Novel Fluorescent Pyxinol-Based Probes: Design, Synthesis and Biological Evaluation

Pyxinol ((20S, 24R)-epoxydammarane-3 beta, 12 beta, 25-diol), the 24R-ocotillol type sapogenin, shows the well protective activity against myocardial ischemia-reperfusion injury (MIRI) and is the main metabolite of 20(S)-protopanoxadiol. To build up the pyxinol fluorescent probes retaining the original biological activity, the linkers with different physical properties were designed to connect the fluorescein isothiocyanate (FITC, the common fluorescent dyes) to pyxinol to reduce the steric interference of bulky fluorescent group and pyxinol. The synthesized fluorescent probes were evaluated the in vitro anti-MIRI activity using H9C2 cardiac myocytes. The results showed that the molecular fluorescent probe with hydrophilic flexible polyethylene glycol (PEG) linker retained the anti-MIRI activity of pyxinol. The first synthesis of active molecular fluorescent probe will provide the key molecular tool for studying biological activity mechanism of pyxinol and other ginsenosides.