Constituents from <i>Nauclea latifolia</i> with Anti-<i>Haemophilus influenzae</i> Type b Inhibitory Activities.
Kezetas Bankeu JJ, Kenou Kagho DU, Fotsing Fongang YS, Kouipou Toghueo RM, Mba'ning BM, Tchouya Feuya GR, Boyom Fekam F, Tchouankeu JC, Ngouela SA, Sewald N, Lenta BN, Ali MS.
Three previously undescribed indole alkaloids, named latifolianine A (<b>1</b>) and latifoliaindoles A and B (<b>2</b> and <b>3</b>), along with 10 known compounds (<b>4</b>-<b>13</b>), were isolated from the heartwood of <i>Nauclea latifolia</i>. Their structures were elucidated based on the analysis of their NMR and MS data. Latifolianine A (<b>1</b>) represents an unusual and unprecedented monoterpene indole alkaloid unit condensed with an ursane-type pentacyclic triterpenoid moiety. Plausible biogenetic routes toward latifolianine A (<b>1</b>) and latifoliaindoles A and B (<b>2</b> and <b>3</b>) were proposed. All the isolates were assessed in vitro for their inhibitory effects on <i>Haemophilus influenzae</i>. Naucleidinal (<b>7</b>) 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).