Position Impact of Hydroxy Groups on Spectral, Acid-Base Profiles and DNA Interactions of Several Monohydroxy Flavanones

Structure-related biological activities of flavanones are still considered largely unexplored.
Since they exhibit various medicinal activities, it is intriguing to enter deeper into their chemical
structures, electronic transitions or interactions with some biomolecules in order to find properties
that allow us to better understand their eects. Little information is available on biological activity of
flavanone and its monohydroxy derivatives in relation to their physicochemical properties as spectral
profiles, existence of protonated/deprotonated species under pH changes or interaction with Calf
Thymus DNA.We devoted this work to research demonstrating dierences in the physicochemical
properties of the four flavanones: flavanone, 20-hydroxyflavanone, 6-hydroxyflavanone and
7-hydroxyflavanone and linking them to their biological activity. Potentiometric titration, UV–Vis
spectroscopy were used to investigate influence of pH on acid–base and spectral profiles and to
propose the mode of interaction with DNA. Cyclic voltammetry was applied to evaluate antioxidant
potentiality and additionally, theoretical DFT(B3LYP) method to disclose electronic structure and
properties of the compounds. Molecular geometries, proton anities and pKa values have been
determined. According to computational and cyclic voltammetry results we could predict higher
antioxidant activity of 6-hydroxyflavanone with respect to other compounds. The values of Kb
intrinsic binding constants of the flavanones indicated weak interactions with DNA. Structure–activity
relationships observed for antioxidant activity and DNA interactions suggest that 6-hydroxyflavanone
can protect DNA against oxidative damage most eectively than flavanone, 20-hydroxyflavanone
or 7-hydroxyflavanone.