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).