2.2. General information for chemical procedures.

ChlA-F with purity over 99% was prepared according to the developed protocol (see Patent ZL201310034985.5 and PCT/CN2014/071751). All the reactions were performed under argon atmosphere using flame-dried glassware unless otherwise noted. Dichloromethane (DCM) was treated as anhydrous solvents prior to use. All reagents were commercial available and used without further purification unless indicated otherwise. Flash Chromatographies were performed with 300–400 mesh silica gels. Thin layer chromatographies (TLC) were carried out on GF254 plates (0.25 mm layer thickness). Visualization of the developed chromatogram was performed by fluorescence quenching or by ceric ammonium molybdate. Yields reported were for isolated, spectroscopically pure compounds. High-resolution mass spectra (HRMS) were taken on a VG Auto Spec-3000 or on a Finnigan MAT 90 instrument. Optical rotations were measured with a Horiba SEPA-300 polarimeter. ¹H–NMR and ¹³C–NMR experiments were performed on a Bruker AM-300 NMR spectrometer at ambient temperature. Chemical shifts were given in δ with TMS as internal reference.

Cheliensisin A was isolated as white crystal with purity more than 99.0% from Goniothalamus cheliensis according to the previously reported procedure [28].

(7S,8R)-7- Hydroxyl −8-fluoro cheliesisin A

To a solution of cheliensisine A (548 mg, 2 mmol) in DCM (5 mL) at −78oC under N2 was added a solution of BF3·OEt2 (202 µL) in DCM (3 mL) dropwise. The mixture was stirred at this temperature for 0.5 hour until no starting material was detected. The mixture was quenched by a saturated aqueous NaHCO3 solution. The aqueous phase was extracted with dichloromethane (30 mL×3). The combined organic layers were washed with brine, dried over anhydrous Na2SO4 and concentrated. The crude product was purified by flash chromatography on silica gel (ethyl acetate/petrol ether = 1:1.5) to afford ChlA-F as a white foam (312 mg, 53%). High-resolution electrospray ionisation mass spectrometry (m/z): calculated for C15H15FO5Na [M+Na]+, 317.0801,found 317.0795.

For performing the in vitro experiments, ChlA-F was dissolved in Dimethyl sulfoxide (DMSO, Sigma-Aldrich Corporation, USA, 67–68-5) to make a stock concentration at 8 mM. It was the further diluted in DMEM/Ham’s F12 medium with final DMSO concentration at 0.1% (v/v) for cell culture experiments. The same amount of DMSO was used as a vehicle control in all experiments.