Antioxidant activity of Rhizoma Smilacis Glabrae extracts and its key constituent-astilbin

Rhizoma Smilacis Glabrae is widely consumed by Chinese as functional food and in folk medicine for its medicinal properties. In this study, methanol and water extracts of Rhizoma Smilacis Glabrae were prepared. The water extract was further divided into polysaccharide and supernatant fractions. Constituents in different extracts were analysed by capillary electrophoresis, and levels of total phenolics were also determined using the Folin-Ciocalteu method. Astilbin, the main constituent in the herb, was isolated and purified. Different antioxidant tests were employed to evaluate the antioxidant activities of the extracts and the isolated astilbin, and the results were compared with two commonly used synthetic antioxidants-butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Methanol, water extract and supernatant fraction showed concentration dependent antioxidant activity while polysaccharide didn’t show any antioxidant activity. Purified astilbin showed the strongest antioxidant activity in comparison to any other extracts.     

决明子提取物的体外抗氧化实验研究

以决明子为原料，分别用乙酸乙酯、正丁醇和水制备粗提取物。利用自由基清除、还原力和抑制低密度脂蛋白氧化实验，对不同溶剂提取物的体外抗氧化特性进行研究。     

Antioxidant and free radical scavenging activities of polyphenol-enriched curry leaf (Murraya koenigii L.) extracts

The in vitro antioxidant properties of different extracts (water, alcohol, alcohol:water, hexane or chloroform extract) of curry leaves (Murraya koenigii L.) were evaluated using various assays. The alcohol:water (1:1) extract of curry leaves (AWEC) showed the highest antioxidant and free radical scavenging activity. It inhibited membrane lipid peroxidation by 76%, at 50 μg/ml, scavenged 93% of superoxides at 200 μg/3 ml and scavenged approximately 90% of hydroxyl and 1,1-diphenyl-2-picrylhydrazayl radicals at 4–5-fold lower concentrations compared to the other tested extracts. In addition, the alcohol:water extract reduced cytochrome c and ferric ion levels, chelated ferrous ions and inhibited ferrous sulfate:ascorbate-induced fragmentation and sugar oxidation of DNA. These results establish the antioxidant potential of AWEC, which could be used as natural antioxidant source.     

Antioxidant activity of anthraquinones and anthrone

The antioxidant properties of anthraquinones (AQs) and anthrone were evaluated using different model systems. The antioxidant activity of these compounds (200 ppm) on the inhibition of peroxidation of linoleic acid was found to be in the order of BHA (96%), anthrone (95%), alizarin (93%)>aloe-emodin (78%)>rhein (71%)>emodin (36%)>anthraquinone (8%). Chrysophanol accelerated the peroxidation of linoleic acid. Anthrone and alizarin exhibited a reducing power, although the other AQs did not show any reducing power. AQs and anthrone exhibited a weak chelating ability on iron (II). At a concentration of 0.25 mg/ml, the scavenging effects of anthrone, aloe-emodin and emodin, on hydroxyl radicals produced by the Fenton reaction were 26.2, 16.6 and 41.8%, respectively. However, at the same concentration, anthraquinone, alizarin, chrysophanol and rhein accelerated the production of hydroxyl radicals. These results suggest that the antioxidant mechanism, for both emodin and aloe-emodin, possibly depends on scavenging hydroxyl radicals. The strong activity shown by anthrone could be due to its reducing power and scavenging effects on hydroxyl radicals. The pro-oxidant activity exhibited by chrysophanol might be due to the enhanced production of free radicals.     

Antioxidant activity of the extracts from Dillenia indica fruits

There has been growing interest in the beneficial health effects of consuming fruits and vegetables. Mainly, the presence of phenolic antioxidants is believed to have the protective mechanisms. In the present study the fruit of Dillenia indica was extracted with ethyl acetate, methanol and water. The total phenolic content of the extracts was determined by Folin–Ciocalteu method and antioxidant activity of the extracts was assayed through some in vitro models such as antioxidant capacity by phosphomolybdenum method, β-carotene-linoleate model system, and radical scavenging activity using ,-diphenyl-β-picrylhydrazyl (DPPH) method. The total phenolic contents of the fruit extracts as tannic acid equivalents were found to be highest in methanol extract (34.1%) followed by ethyl acetate extract (9.3%) and water extract (1.4%). Antioxidant capacity of the extracts as equivalent to ascorbic acid (μmole/g of the extract) was in the order of methanol extract > ethyl acetate extract > water extract. In comparison with butylated hydroxyanisole (BHA), at 100 ppm of concentration, the antioxidant and free radical scavenging activities of the extracts assayed through β-carotene-linoleate model system, and DPPH method were also found to be highest with methanol extract followed by ethyl acetate and water extracts. The results indicated that the extent of antioxidant activity of the extract is in accordance with the amount of phenolics present in that extract and the fruit of D. indica is rich in phenolics may provide a good source of antioxidant.     

Antioxidant activity of peptides isolated from alfalfa leaf protein hydrolysate

Alfalfa leaf protein, a potential source of high quality protein for human consumption, was hydrolyzed with protease. Alfalfa leaf protein hydrolysate was fractionated by ultrafiltration and the obtained peptides were purified by dynamical adsorption. The antioxidant activity of alfalfa leaf peptides (ALPs) was investigated and compared with that of a native antioxidant, reduced glutathione (GSH), which was used as a reference. The reducing power of ALPs was 0.69 at 2.00 mg/mL. ALPs at 1.60 mg/mL and 0.90 mg/mL exhibited 79.71% and 67.00% of scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide radical, respectively. In addition, ALPs showed 65.15% chelating effect on ferrous ion at 0.50 mg/mL. The molecular weight of the peptides was determined and 67.86% of the total amount was below 1000 Da. Combined with the result of the amino acid profiles, ALPs was believed to have high nutritive value in addition to antioxidant activity.     

Antioxidant and free radical scavenging activity of an aqueous extract of Coleus aromaticus

The leaves of Coleus aromaticus Benth., (Lamiaceae), commonly called Indian Borage, are often eaten raw with bread and butter. The chopped leaves are also used as a substitute for sage (Salvia officinalis Linn.) in stuffing. In the present study, the antioxidant potency of freeze-dried aqueous extract of C. aromaticus was investigated, employing various established in vitro systems, such as the β-carotene-linoleate model system, 1,1-diphenyl-2-picrylhydrazyl (DPPH)/superoxide/nitric oxide radical scavenging, reducing power, and iron ion chelating activity. Freeze-dried aqueous extract of C. aromaticus (CAE) showed notable inhibitory activity in the β-carotene-linoleate model system. Furthermore, CAE exhibited a moderate concentration-dependent inhibition of the DPPH radical. The multiple antioxidant activity of CAE was evident as it showed significant reducing power, superoxide scavenging ability, nitric oxide-scavenging activity and also ferrous ion chelating potency. The data obtained in the in vitro models clearly establish the antioxidant potency of freeze-dried extract of C. aromaticus.     

Antioxidant properties of methanolic extracts from monascal adlay

Both the fungus Monascus sp. and adlay possess functional components effective in improving human health. The fungus was inoculated into adlay and a new product was produced after the colonization of fungal mycelia. Our objective was to evaluate the antioxidant properties of methanolic extracts from inoculated products [monascal polished adlay (MPA) and monascal dehulled adlay (MDA)] as compared to uninoculated products [polished adlay (PA) and dehulled adlay (DA)]. With regard to EC₅₀ values (mg extract ml⁻¹) of methanolic extracts, antioxidant activities were excellent and in the descending order of MDA (0.05) ? MPA (0.75) > DA (0.83) ? PA (6.35). Effectiveness in reducing powers was in a descending order of MPA (0.78) > MDA (1.53) ? PA (13.24) ∼ DA (13.67 mg ml⁻¹). Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating abilities on ferrous ions were in the descending order of MPA > MDA > DA > PA. Total phenols were the major naturally occurring antioxidant components found. Overall, monascal adlay products displayed higher antioxidant activity, reducing power, scavenging and chelating abilities and higher in total phenol content than uninoculated adlay products.     

Antioxidant and pro-oxidant in vitro evaluation of water-soluble food-related botanical extracts

The total phenol content, antioxidant and pro-oxidant activities of deodourised, water-soluble aniseed, basil, caraway, cardamon, fennel, ginger, juniper, laurel and parsley extracts were estimated using a number of in vitro assays. The laurel and basil extracts contained the highest phenol content of 107.3 ± 1.3 GAE [mg gallic acid equivalents/g (dry wt.) extract] and 98.5 ± 1.4 GAE, respectively, whilst the ginger extract contained the lowest content at 14.9 ± 0.9 GAE. Juniper, laurel and basil extracts were consistently better than the other extracts in terms of iron(III) reducing activity, inhibition of β-carotene-linoleate thermal co-oxidation and N,N-dimethyl-p-phenylenediamine and hydroxyl radical scavenging assays. Potential pro-oxidant activities of the extracts were assessed using both DNA and bovine serum albumin (BSA) as substrates. None of the extracts were capable of stimulating hydroxyl-mediated DNA fragmentation; however, the extracts could be categorised in the protein oxidation assay as extracts with (i) no significant (p > 0.05) effect, (ii) a significant (p < 0.05) protective effect or (iii) a significant (p < 0.05) pro-oxidant effect. The extracts from juniper, laurel and basil had a pro-oxidative effect upon BSA at a dose of 2 mg/ml, as estimated from the degree of carbonylation measured.     

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.     

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 phenolic compounds from Smilax sebeana Miq.

Methanol extract and sub-fractions of Smilax sebeana rhizomes and roots were analyzed to evaluate the compounds involved in antioxidant activity. In all separated fractions of the different polarity solvents, ethyl acetate fraction showed the highest antioxidant activity and total phenolic content. This fraction was subjected to the sephadex LH-20 column and preparative HPLC for purification. Six phenolic compounds, chlorogenic acid (1), 4-formylphenol (2), epicatechin (3), cinchonain IIa (4), Ia (5) and Ib (6) were isolated and identified by spectroscopic analyses and further evaluated their potential antioxidant activities by DPPH and superoxide radical scavenging assays. Compared with synthetic antioxidant Trolox, except 4-formylphenol, the other isolated five compounds exhibited excellent antioxidant activities. This is the first report on the chemical constituents of S. sebeana which potentially involved in antioxidant activity. The results suggest that the ethyl acetate extract of S. sebeana might be used as a readily accessible source of natural antioxidant.     

Antioxidant activity and phenolic composition of sumac (Rhus coriaria L.) extracts

Antioxidant activity and phenolic compounds of sumac extracts were investigated. Sumac was extracted in methanol and subjected to solvent–solvent partitioning to yield two fractions as ethyl acetate and aqueous. Methanol extract was further fractioned over Sephadex LH-20 column. Antioxidant activity of extracts and fractions were screened using ferric thiocyanate and DPPH radical scavenging methods. Phenolic composition of active fraction(s) was determined by HPLC–MS systems. Those fractions which exhibited strong antioxidant activity were rich in anthocyanins and hydrolysable tannins. While gallic acid was the main phenolic acid in the extracts, anthocyanin fraction contained cyanidin, peonidin, pelargonidin, petunidin, and delphinidin glucosides and coumarates. Pentagalloyl glucose was abundant in the hydrolysable tannin fraction. Effective scavenging concentration (EC₅₀) on DPPH radical was 0.70 μg/mL both in ethyl acetate and tannin fractions, and 5.33 μg/mL in anthocyanin rich fraction. Same extracts and fractions showed moderate lipid peroxidation inhibition effect compared with the synthetic antioxidants. The findings demonstrate that sumac can be used as a natural antioxidant.     

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 activity of Gardenia jasminoides Ellis fruit extracts

The objective of this study was to characterise the antioxidant properties of both water and ethanol extracts from the fruit of Gardenia jasminoides Ellis (GJE). The IC₅₀ values for DPPH (1,1-diphenyl-2-picryl-hydrazyl), ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)diammonium salt], hydroxyl and superoxide radical-scavenging activities were 0.14, 0.21, 1.08 and 1.43 mg/ml for the water-based extract, and 0.36, 0.39, 1.56 and 1.99 mg/ml for the ethanol-based extract, respectively. The extracts also showed strong reducing power, nitrite-scavenging activity, inhibition of linoleic acid oxidation, superoxide dismutase-like (SOD-like) activity and catalase activity. However, the water extract had a higher antioxidant activity than the ethanol extract. In addition, the antioxidant activities were highly correlated with the observed phenolic and flavonoid contents. Therefore, our study strongly suggests that extracts derived from the fruit of Gardenia jasminoides could be an excellent source of antioxidants as dietary supplements.     

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 activities and total phenolic contents of various extracts from defatted wheat germ

Defatted wheat germ (DWG) is the main by-product of the wheat germ oil extraction process. Its nutritional value has well been accepted. In this study, the antioxidant properties of 30% ethanol, 50% ethanol, 70% ethanol, 100% ethanol, and aqueous extracts of DWG were measured using various in vitro assays. Among the DWGEs (DWG extracts) tested, the 70% ethanol extract showed the best DPPH radical scavenging power while the 100% ethanol extract showed the highest ABTS radical scavenging activity and reducing power. In addition, both the 70% ethanol extract and the 50% ethanol extract exhibited relatively higher antioxidant activity in linoleic acid system. The extracts in question exhibited total phenolic contents ranging from 13.98 to 16.75 mg GAE/g. DWG, as a source of natural antioxidants, can be used to formulate nutraceuticals with potential applications to reducing the level of oxidative stress. The antioxidant potency of the DWG extracts could be the basis for its health promoting potential.     

DPPH法测甘蔗提取物抗氧化活性研究

本研究对甘蔗制糖过程中的各种原料进行活性物质的提取，并用DPPH（二苯代苦味酰基自由基）法测定其抗氧化活性，同时探讨了pH、加热温度、加热时间对自由基清除率的影响。结果表明各种原料均具有较强的抗氧化活性；pH值对抗氧化活性影响很大，而加热时间温度对抗氧化活性无显著影响。初步推断该活性物质属酚类。     

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.