Structure-Based Molecular Networking for the Target Discovery of Oxahomoaporphine and 8-Oxohomoaporphine Alkaloids from Duguetia surinamensis.  In addition to seven known alkaloids (2, 6-11) and 1,2,4-trimethoxybenzene (1), three isoquinoline-derived alkaloids (3-5), namely, duguetinine (3), a compound based on an unprecedented oxahomoaporphine scaffold, and two new 8-oxohomoaporphine alkaloids, duguesuramine (4) and 11-methoxyduguesuramine (5), and a new asarone-derived phenylpropanoid (10) were isolated from the bark of Duguetia surinamensis. The isolation workflow was guided by HPLC-HRESIMS/MS and molecular networking-based analyses. Twenty-four known alkaloids were dereplicated from the D. surinamensis alkaloid-rich fraction network and were assigned by manual MS/MS interpretation. Their cytotoxic potential was evaluated.