Antioxidant constituents in feverfew (Tanacetum parthenium) extract and their chromatographic quantification

Medicinal herb feverfew (Tanacetum parthenium) has been reported to possess prophylactic properties over migraine and arthritis. However, less attention has been given to its antioxidant activities. In our study the antioxidant activities of the feverfew extract and its bioactive components in terms of their free radical-scavenging activities against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and their Fe²⁺-chelating capacities were determined. In addition, the bioactive constituents in feverfew were determined by GC–MS and HPLC–UV. The results showed that feverfew powder extracted by 80% alcohol contained camphor, parthenolide, luteolin and apigenin in 0.30 ± 0.08%, 0.22% ± 0.03%, 0.84% ± 0.10% and 0.68% ± 0.07%, respectively. Total phenolic content of the feverfew extract was measured in 21.21 ± 2.11 μg gallic acid equivalent per mg dry material. The feverfew alcoholic extract possessed a strong DPPH free radical-scavenging activity of 84.4% and moderate Fe²⁺-chelating capacity of 53.1%. Luteolin also showed strong DPPH scavenging activity of approximately 80% at ? 0.52 mg/mL. Parthenolide exhibited weak DPPH scavenging activity of 15% and moderate Fe²⁺-chelating capacity of nearly 60%. Similar moderate Fe²⁺-chelating activity (approximately 60%) was observed for luteolin and apigenin at 2 mg/mL.     

Characterisation and free radical scavenging activities of novel red pigment from Osmanthus fragrans’ seeds

A novel red pigment (RP) was isolated from Osmanthus fragrans  ’ seeds. The optimised experimental parameters of extraction obtained with a four-factor at three-level orthogonal array experimental design _L9(3⁴)$L_9(3^4)$ were ethanol concentration, temperature, pH and extraction time as 90%, 78 °C, 2.5 and 40 min, respectively. A yield of 34.6 ± 2.2 g/100 g was obtained under optimised conditions. The red pigment directly from O. fragrans’ seeds can be dissolved in alkaline, acidic waters solutions and hydrophilic organic solvents in common use. The colour of a water solution of RP changed with pH. RP was stable to heat in the temperature range of 25–100 °C. Physical and chemical properties of RP revealed that the red pigment was also stable in the presence of Na₂SO₃, NaCl, amino acid, organic acid, sugar, starch or metal-ions (such as Ca²⁺, Cu²⁺, Fe³⁺, Zn²⁺, Al³⁺, Mg²⁺ and Na⁺), but was bleached by strong oxidants (KMnO₄, K₂Cr₂O₇ and NaOCl). Subsequently, free radical scavenging activities of RP were assessed using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals using a new resonance scattering spectral method. RP showed an excellent DPPH radical scavenging activity and was superior to butylated hydroxytoluene (BHT), and exhibited quite a strong concentration-dependent inhibition of hydroxyl radical at low concentrations compared with ascorbic acid and quercetin. When the concentration of RP was 0.03 μg/ml, the scavenging percentage of hydroxyl radical reached 92.3%. Salidroside was isolated as an active principle.     

Extraction optimisation,purification and major antioxidant component of red pigments extracted from Camellia japonica

The optimised extraction conditions of red pigments (RP) from Camellia japonica obtained with an orthogonal design L₉(3⁴) were solid/liquid ratio, temperature, pH and extraction time as 1/10, 60 °C, 1.5 and 4 h, respectively. The RP were then purified by the macroporous resin method, which showed the resin LX-68 was appropriate for purifying the pigments from C. japonica. The antioxidant activities of these pigments were also investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical in vitro model systems. The DPPH scavenging activity of pigment extract was comparable to that of standard butylated hydroxyanisole (BHA). The IC₅₀ values of the RP and BHA were 4.55 and 4.17 μg ml⁻¹, respectively. The pigments showed higher hydroxyl radical-scavenging activities than that of mannitol at the same concentration. Following activity-oriented separation, (−)-epicatechin was isolated as an active principle, which exhibited excellent DPPH free radical scavenging activities with IC₅₀ 5.08 μg ml⁻¹.     

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.     

Evaluation of antioxidant activity of aqueous extract of some selected nutraceutical herbs

The objectives of this study were to examine the antioxidant activities and free radical scavenging effects of extracts of aqueous leaves of Psidium guajava L. (PE), Camellia sinensis (GABA tea; CE), Toona sinensis Roem. (TE) and Rosemarinus officinalis L. (RE). Among the four extracts, PE exhibited the strongest efficiency and showed over 50% scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals at the concentration of 100 μg/mL. The reducing power of four nutraceutical herbs was in the order of PE > RE > CE > TE. The antioxidant activities of nutraceutical herbs were evaluated in a liposomes oxidation system promoted by Fe³⁺/ascorbic acid/H₂O₂. PE still showed the strongest antioxidant activity and exhibited over 95% inhibition at concentration of 50 μg/mL. The antioxidant activity of TE was still lower than that of other herbal plants; however, it also displayed 89% inhibition at concentration of 250 μg/mL. RE exhibited well inhibitory effects on the UVB-induced oxidation of erythrocyte ghosts at lower concentration (100 μg/mL). However, the protection of PE on the UVB-induced oxidation was significantly raised with increasing the concentrations and reached 95.4% inhibitory effects at concentration of 500 μg/mL. These results show that the tested herbal tea, especially PE could be considered as a natural antioxidant source.     

Polyphenol contents and in vitro antioxidant activities of lyophilised aqueous extract of kiwifruit (Actinidia deliciosa)

The aim of this study was to determine the antioxidant potency and total phenolic and flavonoid contents of kiwifruit (Actinidia deliciosa) in vitro by analysing the radical scavenging activity of lyophilised water extract from kiwifruit (LEK) for 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picryl-hydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), and superoxide anion radical (O₂⁻) as well as the total reducing power by FRAP and CUPRAC assays and the metal chelating activities. LEK showed efficient radical scavenging activity with DPPH, ABTS, DMPD, and O₂⁻ radicals; ferric (Fe³⁺) and cupric (Cu²⁺) ion reducing power and metal chelating activities. Moreover, the amounts of phenolic compounds, such as caffeic acid, ferulic acid, syringic acid, ellagic acid, catechol, pyrogallol, p-hydroxy benzoic acid, vanillin, p-coumaric acid, gallic acid, quercetin, ??-tocopherol and ascorbic acid, in LEK were quantified by LC-MS-MS. The results show that pyrogallol (2070.0 mg/kg LEK) is the main phenolic compound responsible for the antioxidant and radical scavenging activities of LEK. Finally, total phenolic and flavonoid contents were determined as gallic acid (GAE) and quercetin equivalents (QE). The GAE and QE values in LEK were 16.67 ± 2.83 ??g GAE/mg and 12.95 ± 0.52 ??g QE/mg, respectively. The results suggest that consumption of kiwifruit (A. deliciosa) can be beneficial effects due to its antioxidant properties.     

Antioxidant activity of ethanolic extract of Cortex fraxini and use in peanut oil

Cortex fraxini was extracted with 95% ethanol to obtain a crude antioxidant extract. The antioxidant activity was evaluated using the linoleic acid peroxidation method and the free radical scavenging assays, namely 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. Cortex fraxini extract (CFE) showed high inhibition of peroxidation of linoleic acid when compared with butylated hydroxytoluene (BHT). CFE also exhibited excellent scavenging activity on DPPH and hydroxyl radicals. Total antioxidant activity was measured by the reduction of Mo(VI) to Mo(V) by the extract, and subsequent formation of a green phosphate/Mo(V) complex at acid pH. CFE had significant total antioxidant activity and the effects were increased with increasing reaction time. The total phenolic content of the sample, analyzed by using Folin–Ciocalteu’s reagent, was 91.33 mg/g dry weight expressed as pyrocatechol equivalents. Then the suitability of CFE as an antioxidant was determined in peanut oil, and the decrease of lipid oxidation was monitored using thiobarbituric acid-reactive substances (TBARS) assay. CFE treatment significantly (P < 0.05) reduced lipid oxidation in peanut oil compared to the control. No significant differences (P = 0.05) in lipid oxidation were detected between CFE antioxidant and BHT antioxidant samples.     

Antioxidant activity of Knipholone anthrone

Knipholone anthrone (KA), isolated from an Ethiopian medicinal plant, Kniphofia foliosa, Hochst (Asphodelaceae) has been shown to display a potent antiprotozoal activity and a relatively little cytotoxic effect on mammalin cells. In the present study, the antioxidant potential of KA was assessed using a variety of in vitro assay models. KA displayed a concentration-dependant scavenging effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The IC₅₀ values obtained for KA and the positive control (−)-epicatechin (EC) in the DPPH assay were 22 ± 1.5 and 8.7 ± 0.9 μM (mean ± SEM; n = 3 separate experiments), respectively. KA displayed a better activity than EC in scavenging superoxide anions and preventing deoxyribose degradation by hydroxyl radicals. KA appeared to form a complex with Fe²⁺, displayed a concentration-dependant reducing power, and also protected (at concentrations of 4.4 μM and above) isolated DNA from damage induced by Fenton reaction-generated hydroxyl radicals.     

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 potential and phenolic constituents of Salvia cedronella

The acetone extract of the aerial parts of the plant Salvia cedronella Boiss. was screened for its total phenolic content and flavonoid content. The antioxidant potential was evaluated, in vitro, by using three different assays; β-carotene–linoleic acid test system for total antioxidant activity, DPPH for free radical scavenging activity, Fe²⁺–ferrozine test system for metal chelation. A high content of phenolics, potent radical scavenging ability and significant iron chelating effect were observed. However, the inhibition of lipid peroxidation was not significant in β-carotene–linoleic acid test system. A phytochemical analysis yielded a new coumarin, 3-methoxy-4-hydroxymethyl coumarin, together with p-hydroxyphenylethyl docosanoate, and two triterpenoids oleanolic acid and betulinic acid.     

Antioxidant properties of extract and fractions from Enteromorpha prolifera, a type of green seaweed

The ethanol extract and its solvent subfractions, partitioned by n-hexane (HX), chloroform (CF) and ethylacetate (EA), from Enteromorpha prolifera were measured for antioxidant activities, and a structural identification of the active compound was performed using spectroscopic techniques. The CF fraction showed the most potent 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl (OH) radical scavenging activities with strong reducing ability. The DPPH and hydroxyl radical scavenging capacities of the CF fraction were comparable to the capacities of the positive controls, BHA and α-tocopherol, at concentrations ranging from 0.25 to 1.0 mg/mL. However, little correlation (r² = 0.03–0.48) was observed between antioxidant activities and total phenolic contents of the extracts. Further fractionation and spectroscopic analysis of the CF fraction suggested that the strong antioxidant activity of the extracts from E. prolifera was because of a chlorophyll compound, pheophorbide a, rather than phenolic compounds.     

Enzymatic hydrolysis of hemp (Cannabis sativa L.) protein isolate by various proteases and antioxidant properties of the resulting hydrolysates

Enzymatic hydrolysis of hemp protein isolate (HPI) by six proteases (alcalase, flavourzyme, neutrase, protamex, pepsin and trypsin) and antioxidant activities of the resulting hydrolysates, obtained for 2 and 4 h were investigated. The yield of trichloroacetic acid (TCA)-soluble peptides (Y_sp), protein composition and surface hydrophobicity (H_o) of the hydrolysates were evaluated. The results showed that the hydrolysates exhibited varying DPPH radical scavenging (with lowest IC₅₀, ∼2.3 mg/mL) and Fe²⁺⁺ chelating (with lowest IC₅₀ of 1.6–1.7 mg/mL) abilities and reducing power (with highest absorbance at 700 nm of 0.31–0.35), depending on their Y_sp and H_o values. The DPPH radical scavenging and Fe²⁺⁺ chelating abilities of the hydrolysates were positively correlated with their Y_sp or H_o values. The results suggest that enzymatic hydrolysis can be used as an effective technique to produce high value-added products of hemp proteins.     

Purification and characterization of an antioxidant protein (∼16 kDa) from Terminalia chebula fruit

Terminalia chebula fruit is used as folk medicine in India and Southeast Asia. An antioxidant protein was isolated by bioassay guided fractionation of T.chebula fruit by homogenizing in the citrate phosphate buffer. The isolated protein (TCP-III) obtained from fruit was purified by gel chromatography and preparative HPLC, showed apparent molecular weight of 16 kDa by SDS-PAGE and MALDI-TOF/MS analyses. Amino acid sequence obtained by LC-MS^E analysis showed homology with the predicted protein fragments of Populus trichocarpa, putative uncharacterized protein fragments from Oryza sativa and with fragments of 17 kDa thylakoid lumenal protein from Spinacia oleracea. TCP-III exhibited significant radical scavenging in DPPH, NO, H₂O₂ and ABTS assays. In addition, TCP-III inhibited oxidation of linoleic acid in β-carotene bleaching assay, reduced ferric ions and chelated ferrous ions. The present finding demonstrates uniquely, for the first time, characterization of an antioxidant protein from T. chebula fruit.     

Antioxidant and free radical scavenging activities of pigments extracted from molasses alcohol wastewater

The pigments from molasses alcohol wastewater were extracted by the macroporous resin adsorption method. The antioxidant and free radical scavenging activities of these pigments were also investigated. The adsorptive characteristics of five macroporous resins including HPD-600, HPD-500, D301-R, NKA-II and D296-R were studied and the results showed that the macroporous resin HPD-600 was most appropriate for extracting the pigments from molasses alcohol wastewater. The antioxidant and free radical scavenging activities of pigments extracted from alcohol wastewater were evaluated using nitrate, hydroxyl radical, superoxide anion radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro model systems. The pigment extract exhibited a concentration-dependent radical scavenging activity in all the systems. Meanwhile, scavenging activity of pigment extract in the DPPH system was found to be significantly (P < 0.05) higher than that in other systems and the 50% inhibitory concentration (IC₅₀ value) was about 0.07 mg/ml. The scavenging effect of pigment extract on superoxide anion radical was very weak with IC₅₀ value greater than 10 mg/ml.     

Antioxidant activity of lactic-fermented Chinese cabbage

Lactic-fermented cabbage, similar to Kimchi in Korea, is a very popular fermented vegetable product in Taiwan and China. In this study, fermented cabbage prepared by a dry-salt method was first extracted with water and methanol. Antioxidant activity such as DPPH radical scavenging effects, reducing power and Fe²⁺-chelating ability of the solvent extracts of fermented cabbage was determined and the effect of fermentation on the change of antioxidant activity, total phenolic and total flavonoid content was also investigated. Results revealed that antioxidant activity observed on the Chinese cabbage mixture may vary with extraction solvents and fermentation. Generally, the methanol extract of the cabbage mixture showed a higher DPPH radical scavenging activity and reducing activity than the water extract. Although, fermentation did not alter the Fe²⁺-chelating ability and reducing activity of the methanol extract of the cabbage mixture, it reduced these same antioxidant activities in the water extract. Amongst the various extracts examined, the methanol extract of fermented cabbage showed the highest DPPH radical scavenging effect. On the other hand, the highest Fe²⁺-ion chelating and reducing activities were exerted by the methanol extracts of both the cabbage mixture and the fermented cabbage, which showed no significant difference (p < 0.05). Additionally, the type of solvent and fermentation were also found to affect the total phenolic and flavonoid content of the extracts. Fermentation increased the total phenolic content of the methanol extract, whilst reducing the total flavonoid content of the water extract. Furthermore, changes in the antioxidant activity observed on the extracts of the cabbage mixture and fermented cabbage did not coincide exactly with the total phenolic and total flavonoid content.