Microwave‐assisted extraction optimised with response surface methodology and antioxidant activity of polyphenols from hawthorn (Crataegus pinnatifida Bge.) fruit

Microwave‐assisted extraction (MAE) of polyphenols from hawthorn (Crataegus pinnatifida Bge.) fruit was investigated, and the best combination of extraction parameters was obtained using response surface methodology (RSM). The optimised procedure was achieved by soaking the sample powder with 83% ethanol for 90 min at solid–liquid ratio of 1–20, and then microwave irradiation for 13 min at power of 440 W. Under this condition, an extraction yield of 23.5% was obtained and the percentage of phenolic compounds in the extract reached 41.2%. The total content of polyphenols in hawthorn fruit was 96.9 ± 4.3 mg gallic acid equivalents per gram of dry weight measured by Folin‐Ciocalteu reagent method, and the main phenolic compounds were determined as procyanidin B₂, epicatechin, chlorogenic acid, procyanidin C₁ and rutin. Biological studies showed that the extract possessed a strong inhibitory effect against DPPH, hydroxyl radicals and lipid peroxidation, as well as strong reducing power.     

Effect of different solvents on the chemical composition,antioxidant activity and alpha‐glucosidase inhibitory activity of hawthorn extracts

The aim was to investigate chemical composition of different extracts prepared from hawthorn fruit using 80% ethanol, 80% methanol, 80% acetone and pure deionised water, and evaluate their antioxidant and anti‐alpha‐glucosidase activities. The highest alpha‐glucosidase inhibitory activity was determined in 80% acetone extract, while the highest DPPH scavenge capacity and ferric reducing power both exhibited in deionised water extract. In the correlation analysis, polyphenols, triterpenoids, protocatechuic acid and epicatechin all contribute to the alpha‐glucosidase inhibitory activity, while flavonoids, polyphenols, vanillic acid, gallic acid, catechin and chlorogenic acid all contribute to the antioxidant activity. By HPLC‐MS, thirty six compounds were identified, and fifteen of them were found from hawthorn fruits for the first time. Our results would provide a good reference for the further study on the antidiabetes activity of hawthorn, and also support that deionised water extract has the potential to be used as ingredients of functional food products.     

Antioxidant and anti‐inflammatory activities of water distillate and its dichloromethane extract from licorice root (Glycyrrhiza uralensis) and chemical composition of dichloromethane extract

BACKGROUND: Licorice root is one of the most widely used medicinal herbs and its medicinal properties, such as antibacterial, anti‐ulcer, anti‐tumorigenic and anti‐atherosclerotic activities, have been widely reported. However, there are only a few reports on basic chemical and biological studies of the water distilled components of licorice root. RESULTS: Chinese licorice root was water distilled and the distillate was subsequently extracted with dichloromethane. Residual aqueous solution from the extraction was fractionated using column chromatography. A total of 127 chemicals were identified in the dichloromethane extract, which inhibited hexanal oxidation by over 90% for 45 days at the level of 50 µg mL^?1. A fraction eluted from the residual aqueous solution with acetone exhibited potent antioxidant activities both in a thiobarbituric acid assay and in a malonaldehyde/gas chromatography assay. The acetone fraction also exhibited strong anti‐inflammatory activity (77.9% inhibition at the level of 62 µg mL^?1) in a lipoxygenenase inhibitor screening anti‐inflammatory assay. CONCLUSION: This study demonstrated the antioxidant and anti‐inflammatory activities of the water distillate obtained from Chinese licorice root. Some volatile chemicals among the many components identified in the water distillate exhibited antioxidant activity, suggesting that many medicinal compounds escape with water vapor into the ambient air during the preparation of herbal medicine. Copyright © 2008 Society of Chemical Industry     

Antioxidative and anti‐inflammatory potential of phenolics from purple basil (Ocimum basilicum L.) leaves induced by jasmonic,arachidonic and β‐aminobutyric acid elicitation

The study presents changes in the phenolic levels, antioxidant and anti‐inflammatory potential of purple basil leaves caused by different chemical elicitors: arachidonic acid (AA), jasmonic acid (JA) and β‐aminobutyric acid (BABA). The application of the all tested elicitors increased the concentration of phenolic compounds, including flavonoids and phenolic acids; especially, in comparison with control (457.62 μg g^?1 FW), the rosmarinic acid level significantly increased after AA and JA treatment ‐ 705.0 and 596.5 μg g^?1 FW, respectively. Phenolics from AA‐elicited plants showed the highest anti‐inflammatory activities designated as lipoxygenase (EC₅₀ = 1.67 mg FW mL^?1) and cyclooxygenase inhibition (EC₅₀ = 0.31 mg FW mL^?1). Elicitors' treatments (especially AA and JA) may be a very useful biochemical tool for improving the production of phenolic compounds in purple basil leaves.