The chemical study of 11 Gabonese plant species, some being used in traditional medicine, was performed in search of antiplasmodial compounds with new structures. Two Apocynaceae (Pleiocarpa mutica Benth., Callichilia inaequalis Stapf) and a Gelsemiaceae (Mostuea brunonis Didr.) were more specifically investigated, using LC-MS/MS data in a dereplicative approach based on the “molecular networking” strategy, with an annotation performed using an “in-house” monoterpene indole alkaloids database (MIADB). This approach was used to guide the isolation of original alkaloids, in terms of substitution patterns or of linkage. From the stem bark of P. mutica, 7 previously undescribed bis-indoles were obtained: five are bis-aspidofractanes, four of them being linked by a methylene bridge (pleiokomenines A-D); Two are aspidofractane-eburnane dimers analogous to pleiomutine.The twigs and roots of C. inaequalis yielded 2 new bis-indoles analogous to criophylline, among which one is the first natural sulfate-bearing indole monoterpene. Inaequalisine A, the first monomeric indole monoterpene linked to a phenylpropene moiety by a C-C linkage was also obtained.The study of the twigs and leaves of M. brunonis lead to 4 new compounds: A monomeric sarpagine (16-epi-methylester-panarine) and 3 unknown bis-vobasines which constituting monomers are linked by a sulfide bridge (theionbrunonines A-C).Known compounds were also isolated, some of which were previously undescribed in the genera studied here. Several of the new molecules exhibited antiplasmodial in vitro activity in the micromolar range against a chloroquine-resistant strain of P. falciparum.