ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Novel quercetin derivatives: synthesis and screening for anti-oxidant activity and aldose reductase inhibition

Miroslav Veverka, Ján Gallovič, Emil Švajdlenka, Eva Veverková, Naďa Prónayová, Ivana Miláčková, and Milan Štefek

Bel/Novamann International, s.r.o., 811 07 Bratislava, Slovakia

E-mail: miroslav.veverka@ba.bel.sk

Abstract: The direct acylation of quercetin (I) with 3-chloro-2,2-dimethylpropanoyl chloride (II) gives a complex reaction mixture. The synthesis of different acylated quercetin with from mono- to tetra-O-substituted functions was achieved in a simple procedure wherein the yield of isomers depended on the stoichiometric ratio of reagents. The crude reaction mixtures were analysed (LC-MS) and compared with the isolated products. Unambiguous structural characterisation of isomeric quercetin derivatives was confirmed by NMR analysis. In addition, the quercetin dimer can be obtained in a high yield in the simple procedure. The anti-oxidant activity and aldose reductase inhibition of the compounds were screened with the aim of providing bi-functional remedies to treat diabetic complications and other diseases where oxidative stress and the polyol pathway are key etiological factors.

Keywords: quercetin – acylation – naphthoquinone – quercetin dimer – LC-MS – aldose reductase

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-012-0240-5

Chemical Papers 67 (1) 76–83 (2013)