Extraction and quantification of rosmarinic acid in lemon balm (Melissa officinalis L.)

Abstract

This study aimed to determine the optimal method for extracting rosmarinic acid (RA) from lemon balm using pressurized liquid extraction (PLE). Additionally, the effect of filtration during sample preparation on the concentration of rosmarinic acid (RA) was investigated. Moreover, the RA content was compared in various lemon balm samples including: commercial dried lemon balm, commercial lemon balm extract powder, company’s dried lemon balm, air-dried leaves, and fresh plants.
Two experimental designs were employed to examine the effect of different parameters, including temperature, flow rate, and solvent composition (ethanol/ water) on the yield of RA. High-performance liquid chromatography (HPLC) was used to quantify the extracted RA. The final condition for extracting RA from lemon balm using PLE were determined as (EtOH/ H2O/ formic acid) (46/ 53.9/ 0.1, v/v) for solvent ratio, 103 °C, and 30 minutes of extraction time. It was confirmed that filtration didn’t lead to a loss of RA. Lastly, the highest RA was observed in the commercial lemon balm extract powder.

Popular Abstract

Rosmarinic acid (RA) is a valuable compound found in many plants, for instance, lemon balm. It has several biological properties, such as antioxidant, anti-diabetic, and anti-spasmolytic. In this research, the purpose is to develop an extraction method to extract RA from lemon balm leaves. Temperature, extraction time, and extraction solvent composition play vital roles in extraction. In this research, it was studied under which conditions, regarding temperature, extraction duration, and solvent composition, a higher concentration of RA can be extracted.
To find the optimum extraction condition, two design of experiments (DoE) were applied. In DoE different experiments with different conditions are designed by a software, MODDE, to find out in which condition the highest amount of RA would be observed. So, temperature range 60 – 140 °C, extraction time 5 – 20 minutes and solvent composition of 0.1 % formic acid in water with various proportion of ethanol (40 - 80 %), with flow rate 2 ml/min were examined. The optimized condition suggested by the software were found at 103 °C, extraction solvent proportion of water/ formic acid/ ethanol (53.9/ 0.1/ 46, v/v) and 20 min for extraction time. However, the time was prolonged to 30 minutes to make certain the highest amount of RA was extracted. Then, different lemon balm samples, such as fresh, air-dried, freeze- dried, company’s dried and commercial dried leaves were extracted in the optimum condition and analyzed with HPLC method to discover which one contain the highest amount of RA. Moreover, there was a commercial extract powder dissolved with water/ ethanol (70/ 30 v/v) and then was analyzed with HPLC. At the end commercial extract powder had the highest amount of RA following by commercial dried leaves sample.
Prior to analyzing the extract sample by HPLC, it is passed through a tiny filter to clarify the sample. There was a question of whether the concentration of rosmarinic acid would decline during this process or not. So, RA concentrations were compared after and before filtration. But no significant difference was observed. Thus, filtration wouldn’t affect RA content.
After finding the method for extraction, different lemon balm samples were examined to check which one had the highest RA.

• author: Norouzi, Mahsa
• supervisor: Charlotta Turner
• organization: Department of Chemistry
• course: KEMR45 20231
• year: 2023
• type: H2 - Master's Degree (Two Years)
• subject: Chemistry
• keywords: Caffeic acid, Lemon balm, Pressurized liquid extraction, Rosmarinic acid, Analytical chemistry
• language: English
• id: 9132963
• date added to LUP: 2023-07-13 13:50:56
• date last changed: 2023-07-13 13:50:56