Euchrestifolines A–O, fifteen novel carbazole alkaloids with potent anti-ferroptotic activity from Murraya euchrestifolia

Fifteen novel carbazole alkaloids, euchrestifolines A–O (1–15), were obtained from Murraya euchrestifolia. Their structures were elucidated by spectroscopic analysis, Mosher’s ester, calculated ECD, and transition metal complex ECD methods. Notably, euchrestifolines A–C (1–3) are the first naturally occurring pyrrolidone carbazoles to be identified, while euchrestifolines D–F (4–6) represent rare carbazole alkaloids containing a phenylpropanyl moiety; euchrestifoline G (7) features a unique benzopyranocarbazole skeleton. More importantly, these compounds exhibited significant anti-ferroptotic activity, along with inhibitory effects of nitric oxide (NO) production and notable cytotoxicity. This study marks the first disclosure of carbazole's inhibitory effects against ferroptosis, and the EC₅₀ values of some carbazoles ranging from 0.04 to 1 μM, substantially lower than the positive control, ferrostatin-1. In sum, this research not only enhances our understanding of carbazole alkaloids but also opens new avenues for the discovery of ferroptosis-related leading compounds.

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