DPPH (1,1-Diphenyl-2-Picrylhydrazyl) Radical Scavenging Activity of Flavonoids Obtained from Some Medicinal Plants.

Abstract

Flavonoids are a group of polyphenolic compounds, which have the diphenylpropane (C 6 -C 3 -C 6 ) skeleton, ubiquitously found in fruits and vegetables. The flavonoid family includes flavones, flavonols, flavanones, flavanonols, flavans, flavanols, leucoanthocyanidins, anthocyanidins, aurones, chalcones, and isofavones. The structural difference in each flavonoid family results from the variation in the number and arrangement of the hydroxyl groups and the extent of glycosylation of these groups. 1)Epidemiological studies suggest that the consumption of flavonoids is effective in lowering the risk of coronary heart disease. [2][3][4] In addition, the flavonoids exhibit a wide range of biological activities, including anticarcinogenic, antiinflammatory, antiradical, and antioxidant actions. Especially, they may exert antioxidative effects as free radical scavengers, hydrogen-donating compounds, singlet oxygen quenchers, and metal ion chelators, properties attributed to the phenolic hydroxyl groups attached to the ring structures.Nowadays, it is reported that a reactive oxygen species (ROS) is implicated in a wide range of human diseases such as atherosclerosis and certain cancers. When an imbalance between ROS generation and antioxidants occurs, oxidative damage will spread over all the cell targets (DNA, lipids, proteins). 5) Antioxidants in foods and medicinal plants (or herbs) have attracted interest in recent years. Flavonoids given as biological substances in foodstuffs may contribute to the prevention of diseases, although they do not have strong biological activities. [6][7][8] In the preceding paper, 9) we reported the antioxidative effects of flavon C-glycosides isolated from young green barley (Hordeum vulgare var. nudum) leaves. Herein, we present antioxidative effects of various types of flavonoids obtained from some medicinal plants, using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity by ESR. MATERIALS AND METHODSFlavonoids Flavone C-glycosides, isovitexin (1), saponarin (2), isovitexin 4Ј,7-diglucoside (3), isovitexin 7-rhamnosylglucoside (4), 6ٞ-sinapoylsaponarin (5), 6ٞ-feruloylsaponarin (6) and 4Ј-glycosyl-6ٞ-sinapoylsaponarin (7) were isolated from young barley leaves.9) A flavone, baicalin 10) (8) was obtained from Scutellariae Radix (Scutellaria baicalensis). Flavonols, quercetin (9), kaempferol (10) and rutin (11) were obtained from Sophorae Flos (Sophora japonica). 11)Flavanols, gallocatechin (12) was obtained from Ephedrae Herba (Ephedra sinica) and epicatechin (13) and their polymers (14-16) were from cinnamon (Cinnamomum cassia).12) Isoflavones, 13) daidzin (17), genistin (18) and glycitin (19), and their metabolites 14) (20-25) were obtained from soybeen (Glycine max). Flavonolignans, silybin (26) and silychristin (27) were isolated from a silymarin group (Silybum marianum).15) (Fig. 1). DPPH Radical Scavenging Activity by ESR The DPPH radical scavenging activity of a test sample was estimated by ESR according to the method of Tateyama et al. 16)Various concentrations ...

Characterization of volatile composition of Laurencia dendroidea by gas chromatography-mass spectrometry

“…However, formation of free radical intermediates from oxidized compounds, which could become important propagators of free radical chain reactions, cannot be detected by this assay (Okawa et al, 2001). The chemiluminescence method, the other experimental model used, is based on the antioxidantdependent quenching of the chemiluminescence generated by luminol/peroxidase/H 2 O 2 (Dodeigene et al, 2000).…”

Antioxidant, Antibacterial and Brine Shrimp Lethality Bioassay of Amoora cucullata, a Mangrove Plant

“…Polyphenols are the most active antioxidant derivatives in plants. 20 Total phenolics and flavonoids content results obtained in the present study revealed that the level of these compounds in the extracts were considerable. Therefore extracts with good amount of phenolic compounds but weaker scavenging activity could be due to the fact that the free radical scavenging assay was a combined activity of a wide range of compounds, 21 absence of only flavonoids with particular hydroxyl position in the molecule 19 and finally radical scavenging activity is not only specific to presence of polyphenol groups or flavonoids.…”

Plant Polyphenols as Antioxidants Influencing the Human Health

“…2) and resulting colour change, proportional to the effect, can be quantified spectrophotometrically. Based on the DPPH free radical scavenging effectiveness, it has been established that numerous polyphenolic compounds of different classes are strong antioxidants (Okawa et al, 2001;Villaño et al, 2007;Vladimir-Knežević et al, 2011). Also frequently used colorimetric method is Trolox equivalent antioxidant capacity (TEAC) assay, which is based on scavenging of blue-green ABTS radical cation by antioxidants present in sample (Nenadis et al, 2004).…”