d -chiro -Inositol Derivatives with Multidrug Resistance Reversal Activities from the Fruits of Chisocheton siamensis .

Chisosiamols A-K ( 1 - 11 ), 11 new d- chiro -inositol derivatives, along with a known analogue ( 12 ) were isolated from the fruits of Chisocheton siamensis . Their planar structures and relative configurations were elucidated by the comprehensive application of spectroscopic methods, especially from the characteristic coupling constants, and 1 H- 1 H COSY spectra. The absolute configurations of the d- chiro -inositol core were determined using the ECD exciton chirality and X-ray diffraction crystallographic analytical methods. This is the first crystallographic data reported for the d- chiro -inositol derivatives. A structural elucidation strategy mainly combining 1 H- 1 H COSY correlations and ECD exciton chirality for determining the structure of d- chiro -inositol derivatives was developed, which also led to the revisions of previously reported structures. Bioactivity evaluation indicated that chisosiamols A, B, and J can reverse multidrug resistance in MCF-7/DOX cells in the IC 50 range of 3.4-6.5 μM (RF: 3.6-7.0).