Total Hydroxycinnamic Acids Assay: Prevalidation and Application on Lamiaceae Species

In this work, qualitative and quantitative analyses of total hydroxycinnamic acid (THA) derivatives in leaves, flowers and aerial parts of 32 Lamiaceae species were carried out. HPTLC analysis of plant material indicated rosmarinic acid as the main phenolic acid in 22 Lamiaceae plant extracts, while chlorogenic acid predominated in other 10 investigated species. Determination of THA in different medicinal plants was performed by colorimetric methods using chromogenic system of HCl-NaNO₂–Na₂MoO₄–NaOH and two standards: rosmarinic acid (R-THA procedure) and chlorogenic acid (C-THA procedure). Performance characteristics of THA assay were established, and the quality of the analytical procedures was evaluated using valuable prevalidation strategy. Good quality of the measurements at the lower analyte level, excellent resolution of blank and analyte signals, homogenous data material, ideal linear calibration and analytical evaluation functions, very low limit of detection [L _D(R-THA)?=?0.53 μg; L _D(C-THD)?=?1.75 μg] and limit of quantitation [L _Q(R-THD)?=?1.76 μg; L _Q(C-THD)?=?4.21 μg], and high precision and accuracy confirmed the high quality of investigated procedures as valuable tools in THA analysis. Application of these prevalidated, simple and rapid analytical methods revealed that the studied Lamiaceae plants differ greatly in their THA contents, ranging from 1.95 % (Acinos arvensis) to 11.03 % (Satureja subspicata). The results obtained from qualitative and quantitative analysis provided new information regarding phytochemical characterization of Lamiaceae species originating from Croatia and highlighted members of the genus Micromeria, Origanum, Melissa and Satureja as rich sources of hydroxycinnamic acids.