Abstract

• The present study concerned with the determination of phytochemical constituents, nutritional values and biological activities such as antimicrobial, antioxidant, total phenol and flavonoid contents of leaves and flowers of Melastoma malabathricum L. (Nyaung-ye-o-pan, NYOP). The preliminary phytochemical results showed the presence of alkaloids, α-amino acids, carbohydrates, flavonoids, glycosides, organic acids, phenolic compounds, reducing sugars, saponins, starch, steroids, tannins and terpenoids in both leaves and flowers of NYOP. Some nutritional values such as the moisture contents (6.00 % and 8.00 %), the ash contents (7.53 % and 4.00 %), the fiber contents (13.81 % and 11.17 %), the fat contents (4.16 % and 2.44 %), the protein contents (4.55 % and 3.47 %), and the carbohydrate contents (63.95 % and 70.92 %) of leaves and flowers of NYOP were determined by using the respective methods. The screening of antimicrobial activity of crude extracts such as PE, EtOAc, EtOH and H2O indicated that antimicrobial activity with inhibition zone diameters ranged between 13 mm~25 mm in NYOP (L) and 13 mm~27 mm in NYOP (F). The NYOP (F) showed higher activity than NYOP (L). The antioxidant activity of ethanol and watery crude extracts of Nyaung-ye-o-pan leaves and flowers was investigated by DPPH free radical scavenging assay. The IC50 values of NYOP (L) watery and ethanol crude extracts were17.14 μg/mL and 15.91 μg/mL, respectively, and those of NYOP (F) watery and ethanol extracts were 35.39 μg/mL and 21.95 μg/mL. Since the lower IC50 values, the higher antioxidant activity of the samples occurs. Thus, the ethanol extract of NYOP (L) was greater antioxidant activity than that of NYOP (F) whereas watery extract of NYOP (F) was greater than that of NYOP (L). The total phenolic contents in watery and ethanol extracts of NYOP (L) and (F) were found to be 416.2 and 212.2; 320.7 and 195.9 mg of GAE/g of extract respectively. Among these, watery extract of NYOP (L) contained the highest phenolic content. The total flavonoid contents in watery and ethanol extracts of NYOP (L) and NYOP (F) were 88.9 and 114.4; 125.6 and 112.2 mg of QE/g of extract respectively. Among these, watery extract of NYOP (F) has highest flavonoid content.