Isolation and Structure Elucidation of Radical Scavengers from Thymus vulgaris Leaves

Abstract

2,2-Diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging activity-guided fractionation of a leaf extract of Thymus vulgaris led to the isolation of the radical scavengers rosmarinic acid 1, eriodictyol, taxifolin, luteolin 7-glucuronide, p-cymene 2,3-diol, p-cymene 2,3-diol 6-6'-dimer, carvacrol, thymol, and a new compound, 2. The fractionation was considerably facilitated by using an on-line HPLC detector for radical scavenging activity. In this detector activity is monitored as the disappearance of the color of a postcolumn added stable radical after reacting with radical scavengers in a reaction coil. Compound 2, which consists of rosmarinic and caffeic acid moieties linked via a C-3'-C-8' ' ether bridge, was mainly elucidated by various NMR techniques and CD. Phenylpropanoid trimer 2 was a weaker and stronger radical scavenger than rosmarinic acid 1 in off-line TEAC and DPPH* assays, respectively.

Isolation of eriocitrin (eriodictyol 7‐O‐rutinoside) as an arachidonate lipoxygenase inhibitor from Lumie fruit (Citrus lumia) and its distribution in Citrus species

“…2), an aglycone of eriocitrin, has been more commonly studied and is reported to inhibit the metabolism of the carcinogen benzo[a]pyrene by hamster embryo cells in tissue culture 25 as well as to possess 1,1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging activity. 26 Eriocitrin and eriodictyol, however, have not been reported to have inhibitory effects on arachidonate LOX activity. The dose-response curves of eriocitrin and eriodictyol for LOX activity and LTB 4 production are shown in Figs 3-5.…”

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>

“…grossheimii were collected from Yarımca Village C-NMR data of 1-7 agree with the literature. [24][25][26][27][28][29][30][31][32][33][34] Ursolic Acid (1) [24][25][26][27] 1 g, B) were subjected to silica gel column by eluting with 1H, d, J=15.8 Hz, H-8), 5.19 (1H, m, H-8′), 3.70 (3H, s, -OCH 3 ), 3.03 (1H, m, H-7a′), 3.03 (1H, m, H-7b′); Remaining aqueous extract (27 g) was subjected to reversed phase silica gel column and eluted with H 2 O : MeOH (100 : 0 0 : 100). The fractionation and isolation scheme is given in Fig.…”

Recent developments in the rapid analysis of plants and tracking their bioactive constituents

“…This saves not only expensive chemicals and time but also avoids possible decomposition of relatively instable antioxidants. An application is the identification of rosmarinic acid and a new caffeic acid trimer in a methanolic extract of thyme leaves (Dapkevicius et al 2002). Although high resolution screening speeds up the identification of active constituents as no time is wasted on the purification of inactive constituents, still much time is lost if active constituents need to be isolated for the determination of their structure.…”