Antioxidant properties of three extracts from Pleurotus citrinopileatus

Pleurotus citrinopileatus Sing. (Lentinaceae) was successfully cultivated and commercially available in Taiwan. The ethanolic, cold and hot water extracts were prepared from P. citrinopileatus fruit bodies, mycelia and fermentation filtrate and their antioxidant properties studied. For three samples, ethanolic extracts exhibited higher antioxidant activities than water extracts. Reducing powers of three extracts from fruit bodies were effective and 1.03-1.10 at 5 mg/ml. With regard to EC₅₀ values of scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals, the effectiveness was in a descending order: ethanolic>hot water>cold water extracts. Scavenging abilities of water extracts from three samples on hydroxyl radicals were 53.4-80.1% at 20 mg/ml. Chelating abilities of cold and hot water extracts on ferrous ions were higher than those of ethanolic extracts. Contents of total phenols were in the descending order: fruit bodies (8.62-12.38 mg/g)>mycelia (5.84-7.85 mg/g)>filtrate (4.80-5.57 mg/g). Overall, three extracts from fruit bodies were more effective in antioxidant properties assayed than those from mycelia and filtrate. Ethanolic extracts were more effective in antioxidant properties assayed, except for scavenging abilities on hydroxyl radicals.     

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 properties of methanolic extracts from Agrocybe cylindracea

Agrocybe cylindracea (DC: Fr.) Mre. (Bolbitiaceae) was available in the form of fruit bodies, mycelia and fermentation filtrate. From these three forms, methanolic extracts were prepared and their antioxidant properties studied. The methanolic extract from fruit bodies showed high inhibitory ability on lipid oxidation (90.0-97.3%) at 5-20 mg/ml and had an EC₅₀ value of 0.94 mg extract/ml. EC₅₀ values in reducing power were 2.36, 6.89 and 5.00 mg extract/ml for fruit bodies, mycelia and filtrate, respectively. The scavenging ability of the methanolic extract from fruit bodies on 1,1-diphenyl-2-picrylhydrazyl radicals was 89.0% at 1 mg/ml whereas those from mycelia and filtrate was 91.4% and 94.9% at 10 mg/ml, respectively. The chelating abilities of methanolic extracts from fruit bodies, mycelia and filtrate on ferrous ions were 90.6%, 84.6% and 96.3% at 5 mg/ml, respectively. Total phenols were the major detected naturally occurring antioxidant components found in methanolic extracts from A. cylindracea and in the range of 15.55-23.47 mg/g. Based on EC₅₀ values, A. cylindracea was good in antioxidant properties, except for the scavenging ability on hydroxyl radicals.     

Antioxidant properties of aqueous extracts from Terminalia catappa leaves

Aqueous extracts were prepared from green, yellow fallen and red fallen leaves of Terminalia catappa L. (Combretaceae) and their antioxidant activity, scavenging and chelating abilities were evaluated. Aqueous extracts from three different leaves showed high antioxidant activities and moderate scavenging abilities on hydroxyl radicals at 1 mg/ml. EC₅₀ values in antioxidant activity were 0.549-0.557 mg/ml whereas those in scavenging ability on hydroxyl radicals were 0.631-0.686 mg/ml for aqueous extracts prepared from three leaves with boiling water for 3 min. EC50 values in reducing power were 0.15-0.23 mg/ml. EC50 values in scavenging abilities on superoxide anion and 1,1-diphenyl-2-picrylhydryl radicals were 0.36-0.44 and 10.4-35.3 mg/ml, respectively. EC50 values in chelating abilities on ferrous and cupric ions were 0.41-2.50 and 8.96-9.89 mg/ml, respectively. Based on the results obtained, the aqueous extracts displayed higher antioxidant properties. Six phenolic compounds identified in the aqueous were p-hydroxybenzoic acid, 4-hydroxyphenylpropionic acid, m-coumaric acid, 3,4-dihydroxybenzoic acid, p-coumaric acid and gallic acid. Therefore, the aqueous extracts from three different leaves of T. catappa might be a potential antioxidant supplement for application in food products or as a drink.     

Antioxidant properties of polysaccharides from Ganoderma tsugae

Ganoderma tsugae Murrill (Ganodermataceae) were available in the form of mature and baby Ling chih, mycelia and fermentation filtrate. From these four forms, hot water extracted and hot alkali extracted polysaccharides were prepared and their antioxidant properties were studied. Polysaccharides showed good antioxidant activity as evidenced by their particularly low EC₅₀ values (<0.1 mg/ml). At 20 mg/ml, both extracted polysaccharides from mycelia showed reducing powers of 0.41–0.52 whereas reducing powers of other polysaccharides were in the range of 0.87 to 1.14. At 20 mg/ml, scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals increased to 93.7–100%, except for that of the hot water extracted polysaccharide, from filtrate, being 74.9%. At 20 mg/ml, scavenging abilities of both extracted polysaccharides from mycelia on hydroxyl radicals were 13.9 and 24.4%, respectively whereas scavenging abilities of the other polysaccharides were in the range of 39.0–55.2%. At 10 mg/ml, the chelating abilities of polysaccharides from mature and baby Ling chih, mycelia and filtrate were 93.9–100%, 97.6–100%, 85.1–88.0% and 51.2%, respectively. Overall, both extracts of polysaccharides possessed good antioxidant properties except for scavenging ability on hydroxyl radicals and can be developed as a new dietary supplement and functional food.     

Antioxidant properties of methanolic extracts from Agaricus blazei with various doses of γ-irradiation

Agaricus blazei Murrill (Agariaceae) was irradiated with gamma rays at doses of 2.5, 5, 10, 15 and 20 kGy and the antioxidant properties of its methanolic extracts were studied. At 7.5 and 10.0 mg/ml, antioxidant activities of methanolic extracts from 2.5 to 20 kGy γ-irradiated A. blazei were significantly higher than those of methanolic extract from the nonirradiated control. At 0.5-7.5 mg/ml, reducing powers of methanolic extracts from A. blazei with 2.5, 10, 15 and 20 kGy of irradiation and without irradiation were comparable. All methanolic extracts showed excellent scavenging abilities of 95.2-100.7% against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals at 0.5 mg/ml. With regard to the scavenging ability against hydroxyl radicals, unirradiated and γ-irradiated A. blazei were comparable. Total phenols were the major naturally occurring antioxidant components found in the range of 18.77-21.48 mg/g. All EC₅₀ values were below 10 mg/ml, except values in reducing power, scavenging ability against DPPH radicals and chelating ability against ferrous ions were below 1 mg/ml. That indicates the unirradiated and irradiated A. blazei were good in antioxidant properties. Summarily, up to 20 kGy of irradiation did not remarkably affect the amounts of total antioxidant components in A. blazei.     

Flavour components and antioxidant properties of several cultivated mushrooms

Three mushrooms, Clitocybe maxima, Pleurotus ferulae and Pleurotus ostreatus grey strain were used to study their flavour components and antioxidant properties. The volatile flavour components found comprised of six eight-membered carbon compounds and two aromatic compounds. The content total of soluble sugars and polyols was 125–270 mg/g. The content of monosodium glutamate-like components was 1.76–8.89 mg/g. The contents of flavour 5′-nucleotides ranged from 1.89 to 7.59 mg/g. Based on the results obtained, three mushrooms possessed highly intense umami taste. Ethanolic extracts were more effective in the inhibition of conjugated diene and scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals, whereas hot water extracts were more effective in the scavenging ability of hydroxyl radicals. EC₅₀ values were less than 14 and 30 mg/ml for ethanolic and hot water extracts, respectively, indicating that the three mushrooms were relatively effective as they exhibited antioxidant properties, despite having scavenging abilities for hydroxyl radicals. Phenols were the major antioxidant components and the total contents were 5.10–11.1 mg gallic acid equivalents/g.     

Antioxidant properties of methanolic extracts from Antrodia camphorata with various doses of γ-irradiation

The mycelia of Antrodia camphorata (Chang & Chou) Wu, Ryvarden & Chang were irradiated with gamma rays at doses of 2.5, 5, 10, 15 and 20 kGy and the antioxidant properties of the methanolic extracts were studied. At 2.5 mg/ml, antioxidant activities of methanolic extracts from 10 to 20 kGy-irradiated mycelia were significantly higher than those of the non-irradiated control. Reducing powers of methanolic extracts from unirradiated and 0.5–7.5 kGy-irradiated mycelia were comparable except for the 20 kGy-irradiated mycelia. At 2.5 mg/ml, all methanolic extracts showed excellent scavenging abilities of 92.3–103% on DPPH radicals. Scavenging abilities of methanolic extracts from 2.5 to 20 kGy irradiated mycelia were better than that of the unirradiated control at 10 mg/ml. With irradiation at 5–20 kGy, mycelia possessed higher chelating ability on ferrous ions than did the unirradiated control. The EC₅₀ values were below 15 mg/ml, except for values of scavenging ability of the unirradiated control on hydroxyl radicals. Total phenols were the major naturally occurring antioxidant components found in the range of 13.0–15.5 mg/g. In summary, γ-irradiation not only maintained the antioxidant properties of mycelia but also enhanced the antioxidant properties to some extent.     

Antioxidant properties of hot water extracts from Agrocybe cylindracea

Agrocybe cylindracea (DC: Fr.) Mre. was available in the form of fruit bodies, mycelia and fermentation filtrate. From these three forms, hot-water extracts were prepared and their antioxidant properties were studied. Antioxidant activities of hot-water extracts from fruit bodies, mycelia and filtrate were 63.6%, 81.6% and 56.8% at 20 mg ml⁻¹, respectively. EC₅₀ values in reducing power were 2.72, 3.97 and 3.09 mg ml⁻¹ whereas those in scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl radicals were 0.62, 1.66 and 0.82 mg ml⁻¹ for fruit bodies, mycelia and filtrate, respectively. At 20 mg ml⁻¹, the scavenging abilities of hydroxyl radicals were 80.1%, 57.0% and 54.3% for fruit bodies, mycelia and filtrate, respectively. With regard to EC₅₀ values in chelating abilities on ferrous ions, the hot-water extract from filtrate was better than that from mycelia. Total phenols were the major naturally occurring antioxidant components found in hot-water extracts and in the range of 23.74–30.16 mg g⁻¹. From EC₅₀ values obtained, it can be concluded that hot-water extracts from three forms of A. cylindracea were good in antioxidant properties.     

Antioxidant properties of solid-state fermented adlay and rice by Phellinus linteus

Phellinus linteus (Berkeley & Curtis) Teng (Hymenochaetaceae) was inoculated into cooked grains, and new products were formed after the colonisation of fungal mycelia. Our objective was to evaluate the antioxidant properties of ethanolic and hot water extracts from fermented products [Phellinus-fermented adlay (PFA) and rice (PFR)] as compared to uninoculated controls [polished adlay (PA) and rice (PR)]. PFA and PFR were more effective than were PA and PR in antioxidant activity by the conjugated diene method, reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions. Total phenols were the major antioxidant components found in both extracts (1.31–9.10 mg/g). Flavonoid contents were in the range of 0.07–1.26 mg/g. Total phenols and flavonoids of two extracts were associated with antioxidant properties. Based on the results obtained, Phellinus-fermented products possessed effective antioxidant properties.     

A comparative study of tocopherols composition and antioxidant properties of in vivo and in vitro ectomycorrhizal fungi

In aerobic organisms, the free radicals are constantly being produced during the normal cellular metabolism. The antioxidant properties of many organisms and particularly of wild mushrooms with their content in antioxidant compounds such as tocopherols, can detoxify potentially damaging forms of activated oxygen. Herein, a comparative study of tocopherols composition and antioxidant properties of in vivo (fruiting bodies) and in vitro (mycelia) ectomycorrhizal fungi: Paxillus involutus and Pisolithus arhizus. Tocopherols were determined by high performance liquid chromatography (HPLC) coupled to a fluorescence detector. The antioxidant properties were studied in terms of DPPH radical-scavenging activity, reducing power and inhibition of β-carotene bleaching. Fruiting bodies revealed the highest antioxidant properties, including scavenging effects on free radicals (EC₅₀ = 0.61 and 0.56 mg/ml) and inhibition of lipid peroxidation capacity (EC₅₀ = 0.40 and 0.24 mg/ml for P. involutus and P. arhizus, respectively), than mycelia produced in vitro cultures. Nevertheless, mycelia revealed higher levels of total tocopherols than fruiting bodies, and particularly P. arhizus mycelium proved to be a powerful source of γ-tocopherol (154.39 μg/g dry weight).     

Antioxidant properties of fungal chitosan from shiitake stipes

Fungal chitosan B or C was prepared by alkaline N-deacetylation of crude chitin B or C for 60, 90 and 120 min, which was obtained from air-dried shiitake stipes and its antioxidant properties studied. Chitosan showed antioxidant activities of 61.6-82.4% at 1 mg/ml and showed reducing powers of 0.42-0.57 at 10 mg/ml. At 10 mg/ml, scavenging abilities of chitosan B60 and C60 on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were 28.4-31.3% whereas those of chitosan B90, B120, C90 and C120 were 44.5-53.5%. With regard to the scavenging ability on hydroxyl radicals at 0.1 mg/ml, chitosan B60 and C60 were 61.9% and 63.6%, chitosan B90 and C90 were 68.3% and 69.9% and chitosan B120 and C120 were 77.7% and 77.2%, respectively. At 1.0 mg/ml, chelating abilities of chitosan B60 and C60 on ferrous ions were 88.7-90.3% whereas those of the rest chitosan were 97.8-103%. EC₅₀ values of antioxidant activity were below 1 mg/ml whereas those of reducing powers and scavenging abilities on DPPH radicals were 7.69-16.3 mg/ml. EC₅₀ values of scavenging abilities on hydroxyl radicals were below 0.1 mg/ml whereas those of chelating abilities on ferrous ions were 0.58-0.69 mg/ml.     

Effect of different brewing methods on antioxidant properties of steaming green tea

The extracts were prepared from cold or hot brewed steaming green tea at different concentrations (2, 6, and 10%), its antioxidant properties studied and potential antioxidant components determined. The yields of hot water extracts (17.49–28.27%) were significantly higher than those of cold water extracts (11.72–14.70%). EC₅₀ values in antioxidant activity determined by the conjugated diene method and reducing power were 2.19–3.10 and 0.22–0.28 mg/ml, respectively. EC₅₀ values in scavenging ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals were 29.45–43.80 and 2.88–3.22 mg/ml, respectively. EC₅₀ values in chelating ability on ferrous ions were 6.45–13.51 mg/ml. Contents of total phenols were 221.71–330.22 mg/g whereas those of total catechins in cold and hot water extracts were 135.05–193.14 and 161.57–195.05 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity and reducing power. However, cold water extracts were more effective in scavenging ability on DPPH and hydroxyl radicals, and chelating ability on ferrous ions. Summarily, the cold brewing method would be a new alternative way to make a tea.     

Non-volatile taste components of Agaricus blazei, Agrocybe cylindracea and Boletus edulis

Three species of dried mushrooms are commercially available in Taiwan, namely Agaricus blazei (Brazilian mushroom), Agrocybe cylindracea (black popular mushroom) and Boletus edulis (king bolete), and their non-volatile taste components were studied. All mushrooms were high in contents of carbohydrate, crude fiber and protein but low in contents of crude ash and fat. Arabitol, myo-inositol, mannitol and trehalose were detected in these three mushrooms, whereas glucose was not found in B. edulis. Contents of total soluble sugars and polyols ranged from 150.33 to 225.08 mg/g. Total free amino acid contents were low in these three mushrooms and ranged from 8.97 to 14.91 mg/g. The contents of MSG-like components ranged from 1.24 to 4.40 mg/g were in the descending order of the A. blazei, A. cylindracea and B. edulis. Total 5′-nucleotides contents of A. blazei and A. cylindracea were higher than that of B. edulis whereas flavor 5′-nucleotides content of A. blazei was higher than those of A. cylindracea and B. edulis. Equivalent umami concentrations values in three mushrooms ranged from 10.46 to 135.90 g per 100 g. Overall, these three mushrooms possessed highly umami taste.     

Determination of antioxidant activities of various extracts and essential oil compositions of Thymus praecox subsp. skorpilii var. skorpilii

The aim of this work is to examine the chemical composition and antioxidant activity of separated essential oils and different solvent extracts of Thymus praecox subsp. skorpilii var. skorpilii (TPS). The ethanol, acetone, methanol, hexane, aqueous extracts and separated essential oils of TPS were assessed for their antioxidant activities. Antioxidant activities were evaluated by reduction of Mo(VI) to Mo(V), reducing power, superoxide scavenging activity, free radical-scavenging activity, metal chelating activity, linoleic acid peroxidation, hydrogen peroxide scavenging activity and peroxide scavenging activity. Essential oils were characterized in total to be 41 components, whereas 9 components were isolated by column chromatography for antioxidant activity. TPS essential oil was found to contain thymol (40.31%) and o-cymene (13.66%) as the major components. The ethanol, methanol and water extracts exerted significant free radical-scavenging activity. The methanol and water extracts displayed highest superoxide scavenging activity. The water extract has the highest total phenolics (6.211 mg gallic acid (GAE)/g DW) and flavonoids (0.809 mg quercetin/g DW).     

Antioxidant activity and proline content of leaf extracts from Dorystoechas hastata

Dorystoechas hastata (D. hastata) is a monotypic plant endemic to Antalya province of Turkey. D. hastata leaves are used to make a tea locally called “çalba tea”. Diethyl ether (E), ethanol (A), and water (W) were used for the sequential preparation of extracts from dried D. hastata leaves. A hot water extract (S) was also prepared by directly boiling the powdered plant in water. The antioxidant activities of the extracts were tested by ferric thiocyanate (FTC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging methods. E extract exhibited the greatest antioxidant activity with FTC method, whereas S extract exhibited the lowest IC₅₀ value (6.17 ± 0.53 μg/ml) for DPPH radical scavenging activity. Total phenolic contents of the extracts were estimated by Folin–Ciocalteu method and S extract was found to contain the highest amount (554.17 ± 20.83 mg GAE/g extract) of phenolics. Extract A contained highest flavonoid content and there was a inverse linear correlation (R² = 0.926) between IC₅₀ values for DPPH radical scavenging activity and flavonoid contents of all extracts. Reducing power of extracts increased in a concentration-dependent manner. S extract was found to possess higher reducing power than equivalent amount of ascorbic acid at 20 and 25 μg/ml concentrations. Linear correlation between reducing power and concentration of E, A, and W extracts (R² > 0.95) was observed. A, W, and S extracts contained relatively high levels of proline. The results presented suggest that D. hastata may provide a natural source of antioxidants and proline.     

Determination of antioxidative potential of lichen Usnea ghattensis in vitro

The study was aimed at evaluating the antioxidant activities of extract of Usnea ghattensis. The antioxidant activity, reducing power, superoxide anion radical scavenging and free radical scavenging activities were studied. The antioxidant activity increased with the increasing amount of extracts (2-20 mg/ml) added to the linoleic acid emulsion. Lipid peroxidation upto 73.3% was inhibited by the extract of 20 mg/ml and 39.2% by α-tocopherol at the same concentration. These effects were statistically significant (r²=0.876,P<0.01) when compared with control. However, the extract had no significant effect on superoxide anion scavenging by the PMS/NADH-NBT method. Like antioxidant activity, the reducing power and free radical scavenging activity of extract depends on concentration and increasing with increased amount of sample. The reducing power and DPPH radical-scavenging activity of U. ghattensis extract were found greater than the BHA and BHT. The results obtained in the present study indicate that U. ghattensis is a potential source of natural antioxidant.     

The in vitro and in vivo antioxidant properties of seabuckthorn (Hippophae rhamnoides L.) seed oil

The antioxidant capacity of seabuckthorn (Hippophae rhamnoides L.) seed oil was investigated with a number of established in vitro assays and in an in vivo study of carbon tetrachloride (CCl₄)-induced oxidative stress in mice. The results showed that DPPH radical scavenging activity, ferrous ion chelating activity, reducing power and inhibition of lipid peroxidation activity all increased with increasing concentrations of seabuckthorn seed oil. Moreover, the EC₅₀ values of seabuckthorn seed oil from the hydrogen peroxide, superoxide radical, hydroxyl radical scavenging assays were 2.63, 2.16 and 0.77 mg/ml, respectively. In the in vivo study, seabuckthorn seed oil inhibited the toxicity of CCl₄, as seen from the significantly increased activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. The GSH content in the liver was also increased, whereas hepatic malondialdehyde was reduced. Taken together, these results clearly indicate that seabuckthorn seed oil has significant potential as a natural antioxidant agent.     

Antioxidant and radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.