Table 2.

FRAP units, trolox equivalent, and gallic acid equivalent obtained for a selected group of terpenes via FRAP assay modified by the addition of Tween 20.

Terpenes	FRAP Units (Fe2+ µg·mL−1)		Trolox Equivalent (µg·mL−1)		Gallic Acid Equivalent (µg·mL−1)
	0.1 M	1 mg·mL−1	0.1 M	1 mg·mL−1	0.1 M	1 mg·mL−1
γ-terpinene *	-	1.38 (for 0.25 mg·mL−1)	-	7.51	-	1.04
citral	3.21	1.04	7.43	2.52	1.03	0.32
Carvone **	False-positive results	0.28	False-positive results	0.83	False-positive results	0.08
α-phellandrene	2.47	1.45	5.74	3.45	0.79	0.45
α-terpinene ***	-	5.75 (for 0.1 mg·mL−1)	-	13.09		1.84
isopulegol	0.38	0.01	1.06	0.05	0.11	0.01
linalool	0.34	0.09	0.96	0.40	0.09	0.01
α-pinene	False-positive results ****
farnesene	clouding/lack of color
eucalyptol	clouding/lack of color
terpinene-4-ol	clouding/lack of color
p-cymene	clouding/lack of color
β-myrcene	clouding/lack of color
citronellal	clouding/lack of color
menthol	clouding/lack of color

* γ-Terpinene: This terpene revealed high activity at a concentration of 0.1 M and 1 mg·mL⁻¹, for which absorbance was >3.000. The measurements were performed at a concentration of 0.25 mg·mL⁻¹. ** Carvone: Measurements were performed at a concentration of 0.5 mg·mL⁻¹. *** α-Terpinene: This terpene exhibited high activity at a concentration of 0.1 M and 1 mg·mL⁻¹, for which absorbance was >3.000. The measurements were performed at a concentration of 0.1 mg·mL⁻¹. **** False-positive results: This effect was observed for probes with the blue color but clouding appeared simultaneously.