Antioxidative Properties of Harumanis Mango Leaves using Microwave-Assisted Extraction

Abstract. In this study, a microwave-assisted extraction technique (MAE) was used to extract antioxidant compounds from the pruned leaves of Harumanis mango with water as the solvent. The one-factor-at-a-time (OFAT) approach was used to study the effect of several important parameters in the extraction process on antioxidant activity. These parameters include particle size (200, 100, 60, 30 and <30 mesh), sample size (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 g), and sample-to-solid ratio (2:50, 2:100, 2:150, 2:200, and 2:250 g/mL). Antioxidant activity was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay (ABTS), the reducing antioxidant power assay of iron (FRAP), and the reducing power (RP) assay. The Harumanis mango leaves were found to have high antioxidant activity in all the assays tested. The optimal parameters for extraction of antioxidant properties were a particle size of 200 mesh, a sample size of 2 g, and a sample-to-solvent ratio of 2:50 (g/mL). This set of parameters resulted in the most favourable results in the DPPH, ABTS, FRAP, and RP assays. The highest values observed in the DPPH, ABTS, FRAP and RP tests are 74.9%, 95.2%, 196.6 mg/mL and 797.2 mg/mL, respectively. Based on the R2 of the kinetics model tested, power law model was the most suitable to explain the variations of the extraction process of Harumanis mango leaves using MAE.