This study aimed to evaluate the antioxidant and antibacterial activities of some plants collected in Kien
Giang province, Vietnam. The antioxidant property was determined for their antioxidant activity by DPPH,
ABTS●+, RP và TAC methods in vitro. The results showed that the ethanolic extract of Artemisia vulgaris
displayed in vitro antioxidant activities with its IC50 (half maximal inhibitory concentration) values of
734.323 µg/mL, 43.871 µg/mL, 185.32 µg/mL and 62.714 µg/mL, respectively. Antioxidant assay identified
that, the ethanolic extract of Costus speciosus exhibited DPPH scavenging with IC50 of 1158.24 μg/mL in
comparison with the extract of Pouzolzia zeylanica expressing IC50 at an amount of 1034.55 μg/mL.
However, antioxidant capacity of Costus speciosus was approximately 2.85 times higher than that of
Pouzolzia zeylanica in TAC method. Total phenolic and flavonoid contents of Artemisia vulgaris extract
reached the highest at 103.8 mg GAE/g and 287.65 mg QE/g, respectively. These findings concluded that
Artemisia vulgaris is a very potential herb containing natural antioxidant compounds.
Keywords: antioxidant, Artemisia vulgaris, Costus speciosus, Pouzolzia zeylanica.