Vakhtang Barbakadze
Tbilisi State Medical University, Georgia
Title: Caffeic Acid-Derived Biopolyether from Medicinal Plants as Anticancer Agent
Biography
Biography: Vakhtang Barbakadze
Abstract
A new series of linear and regular caffeic acid-derived polyether, namely poly[3-(3,4-dihydroxyphenyl)glyceric acid] (PDPGA) was isolated and identified in the water-soluble, high molecular weight fractions obtained from Symphytum asperum, S.caucasicum, S.officinale, S.grandiflorum and Anchusa italica (Boraginaceae). According to data of 13C, 1H NMR, 2D 1H/13C HSQC experiment the polyoxyethylene chain is the backbone of the polymer molecule. The 3,4-dihydroxyphenyl and carboxyl groups are regular substituents at two carbon atoms in the chain. The repeating unit of this polymer is 3-(3,4-dihydroxyphenyl)glyceric acid residue. Most of the carboxylic groups of PDPGA from A. italica and S.grandiflorum unlike the polymer of S.asperum, S.caucasicum and S.officinale are methylated. The 2D DOSY experiment gave the similar diffusion coefficient for the methylated and non-methylated signals of A. italica PDPGA. Both sets of signals fell in the same horizontal. This would imply a similar molecular weight for methylated and non-methylated polymers. The synthesis of racemic monomer of PDPGA was carried out via asymmetric dihydroxylation of trans-caffeic acid derivatives using a potassium osmate catalyst and cinchona alkaloid derivatives as chiral auxiliaries. PDPGA and monomer exerted anti-cancer efficacy in vitro and in vivo against human prostate cancer (PCA) cells via targeting androgen receptor, cell cycle arrest and apoptosis without any toxicity, together with a strong decrease in prostate specific antigen level in plasma. However, our results showed that anticancer efficacy of PDPGA is more effective compared to its synthetic monomer. Overall, this study identifies PDPGA as a potent agent against PCA without any toxicity, and supports its clinical application.