Structure-activity Relationships of Antioxidant Activity in vitro about Flavonoids Isolated from Pyrethrum Tatsienense

Abstract

Aim:Antioxidant activity is one of the important indexes for estimating medicinal value for the traditional Chinese medicine. The aim of this study is to investigate the antioxidant activity of 11 flavonoids mainly revealing luteolin as mother nucleus isolated from Pyrethrum tatsienense.Materials and Methods:The antioxidant activity of 11 flavonoids was measured in vitro using the classical 1,1-diphenyl-2-picrylhydrazyl removal method. The percentages of scavenging activity of 11 flavonoids were analyzed by taking the choice of a-tocopherol as positive drugs, and the scavenging activity was plotted against the sample concentration to obtain the IC50 values.Results:Ten flavonoids containing phenolic hydroxyl groups have different levels of antioxidant activity. Antioxidant activity mainly depends on the numbers and the substitutional positions of phenolic hydroxyls in B ring. When C-3', 4' positions in B ring of flavonoids are replaced by hydroxyl groups, the antioxidant activity improved remarkably. Phenolic hydroxyl groups in A ring contribute some to antioxidant activity because of the electrophilic effect of C ring, and the numbers and substitutional positions of methoxyl and glycosyl have a little effect on the antioxidant activity.Conclusion:Structure-activity relationships of antioxidant activity about flavonoids isolated from P. tatsienense are concluded, which will be beneficial to deep understanding the pharmacological functions of this Tibetan medicine in vivo from the point of antioxidation.

Cellular antioxidant activity and in vitro intestinal permeability of phenolic compounds from four varieties of mango bark (Mangifera indica L.)

“…36 GA may be responsible for the CAA values, as it has been reported to possess antioxidant activity due to its hydroxyl groups. 37 GA has been reported to possesses higher antioxidant activity than MG [half maximal effective concentration (EC 50 ) = 1.2 μg mL −1 versus EC 50 = 32.9 μg mL −1 , respectively]. Additionally, in the same study a synergistic antioxidant effect was reported in the mixture of curcumin and GA, whereas the mixture of curcumin and MG did not display this synergistic effect.…”

“…However, the major compounds present in the MBE were MG and GA, which have been reported to have high antioxidant potential . GA may be responsible for the CAA values, as it has been reported to possess antioxidant activity due to its hydroxyl groups . GA has been reported to possesses higher antioxidant activity than MG [half maximal effective concentration (EC 50 ) = 1.2 µg mL −1 versus EC 50 = 32.9 µg mL −1 , respectively].…”

Phenolic compounds can delay the oxidation of polyunsaturated fatty acids and the growth of Listeria monocytogenes: structure‐activity relationships

“…The formation of catechol groups by adding a second hydroxyl group in the ortho ‐position on the aromatic ring of phenolic acids (caffeic acid versus p ‐coumaric acid, protocatechuic acid versus p ‐hydroxybenzoic acid) or the B ring of flavonoids (eriodictyol versus naringenin, luteolin versus apigenin, quercetin versus kaempferol) significantly improved the antioxidant potential. Such higher antioxidant activity is due to stabilization by the catechol groups of their corresponding radicals by intramolecular hydrogen bonding or the regeneration of a catechol group, in parallel with quinone formation, from two catechol radicals . In contrast, adding a third hydroxyl group (gallic acid versus protocatechuic acid) slightly decreased the antioxidant potential, which may have been due to higher steric hindrance.…”

“…Such higher antioxidant activity is due to stabilization by the catechol groups of their corresponding radicals by intramolecular hydrogen bonding or the regeneration of a catechol group, in parallel with quinone formation, from two catechol radicals. 12,[35][36][37][38][39][40][41] In contrast, adding a third hydroxyl group (gallic acid versus protocatechuic acid) slightly decreased the antioxidant potential, which may have been due to higher steric hindrance. Concerning antibacterial activity, adding a second or third hydroxyl group to the phenolic ring of phenolic acids increased the MIC.…”

Metabolic profiling of luteolin‐7‐O‐glucoside in rat urine, plasma, bile and feces after oral administration using ultra‐high‐performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry

“…In recent years, several studies have been focusing on physalins; however, flavonoids are always ignored by researchers. Luteolin‐7‐ O ‐glucoside was reported to be one of the major flavonoids in Chinese Lantern, which has various biological activities, such as anti‐inflammatory, anti‐oxidant, anti‐malarial, anti‐mutagenic and radical scavenging, anti‐tumor, anti‐asthmatic, and anti‐hepatitis B virus (HBV) activities. However, its oral bioavailability is very low, similar to some other natural compounds .…”