Crotalionosides A-C, three new megastigmane glucosides, two new pterocarpan glucosides and a chalcone C-glucoside from the whole plants of Crotalaria zanzibarica.

From a 1-BuOH-soluble fraction of the MeOH extract of the leaves of Crotalaria zanzibarica collected in the Okinawa Islands, three new megastigmane glucosides, named crotalionosides A-C, two new pterocarpan glucosides and a chalcone C-glucoside were isolated together with two known flavonoid glycosides and one known megastigmane glucoside. The structures of the new compounds were elucidated by a combination of spectroscopic analyses. The absolute configurations of allenic megastigmane glucosides were determined by application of the modified Mosher's method. Those of the allenic moieties were determined by interpretation of the circular dichroism (CD) spectra of the reduction products derived from citrosides A and B. The aglycones of pterocarpan glucosides were found to be melilotocarpan B and the absolute structure of the chalcone C-glucoside was determined by comparison of the CD spectral behavior with the reported values.