Discovery of Natural Co-occurring Enantiomers of Monoterpenoid Indole Alkaloids

Main observation and conclusion Two new pairs of monoterpenoid indole alkaloids (MIAs) enantiomers as well as their new congeners were isolated from stems of Tabernaemontana bovina Lour. (Apocynaceae). Their structures were elucidated by spectroscopic analyses and confirmed by X-ray diffractions and computational calculations. Tabovine A, tabovine B and tabovines C-D possessed unprecedented 6/5/5/6/6, 6/5/5/6/5 and 6/5/6/6/6 ring systems, respectively. It is the first time to report co-occurring enantiomers of MIAs. Additionally, the explanation concerning biogenesis of MIAs was provided. The findings would open a new window where we could disclose more diverse MIAs.

Automated summary

The study isolated two new pairs of monoterpenoid indole alkaloids (MIAs) enantiomers as well as their new congeners from the stems of Tabernaemontana bovina Lour., revealing unprecedented ring system structures and reporting co-occurring enantiomers of MIAs for the first time. It also provided an explanation for the biogenesis of MIAs, suggesting potential for further exploration and diversification of MIAs.