A methanolic extract of Oroxylum indicum strongly inhibited the mutagenicit
y of Trp-P-1 in an Ames test. The major antimutagenic constituent was ident
ified as baicalein with an IC50 value of 2.78 +/- 0.15 muM. The potent anti
mutagenicity of the extract was correlated with the high content (3.95 +/-
0.43%, dry weight) of baicalein. Baicalein acted as a desmutagen since it i
nhibited the N-hydroxylation of Trp-P-2.