Yanhusanines A-F, Isoquinoline-Derived Alkaloid Enantiomers from and Their Biological Activity.

Six new pairs of isoquinoline alkaloid enantiomers, designated as yanhusanines A-F (-), were isolated from an aqueous extract of tubers. The structures of these enantiomers were elucidated via physicochemical analysis and a variety of spectroscopic methods. All compounds were resolved into their enantiomers via chiral-phase HPLC, and their configurations were determined by DP4+ NMR calculation methods, specific rotations, and comparison of experimental and calculated ECD spectra. Compounds - bear a rare 9-methyl moiety, and compound possesses a rare 1-oxa-6-azaspiro[4.5]decane core containing an -CHO group. Compounds (+)-, (-)-, (+)-, (-)-, (+)-, (-)-, (+)-, and (-)- exhibited selective inhibitory activities against human carboxylesterase (hCE2), in the IC value range of 2.0-13.2 μM.