Peraksine derivatives with potential anti-inflammatory activities from the stems of Rauvolfia vomitoria

Five new peraksine derivatives rauvomine C-G (1-5) along with four known analogues (6-9) were isolated from the stems of Rauvolfia vomitoria Afzel. (Apocynaceae). Structural determinations of the new monoterpene indole alkaloids were elucidated via comprehensive spectroscopic analyses and ECD calculations. Rauvomine C (1) with an unprecedented framework type represents the first example of C₁₈ peraksine-type nor-monoterpene indole alkaloid featuring a chlorine atom at C-16 and its plausible biosynthetic pathway was also proposed. All the isolates were evaluated for their anti-inflammatory, cytotoxic, and acetylcholinesterase inhibitory activities. Among them, the new framework alkaloid rauvomine C (1) showed significant anti-inflammatory activities on NO production in LPS-induced RAW264.7 mouse macrophages with IC₅₀ value of 10.76 μM. Additionally, peraksine-type alkaloids featuring pyran ring (5, 8, and 9) exhibited potential anti-inflammatory activities with IC₅₀ values ranging from 17.52 to 20.99 μM.

Keywords: Anti-inflammatory activity; Apocynaceae; Monoterpene indole alkaloids; Peraksine derivatives; Rauvolfia vomitoria.