Evaluation of extraction factors influence on total phenolic content and antioxidant activity of Melissa officinalis L. leaves extracts

Abstract

Extraction factors influence the quantity and quality of extracts. It is important to choose suitable conditions for production of valuable products. The aim of this study was to evaluate the influence of extraction factors on the quality of lemon balm extracts. Dry leaves of Melissa officinalis L. were extracted by dynamic maceration using ultrasound. Extraction factors were solvents – water and 50% ethanol; the extraction time was 5, 10, 15 and 30 min, the raw material and solvent ratio was 1:10, 1:20 and 1:30, and the particle size of dry leaves. Qualitative parameters – the amount of the total phenolic content and antiradical activity using the 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical inactivation method – were determined spectrophotometrically. The total quantity of phenolic compounds of all determinations ranged between 40.13 ± 2.0 and 78.49 ± 3.9 mg of rosmarinic acid equivalents per weight of dry leaves of lemon balm. The higher amount of phenolics was extracted with 50% ethanol than with water. 1:10 ratio of leaves and solvent was most effective using ethanol as a solvent. 1:30 ratio was most effective using water as a solvent. The reduction of particle size increased the yield of phenolics over 20%. The antioxidant activity of all measurements ranged between 37.60 ± 1.9–89.48 ± 4.5% inactivated DPPH radicals. The highest antiradical activity was achieved with ethanolic extracts at 1:10 ratio after 15 minutes of sonication using a reduced particle size of leaves. The relationship between the total content of phenolics and antiradical activity was evaluated and the correlation was not determined.