (2), 5-hydroxymethyl-2-furfural (3), 5-(sorbitoloxymethyl)-furan-2-carboxaldehyde (4), 5-(mannitoloxymethyl)-furan-2-carboxaldehyde (5), and 5-(α-d-glucopyranosyloxymethyl) furan-2-carboxaldehyde (6). Four compounds, oleanolic acid (7), ursolic acid (8), kaempferol-3-O-α-l-rhamnopyranosyl (1 ← 2) rhamnopyranoside (9), and kaempferol-3-O-α-l-rhamnopyranoside (10) were isolated from the ethyl acetate extract of fresh fruits of Amelanchier arborea. The compounds were isolated and purified by various chromatographic techniques and characterized by NMR and GC/MS methods. The isolated compounds inhibited lipid peroxidation (by 85%) at 100 ppm when compared to 89%, 87%, and 98% for the commercial antioxidants butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroxyquinone (TBHQ) at 1.67, 2.2, and 1.67 ppm, respectively. Although not selective, some of these compounds inhibited cyclooxygenase (COX)-1 and -2 enzymes. Compounds 3–6 were isolated for the first time from A. canadensis and compounds 7–10 were isolated for the first time from A. arborea fruits.     

Antioxidant properties of Agaricus blazei, Agrocybe cylindracea, and Boletus edulis

Three mushrooms are currently available in Taiwan, including Agaricus blazei, Agrocybe cylindracea, and Boletus edulis. Their ethanolic and hot water extracts were prepared and antioxidant properties studied. Ethanolic extracts from three mushrooms were more effective than hot water extracts in antioxidant activity using the conjugated diene method and scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals whereas hot water extracts were more effective in reducing power, scavenging ability on hydroxyl radials and chelating ability on ferrous ions as evidenced by their lower EC₅₀ values. Overall, for both extracts, B. edulis was more effective among antioxidant properties assayed. Naturally occurring antioxidant components including total tocopherols (3.18-6.18 mg/g) and total phenols (5.67-5.81 mg/g) were found in the extracts and their contents were associated (r=0.636-0.907) with EC₅₀ value of antioxidant properties. Based on the results obtained, both extracts from these three mushrooms were effective in antioxidant properties.     

Antioxidant activity of cichoric acid and alkamides from Echinacea purpurea, alone and in combination

The antioxidant activity of extracts of the stems, leaves, and roots of Echinacea purpurea was compared with the antioxidant activity of purified cichoric acid and alkamides, both constituents of Echinacea purpurea. The antioxidant activity was determined using different methods: effect on oxygen consumption rate of a peroxidating lipid emulsion, and scavenging of radicals, i.e. 2,2-diphenyl-1-picrylhydrazyl (DPPH), measured by two different techniques. The efficacy of the extracts in the reaction with DPPH correlated well with the amount of cichoric acid present in the various extracts. The alkamides alone showed no antioxidant activity in any of the tests. Alkamides present in the extract increased, however, the antioxidative effect of cichoric acid in the peroxidating lipid emulsion. The activity was further compared with that of rosmarinic acid, a well-characterised antioxidant, and the extracts as well as cichoric acid were found to be efficient scavengers of radicals with an activity comparable to that of rosmarinic acid. Cichoric acid was found to have a stoichiometric factor of 4.0 in scavenging DPPH and to react in a second-order reaction with DPPH with a rate constant of 40 l/mol/s at 25 °C in methanol.     

Antioxidant and cytotoxic flavonoids from the flowers of Melastoma malabathricum L.

Phytochemical and bioactivity studies of the flowers of Melastoma malabathricum L. (Melastomataceae) have been carried out. The ethyl acetate extract yielded three compounds, identified as naringenin, kaempferol and kaempferol-3-O-d-glucoside, and methanol extract gave kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl)glucoside and kaempferol-3-O-d-glucoside. The crude extracts and isolated compounds were screened for their antioxidant and cytotoxic activities. The antioxidant assay was carried out by the DPPH radical-scavenging electron spin resonance (ESR) spectroscopic method. The cytotoxicity was measured by the MTT assay against a MCF7 cell line. Naringenin, kaempferol, kaempferol-3-O-d-glucoside, kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl) glucoside, ethyl acetate and methanol extracts were found to be active as radical-scavengers with IC₅₀ values of 0.52 mM, 81.5 μM, 1.07 mM, 35.8 μM, 7.21 μg/ml and 6.59 μg/ml, respectively. Naringenin and kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl)glucoside were also found to be active in inhibiting cell proliferation of MCF7 with IC₅₀ values of 0.28 μM and 1.3 μM, respectively.     

Antioxidant and antibacterial activities of Nephelium lappaceum L. extracts

Ether, methanolic and aqueous extracts of lyophilized rambutan (Nephelium lappaceum L.) peels and seeds were evaluated for phenolic contents, antioxidant and antibacterial activities. High amounts of phenolic compounds were found in the peel extracts and the highest content was in the methanolic fraction (542.2 mg/g dry extract). Several potential antioxidant activities, including reducing power, β-carotene bleaching, linoleic peroxidation and free radical scavenging activity, were evaluated. The peel extracts exhibited higher antioxidant activity than the seed extracts in all methods determined (P < 0.05). The methanolic fraction was found to be the most active antioxidant as shown by their 50% DPPH inhibition concentration, 4.94 μg/mL. The results indicated this fraction exhibited greater DPPH radical scavenging activity than BHT and ascorbic acid (0.32 g dry extract/g BHT or ascorbic acid). Antibacterial activity against eight bacterial strains was assessed by disc diffusion and broth macrodilution methods. All peel extracts exhibited antibacterial activity against five pathogenic bacteria. The most sensitive strain, Staphylococcus epidermidis, was inhibited by the methanolic extract (MIC 2.0 mg/mL).     

Antioxidant properties of Prangos ferulacea (L.) Lindl., Chaerophyllum macropodum Boiss. and Heracleum persicum Desf. from Apiaceae family used as food in Eastern Anatolia and their inhibitory effects on glutathione-S-transferase

Therapeutic effects of several medicinal plants and vegetables, which are commonly used as food and in folk medicine against many disease, are well known. Antioxidant capacities of Heracleum persicum Desf., Prangos ferulacea (L.) Lindl., Chaerophyllum macropodum Boiss. species from Apiaceae family were evaluated by determining their effects on DPPH radical scavenging, and lipid peroxidation inhibition, as well as their total phenolic contents. Potential natural glutathione-S-transferase inhibitors have gained great importance in the last decade especially because of the role of glutathione-S-transferases in developing resistance to chemotherapy. Selected plants were therefore further investigated for their influence on the activity of glutathione-S-transferase enzyme.     

Evaluation of the antioxidant activity of five endemic Ligustrum species leaves from Taiwan flora in vitro

Leaves from the plant species belonging to the genus Ligustrum are widely used as tea or herbal medicine in Europe, China, and Japan. The antioxidant properties of five Ligustrum species from Taiwan were compared using in vitro antioxidant methods such as DPPH radical scavenging, TEAC, and FRAP assays. Cell-based antioxidant methods were used, including Fe²⁺/ascorbate-induced lipid peroxidation on brain homogenate and AAPH-induced erythrocyte haemolysis. The amounts of major phenolic compounds from the Ligustrum species, including phenylpropanoids, flavonoids, and iridoids, were determined by spectrophotometric methods. The results showed that all Ligustrum species exhibited antioxidant, radical-scavenging, anti-haemolytic, and lipid peroxidation-inhibiting activities at different magnitudes of potency. A significant correlation was found between antioxidant activity and the amount of antioxidant components, in particular, total phenolics and phenylpropanoids. Among all Ligustrum species from Taiwan, Ligustrum morrisonense is presented as potential source of natural antioxidants.