Alstomairines D-G: New monoterpenoid indole alkaloids with cytotoxic activity from Alstonia mairei

The chemical constituents of the roots and stems of Alstonia mairei were investigated, leading to the isolation of twenty-four monoterpenoid indole alkaloids (MIAs), 1-24, including four new compounds, alstomairines D-G (1-4). The structures were elucidated based on NMR spectroscopic techniques, mass spectrometry, ECD spectrum calculations, single-crystal X-ray diffraction and comparison with the literature. Among the known compounds, the spectroscopic data of 19-O-acetylhorhammericin (5) was reported in detail for the first time. Moreover, the cytotoxic activities of the isolates were evaluated. The results indicated that compounds 1, 2, 4-7, and 11-19 exhibited cytotoxicity against A549 lung cancer cells tested with IC50 values in the range of 5.6-77.1 mu M. Especially, compounds 2, 6, 7, 14, 17, and 19 exhibited potent inhibitory activities against A549 lung cancer cells with IC50 values ranging from 5.6 to 13.1 mu M. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the chemical constituents of Alstonia mairei and isolated twenty-four monoterpenoid indole alkaloids. Four new compounds were discovered. The structures of these compounds were characterized using various techniques. The cytotoxic activities of the isolated compounds were evaluated, and several compounds demonstrated potent inhibitory activities against A549 lung cancer cells.