A Comparative Study of the Phytochemicals and Antioxidant Activity of Pruned Harumanis Mango Leaves Using Microwave-Assisted Extraction

Harumanis mango is one of the best mangoes in the world, and it is only produced in Perlis, Malaysia. Pruning of the Harumanis plant is an important and routine step to maximize both the quantity and quality of the fruits. During pruning season, a lot of leaves and branches are typically discarded. The leaves can however be upcycled into a source of phytochemicals and antioxidants, and this may be used to partially offset the cost of producing the Harumanis. Therefore, in line with zero waste practice, this study examines the phytochemical content and antioxidant activity of young and matured pruned Harumanis leaves. Microwave-assisted extraction (MAE) with water as the solvent was used to extract the phytochemical and antioxidant compounds. The total phenolic compounds (TPC) and total flavonoid compounds (TFC) were then quantified, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was used to determine antioxidant activity. It was found that ground leaves sieved to a particle size of 200 mesh, a sample-to-solvent ratio of 2:50 (g/mL), and a sample size of 2 g yielded the best results for extracting antioxidants and phytochemical compounds from young and matured leaves. The matured leaves were found to contain higher TPC and TFC values (11.05 ± 1.10 mg GAE/g and 46.98 ± 0.03 mg QE/g, respectively) compared to young leaves (10.30 ± 0.03 mg GAE/g and 39.34 ± 0.05 mg QE/g, respectively). However, DPPH activity was found to be higher in young leaves compared to matured leaves (75.78 ± 0.48% and 70.52 ± 0.83%, respectively). It is concluded that both young and matured Harumanis leaves are a good source of phytochemicals and antioxidants.