Comparative analysis of Rosmarinic acid content in selected commercial samples of Melissa officinalis L. available on the Lithuanian market

Abstract

Introduction. Rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid is the predominant phenolic acid in the plants of family Lamiaceae, subfamily Nepetoidae [1]. Scientific studies have shown the antioxidant, anti-inflammatory, anti-allergic and anti-depression activity of rosmarinic acid and its containing raw materials [2]. The European Pharmacopoeia defines the quality of Melissa officinalis L. by the amount of no less that 1 % of rosmarinic acid content [3]. Implementing the Pharmacopeial methods in the laboratories complied with the accreditation standard LST EN ISO / IEC 17025: 2018 is particularly important for businesses, public authorities and the general public to have confidence in the results of testing, calibration, control or certification. Materials and methods. Four commercial samples of Melissa officinalis L. were purchased (CS1, CS2, CS3 and CS4). The HPLC method was applied from 01/2011:1447 Eur. Ph. Briefly, the 0.100 g of the powdered raw plant material sample was extracted in a water-bath under a reflux condenser for 30 min. The obtained extract was cooled and filtered into a 100 mL volumetric flask. Extracts were filtered through a 0.45 μm filter. Rosmarinic acid CRS was used as a reference material. Quantitative analysis was performed using a “Waters 2695 Alliance system” (Waters, Milford, MA, USA) with a photodiode array detector “Waters 996”. Separation was performed using “ACE” (ACT, UK) column (C18, 250 mm × 4.6 mm, particle size 5 μm). The mobile phase of the chromatographic method consisted of eluent A (phosphoric acid R, acetonitrile R, water R (1:19:80 V/V/V)) and B (phosphoric acid R, methanol R, acetonitrile R (1:40:59 V/V/V). The gradient variation consisted of: 0-20 min – 0-45% B, 20-25 min – 45-100% B, 25-30 min – 100-0% B. Eluent flow rate – 1.2 ml/min, injection volume – 20 μl. The temperature of the column was controlled and maintained at 23°C. Detection was performed at wavelength 330 nm. [...].