Relationship between chemical structure and antioxidant activity of luteolin and its glycosides isolated from Thymus sipyleus subsp. sipyleus var. sipyleus

Abstract

One triterpenic acid (ursolic acid), one phenolic acid (rosmarinic acid), and four flavonoids (luteolin, luteolin 7-O-(6"-feruloyl)-β-glucopyranoside, luteolin 5-O-β-glucopyranoside, and luteolin 7-O-β-glucuronide) were isolated from the aerial parts of Thymus sipyleus subsp. sipyleus var. sipyleus and identified by spectroscopic methods. In vitro lipid peroxidation inhibition effects of the compounds were determined using TBA test method in a bovine brain liposome system. All compounds inhibited lipid peroxidation in various degrees except for ursolic acid. The order of the lipid peroxidation activities of luteolin, its glycosides and rosmarinic acid were: Luteolin 7-O-β-glucuronide> luteolin 5-O-β-glucopyranoside> luteolin 7-O-(6"-feruloyl)β-glucopyranoside > rosmarinic acid >luteolin. However, the activity order of the compounds was completely different in DPPH radical-scavenging activity. None of the compounds shows Fe 2+ chelating activity. The results were discussed based on their chemical structures and polarities.

Simultaneous characterization and quantification of phenolic compounds in Thymus x citriodorus using a validated HPLC–UV and ESI–MS combined method

“…The coupling constant of the H-1 of the sugar moiety (J = 7.3 Hz) indicates the presence of the β-anomer. To our knowledge, for Thymus plants the latter luteolin derivative has only been previously detected in T. sipyleus and in T. praecox (Ozgen et al, 2011).…”

“…H-1″ of the sugar residue appears as a broad singlet, which is only compatible with an α-configuration. Note that despite the fact that luteolin-O-glucuronide has been previously described in several Thymus plants (Justesen, 2000;Miron, Plaza, Bahrim, Ibanez, & Herrero, 2011), only the 7-O-β-isomer has been previously identified by NMR analysis (Fecka & Turek, 2008;Ozgen et al, 2011).…”

Phtytochemical Studies and Quantitative HPLC Analysis of Rosmarinic Acid and Luteolin 5-<i>O</i>-β-D-Glucopyranoside on <i>Thymus praecox</i> subsp. <i>grossheimii</i> var. <i>grossheimii</i>

“…6,7) Thymus species growing in Turkey are rich in essential oils, triterpenes, phenolic acids, flavonoids and monoterpene glucosides. [6][7][8][9][10][11][12][13][14][15][16][17][18] T. praecox ssp. grossheimii var.…”

Validated RP-HPLC Method for Quantification of Phenolic Compounds in Methanol Extracts of Aerial Parts and Roots of <i>Thymus sipyleus</i> and Evaluation of Antioxidant Potential

“…It is very important to consider plants first in order to eliminate the risk of such disorders. Numerous crude extracts and natural compounds have been reported to have antioxidant and radical scavenging properties [3][4][5]. Phenolic compounds like flavonoids, tannins, caffeic acid derivatives are known to be the potential antioxidants of the natural sources [2].…”