Antioxidant properties of extracts from juemingzi (Cassia tora L.) evaluated in vitro

Methanol extract from juemingzi (Cassia tora L.) was fractionated by liquid-liquid partition using ethyl acetate, n-butanol and water, respectively. The antioxidant activity of three different fractions was evaluated using different antioxidant tests, including inhibition of peroxidation of linoleic acid, reducing power, free-radical scavenging and ferrous ions chelating activity. In the above four assays, all the fractions showed antioxidant potential to varying degrees. Among these fractions, ethyl acetate fraction exhibited more antioxidant potency than other fractions. Furthermore, ethyl acetate fraction was found to be more effective in protecting LDL against oxidation in a concentration-dependent manner. The data suggest that juemingzi especially ethyl acetate-soluble fraction may have a preventive effect against atherosclerosis by inhibiting LDL oxidation.     

Kinetics studies of some physico-chemical substances during roasting and preparation of beverage made by Cassia occidentalis seeds

Cassia occidentalis seeds are commonly used in West of Africa to prepare a beverage which serves as a substitute for coffee. A study was carried out to investigate the effect of roasting conditions on some organic compounds in the seeds and to determine the extraction rate of some physico-chemical constituents into an aqueous infusion. With the exception of phytate, the results showed that roasting significantly decreased (P?0.05) the level of the chemical parameters measured (proteins, carbohydrates, total phenols and tannins). Degradation of these compounds during roasting follows first-order reaction and this degradation conforms to the Arrhenius equation. From the rates of increase of the physico-chemical concentration of beverage with extraction time, first order rate constants of infusion were determined and kinetic extraction was found to follow the quasi-steady-state theory of extraction from spherical particles.     

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 compounds isolated from the pyroligneous acid, Rhizophora apiculata

The polyphenols (CPAE II) was isolated from the dichloromethane extract of the pyroligneous acid, Rhizophora apiculata by simultaneous acid base and solvent extraction method. Its qualitative and quantitative composition was studied by gas chromatography mass spectroscopy (GC/MS) and out of 57 peaks, 52 compounds were identified, representing 95.47% of the total polyphenols. The CPAE II was then fractionated to four fractions (F1–F4) by means of thin layer chromatography and silica gel column chromatography with dichloromethane, dichloromethane/chloroform/ethyl acetate mixture (8:1:1; 4:3:3, v/v/v), and ethyl acetate, respectively. The antioxidant properties of the CPAE II and the fractions were evaluated. Among the four fractions, fraction 1 (F1) was the most potent in DPPH radical scavenging activity and molybdenum (VI) reducing power. It was subjected to further purification by means of silica gel column chromatography with hexane, hexane/diethyl ether mixture (9:1, 6:1, 3:1, v/v), and diethyl ether, respectively. 2,6-Dimethoxyphenol (syringol) and dihydroxybenzenes (catechol and 3-methoxycatechol) were isolated and identified by GC/MS, ¹H NMR, ¹³C NMR spectral analyses, and confirmed by GC co-injection with authentic standards. Syringol, catechol and 3-methoxycatechol constitute 39.08, 4.21 and 1.10% of F1, respectively. Their antioxidant activities were evaluated by DPPH radical scavenging activity, ABTS radical cation scavenging activity, phosphomolybdenum and ferric reducing antioxidant power (FRAP). The trend in antioxidant capacity was similar in all the four assays, with dihydroxybenzenes > 2,6-dimethoxyphenols, although discrepancies in the ranking within the dihydroxybenzenes were present. These three compounds which showed significant antioxidant activities were isolated for the first time from the pyroligneous acid, R. apiculata.     

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 and phenolic compounds of fractions from Portulaca oleracea L.

Portulaca oleracea fractions obtained from the crude extract of the plant by reversed-phase separation were investigated for their antioxidant activities and phenolic compounds content. Five fractions were classified based on optical absorption between the wavelength range of 200–400 nm. Fraction 3 displayed higher absorption than the other fractions. The total amount of quantified phenolics in this fraction was found to be quite high compared to that of crude extract. Chlorogenic, caffeic, p-coumaric, ferulic and rosmarinic acids were the free phenolic acids, and quercetin and kaempferol were the free flavonoids detected in Fraction 3. IC₅₀ value of crude extract was found to be 511.8 μg/ml whereas Fraction 3 exhibited an IC₅₀ value of 154.1 μg/ml. TEAC of Fraction 3 was found to be almost four times higher than that of the crude extract. Fraction 3 was also found to show the highest lipid peroxidation inhibiting capacity, determined by TBARS assay.     

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.     

Assessment of in vitro antioxidant capacity and polyphenolic composition of selected medicinal herbs from Leguminosae family in Peninsular Malaysia

Determination of total phenolic (TPC), flavonoid and anthocyanin contents, and various antioxidant activities (2,2-diphenyl-1-picrylhydrazyl radical scavenging, ferric reducing power, ferrous ion chelating and lipid peroxidation inhibition) of leaves and flowers of Bauhinia kockiana, Caesalpinia pulcherrima and Cassia surattensis were performed in this study. The B. kockiana flower was found to possess the highest TPC (8280 ± 498 mg GAE/100 g), free radical scavenging activity (ascorbic acid equivalents 14,600 ± 2360 mg AA/100 g) and reducing ability (72.4 ± 8.7 mg GAE/g). Rutin and chlorogenic acid were detected in the plants, where the C. pulcherrima leaf contained the highest amount of rutin (669 ± 26 mg/100 g), while minute amounts of chlorogenic acid were detected in C. surattensis leaf (9.13 ± 0.44 mg/100 g). The C. pulcherrima leaf displayed the highest ferrous ion chelating and lipid peroxidation inhibition activities. Positive correlation was observed between TPC and various antioxidant activities.     

Kaempferol acetylated glycosides from the seed cake of Camellia oleifera

The seed cake is a big by-product after crushing cooking oil from the seeds of Camellia oleifera Abel. Chemical investigation on the seed cake of C. oleifera led to the isolation of two new kaempferol acetylated glycosides (1 and 2). In addition, five kaempferol glycosides (3–7) and their aglycone, kaempferol (8), were also obtained, in addition to gallic acid (9). Their structures were determined by the detailed spectroscopic analysis and acidic hydrolysis. The new compounds were characterised as kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (1) and kaempferol-3-O-[4′′′′-O-acetyl-α-l-rhamnopyranosyl-(1→6)]-[β-d-xylopyranosyl-(1→2)]-β-d-gluco-pyranoside (2), respectively. The DPPH radical scavenging activity of all the isolated compounds was described.     

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 radical scavenging activities of the pyroligneous acid from a mangrove plant, Rhizophora apiculata

Total phenolics content, free radical scavenging activity, reducing power, and antioxidant activity of the pyroligenous acid from a mangrove plant, Rhizophora apiculata were evaluated. Dichloromethane extraction of the raw pyroligneous acid successfully yield 2 extracts, i.e. concentrated pyroligneous acid (CPA) and concentrated pyroligneous acid extract (CPAE). Phenolic contents in CPAE and CPA, expressed as (±)-catechin equivalents/g of the sample were 5465 ± 367 mg and 2502 ± 152 mg, and expressed as gallic acid equivalents/g of the sample were 2919 ± 209 mg and 1348 ± 90 mg, respectively. CPAE exhibited superior free radical scavenging activity with EC₅₀ value = 0.1235 mg/ml, or 80.96% of free radical scavenging capability. The ferric reducing power of CPAE was approximately 3.7, 5.1, 6.1, and 21.3 times higher than that of ascorbic acid, BHA, BHT and alpha-tocopherol. In phosphomolybdenum assay, CPAE showed the greatest antioxidant efficacy (A₆₉₅ = 1.278) compared to those of CPA and different standards. In addition, the free radical scavenging activity, ferric reducing power and total antioxidative activity of CPAE and CPA showed positive correlation with their total phenolic content with R² values ranging from 0.9624 to 0.9979.     

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.