Investigation of chemical contents and biological activities of lemon balm (Melissa officinalis L.) plant

In this study, the antioxidant, antimicrobial, phenolic compound, and essential oil profiles of Melissa officinalis L. were evaluated with a holistic approach. The plant material was first subjected to extraction using methanol, and its antioxidant capacity was analyzed by various spectrophotometric methods. The total phenolic content was determined as 7.78±0.43 mg GAE/g, and the total flavonoid content as 5.09±0.06 mg quercetin/g. These values demonstrate the high phenolic content and associated antioxidant potential of lemon balm. The IC₅₀ value of 0.91 mg/mL as a result of DPPH● analysis indicated that the plant has a strong radical scavenging capacity. Furthermore, FRAP and CUPRAC analyses yielded values of 0.13 μmol FeSO 4 .7H2O/g sample and 0.65 mmol TEAC/g, respectively. Antimicrobial analyses revealed that the methanolic extractive of Melissa officinalis L. exhibited MIC values ranging from 2000 to 4000 µg/mL against bacteria and yeast species. Antifungal activity was observed especially against Candida albicans and Candida krusei at 2000 µg/mL, and against Candida glabrata at 4000 µg/mL, suggesting that lemon balm may have a selective effect against yeast species. GC-MS analyses identified a total of 27 essential oil compounds; menthalactone, (Z)-anethole, pentadecanolide, isoisopulegol, menthone, and limonene were the most dominant components. HPLC-UV analysis identified only chlorogenic acid among standard phenolics, and its amount was calculated as 45.52 ppm (40.3%).