Table 5.

Antioxidant activity of essential oil of Isodon rugosus at various concentrations.

Test sample	Free radicals	Conc. 62.5 μg/ml	Conc. 125 μg/ml	Conc. 250 μg/ml	Conc. 500 μg/ml	Conc. 1,000 μg/ml	IC50 μg/ml
EO	DPPH	33.00 ± 1.15***	41.33 ± 0.88***	46.33 ± 0.33***	56.67 ± 0.67***	63.67 ± 1.20***	338
EO	ABTS	39.67 ± 1.76***	51.00 ± 0.57***	56.67 ± 1.20***	62.00 ± 0.57***	64.33 ± 0.88***	118
A.A	DPPH	77.33 ± 0.88	79.67 ± 0.88	83.00 ± 1.73	86.33 ± 1.45	89.00 ± 1.73	<62.5
A.A	ABTS	75.00 ± 0.57	78.00 ± 1.15	81.67 ± 0.67	85.67 ± 0.33	91.33 ± 0.88	<62.5

EO, Essential oil; A.A, Ascorbic acid.

^***P < 0.001.