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

Abstract

Thymus x citriodorus is a Lamiaceae plant extensively cultivated in the Mediterranean region and used for centuries in culinary and in traditional medicine. The present work describes the detailed phenolic composition of T. x citriodorus for the first time, by means of HPLC-DAD, ESI-MS and MS n and nuclear magnetic resonance (NMR) analyses. The ethanolic extract of T. x citriodorus was analyzed by reversed phase HPLC. The method of analysis was also validated concerning its linearity, instrumental and method precision (for repeatability, immediate precision and intermediate precision) and accuracy (absolute recovery study). The technique was combined with electrospray mass spectrometry in order to identify the phenolic compounds and the structure of the main phenolics was also confirmed by NMR analysis. The in-house validated HPLC-DAD method showed good linearity for the tested reference compounds as well as satisfactory repeatability and immediate precision values, for both instrument and method. Furthermore, the satisfactory results of intermediate precision analysis and recovery assays indicated that the chromatographic method could be used to quantify the main phenolic compounds of T. x citriodorus with adequate precision and accuracy. The extract was rich in rosmarinic acid (10.4 ± 0.6 mg/g extract) that is a widespread phenolic acid in Thymus plants, but also in luteolin-7-O-α-glucuronide (12 ± 2 mg/g extract), that was herein reported in Thymus for the first time. Other novel compounds comprised one eriodictyol dihexoside with O-glycosidic linkages, two eriodictyol-O-monohexosides, one quercetagetin dimethyl ether-O-hexoside, one naringenin-O-hexoside and chrysoeriol-7-β-O-glucoside. Having in mind the health-promoting properties reported in literature for some of the main polyphenols found in T. x citriodorus, we suggest that this plant has a high potential for being used as a functional food.

Dietary-flavonoid-rich flowers ofRumex nervosusVahl: Liquid chromatography with electrospray ionization tandem mass spectrometry profiling and in vitro anti-inflammatory effects

“…*indicates a statistical difference from the control (P < 0.05). level might be attributed to a matrix effect during the extraction process in addition to the relatively low concentration in case of naringenin [37]. The validation results indicated that the method was reliable for quantification of flavonoids in the plant sample.…”

Influence of seasonal variation on Thymus longicaulis C. Presl chemical composition and its antioxidant and anti-inflammatory properties

“…(Koukoulitsa et al, 2006;Pereira et al, 2013). The mass spectrum showed the [M-H] À ion at m/z 387 which provided the ion at m/z 207 as base peak.…”

“…The molecule has recently been reported as a component of Thymus x citriodorus (Pereira et al, 2013) and identified by 1D and 2D NMR spectroscopic techniques in Thymus sipyleus subsp. sipyleus var.…”

Bioassay guided screening, optimization and characterization of antioxidant compounds from high altitude wild edible plants of Ladakh

“…The mass difference of m/z 14 between deprotonated molecules of 4 and 2 indicated that compound 4 could be the methyl ester derivative of RA. As, both the compounds were present in excess, they were isolated by semi-prep HPLC and were characterized by comparing 1 H and 13 C NMR data with the reported literature data and were unambiguously identified as rosmarinic acid and methylrosmarinate (Pereira et al 2013).…”