Study of the antioxidant activity of Thymus sibthorpii Bentham (Lamiaceae)

Abstract

From the aerial parts of Thymus sibthorpii Bentham (Lamiaceae), five flavonoids apigenin (1), 7-methoxy-apigenin (2), naringenin (3), eriodictyol (4) and eriodictyol-7-glucoside (5), have been isolated together with caffeic acid methyl ester (6), rosmarinic acid (7) and rosmarinic acid methyl ester (8). The structures of the isolated compounds were established by spectroscopic methods. The extracts and the isolated compounds were tested for their free radical scavenging activity using the following in vitro assays: (i) interaction with the free stable radical of DPPH (1,1-diphenyl-2-picrylhydrazyl), (ii) inhibition of linoleic acid lipid peroxidation induced by the dihydrochloric acid of 2,2-azobis-2-amidinepropane (AAPH) and (iii) the scavenging activity of enzymatically produced superoxide anion. Their inhibitory activity toward soybean lipoxygenase was evaluated in vitro, using linoleic acid as a substrate. The antioxidant results of the extracts are discussed in terms of their constitution in phenolic compounds, which were determined following the Folin-Ciocalteu method.

Extraction Processes Affect the Composition and Bioavailability of Flavones from Lamiaceae Plants: A Comprehensive Review

“…For Thymus species, multiple studies have been conducted using mostly ethanol, methanol, water, and their mixture as solvents, in which not much variety was observed in the flavones extraction of such species as T. alternans, T. caespititius, T. fragrantissimus, T. mastichina, T. pulegioides, T. serpyllum, and T. vulgaris, among others [68,71,[117][118][119][120][121]. However, using fractionation techniques, it is possible to obtain flavones that have not been identified in crude extracts such as 7-methoxyapigenin (genkwanin) [122] and nobiletin [123,124], while, by using dichloromethane, hydroxyluteolin and hydroxyapigenin derivatives can be extracted from T. mastichina [125]. Furthermore, the water residue from hydrodistillation from T. vulgaris process has shown to be a valuable source of flavones such as luteolin and apigenin glucuronide derivatives [126].…”

Zinc(ii) complexes of 3-bromo-5-chloro-salicylaldehyde: characterization and biological activity

“…Within this context, the antioxidant activity of the compounds was examined regarding the scavenging of DPPH and ABTS radicals and reduction of H 2 O 2 and was compared with that of the well-known antioxidant agents NDGA, BHT, Trolox and L-ascorbic acid, which are used as reference antioxidant agents. 61,62 The results are summarized in Table 6.…”

Evaluating the In Vitro Potential of Natural Extracts to Protect Lipids from Oxidative Damage

“…Emulsification of LA in PB 20 mM pH 7, using Tween-20 (5.6 µg/mL LA and 5.6 µg/mL Tween-20) Mixture of emulsion in PB, water and sample dissolved in 80% methanol [70] Dissolution of LA (8 mM) in Borate buffer 50 mM pH 9 Mixture of previous solution with FeSO 4 , EDTA, H 2 O 2 , sample dissolved in methanol and PB 0.4 M pH 6.75 [126] Dissolution of sodium linoleate in water (16 mM) Mixture of previous solution in PB 50 mM pH 7.4 [127] Dissolution of LA in ethanol, 2.5% (v/v) Mixture of previous solution with distilled water, PB 50 mM pH 7 and sample [74] Ethanol Dissolution of LA (1.3% (v/v)) and NP in ethanol:water 3:1 (v/v) [76] Different methods available to disperse linoleic acid in a medium that is compatible with oxidizing conditions allow the adaptation of the medium for NP dissolution. For instance, the work of Freitas et al [76] used a system mostly composed of ethanol, which might allow the LPIP determination of a wider range of NPs (including some less polar extracts) using water-soluble radical initiators (such as AAPH) or transition metals.…”