In order to investigate the optimal microwave-assisted extraction condition of bioactive
compounds from fresh leaf and stem of Thai water spinach (TW). Bioactive compounds were
extracted with ethanol and water by microwave at 450, 600 and 850 watt for 60 seconds on
ratio of 1 to 5 (sample: solvent). Phytochemical screening, total flavonoid content (TFC) and
DPPH-radical scavenging activity of the extracts were determined. The highest yield was
found in ethanolic extract of leaf at 600 watt (1.58%). From phytochemical screening test, all
samples showed positive for alkaloids, carbohydrates, terpenes, phenols, tannins and
flavonoids. The ethanolic extracts showed higher TFC than those of water extracts in all
experiment conditions. The ethanolic stem extracts showed higher DPPH radical scavenging
activity than those of aqueous extracts. While the aqueous leaf extracts were higher
scavenging activity than those of ethanolic leaf extracts. The significantly highest flavonoid
contents were found in ethanolic leaf extracted at 850 watt of power (349.69 mg QE/g dw),
whereas the highest antioxidant activity was occurred in ethanolic stem extract at highest
power (54.49 mg TEAC/g dw) (p