Evaluation of natural antioxidants of Leuzea carthamoides as a result of a screening study of 88 plant extracts from the European Asteraceae and Cichoriaceae.
In recently, there has been a great interest in natural antioxidants as bioactive components of food, nutraceuticals or potential drugs against several diseases. In our study, 88 extracts from various parts of plants from European Asteraceae and Cichoriaceae were assayed for radical scavenging activity by means of DPPH (1,1-diphenyl-2-picryl hydrazyl radical) test using the SIA (Sequential injection analysis) method developed for this purpose in our laboratory. DPPH radical scavenging activity of all tested plant extracts was evaluated according to the IC(50) parameter. 29 extracts exhibited IC(50) value lower than 0.1 mg/mL. The leaves of Leuzea carthamoides (IC(50) = 0.046 mg/mL) were chosen as the most promising sample for a subsequent phytochemical study, which resulted in isolation of seven natural compounds, namely, 4',5,7-trihydroxy-6-methoxyflavone (hispidulin) (1), 5, 7, 3', 4'- tetrahydroxyflavanone (eriodictyol) (2), 3',4',5,7-pentahydroxy-6-methoxyflavonol (patuletin) (3), eriodictyol-7-beta-glucopyranoside (4), 6-hydroxykaempferol-7-O-(6''-O-acetyl-beta-D-glucopyranoside) (5), 4-hydroxybenzoic acid (6) and 3,4-dihydroxybenzoic acid (protocatechuic acid) (7). Antioxidant activity of the isolated compounds was evaluated by DPPH test and ferric reducing antioxidant power (FRAP) test and compared with trolox and quercetin. Both tests evaluated the flavonoid (5) as the most active antioxidant. This result was confirmed by comparison with known data concerning the structure/activity relationships of flavonoids.
Koleckar
Vit
V
Department of Pharmaceutical Botany and Ecology, Faculty of Pharmacy, Charles University, Hradec Kralove, Czech Republic.
Opletal
Lubomir
L
Brojerova
Eliska
E
Rehakova
Zuzana
Z
Cervenka
Frantisek
F
Kubikova
Katerina
K
Kuca
Kamil
K
Jun
Daniel
D
Polasek
Miroslav
M
Kunes
Jiri
J
Jahodar
Ludek
L
D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D019659:Asteraceae / Q000737:chemistry*; D001688:Biological Products / Q000737:chemistry* / Q000494:pharmacology*; D001713:Biphenyl Compounds; D002839:Chromans / Q000737:chemistry / Q000302:isolation & purification; D004353:Drug Evaluation, Preclinical; D005060:Europe; D006834:Hydrazines; D043843:Leuzea / Q000737:chemistry*; D015394:Molecular Structure; D010851:Picrates; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011794:Quercetin / Q000737:chemistry / Q000302:isolation & purification; D000461:Rhodophyta / Q000737:chemistry*; D013329:Structure-Activity Relationship
D000975:Antioxidants; D001688:Biological Products; D001713:Biphenyl Compounds; D002839:Chromans; D006834:Hydrazines; D010851:Picrates; D010936:Plant Extracts; D011794:Quercetin; C004931:1,1-diphenyl-2-picrylhydrazyl; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid