Inhibition of 4-nitroquinoline-1-oxide (4-NQO) genotoxicity by a probiotic strain of
Lactobacillus rhamnosus (IMC501) was assessed by the prokaryotic short-term bioassay SOSChromotest,
using Escherichia coli PQ37 as the target organism. Results showed the ability of
strain IMC501 to rapidly and markedly counteract, in vitro, the DNA damage originated by the
considered genotoxin. The inhibition was associated with a spectroscopic hypsochromic shift
of the original 4-NQO profile and progressive absorbance increase of a new peak. IR-Raman
and GC-MS analyses confirmed the disappearance of 4-NQO after contact with the
microorganism, showing also the absence of any genotoxic molecule potentially available for
metabolic activation (i.e., 4-hydroxyaminoquinoline-1-oxide and 4-nitrosoquinoline-1-oxide).
Furthermore, we have shown the presence of the phenyl-quinoline and its isomers as major
non-genotoxic conversion products, which led to the hypothesis of a possible pattern of
molecular transformation. These findings increase knowledge on lactobacilli physiology and
contribute to the further consideration of antigenotoxicity as a nonconventional functional
property of particular probiotic strains.
Probiotics, Lactobacillus rhamnosus, antigenotoxicity, 4-nitroquinoline-1-oxide