Determination of antioxidant capacity of bee balm (Melissa officinalis subsp. officinalis L.) kallus cultures stimulated with different plant growth organizations

The aim of this study is to determine the phenolic and antioxidant properties of Melissa officinalis subsp. officinalis L. calli cultured in combination with different plant growth regulator combinations in vitro. Melissa officinalis subsp. officinalis L. nodules were used as explant source. Nodules were promoted with different plant growth regulator combinations for callus formation in Murashige Skoog medium. In the resulting callus, the highest amount of phenolic substance was found in ethanol extracts with 1.523±0.117 mg GAE/g and 1.5 mg/L 2,4-D + 0.5 mg/L BAP induced callus. 1.178±0.064 mg GAE/g and the lowest phenolic substance in callus ethanol extracts in culture medium containing 2 mg/L 2,4-D + 0.5 mg/L BAP. The highest total phenolic content in callus water extracts was obtained in the medium containing 1.5 mg/L PIC + 0.5 mg/L BAP as 1.288±0.075 mg GAE/g. The lowest total phenolic content was 0.699±0.035 mg GAE/g in callus water extract at 1.5 mg/L 2,4-D + 1 mg/L PIC + 0.5 mg/L KIN medium. The amount of flavanoid was detected in callus ethanol extracts grown at 2 mg/L PIC + 0.5 mg/L BAP medium as the highest 4.392±0.368 mg quercetin/g. The amount of flavonoids was found in callus ethanol extracts at KIN of 1.5 mg/L 2,4-D + 1 mg/L PIC + 0.5 mg/L as the lowest 2.709±0.157 mg quercetin/g. The highest total flavonoid content in callus water extracts was 1.387±0.095 mg quercetin/g in combination with 1 mg/L 2,4-D + 0.5 mg/L BAP, the lowest 0.930±0.047 mg quercetin/g in 1.5 mg/L 2,4 -D + 0.5 mg/L BAP combination. Finally, the antioxidant capacity of callus was determined by the ABTS method and the results were given as "TEAC (tropoxy equivalent antioxidant capacity) equivalent". The highest antioxidant capacity was 14.61±1.14 mmol/g in ethanol extracts, 1.5 mg/L in 2,4-D + 1 mg/L PIC + 0.5 mg/L in KIN induced callus and lowest as 7.66±0.51 mmol/g in 1.5 mg/L 2,4-D + 0.5 mg/L BAP induced calli. The highest antioxidant capacity in water extracts was found to be the highest in the BBD combination of 1 mg/L 2,4-D + 1 mg/L PIC + 0.5 mg / L KIN as 9.15 ± 0.74 mmol / g, the lowest as 2.42 ± 0.14 mmol /g in 2 PIC + 0.5 mg / L BAP BBD combination. Key Words: Melissa officinalis subsp. officinalis L., callus, phenolic substance, flavonoid, antioxidan