Origanum majorana Essential Oil Lacks Mutagenic Activity in the Salmonella/Microsome and Micronucleus Assays

Table 3

Induction of his+ revertants in S. typhimurium strains by Origanum majorana essential oil with and without metabolic activation (S9 mix).

Substance	Concentration	S. typhimurium strains
		TA98		TA97a		TA100		TA1535		TA102
		Without metabolic activation (−S9)
	—		—		—		—		—		—
Essential oil; (µL/plate)	0.0025		1.03		1.32		0.99		1.09		0.92
	0.005		0.74		1.22		1.07		1.45		0.88
	0.01		0.77		1.28		0.92		0.46		0.87
	0.02		0.53		1.03		0.73		0.92		0.60
	0.04		0.47		1.03		0.40		0.31		0.38
(µg/plate)	0.5 (4NQO)		20.68		6.66	—	—	—	—		3.54
	1 (NaN3)	—	—	—	—		4.12		72.13	—	—
With metabolic activation (+S9)
	—		—		—		—		—		—
Essential oil; (µL/plate)	0.005		1.24		1.09		0.87		1.1		0.95
	0.01		1.52		1.11		0.79		0.86		1.04
	0.02		1.01		1.14		0.75		0.83		1.02
	0.04		1.37		1.13		0.62		0.89		0.93
	0.08		1.22		1.31		0.55		0.83		0.91
(µg/plate)	1 (AFB1)		103.5		5.83		3.68	—	—	—	—
	10 (2-AF)	—	—	—	—	—	—		11.18		2.36

of revertants/plate: mean of three independent experiments SD; : mutagenic index (number of his+ induced in the sample/number of spontaneous his+ in the negative control). control: DMSO (10 µL) used as solvent for the extract. control (−S9): NaN₃ (sodium azide) to TA100 and TA1535 and 4-NQO to TA97a, TA98, and TA102. control (+S9): AFB₁ (aflatoxin B₁) for TA97a, TA98, and TA100 and 2-aminofluorene for TA102 and TA1535; ; , in relation to the negative control.