Optimization of total flavonoid content from cardamom fruits using a simplex-centroid design, along with the evaluation of the antioxidant properties

Abstract

The fruits of Cardamom (Amomum compactum Sol. Ex Maton; Zingiberaceae), commonly known as Queen species, which contained flavonoid compounds, have a variety of pharmacological properties and are used in traditional medicine. Therefore, this study aimed to employ solvent macerations to optimize the total flavonoid extraction from Cardamom fruits, as well as evaluate their antioxidant activity. The fruits were collected from a local farmer in Bogor, Indonesia, in August 2019. Then, different extraction solvents, namely water, acetone, methanol, and ethanol, alongside their binary, ternary, and quaternary combinations, were investigated using a simplex-centroid design. The optimized extracts were tested for their flavonoid content using an aluminium chloride reagent and their antioxidant activity compared by utilizing 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Water extracts showed the maximum flavonoid content of 88.01 mg/g DW with the highest reducing antioxidant activity at 1110.95 μmol TE/g DW by FRAP assay. Meanwhile, the radical scavenging activity by the DPPH method revealed the highest value for the water-ethanol binary mixture to be 153.17 μmol TE/g DW. Consequently, the water and water-ethanol are the optimal solvents for extracting cardamom flavonoid compounds with antioxidant properties.