Novel Biologically Active Phenolic Polymers from Different Species of Genera Symphytum and Anchusa (Boraginaceae)

The presented special communication summarizes data concerning novel caffeic acid-derived polyether from the species of two genera (Symphytum and Anchusa) of Boraginaceae family Symphytum asperum, S. caucasicum, S. officinale and Anchusa italica and structure elucidation of its main structural element. The high-molecular fractions were isolated from crude polysaccharides by ultrafiltration on membrane filter with cut-off value of 1000 kDa. The structure elucidation of the main structural element of these fractions was carried out using C and H NMR, APT, 1D NOE, 2D heteronuclear H/C HSQC and 2D DOSY experiments. According to spectral data the main structural element of these preparations was found to be a regularly substituted polyoxyethelene, 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 from Symphytum species are methylated. In in vitro and in vivo experiments PDPGA exhibits pronounced antioxidant, anti-inflammatory, wound-healing and anticancer efficacy. 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 therapeutic agent.