The isolation and structure determination of cryptomisrine, a novel indolo[3,2‐<i>b</i>]quinoline dimeric alkaloid from <i>cryptolepis sanguinolenta</i>

Abstract

Abstract The isolation and structure determination of cryptomisrine, a novel indolo[3,2‐ b ]quinoline dimeric alkaloid obtained from extracts of the roots of the Ghanaian medicinal plant Cryptolepis sanguinolenta is reported. The structure determination was made via a consideration of the spectral data, including uv, ir, nmr, and mass spectra. In particular, one‐dimensional proton/carbon nmr, one‐dimensional nOe difference nmr, and a series of homonuclear (COSY) and inverse‐detected heteronuclear two‐dimensional (HMQC, HMBC) experiments were utilized, as well as high resolution FABMS. Cryptomisrine is most unusual in that its two monomeric parts apparently exist in such a C 2 symmetric environment that only one set of proton and carbon nmr resonances are observed. Cryptomisrine is the first example of a dimeric indolo‐[3,2‐ b ]quinoline alkaloid to have been isolated from nature.