javanica Miq. flower DMSO extract was tested
at 3 doses: 0.05, 0.5 and 5.0 mg/plate (100 µl).
The major isolated compound was tested at 207
µg/plate in DMSO (100 µl). AFB1 (0.3 µg/plate
for TA 98 and TA 100) and B(a)P (10 µg/plate for
TA 98; 5 µg/plate for TA 100) were used as standard mutagens. In brief, mutagen (0.1 ml) was
distributed in sterilized capped tubes, and then
0.1 ml of tested S. typhimurium bacterial suspension from an overnight culture (1 x109 to 2 x
109 cells/ml) and 0.1 ml of Sesbania javanica
Miq. flower DMSO extracts were added. Then,
0.5 ml of S9 mix was added. The entire mixture
was pre-incubated (Matsushima et al, 1980),
while shaking, at 37ºC for 20 minutes before 2
ml of molten top agar was added, then the mixture was poured onto a minimal medium agar
plate. The plates were incubated at 37ºC for 48
hours, then the His+ revertant colonies on each
plate were counted. Each sample was assayed
using duplicate plates. The data is presented as
the mean ± standard error of the two independent assays. Plates without mutagens and without Sesbania javanica Miq. flower DMSO extracts were considered as negative controls and
plates with mutagens as positive controls. The
antimutagenicity effect is expressed as percentage of inhibition (% inhibition) =100 - (R1/R0 x
100), where R1 is the number of His+ revertant/
plate of plates exposed to mutagens and
Sesbania javanica Miq. flower extracts and the
R
0 is the number of His+ revertant/plate of the
positive controls. The number of spontaneous
revertants was substracted from the numerator
and denominator. The mutagenicity of the mutagens (positive control) in the absence of
Sesbania javanica Miq. flower DMSO extract was
defined as 0% of the inhibition. The antimutagenic effect was considered moderate when
the inhibitory effect of the Sesbania javanica Miq.
flower DMSO extract was in the range of 25-
40%, and strong when the inhibitory effect was
>40%. An inhibitory effect