Betulin-3,28-diphosphate. Physico-chemical properties and in vitro biological activity experiments

Abstract

Betulin-3,28-diphosphate (BDP) obtained by phosphorylation of betulin using POCl3 has two main structural forms—BDP-1 and BDP-2—which differ in ethanol solubility, melting point, FTIR spectra, thermoanalytical characteristics and biological activity. Betulin-3,28-diphosphate and its sodium salt (Na-BDP) were characterized using 13C and 31P-NMR spectra, powder XRD experiments, as well as differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) methods. The exo-effects at 193 ± 8 ◦C for ethanol soluble BDP-1 samples (−19.7 ± 0.2 kJ·mol−1) were about three times less than for ethanol insoluble BDP-2 samples f (−70.5 ± 0.7 kJ·mol−1). The DSC curves of Na-BDP-1 and Na-BDP-2 characterized the endo-effects having a maximum at 95–112 ◦C. Water-soluble Na-BDP-1 was obtained as needle-like crystals, unlike poorly crystalline Na-BDP-2, whereas BDP-1 and BDP-2 aged with time and were isolated as amorphous substances. In vitro experiments on rats showed that compared to the control, Na-BDP-1 increased catalase and SOD activity and improved energy metabolism more effectively than Na-BDP-2.