Effect of selected solvents on the efficient recovery of polyphenols and the antioxidant activity of guava leaf (Psidium guajava L.) extracts

Abstract

Guava leaves (Psidium guajava L.) have been documented as a rich source of phytochemicals with potential health benefits. This study aimed to investigate the effects of selected solvents on the polyphenols content and the antioxidant activity of guava leaf (Psidium guajava L.) extracts. Ethanol 70%, methanol 70%, and hot water are selected solvents. Total phenolic content (TPC) and total flavonoid content (TFC) were determined to evaluate the efficient recovery of polyphenols. The DPPH radical scavenging ability and reducing power assays were performed to assess antioxidant activity. The TPC of tested samples was analysed to be 20-30 mg gallic acid equivalent/g dry weight (DW), and the TFC reached around 10-14 mg quercetin equivalent/g DW. Samples extracted by ethanol 70% and methanol 70% exhibited strong DPPH radical scavenging capacity with the half-maximal inhibitory concentration (IC50) values of 91.87 and 78.06 µg/ml. At a concentration of 250-500 µg/ml, samples extracted by these two solvents showed higher values than those extracted with hot water in the reducing power test. The results showed that the guava leaf extract is suggested as a potential source of natural antioxidants for applications in the functional food/pharmaceutical industry.