Constituents from Nauclea latifolia with Anti- Haemophilus influenzae Type b Inhibitory Activities.

Three previously undescribed indole alkaloids, named latifolianine A ( 1 ) and latifoliaindoles A and B ( 2 and 3 ), along with 10 known compounds ( 4 - 13 ), were isolated from the heartwood of Nauclea latifolia . Their structures were elucidated based on the analysis of their NMR and MS data. Latifolianine A ( 1 ) represents an unusual and unprecedented monoterpene indole alkaloid unit condensed with an ursane-type pentacyclic triterpenoid moiety. Plausible biogenetic routes toward latifolianine A ( 1 ) and latifoliaindoles A and B ( 2 and 3 ) were proposed. All the isolates were assessed in vitro for their inhibitory effects on Haemophilus influenzae . Naucleidinal ( 7 ) exhibited potent antibacterial activity (MIC value of 3.1 μg/mL) as compared to a reference drug, ciprofloxacin (MIC value of 1.6 μg/mL).