Quinone moieties are present in many drugs such as
anthracyclines,
daunorubicin,
doxorubicin,
mitomycin, mitoxantrones and
saintopin, which are used clinically in the
therapy of solid
cancers. The cytotoxic effects of these
quinones are mainly due to the following two factors: (i) inhibition of
DNA topoisomerase-II and, (ii) formation of semiquinone radical that can transfer an electron to
oxygen to produce super
oxide, which is catalyzed by flavoenzymes such as NADPH-cytochrome-P-450
reductase. Both semiquinone and super
oxide of
quinones can generate the
hydroxyl radical, which is the cause of
DNA strand breaks.
1,4-naphthoquinone contains two
quinone groups that have the ability to accept one or two electrons to form the corresponding radical
anion or di-
anion species. It is probably dependent on the
quinone redox cycling that yields "
reactive oxygen species" (ROS) as well as arylation reactions, which is common to
quinones for
biological relevance. In the present review, an attempt has been made to collect the cytotoxicity data on different series of 1,4-naphthoquinones against four different
cancer cell lines that are L1210, A549, SNU-1, and K562, which were acquired by using identical method, and has been discussed in terms of QSAR (quantitative structure-activity relationships) to understand the chemical-
biological interactions. QSAR results have shown that the cytotoxic activities of 1,4-naphthoquinones depend largely on their hydrophobicity.