Comparison of different extraction methods for the determination of α- and ß-thujone in sage (Salvia officinalis L.) herbal tea.

Salvia officinalis L. (sage) is an important industrial plant used both for food and pharmaceutical purposes. The terpene fraction of this plant is responsible for many of its therapeutic and culinary properties. We used different extraction methods Tenax TA® purge and trap, headspace (HS) solid-phase microextraction, HS sorptive extraction, and stir bar sorptive extraction to analyze the terpene fraction extracted from sage tea by GC-MS. Twenty compounds were identified, including α-, ß-thujone, and several other oxygenated monoterpenes (1,8-cineole, linalool, camphor, boneol, and bornyl acetate) and oxygenated sesquiterpenes (caryophyllene oxide, viridiflorol, humulene epoxide I, II, and III). Tenax TA® and HS sorptive extraction extracted a lower number of identified compounds, whereas HS solid-phase microextraction allowed the complete extraction of volatiles with particular reference to α- and ß-thujone. The importance of the determination of thujones content in sage herbal tea is also discussed.

Flavonoids and Phenolic Acids in Methanolic Extracts, Infusions and Tinctures from Commercial Samples of Lemon Balm.

The aim of this study was to quantify the levels of flavonoids (rutin, myricetin, quercetin, kaempferol) and phenolic acids (gallic, p-coumaric, rosmarinic, syringic, caffeic, chlorogenic, ellagic, ferulic) in lemon balm (Melissa officinalis L.) commonly used as a culinary, aromatic and medicinal herb. A rapid and reliable HPLC procedure was developed to determine the phenolic compounds in methanolic extracts, infusions and tinctures prepared from lemon balm. Except for myricetin and quercetin, as well as ellagic, gallic and rosmarinic acids, higher levels of the analytes under study were determined in the methanolic extracts (up to 22 mg/g of dry weight, DW), than in infusions (up to 5 mg/g DW). Tinctures were the poorest in flavonoids and phenolic acids (below 550 µg/g DW), except for ellagic and rosmarinic acids, which were quantified in tinctures at higher levels (mg/g DW). To sum up, the flavonoids were extracted more effectively in the infusions and tinctures than the phenolic acids. Statistically significant correlations were found between phenolic acids, possibly owing to similar biochemical pathways of the compounds. The hierarchical cluster and principal component analyses have also shown that the samples of lemon balm could be differentiated based on the levels of flavonoids and phenolic acids.

Quality consistency evaluation of Melissa officinalis L. commercial herbs by HPLC fingerprint and quantitation of selected phenolic acids.

To evaluate the quality consistency of commercial medicinal herbs, a simple and reliable HPLC method with UV-vis detector was developed, both for fingerprint analysis and quantitation of some pharmacologically active constituents (marker compounds). Melissa officinalis L. (lemon balm) was chosen for this study because it is widely used as an aromatic, culinary and medicine remedy. About fifty peaks were found in each chromatogram of a lemon balm extract, including twelve satisfactorily resolved characteristic peaks. A reference chromatographic fingerprint for the studied medicinal herb was calculated using Matlab 9.1 software as a result of analysing all the 19 lemon balm samples obtained from 12 Polish manufacturers. The similarity values and the results of principal component analysis revealed that all the samples were highly correlated with the reference fingerprint and could be accurately classified in relation to their quality consistency. Next, a quantitation of selected phenolic acids in the studied samples was performed. The results have shown that the levels of phenolic acids, i.e. gallic, chlorogenic, syringic, caffeic, ferulic and rosmarinic were as follows (mg/g of dry weight): 0.001-0.067, 0.010-0.333, 0.007-0.553, 0.047-0.705, 0.006-1.589 and 0.158-48.608, respectively. Statistical analysis indicated that rosmarinic acid occurs in M. officinalis at the highest level, whereas gallic acid in the lowest. A detailed inspection of these data has also revealed that reference chromatographic fingerprints combined with quantitation of pharmacologically active constituents of the plant could be used as an efficient strategy for monitoring of the lemon balm quality consistency.

Methods for extraction and determination of phenolic acids in medicinal plants: a review.

Phenolic acids constitute a group of potentially immunostimulating compounds. They occur in all medicinal plants and are widely used in phytotherapy and foods of plant origin. In recent years, phenolic acids have attracted much interest owing to their biological functions. This paper reviews the extraction and determination methods of phenolic acids in medicinal plants over the last 10 years. Although Soxhlet extraction and ultrasonic assisted extraction (UAE) are commonly used for the extraction of phenolic acids from plant materials, alternative techniques such as supercritical fluid extraction (SFE), and accelerated solvent extraction (ASE) can also be used. After extraction, phenolic acids are determined usually by liquid chromatography (LC) owing to the recent developments in this technique, especially when it is coupled with mass spectrometry (MS). Also detection systems are discussed, including UV-Vis, diode array, electrochemical and fluorimetric. Other popular techniques for the analysis of this group of secondary metabolites are gas chromatography coupled with mass spectrometry (GC-MS) and capillary electrophoresis (CE).