Quantification of Rosmarinic Acid Levels by near Infrared Spectroscopy in Laboratory Culture Grown Spearmint Plantlets

A method for the rapid quantification of rosmarinic acid (RA) in tissues of spearmint using near infrared (NIR) spectroscopy was developed by correlating with the results of methanol extracts analysed on an HPLC photo-diode array (PDA) system. NIR and HPLC analyses performed on over 500 samples were used to develop an NIR analytical algorithm. Applying this algorithm resulted in very good calibration statistics for the prediction of RA concentrations in dried powdered samples prepared from the cultured mints (r 2 = 0.90, SEP=3.1 RPD = 2.6). NIR can be used to rapidly and accurately quantitate the levels of this secondary metabolite in plant samples. High positive correlations occur between CO 2 levels and spearmint plantlet growth (fresh weight), morphogenetic responses (leaves, roots and shoots) and production of the secondary metabolite rosmarinic acid.