Determination of antioxidant properties of Melissa officinalis

Phenolic compounds are aromatic bioactive organic compounds containing aromatic rings and hydroxyl groups, which provide protection against environmental stresses and support structural integrity in plants, and stand out with their strong antioxidant, anti-inflammatory and antimicrobial effects in human health. Various studies suggest that Melissa officinalis L has a high amount of antioxidant activity thanks to its chemical compounds containing high amounts of flavonoids, rosmaric acid, gallic acid, phenolic contents. M. officinalis L (Lamiaceae) is popularly used for digestive, carminative, antispasmodic, sedative, analgesic, tonic and diuretic properties as well as functional gastrointestinal disorders. This thesis was carried out to determine the antioxidant properties of M. officinalis. In this study, the antioxidant properties of the samples obtained from Turkey and Cyprus were determined by various solvent and extraction methods. In order to determine the antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS ) radical scavenging effect were analysed. Phenolic and flavonoid compounds were determined as total phenolic and flavonoid content by spectrophotometric methods. According to the results obtained at the end of the study, total phenolic compound content was highest in Cyprus and Turkey samples by shaking water bath extraction prepared with ethyl acetate solvent. In the determination of DPPH radical scavenging power, it was observed that the shaking water bath method was more efficient for the samples. In Cyprus samples prepared at 1000 µg/mL concentration, methanol solvent (90.83 ± 0.21 µg/mL) was more efficient, while ethyl acetate solvent (90.41 ± 0.14 µg/mL) showed higher activity in Turkey samples. All Turkish and Cypriot samples of M. officinalis prepared with different methods and solvents at a concentration of 1000 µg/mL were found to have very high ABTS radical scavenging properties. The data obtained showed that methanol shaking water bath extracts prepared for Cyprus (92.5% ± 0.13 µg/mL) and Turkey (92.96% ± 0.26 µg/mL) samples had the highest activity. The extracts of M. officinalis prepared by different methods and solvents were analysed by LC-MS/MS and the types and quantities of phenolic compounds were determined. According to the results obtained, M. officinalis plant was found to have Protocatechuic Acid, Caffeic Acid, Siringic Acid and Jaseosidin compounds. In addition, good content of jasmonic acid, salicylic acid, p-coumaric acid and trans-ferulic acid was determined.