Antioxidant activity of Nyctanthes arbor-tristis leaf extract

Nyctanthes arbor-tristis (Harsingar) leaf extracts are extensively used in Indian traditional medicine. The acetone-soluble fraction of its ethyl acetate extract showed impressive antioxidant activity as revealed by several in vitro experiments, e.g., DPPH, hydroxyl and superoxide radicals, as well as H₂O₂ scavenging assays. Moreover, its preventive capacity against Fe(II)-induced lipid peroxidation of liposomes and γ-ray-induced DNA damage also confirmed this. The strong reducing power and high phenolics and flavonoids contents could be responsible for the antioxidant activity.     

Antioxidant activities of Sideritis congesta Davis et Huber-Morath and Sideritis arguta Boiss et Heldr: Identification of free flavonoids and cinnamic acid derivatives

Different solvent extracts of endemic Sideritis (Labiatae) species, Sideritis congesta Davis et Huber-Morath and Sideritis arguta Boiss et Heldr, were analyzed for free flavonoids (quercetin, apigenin, myricetin and kaempferol) and cinnamic acid derivatives (rosmarinic acid, ferulic acid, caffeic acid, p-coumaric acid and chlorogenic acid) using HPLC-DAD. All the phenolics were quantified in acid-hydrolyzed extracts, except rosmarinic acid, chlorogenic acid and myricetin which were quantified in raw samples. Antioxidant activities of extracts of these two plants and many of their components in pure form were evaluated based on DPPH^. and ABTS^.+ assays. In general, S. arguta extracts displayed higher antioxidant activity than S. congesta extracts possibly due to their richness in antioxidant components of strong activity. Acetone extract of S. arguta, with its strikingly high TEAC value of 3.2 mM trolox and low IC₅₀ value of 38.3 ??g/mL showed the highest antioxidant potency among all extracts. ??-tocopherol, the positive control, displayed IC₅₀ and TEAC values of 33.8 ??g/mL and 2.9 mM trolox, respectively. No direct correlation was found between antioxidant activities and total phenolic contents of the plant extracts studied.     

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.     

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.     

Profiling of in vitro neurobiological effects and phenolic acids of selected endemic Salvia species

The ethyl acetate and methanol extracts from 16 Salvia L. species were screened for their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, lipoxygenase, and tyrosinase; the enzymes linked to neurodegeneration. Their antioxidant activity was also tested using DPPH radical scavenging, metal-chelation, and ferric-reducing antioxidant power (FRAP) assays. Total flavonoid content of the extracts was determined by AlCl₃ reagent, while HPLC technique was applied for analysis of various phenolic acids in the extracts. The extracts exerted weak cholinesterase and tyrosinase inhibition, and remarkable inhibition against lipoxygenase (13.07 ± 2.73-74.21 ± 5.61%) at 100 μg ml⁻¹. The methanol extracts showed higher antioxidant activity in DPPH radical scavenging and FRAP assays. The extracts were analyzed for their gallic, protocateuchic, p-hydroxy-benzoic, vanillic, caffeic, chlorogenic, syringic, o- and p-coumaric, ferulic, rosmarinic, and tr-cinnamic acid contents and the methanol extract of Salvia ekimiana (153.50 mg 100 g⁻¹) was revealed to be the richest in terms of rosmarinic acid.     

Juniperus sibirica Burgsdorf. as a novel source of antioxidant and anti-inflammatory agents

In order to examine antioxidant properties of methanol extracts of cones and needles of the unexplored Juniperus sibirica Burgsdorf. (Cupressaceae) species, various assays which measure free radical scavenging ability were carried out: DPPH, hydroxyl, superoxide anion and nitric oxide radical scavenger capacity test and reducing power (FRAP) assay. In all of the tests the extracts showed a potent antioxidant effect compared with BHT, a well-known synthetic antioxidant. In addition, the anti-inflammatory activity considering inhibitory potency toward COX-1 and 12-LOX was observed. Both extracts showed markedly anti-inflammatory activity, with needles having somewhat higher potency concerning both assays, reaching IC₅₀ at 1.29 mg/mL towards COX-1 and IC₅₀ at 1.34 mg/mL towards 12-LOX. Besides, in the extracts examined the total phenolic and flavonoid amounts were also determined, together with presence and content of the selected flavonoids: luteolin-7-O-glucoside, apigenin-7-O-glucoside, luteolin, apigenin, rutin and quercetin, which were studied using LC–MS/MS technique. LC–MS/MS analysis showed a noticeable content of natural products according to which the examined J. sibirica Burgsdorf. species could well be regarded as a promising new source of bioactive natural compounds, which can be used both as a food supplement and a remedy.     

A detailed study on the antioxidant activity of the stem bark of Dalbergia sissoo Roxb., an Indian medicinal plant

A detailed study was performed on the antioxidant activity of the aqueous and methanol extracts (AED and MED respectively) of the stem bark of the plant, Dalbergia sissoo Roxb. (Fam. Fabaceae), also known as Indian Rosewood. The antioxidant activity of the extracts was measured by in vitro chemical analyses involving the assays of (1) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (2) ferric ion reducing power (3) ferrous ion chelating activity and (4) Au nanoparticle formation potential. A simplified method was developed based on Au nanoparticles formation to assess the antioxidant activity of any plant extract, and was used for the first time to assay the antioxidant activity of AED and MED. In all the assays, AED showed significantly greater activity over MED. This work provides a scientific support for the high antioxidant activity of this plant and thus it may find potential applications in the treatment of the diseases caused by ROS.     

Antioxidant activity and phenolic compounds of Holotrichia parallela Motschulsky extracts

Insects have been relatively unexplored as potential sources of natural antioxidants. We report the antioxidant activity of extracts of the adult large black chafer beetle Holotrichia parallela Motschulsky, a common crop pest in China. The antioxidant activity of the ethanolic extract (EE) and the water extract (WE) of adult H. parallela were evaluated by four different in vitro assays. EE showed potent metal-chelating activity and inhibition of lipid peroxidation. WE proved to be an excellent antioxidant in the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and metal-chelating activity. Catechin was identified in the ethanolic extract and proteins were the main components in the water extracts. Both compounds could contribute to the antioxidant activity of the species. These results suggest that adult H. parallela might be used as a nutraceutical to alleviate oxidate-induced diseases and as a natural antioxidant additive in the food industry.     

Antioxidant and antimicrobial activity of Cynara cardunculus extracts

The whole, fresh involucral bracts of cardoon, Cynara cardunculus L. (Compositae), were extracted with EtOH and an aqueous suspension of the obtained EtOH extract was partitioned successively with CHCl₃, EtOAc and n-BuOH, leaving a residual water extract. All obtained extracts were evaluated for their antioxidant and antimicrobial properties. The antioxidant potential was evaluated using following in vitro methods: FRAP (ferric reducing antioxidant power) assay, and scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Antimicrobial activity was estimated using a microdilution technique against food-borne, mycotoxin producers and human pathogenic bacteria and micromycetes. The following bacteria were tested: Salmonella typhimurium, Escherichia coli, Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, as well as micromycetes: Aspergillus niger, Aspergillus ochraceus, Aspergillus flavus, Penicillium ochrochloron, Penicillium funiculosum, Trichoderma viride, Fusarium tricinctum and Alternaria alternata. Results showed that all extracts possessed concentration-dependent antioxidant activity. In biological assays, C. cardunculus extracts showed antimicrobial activity comparable with standard antibiotics.     

Antioxidant activity of the roots of Decalepis hamiltonii (Wight & Arn.)

Tuberous roots of Decalepis hamiltonii (Dh) are consumed in southern India as pickles and beverage for their health benefits. The antioxidant potential of the roots was measured using various in vitro assays. Among the extracts, the methanolic and aqueous extracts showed high antioxidant activity measured as scavenging of DPPH, superoxide and hydroxyl radicals. Both the aqueous and methanolic extracts inhibited microsomal lipid peroxidation and exhibited strong reducing power and metal chelating activity. The antioxidant activity did not correlate with the phenolic content of the extracts. These results demonstrate the antioxidant potency of the root extracts which could be the basis for its alleged health promoting potential of Dh. The roots of Dh could serve as a new source of natural antioxidants or nutraceuticals with potential applications to reducing the level of oxidative stress and related health benefits.     

In vitro antioxidant activities of methanol extracts of five Phyllanthus species from India

In this study, the antioxidant activity of methanol extracts of five plants from the genus Phyllanthus was evaluated by various antioxidant assays, including total antioxidant, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, nitric oxide scavenging, reducing power and metal ion chelating activities. The various antioxidant activities were compared to standard antioxidants such as butylated hydroxytoluene and ascorbic acid. All the extracts showed strong antioxidant activity in all the tested methods. Among the five plants Phyllanthus debilis has been found to possess the highest activity in all tested models, the activity decreased in the order Phyllanthus debilis>Phyllanthus urinaria>Phyllanthus virgatus>Phyllanthus maderaspatensis>Phyllanthus amarus. In addition to the antioxidant activity of these plants, the total phenolic compounds, flavonoids and flavonols were measured in the extracts. A correlation between the antioxidant activity and total phenolic content was observed.     

Antioxidant properties of Phyllanthus amarus extracts as affected by different drying methods

The total phenolic content (TPC) and antioxidant activity of fresh and dried Phyllanthus amarus plant materials were evaluated using the Folin-Ciocalteau method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. Different drying treatments led to significant reduction (P<0.05) in antioxidant properties of P. amarus methanolic extracts, with microwave drying causing the highest decrease in TPC and antioxidant activity exhibited by the reduction in both radical scavenging activity and FRAP. On the other hand, boiling water extracts appeared to exhibit significantly stronger antioxidant potentials (P<0.05) even in dried plant materials due to greater solubility of compounds, breakdown of cellular constituents as well as hydrolysis of tannins. Its strong free radical scavenging activity suggests that it has great potential in the food industry as functional food ingredient.     

Protective effect of two edible mushrooms against oxidative cell damage and their phenolic composition

The aim of the study was to investigate phenolic composition, antioxidative, protective and cytotoxic effects of Pleurotus eryngii and Auricularia auricula-judae. Analysis of phenolic compounds in these edible mushrooms species has been carried out by high-performance liquid chromatography (HPLC). Protective effect of these mushrooms on H₂O₂ induced oxidative cell damage was determined by using MTT (3-(4,5-Dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole) assay. Antioxidant activities of the mushrooms extracts were evaluated by using complementary in vitro assays. In addition, the measurement of total antioxidant compounds in the extracts was carried out. All the extracts exhibited protective effect against H₂O₂ induced oxidative cell damage but the highest activity was observed for A. auricula-judae aqueous extract (89.5 ± 1.8% cell viability at 0.1 mg/ml). P. eryngii methanolic extract showed the highest ferrous iron chelating ability (IC₅₀ = 0.42 ± 0.03 mg/ml). A. auricula-judae extracts (at concentration of 0.025–0.100 mg/ml) were not toxic to baby hamster kidney fibroblast cell line (BHK 21). These results suggest that these mushrooms may be used as a potential source of natural antioxidants for food supplementation or in the development of nutraceuticals.     

Antioxidant and free radical scavenging activities of wild bitter melon (Momordica charantia Linn. var. abbreviata Ser.) in Taiwan

Momordica charantia Linn. var. abbreviata Ser. (Cucurbitaceae), also known as “Shan Ku Gua”, is a wild variety of bitter melon (BM) in Taiwan. The size of its fruits is only about one-fifth of the commonly seen BM. It is commonly consumed as vegetable and also used as a popular folk medicine. In this study, the antioxidant and free radical scavenging activities of BM aqueous (BM-H₂O) and ethanol (BM-EtOH) extracts were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), metal chelation, cytochrome c and xanthine oxidase inhibition (XOI) assays, as well as FeCl₂-ascorbic acid induced lipid peroxidation (thiobarbituric acid reactive substances, TBARS) assay in rat liver homogenates in vitro. Total flavonoid and phenol contents of BM extracts were also analyzed. Results showed that both BM-H₂O (IC₅₀=129.94 μg/ml) and BM-EtOH (IC₅₀=156.78 μg/ml) possess potent DPPH radical scavenging activity, which was better than vitamin E (IC₅₀=172.21 μg/ml). These extracts also showed better iron chelating activity than vitamin E. However, they were weaker than vitamin E in free radical scavenging, xanthine oxidase inhibitory and anti-lipid peroxidation activities. With the exception of XOI activity [IC₅₀=7.90 μg/ml (BM-H₂O) vs. 7.69 μg/ml (BM-EtOH)], BM-H₂O showed a lower IC₅₀ value in free radical scavenging [IC₅₀=6.15 μg/ml (BM-H₂O) vs. 7.08 μg/ml (BM-EtOH)] and anti-lipid peroxidation [IC₅₀=53.72 μg/ml (BM-H₂O) vs. 88.51 μg/ml (BM-EtOH) for liver; 82.53 μg/ml (BM-H₂O) vs. 91.83 μg/ml (BM-EtOH) for brain] activities than BM-EtOH. Both BM extracts showed a weak anti-lipid peroxidation activity in plasma. BM-H₂O (62.0 mg/g) possessed a significant higher concentration of total flavonoids than BM-EtOH (44.0 mg/g), but was lower in the total phenol content (BM-H₂O: 51.6 mg/g vs. BM-EtOH: 68.8 mg/g). In conclusion, BM extracts possess potent antioxidant and free radical scavenging activities. These antioxidant activities could have contributed, at least partly, to the therapeutic benefits of the certain traditional claims of wild BM.     

Antioxidant activity of the essential oil and various extracts of Nepeta flavida Hub.-Mor. from Turkey

This study was designed to examine the chemical composition and in vitro antioxidant activity of the essential oil and various extracts (hexane, dichloromethane and methanol sub-fractions) of Nepeta flavida. GC and GC–MS analyses of the essential oil resulted in the identification of 68 compounds, representing 96.4% of the oil; 1,8-cineole (38.9%) and linalool (25.1%) were the main components, comprising 64.0% of the total oil. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In the first case, the IC₅₀ value of the N. flavida essential oil was determined to be 42.8 ± 2.19 μg/ml. Among the extracts, the strongest activity was exhibited by the polar sub-fraction of the methanol extract with an IC₅₀ value of 63.2 ± 1.75 μg/ml. In the β-carotene-linoleic acid system, N. flavida essential oil exhibited 86.3% ± 1.69 inhibition against linoleic acid oxidation. Among the extracts prepared with various solvents, a correlation was observed between the polarity and antioxidant activity. The extracts exhibited the same activity pattern in this system the most active one is the polar sub-fraction, 79.7% ± 0.89. On the other hand, 1,8-cineole, a major compound of the essential oil, exhibited marked antioxidant activity in both systems, whereas the other compound, linalool, did not show any activity. The amount of total phenolics was highest in the polar and non-polar sub-fractions. Particularly, a positive correlation was observed between the total phenolic content and the antioxidant activity of the extracts. As estimated from the results, amounts of phenolic compounds were less in hexane and dichloromethane extracts than in the others. In conclusion, antioxidant potentials of polar and non-polar methanol sub-fractions could be attributed to their high phenolic contents. In both systems, antioxidant capacities of BHT, ascorbic acid, curcumin and α-tocopherol were also determined in parallel experiments.     

Antioxidant activity and rosmarinic acid changes in salicylic acid-treated Thymus membranaceus shoots

In order to characterise the antioxidant activity of Thymus membranaceus Boiss. subsp. membranaceus, an endemic species in Southeast Spain, five different analytical methods were used. Water, methanol and hexane extracts obtained from 60-day-old in vitro-grown shoots were assayed for their antioxidative properties using DPPH (1,1-diphenyl-2-picrylhydrazyl radical), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate), FRAP (ferric reducing antioxidant power), reducing power and conjugated diene assays. Total soluble phenol content, as well as rosmarinic acid, in the different extracts were also determined. Methanolic extracts exhibited the best antioxidant activity and the highest amounts of total soluble phenolics. A single application of salicylic acid (10 μM) on culture media resulted in an increase in rosmarinic acid and phenolic levels, which in turn improved the extracts’ antioxidant properties. These current findings open new opportunities for obtaining valuable natural antioxidants for commercial exploitation by using tissue culture systems.     

Determination of free phenolic acids and antioxidant activity of methanolic extracts obtained from fruits and leaves of Chenopodium album

In this study, determination of phenolic acids as well as investigation of antioxidant activity of methanolic extracts from the fruits and leaves of Chenopodium album is described. Extracts were subjected to acidic hydrolysis in order to obtain total free phenolic acids. However, some of phenolic acids were identified and quantified by HPLC-DAD. The results were confirmed by LC-MS equipped with MS-ESI. In addition, Folin–Ciocalteu method was applied to determine the total phenolic contents. The antioxidant activity of C. album extracts was examined by using DPPH and hydroxyl radical-scavenging activity assays. Results revealed that the leaves extract exhibits better performance in antioxidant assays and in the higher total phenolic contents (3066 mg of GAE/100 g) when compared to fruits extract (1385 mg of GAE/100 g). From these results it has been revealed that the methanolic extracts of C. album from fruits and leaves have great potential as a source for natural health products.     

Antioxidative and anti-inflammatory properties of Citrus sulcata extracts

Citrus sulcata was subjected to ultrasound, high-pressure, and Soxhlet extractions. The antioxidant and anti-inflammatory activities of the extracts were evaluated qualitatively and quantitatively. The antioxidant content of the peel extract was twice that of the fruit extract. The quantitative analysis showed that the narirutin and hesperidin contents in the peel extracts were 8.8 and 7.5 mg/100 g, respectively. These extracts had a total phenolic content of 112.22 ± 2.89 gallic acid equivalent (GAE) mg/100 g, a total flavonoid content of 54.09 ± 1.01 rutin equivalent (RE) mg/100 g, DPPH radical scavenging activity of 46%, and antioxidant activity of 213.25 ± 2.82 μM of Trolox equivalents (TEAC). C. sulcata extracts could prevent hydrogen peroxide (H₂O₂)-induced oxidative stress, reduce expression of the inflammatory markers nuclear Factor kappa B (NFκB) and phosphorylated IκBα (p-IκBα) in A549 human lung carcinoma cells, and inhibit Lipopolysaccharide (LPS)-induced THP-1 monocyte differentiation to an extent of 85%.     

Chemical composition and antioxidative activity of Moldavian balm (Dracocephalum moldavica L.) extracts

Moldavian balm (Dracocephalum moldavica L., Lamiaceae) is a perennial herb native to central Asia and naturalized in eastern and central Europe. It is commonly consumed as a food-related product and as a herbal preparation because of its reputed medicinal properties. Despite its importance, few reports exist in the literature regarding the chemistry or antioxidant activity of this species. In this study, the aerial material of Moldavian balm collected from Iran was extracted by Soxhlet using seven solvents of different polarity, viz., petroleum ether, dichloromethane, acetonitrile, ethyl acetate, methanol, n-butanol and water. The qualitative-quantitative chemical composition of each extract was determined using high-performance liquid chromatography coupled to photodiode array detection. For each extract, the total phenolic content was estimated as was the in vitro antioxidant activity using the iron(III) reduction assay, the β-carotene-linoleic acid bleaching assay and the 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonate) free radical scavenging assays. Hydroxylated cinnamic acids, their derivatives and flavonoids were identified and quantified within the extracts, with rosmarinic acid being the most abundant component identified. The extracts demonstrated different degrees of potency within each assay, however, the observed pattern was not necessarily replicated between assays indicating the importance of the use of more than one screening technique to estimate the antioxidant activity of plant extracts.