Antioxidant and Anticholinesterase Activities of Some Dialkylamino Substituted 3-Hydroxyflavone Derivatives.

BACKGROUND: Flavones, are a class of naturally occuring polyphenolic compounds which have 2-phenylchromen-4-one structure. Various studies showed that flavones have several pharmacological activities such as antioxidant, anti-inflammatory, antimicrobial, cytotoxic, antitumour and antiallergic. In the present study, 3-hydroxyflavones also called flavonols, posessing 4'-dialkylamino moiety were synthesized, and their antioxidant and anticholinesterase activities were investigated by comparison with unmodified 3-hydroxflavone. METHOD: For investigation of antioxidant potential, radical scavenging assays (DPPH•, ABTS+_, O2.-) were used along with CUPRAC and lipid peroxidation inhibitory assays, as well as anticholinesterase activity by Ellman method. RESULTS: The best results were obtained for 4'-N,N-dimethyl flavonol (1) in both antioxidant and anticholinesterase activity tests, possibly due to its least steric hinderance effect. It exhibited remarkable DPPH free radical scavenging activity (2.43±0,09 µg/mL) competing with a standard compound quercetin (2.10±0,10 µg/mL). Moreover, the other tested flavonols also showed high antioxidant activities. Compounds 5 and 6 exhibited close IC50 values to those of compound 1. CONCLUSION: Antioxidant activity test results were found to be well correlated with anticholinesterase activity test results indicating possible role of antioxidant compounds in the treatment of Alzheimer's disease.

Sequence specific recognition of ssDNA by fluorophore 3-hydroxyflavone.

A fully water soluble 3-hydroxyflavone (3HF) derivative, N-(3-hydroxy-4'-flavonyl)-N,N,N-trimethylammonium sulfate (3HFNMe3) was synthesized. Investigation of its emissions at varying wavelengths revealed that it had three emission bands of normal (N(⁎)), anionic (A(⁎)) and tautomeric (T(⁎)), in ultrapure water. Recognition of single-stranded ten ssDNA chains, having different nucleotide sequences was studied, using the ratiometric change of the intensities of the two bands (A(⁎)/T(⁎)), depending upon the varying environment of the 3HFNMe3 with different ssDNA chains. Addition of the ssDNA chains to the 3HFNMe3 solution caused gradual quenching of the A(⁎) band and had almost no effect on the T(⁎) band. As the ratios of the two bands (A(⁎)/T(⁎)) vs increasing amount of the ssDNAs generated characteristic curves for each ssDNA chain, it became possible to identify the chains with their characteristic curves.