V. Barbakadze, L. Gogilashvili, L. Amiranashvili, M. Merlani and K. Mulkijanyan
Plant Biopolymers, Tbilisi Medical University Institute of Pharmacochemistry, Georgia
The high-molecular fractions from the species of two genera (Symphytum and Anchusa) of Boraginaceae family Symphytum asperum, S. caucasicum, S. officinale and Anchusa italica were isolated. According to 13C, 1H NMR and 2D heteronuclear 1H/13C HSQC spectral data the main structural element of these preparations was found to be a regularly substituted polyoxyethylene, namely poly[3-(3,4-dihydroxyphenyl)glyceric acid] (PDPGA) or poly[oxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene]. PDPGA represents a new class of natural polyethers with a residue of 3-(3,4-dihydroxyphenyl)glyceric acid as the repeating unit. Most of the carboxylic groups of PDPGA from A. italica unlike the polymer of Symphytum species are methylated. Such caffeic acid-derived biopolymer to our knowledge has not been known and has been identified for the first time. According to results of in vitro and in vivo experiments PDPGA could be considered as potential antiinflammatory, wound healing and anti-cancer therapeutic agent.
PDPGA exerted anti-cancer efficacy in vitro and in vivo against androgen-dependent and -independent PCA cells via targeting androgen receptor, cell cycle arrest and apoptosis without any toxicity, together with a strong decrease in PSA level in plasma.
Overall, this study identifies PDPGA as a potent agent against PCA without any toxicity, and supports its clinical application.