Antioxidant properties of methanolic extracts from monascal rice

Fungus Monascus (Monascaceae) possesses functional components effective in improving human health. The fungus was inoculated into rice and a traditional product (Monascus-fermented rice, anka, red koji) was produced after the colonization of fungal mycelia. Our objective was to evaluate the antioxidant properties of methanolic extracts from inoculated rice products [monascal polished rice (MPR) and monascal dehulled rice (MDR)] as compared to uninoculated rice products [polished rice (PR) and dehulled rice (DR)]. With regard to EC₅₀ values (mg extract/ml) of methanolic extracts, inhibitions of peroxidation were excellent and in the descending order of PR>DR>MDR>MPR. Effectiveness in reducing powers was in the descending order of MPR?MDR?DR>PR. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were in the descending order of MPR>MDR>PR∼DR. Chelating abilities on ferrous ions were in the descending order of MPR∼MDR>PR>DR. Total phenols were the major naturally occurring antioxidant components found. Overall, monascal rice products were better in reducing power, scavenging and chelating abilities and higher in total phenol content than uninoculated rice products.     

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.     

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 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.     

Effects of genotype and treatment on the antioxidant activity of sweet potato in Taiwan

Six genotypes of sweet potato commercially available in Taiwan, including TNG57, TNG66, TNG68, TYY1, RP and WP, were used as samples in this study of the effects of steaming and kneading with pre-steaming treatments on the antioxidant components and antioxidant properties of methanolic extracts. Steam treatment increased the total phenols contents of all genotypes (2–13 times), flavonoids content of RP (1.3 times) and anthocyanins contents of RP and WP (5–6 times). Steam treatment also increased the reducing power and scavenging DPPH radical effect of sweet potato flours. For the methanolic extracts of steamed and kneaded flours, reducing powers were 0.02–1.70 at 5.0 mg ml⁻¹ and the scavenging effects on DPPH radicals were 19–92% at 2.5 mg ml⁻¹. Both showed the order of RP > WP > TYY1 and TNG66 > TNG57 and TNG68. However, the chelating effect of the six genotypes at 1.0 mg ml⁻¹ ranged from 50% to 73%. Contents of total phenols, flavonoids, and anthocyanins of sweet potato flours were significantly positively correlated with the reducing power and scavenging DPPH radical effects. After steaming and kneading treatments, RP showed the highest increase in the contents of total phenols, flavonoids and anthocyanins among the six genotypes studied.     

Nonvolatile taste components 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 fungal fermentation and their nonvolatile taste components were studied. Contents of ash, fat, fiber, and protein in inoculated products [Phellinus-fermented adlay (PFA) and rice (PFR)] were much higher than those in uninoculated controls [polished adlay (PA) and rice (PR)]. Contents of total soluble sugars and polyols were in the descending order: PFA > PFR > PA > PR. Contents of total free amino acids and total and flavor 5′-nucleotides in PFA and PFR were much higher than those in PA and PR. Equivalent umami concentrations in PFA and PFR (917.17 and 222.96 g monosodium glutamate (MSG)/100 g, respectively) were higher than those in PA and PR (4.88 and 0.32 g MSG/100 g, respectively). Evidently, Phellinus-fermented products possessed high level of umami taste.     

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 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 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 potential of solvent extracts of Kappaphycus alvarezii (Doty) Doty – An edible seaweed

Various solvent extracts of Kappaphycus alvarezii, an edible red seaweed (family Solieriaceae) were screened for total phenol content and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferrous ion chelating activity, reducing power and antioxidant activity assays in a linoleic acid system with ferrothiocyanate reagent (FTC). The total phenol content of different extracts of K. alvarezii varied from 0.683 ± 0.040% to 2.05 ± 0.038%. The radical-scavenging activity of ethanol extract was, as IC₅₀ 3.03 mg ml⁻¹, whereas that of the water extract was IC₅₀ 4.76 mg ml⁻¹. Good chelating activity was recorded for methanol extract (IC₅₀ 3.08 mg ml⁻¹) wherein 67.0 ± 0.924% chelation was obtained using 5.0 mg ml⁻¹ of extract. The reducing power of the samples was in the following order: BHT > methanol > ethanol > ethyl acetate > water > hexane. But, in the linoleic acid system, the ethanol extract proved superior to the synthetic antioxidants butylated hydroxytoluene (BHT). Hence, these extracts could be considered as natural antioxidants and may be useful for curing diseases arising from oxidative deterioration.     

The application of monascal rice in rice beverage preparation

To investigate the effect of antioxidant activity of monascal rice, we used monascal rice only, a mixture of monascal rice and rice, and rice only in the rice beverage production. Reducing sugar and carbohydrate (glucose, maltose, and maltotriose) contents increased with reaction time. When using rice only, there was a higher reducing sugar content than with the use of monascal rice. After 6 h, the reducing sugar content of the rice beverage produced using only rice was 69.8 mg/mL. After 6 h, the maltose contents produced using monascal rice only, a mixture of monascal rice and rice, and rice only were 64.5, 92.9, and 113.9 mg/mL, respectively. After 6 h, the total phenolic contents of the beverages produced with monascal rice only, a mixture of monascal rice and rice, and rice only were 113.9, 92.9, and 69.7 μg/mL, respectively. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities increased linearly up to 4 h of hydrolysis, and then increased slightly beyond that. After 6 h, the IC₅₀ and ascorbic acid equivalent antioxidant activity (AEAC) values of the beverages produced from monascal rice only, a mixture of monascal rice and rice, and rice only were 60.9, 100.6, and 164.4 μg, and 31.5 , 31.2, and 25.7 mg/100 g, respectively. In conclusion, the rice beverage prepared from monascal rice might be somewhat beneficial to the antioxidant protection system of the human body and help protect against oxidative damage.     

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.     

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 activity of methanolic extracts from some grains consumed in Korea

The objectives of this study were to determine antioxidant activity of the methanolic extracts from some grains and to investigate relationships between antioxidant activities and antioxidant contents in the extracts. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation scavenging activities, inhibitory effect on lipid peroxidation, chelating activity and reducing power have been used to investigate the relative antioxidant activities of the extracts from grains. The concentrations of total polyphenolics and carotenoids in the extracts were measured by spectrophotometric methods and vitamin E analysis was carried out by HPLC. The methanolic extracts prepared from red sorghum and black rice showed significantly higher antioxidant activities and contained higher polyphenolic contents than other grains such as white rice, brown rice, mungbean, foxtail millet, prosomillet, barley, and adlay. Polyphenolic compounds were the major naturally occurring antioxidants in grains. The correlation coefficient between total polyphenolic content and ABTS radical cation scavenging activity in the extracts was >0.99. However, no relationship was found between antioxidant activities and carotenoids and vitamin E derivatives.     

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.     

Content of antioxidant hydroquinones substituted by β-1,6-linked oligosaccharides in wheat milled fractions,flours and breads

The objective of this study was to quantify seven antioxidant hydroquinones, substituted by β-1,6-linked oligosaccharides, in wheat-based food products by HPLC. These novel compounds were discovered and characterised in our previous study. All seven compounds were quantified in wheat germ and bran. The most abundant compound, 4-hydroxy-3-methoxyphenyl β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranoside, was present at 6.3 g/kg in germ and 0.7 g/kg in bran. In whole-wheat grains, as well as in several kinds of wheat flour and wheat bread, these antioxidants were present at much lower concentrations; only two of them could be quantified. None of these compounds were detected in low-protein flour mixture. Their total content in analysed wheat products decreased in the following order: germ > bran > whole grains ∼ whole grain flours > refined flours > refined bread ? low-protein flour mixture. It correlated well with the antioxidant capacity of water–ethanol extracts of these products determined by Trolox equivalent antioxidant capacity (TEAC) assay (r² = 0.984). The contribution of the analysed compounds to the total antioxidant capacity of wheat germ extract was 52%, whereas the contribution of the most abundant compound was 38%.     

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.     

Evaluation of antioxidant ability of ethanolic extract from dill (Anethum graveolens L.) flower

Antioxidant activities of ethanolic extract from dill flower and its various fractions were evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging, Trolox equivalent antioxidant capacity, reducing power, chelating power, and β-carotene bleaching assays. The flower extract was successively separated into n-hexane, ethyl acetate and ethanol soluble fractions by liquid–liquid partition. Dill leaf and seed extracts were used for comparison. In all assays, the flower extract showed higher antioxidant activity than the leaf and seed extracts. With regard to various fractions of the flower extract, the sequence for antioxidant activity was ethyl acetate fraction > ethanol fraction > original flower extract > n-hexane fraction. Phenols including flavonoids and proanthocyanidins should be responsible for antioxidant abilities of the flower extract. Chlorogenic acid, myricetin, and 3,3’,4′,5,7-pentahydoxyflavan (4 → 8)-3,3′,4′,5,7-pentahydoxyflavan were the major phenolic acid, flavonoid, and proanthocyanidin, respectively, in the dill flower extract.     

Enhancement of antioxidant activity of monascal waxy corn by a 2‐step fermentation

A 2‐step fermentation process was developed to enhance antioxidant activity of monascal waxy corn, fermented by Monascus purpureus TISTR 3090, compared with the conventional method. The results showed that, after 8 days of fermentation, monacolin K content and pigment intensity of monascal waxy corn from 2‐step fermentation were 62.89 mg kg^?1 dry weight and 3072.70 unit g^?1 dry weight, respectively, higher than those of the conventional method, while the residual reducing sugars were exhausted, giving the observed highest growth. The IC₅₀ values of DPPH, ferric reducing/antioxidant powder (FRAP) and chelating ability on Fe²⁺ assays of the 2‐step fermentation were about 50% less than those of the conventional method. A significantly positive correlation was found between pigment intensity and monacolin K content, while significantly negative correlations were found among monacolin K content, IC₅₀ of FRAP and chelating ability on Fe²⁺. An ideal negative correlation between pigment intensity and chelating ability on Fe²⁺ was found.     

Evaluation of the antioxidant activity of Ruellia tuberosa

The antioxidant activity of Ruellia tuberosa L. (Acanthaceae) was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay and the hydrogen peroxide-induced luminol chemiluminescence assay. The methanolic extract (ME) and its four fractions of water (WtF), ethyl acetate (EaF), chloroform (CfF), and n-hexane (HxF) were prepared and then subjected to antioxidant evaluation. The results of both methods revealed that R. tuberosa possesses potent antioxidant activity. The antioxidant activities of the different fractions tested decreased in the order of EaF > CfF > ME > WtF > HxF according to the hydrogen peroxide-induced luminol chemiluminescence assay, and results were the same with the exception of the rank order of HxF and WtF according to the DPPH free radical-scavenging assay. The results provide useful information on the pharmacological activities associated with free radicals of this traditional folk remedy.