Quantitative HPLC Analysis of Rosmarinic Acid in Extracts of Melissa officinalis and Spectrophotometric Measurement of Their Antioxidant Activities

Abstract

The students prepare tea samples using different quantities of lemon balm leaves (Melissa officinalis) and measure the rosmarinic acid contents by an HPLC–DAD method. The antioxidant properties of the tea samples are evaluated by a spectrophotometric method using a radical-scavenging assay with DPPH· (2,2-diphenyl-1-picrylhydrazyl). Finally the students are asked to correlate the measured antioxidant properties of the different teas with their contents in rosmarinic acid.