Plumbagin, a naphtoquinone present in the roots of Plumbago zeylanica, has been reported to have many beneficial effects such as antibacterial, antifungal, anticancer, antimutagenic and
antioxidant effects, but this compound has also been reported to have many side effects. Given the wide use of P. zeylanica in
traditional medicine and the various potential
therapeutic uses of
plumbagin, the present study was carried out to further elucidate the potential genotoxicity and antigenotoxicity of
plumbagin in mouse
lymphoma L5178Y cells, using the comet assay. Without affecting the cell viability,
plumbagin itself was found to induce significant DNA damage at concentrations as low as 0.25 ng/ml. When the cells were exposed to non-
DNA damaging concentrations of
plumbagin, together with
NQNO (known to interact with
DNA in many different ways) or
catechol (known to induce oxidative DNA damage),
plumbagin was found to significantly reduce the
catechol-induced DNA damage, but to be without protective effect against the
NQNO-induced damage. The fact that non-
DNA damaging concentrations of
plumbagin diminished the DNA damage induced by
catechol, provides further support for the idea that
plumbagin may act as an antioxidative agent at low concentrations.