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 and antidiabetic activity of Dangyuja (Citrus grandis Osbeck) extract treated with Aspergillus saitoi

Dangyuja is a citrus fruit of Cheju Island in Korea, which is known to have a high content of flavanone glycosides, such as naringin and neohesperidin. Flavanone glycosides of Dangyuja (Citrus grandis Osbeck) extract were converted into their aglycones by naringinase and hesperidinase, and into their hydroxylated forms by Aspergillus saitoi.Dangyuja extract treated with A. saitoi had significantly higher antioxidant and antidiabetic activity than both its glycosides and aglycones in oxygen radical absorption capacity (ORAC) and supercoiled DNA strand scission assay, rat intestinal α-glucosidase and porcine pancreatic α-amylase inhibition, suggesting that the fermentation of flavanone aglycones of Dangyuja extract with A. saitoi can increase antioxidant and antidiabetic activity, compared to their glycosides and aglycones. This result suggests that Dangyuja extract prepared with enzymatic and microbial treatments could be used for the development of pharmaceutical foods to control the blood glucose level of diabetic patients by inhibiting α-amylase and α-glucosidase in the intestinal tract.     

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 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 activity of microwave-assisted extract of Buddleia officinalis and its major active component

Buddleia officinalis Maxim, commonly used as rice dye for festivals, was extracted with ethanol using microwave-assisted extraction and Soxhlet extraction. The antioxidant activities of microwave-assisted extract of B. officialis (MEB) and Soxhlet extract of B. officianils (SEB) at the optimum extraction conditions were evaluated and compared with synthetic antioxidant butylated hydroxytoluene (BHT) employing DPPH free radical assay, ABTS assay, total antioxidant activity and reducing power. MEB and SEB had stronger antioxidant activities than BHT in all assays except reducing power, and the effects decreased as follows: MEB > SEB > BHT. The total phenolic contents of MEB and SEB reached 113.56 mg/g and 100.94 mg/g dry weight of extract, respectively, expressed as pyrocatechol equivalents, while the total flavonoids contents were 75.33 mg/g and 62.56 mg/g dry weight of extract, respectively, expressed as catechin equivalents (P < 0.05). Higher phenolic and flavonoids compounds may be major contributors to their higher antioxidant activities. Following activity-oriented separation, luteolin was isolated as an active principle, which exhibited excellent free radical scavenging activities with DPPH IC₅₀ 3.09 μg/ml and ABTS IC₅₀ 2.20 μg/ml.     

Antioxidant activity and hepatoprotective potential of Phyllanthus niruri

Antioxidant activity and hepatoprotective potential of Phyllanthus niruri, a widely used medicinal plant, were investigated. Methanolic and aqueous extract of leaves and fruits of P. niruri showed inhibition of membrane lipid peroxidation (LPO), scavenging of 1,1-diphenyl-2picrylhydrazyl (DPPH) radical and inhibition of reactive oxygen species (ROS) in vitro. Antioxidant activity of the extracts were also demonstrable in vivo by the inhibition of the carbon tetrachloride (CCl₄) – induced formation of lipid peroxides in the liver of rats by pretreatment with the extracts. CCl₄ – induced hepatotoxicity in rats, as judged by the raised serum enzymes, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), was prevented by pretreatment with the extracts, demonstrating the hepatoprotective action of P. niruri.     

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 hepatoprotective activity of ethanolic extract of leaves of Solidago microglossa containing polyphenolic compounds

The antioxidative and hepatoprotective potential of Solidago microglossa D.C, a widely used medicinal plant from Brazil was investigated. The leaf extract showed inhibition against thiobarbituric acid reactive species (TBARS) induced by different prooxidants (10 μM FeSO₄ and 5 μM sodium nitroprusside SNP) in rat liver, brain and phospholipid homogenates from egg yolk. Moreover, the free radical scavenging activities of the extract was evaluated by the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC_50, 3.8 ± 0.5 μg/ml) and hydroxyl radical on benzoic acid hydroxylation (IC_50, 32.3 ± 1.3 μg/ml) and deoxyribose (IC_50, 39.1 ± 2.4 μg/ml) assays. The ethanolic extract showed significant hepatoprotective activity against paracetamol (250 mg/kg) induced liver damage in mice in a dose dependent manner. The phenolic composition and their quantification by high performance liquid chromatography (HPLC) resulted in the identification of gallic acid and flavonoids: quercetrin (quercetin-3-O-rhamnoside), rutin (quercetin-3-O-rutinoside) and quercetin.     

Antioxidant activity of seed polyphenols in fifteen wild Lathyrus species from South Spain

Antioxidant activity of seed phenolics was studied in the following Lathyrus species: Lathyrus hirsutus, Lathyrus filiformis, Lathyrus sativus, Lathyrus cicera, Lathyrus angulatus, Lathyrus sphaericus, Lathyrus annuus, Lathyrus clymenum, Lathyrus pratensis, Lathyrus ochrus, Lathyrus aphaca, Lathyrus latifolius, Lathyrus setifolius, Lathyrus tingitanus and Lathyrus amphicarpos. Phenolic contents ranged from 3.8 mg/g meal in L. setifolius to 29.2 mg/g meal in L. sphaericus. In general, non-cultivated Lathyrus species contained higher phenolic contents than cultivated ones. A negative correlation between seed size and phenolic contents was observed and was related to the higher proportion of hulls in the smaller seeds. L. annuus possessed phenolics with highest specific antioxidant activity. These phenolics were more than two times more antioxidant than equivalent amounts of phenolics extracted from commercial chickpea, lupin or soy. On the other hand, L. aphaca possessed the highest antioxidant activity per mg of flour extract. This antioxidant activity was twice that observed in same amounts of extracted flours from commercial chickpea, lupin or soy. Results show that studied Lathyrus species are rich in phenolic compounds with higher antioxidant activity than phenolics of widely consumed legumes such as soy, chickpea or lupin. In conclusion, Lathyrus may represent an interesting source of phenolic compounds with high antioxidant activity that may be useful as natural antioxidants and contribute to revalorize the cultivation of these legumes.     

Antioxidant activity of Mammea longifolia bud extracts

Mammea longifolia buds (nagkesar) are extensively used in India as a minor spice. The antioxidant activity of its methanol (NM) and aqueous-ethanol (NW) extracts were evaluated by several in vitro experiments, e.g., DPPH, hydroxyl, superoxide radicals and H₂O₂-scavenging assays as well as inhibition of Fe(II)-induced lipid peroxidation of rat liver mitochondria. The extracts were found to possess impressive antioxidant activity in all the tests, the activity of NW being higher than that of NM in most of the assays. The differential activities of NW and NM could be correlated with their respective total phenolic, flavonoid and proanthocyanidin contents.     

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.     

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.     

Antioxidant activity and chemical constituents of edible flower of Sophora viciifolia

The antioxidant activities of crude extract and its derived soluble fractions from the flower of Sophora viciifolia were evaluated in five different test systems (DPPH, ABTS, FRAP, reducing power and inhibition of lipid peroxidant models) for the first time. The ethylacetate soluble fraction exhibited the highest antioxidant effect. Correlation analysis suggested that the flavonoids might be the major contributors for the high antioxidant activity of this flower. In addition, 11 compounds were isolated from this flower, and the antioxidant capacities of 5 flavonoids were evaluated by DPPH assay. Compound 3 (luteolin) had a significant DPPH radical-scavenging activity, and was also present at the highest concentration (5.56 mg/g dry sample), implying an important role of 3 for the antioxidant activity of this flower. The study suggests that the flower of S. viciifolia can provide valuable functional ingredients and can be used for the prevention of diseases related to various oxidant by-products of human metabolism.     

A comparison between bark extracts from Pinus pinaster and Pinus radiata: Antioxidant activity and procyanidin composition

The composition and antiradical activity of procyanidins from the bark of two kinds of pine, Pinus pinaster and Pinus radiata, were compared. Both the total bark extract and the fraction soluble in both water and ethyl acetate (OW) were evaluated, because of their promising results in previous experiments.     

Antioxidant activities of Salvia miltiorrhiza and Panax notoginseng

Traditional Chinese medicinal herb Salvia miltiorrhiza (SM) and Panax notoginseng (PN) have been widely used for the prevention and treatment of vascular diseases in the clinics. To better understand their mechanisms of pharmacological actions, the in vitro antioxidant activities of extract of Salvia miltiorrhiza (ESM) and extract of Panax notoginseng (EPN) were evaluated with different antioxidant testing systems. Their activities of scavenging superoxide anion radicals, DPPH radicals, hydroxyl radicals, and hydrogen peroxide, chelating Ferrous ion, and ferric ion reducing power were assessed. The results showed that the mechanisms of their antioxidant effects were distinct and diverse. ESM possessed strong reducing power and high scavenging activities against free radicals including superoxide anion, hydroxyl and DPPH radicals, but a weaker scavenging activity for hydrogen peroxide. ferrous ion chelating activity of ESM was undetectable at the tested concentrations. In contrary, EPN exhibited strong ferrous ion chelating activity and high scavenging activities against hydrogen peroxide, hydroxyl radicals, and a weak activity against superoxide anion and DPPH free radicals. EPN did not show any ferric ion reducing power. Since their antioxidant mechanisms are complementary, the combined use of ESM and EPN might be even more beneficial. These antioxidant properties of SM and PN are likely part of the reasons that they are effective in the prevention and treatment of vascular diseases.