Cymoside, an original hexacyclic monoterpene indole alkaloid and others compounds from Chimarrhis cymosa (Rubiaceae)

"Dedicated to the memory of Pr François Tillequin"

Monoterpene indole alkaloids are a group of more than 3000 compounds, source of potent bioactives molecules. Our interest has therefore focused on the genus Chimarrhis (Rubiaceae) which has been poorly studied. Indeed, phytochemical studies deal only with the species Chimarrhis turbinata, which led to the description of some original monoterpene indole alkaloids [1]. We report here the structure determination of secondary metabolites from Chimarrhis cymosa, a tree endemic from Lesser Antilles: Cymoside (1), a strictosidine derivative with a hexacyclic-fused core, together with 10-hydroxystrictosidine (2), three known monoterpene indole alkaloids, two bis-monoterpene indole alkaloids, one well known iridoid and a novel diglycosilated iridoid (3).