MODE OF BINDING OF QUERCETIN TO DNA

The difference spectrum of the quercetin-DNA, complex versus quercetin alone was characterized by a peak at 395 mm. An increase in the magni tude of difference spectrum was seen with increased ionic strength. Sp ectrophotometric changes in absorbance and fluorescence of quercetin s howed that ethidium bromide is able to displace quercetin from the que rcetin-DNA complex. These results indicate that the binding of quercet in to DNA does not involve electrostatic interactions but may be inter calative in nature. Experiments using DNase I footprinting technique s howed that the flavonoid does not possess any preferred sites of bindi ng in DNA. Strand scission in DNA by the quercetin-Cu(II) system gave a generally uniform cutting pattern of internucleotide bonds. This led to the observation that the quercetin-Cu(II) cleavage reaction has th e potential of being used as preferred DNA footprinting reagent.