Suadimins A–C, Unprecedented Dimeric Quinoline Alkaloids with Antimycobacterial Activity from Melodinus suaveolens

The suadimins A–C (1–3) from Melodinus suaveolensare the first example of monoterpenoid quinoline alkaloid dimers featuring an unprecedented carbon skeleton. Their structures and absolute configurations were established on the basis of extensive spectroscopic analyses, electric circular dichroism (ECD), and X-ray crystallography. Suadimin A showed significant antimycobacterial activity in vitro with an MIC90of 6.76 μM against the H37Rv strain of M. tuberculosis.