Search

In this study, 11 dehydrodiferulic acids (DFAs) and 8 diethyl dehydrodiferulates (DEFs) were synthesized and evaluated by Trolox equivalent antioxidant capacity (TEAC) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) assays for their antioxidant properties to understand the Structure-Antioxidant Activity Relationship (SAR) of these dehydrodiferulates. In both assays, the order of antioxidant activity for all tested ferulic acid dimers were consistent except for 3-(4-Hydroxy-3-methoxy-benzylidene)-5-(4-hydroxy-3-methoxy-phenyl)-3H-furan-2-one ( 2 , 8-8-lactone DC DFA, not occurred naturally) being the best antioxidant by TEAC test. The order of antioxidant activity of diferulic acid ethyl esters, evaluated by both assays, was not consistent; however, TEAC and DPPH assays provided consistent results for certain set of ethyl diferulates. In this study most of dimeric ferulates, with three exceptions, showed higher radical-scavenging efficacy than the monomers. Comparing the antioxidant activities of the tested diferulates suggested that the phenolic hydroxyl group, electron donating methoxyl group, and stable conjugated transient structures dictate the antioxidant activity of diferulates. [ABSTRACT FROM AUTHOR]

Purpose: The paper tries to assess the protective effect of fisetin against ?OH-induced DNA damage, then to investigate the possible mechanism. Methods:The protective effect was evaluated based on the content of malondialdehyde (MDA). The possible mechanism was analyzed using various antioxidant methods in vitro, including ?OH scavenging (deoxyribose degradation), ?O2 - scavenging (pyrogallol autoxidation), DPPH? scavenging, ABTS?+ scavenging, and Cu2+-reducing power assays. Results: Fisetin increased dose-dependently its protective percentages against ?OH-induced DNA damage (IC50 value =1535.00±29.60 µM). It also increased its radical-scavenging percentages in a dose-dependent manner in various antioxidants assays. Its IC50 values in ?OH scavenging, ?O2 - scavenging, DPPH? scavenging, ABTS?+ scavenging, and Cu2+- reducing power assays, were 47.41±4.50 µM, 34.05±0.87 µM, 9.69±0.53 µM, 2.43±0.14 µM, and 1.49±0.16 µM, respectively. Conclusion: Fisetin can effectively protect DNA against ?OH-induced oxidative damage possibly via reactive oxygen species (ROS) scavenging approach, which is assumed to be hydrogen atom (H?) and/or single electron (e) donation (HAT/SET) pathways. In the HAT pathway, the 3',4'-dihydroxyl moiety in B ring of fisetin is thought to play an important role, because it can be ultimately oxidized to a stable ortho-benzoquinone form. [ABSTRACT FROM AUTHOR]

Abstract: Polysaccharides from Camellia oleifera leaves were extracted by ultrasonic-assisted extraction and optimized with response surface methodology. The optimal conditions of the extraction of polysaccharides were determined to be the extraction time of 1.6h, extraction temperature of 88°C and ratio of liquid to raw material of 20, which contributed to the highest yield of 3.77%. The crude polysaccharide was purified and three fractions (CLP-1, CLP-2 and CLP-3) were obtained. Their physicochemical properties were investigated with chemical method. The results indicated that the uronic acid content of CLP-2 was significantly higher than those of CLP-1 and CLP-3, and CLPs were mainly composed of glucose and galactose residue. In vitro antioxidant assay indicated that three polysaccharide fractions showed remarkable antioxidant activities in a concentration-dependent manner. Compared with CLP-1 and CLP-2, CLP-3 exhibited higher iron chelating activity. CLP-2 possessed significant higher hydroxyl radial and 2,2-diphenyl-1-picrydrazy (DPPH) radical scavenging activities than those of CLP-1 and CLP-3. Overall, the polysaccharides derived from C. oleifera leaves might be explored as potential natural antioxidant. [Copyright &y& Elsevier]

DPPH radical-scavenging activity of the bene hull oil (BHO), sesame oil (SEO), rice bran oil (RBO), the oils' methanolic (CH3OH/H2O, 80:20 v/v) or hexane extracts, and their unsaponifiable matters fraction were measured and compared with each other. As a radical-scavenger, SEO was significantly stronger than RBO and BHO, respectively. Unlike BHO and RBO, the unsaponifiable (USM) fraction of the SEO could not considerably scavenge the free radicals at the concentrations studied. The contribution of aqueous methanolic and hexane extracts of the SEO to the inhibition of the DPPH radicals were calculated to be about 75 and 25%, respectively. The aqueous methanolic extract of the RBO could not considerably scavenge the free radicals at the concentrations experimented and the inhibition activity belonged mainly to the hexane extract. The DPPH radical-scavenging active components of the BHO were approximately distributed equally (48 and 52%) between the two extracts. [ABSTRACT FROM AUTHOR]

The antioxidant and antimicrobial activities as well as the quantity of phenolic substances of Impatiens balsamina L. stem extracts obtained with various solvent were determined in this study. All of the extracts possessed moderate antioxidant potential in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and reducing power assays. Antimicrobial activity was estimated using the cylinder-plate and agar dilution methods against four bacterial and six fungal strains. The extracts showed good antimicrobial activity especially antifungal activity against all of the tested microorganisms. The total phenolic and flavonoid contents ranged from 2.88 to 13.63 mg gallic acid equivalents/g dried extract and 0.98 to 7.87 mg quercetin equivalents/g dried extract, respectively. The results presented here indicate that the I. balsamina stem extracts have antioxidant and antimicrobial properties and are therefore a potential source of antioxidant and antimicrobial agents for the food and pharmaceutical industries. Practical Application: Our work indicates that the I. balsamina stem may be a good candidate as natural antioxidant and antimicrobial agents. It can be applied in food industry for preservation. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the antioxidative properties of vanillic acid esters and compares with antioxidants vanillic acid and Trolox. The study uses several assays including DPPH radical- and galvinoxyl radical-scavenging assays, an ORAC assay, and an oxidative hemolysis inhibition assay (OxHLIA). Results show that the protective effect of vanillic acid esters against free radical-induced biomembrane damage increases as lipophilicity increases.