Table 3.

Pre-incubation method. Mean number of revertants of the different concentrations of rhubarb extract tested, the concentrations of rhubarb extract and positive controls (sodium azide, 2-aminoanthracene, 9-aminocridine and, 2-nitrofluorene and methylmethane sulphonate (MMS) are expressed in µg/plate. Values are expressed as mean ± SD, n = 3.

Strain	TA1535		TA1537		TA98		TA100		WP2 uvrA
Metabolic activation	- S9	+ S9	- S9	+ S9	- S9	+ S9	-S9	+ S9	-S9	+ S9
Untreated	16.0 ± 1.7	20.0 ± 0.3	16.7 ± 1.5	20.3 ± 0.3	32.3 ± 3.0	40.3 ± 2.4	124.3 ± 2.4	132.0 ± 2.6	28.0 ± 1.2	34.0 ± 2.0
Test item (μg/plate)
vehicle	18.0 ± 0.6	15.0 ± 0.6	19.7 ± 0.3	19.3 ± 0.3	35.7 ± 0.9	41.0 ± 2.0	136.7 ± 1.9	129.3 ± 4.1	25.7 ± 1.8	36.7 ± 0.9
313	15.3 ± 1.5	20.7 ± 0.7	19.0 ± 2.5	22.7 ± 0.9	32.3 ± 0.9	39.0 ± 0.6	142.0 ± 5.0	125.7 ± 3.5	24.0 ± 0.0	34.0 ± 0.6
625	20.3 ± 1.3	18.3 ± 0.3	22.3 ± 1.2	22.3 ± 0.9	37.7 ± 0.9	33.3 ± 1.3	145.3 ± 4.7	125.7 ± 6.0	33.7 ± 0.9	29.7 ± 0.9
1250	16.7 ± 1.3	15.7 ± 1.2	19.3 ± 1.3	24.7 ± 2.2	35.0 ± 1.5	30.7 ± 2.6	129.3 ± 3.5	134.3 ± 3.8	30.7 ± 0.9	28.3 ± 2.6
2500	21.7 ± 1.3	18.0 ± 1.5	19.0 ± 1.7*	26.7 ± 1.5	34.0 ± 0.6	34.0 ± 2.5	122.3 ± 2.0*	131.3 ± 3.9	29.7 ± 0.3	32.0 ± 0.6
5000	18.7 ± 1.8	18.7 ± 0.9	17.3 ± 1.8**	25.3 ± 1.5	39.0 ± 0.0	38.3 ± 1.5	107.7 ± 3.2**	130.7 ± 4.5	34.3 ± 0.3	33.3 ± 0.3
Sodium azide
1	518.7 ± 34.3						657.3 ± 39.0
2-Aminoanthracene
1		103.3 ± 4.7		107.3 ± 1.5		612.7 ± 25.8		1238.7 ± 121.0
10										146.0 ± 6.7
9-Aminoacridine
50			110.3 ± 18.0
2-Nitrofluorene
2					197.7 ± 6.7
MMS
500									183.0 ± 6.4

^*Slight thinning of background lawn

^**Moderate thinning of background lawn