Epicatechocorynantheines A and B, and epicatechocorynantheidine were isolated from the stem bark of Corynanthe pachyceras. These molecules were pinpointed, and their isolation streamlined, by a molecular networking strategy. The structural elucidation was unambiguously accomplished from HRMS and 1D/2D NMR data. These compounds represent the first examples of corynanthean-type alkaloids tethered with a flavonoid. Epicatechocorynantheidine notably instigated two connections between the monoterpene indole alkaloid and the flavonoid, yielding an unprecedented octacyclic appendage. These flavoalkaloids exerted moderate antiplasmodial activities.
We herein report on the first chemical assessment of Erythrococca anomala
(Juss. ex Poir.) Prain (Euphorbiaceae), a genus that was – to the best
of our knowledge – not studied yet from a phytochemical perspective. A
molecular networking strategy was implemented to rapidly identify the known
specialized metabolites from untargeted MS/MS analyses of E.
anomala leaves ethanolic extract. This strategy allowed for the
identification of diverse C-glycosyl flavones and a cursory examination
of MS/MS spectra could extend the GNPS-provided annotation to pinpoint
the structural novelty of further derivatives. The isolation of the sought-after
structures could be streamlined based on MS-guidance and their structures,
determined through extensive NMR analyses, displayed structural features in line
with MS²-based predictions. Anticipating sharp structural features at an
early stage of the dereplication process through a critical assessment of the
tandem mass spectrometric landmarks was essential to embark on the isolation of
the newly reported structures owing to the elevated number of flavonoid
glycosides isomers thereof formerly known, which would have deterred us from
isolating them without the support of additional tandem mass spectrometric
information. The isolation of the main components of the ethanolic extract
completed the currently provided chemical report on E. anomala, also
resulting in the description of a new phenylethanoid derivative (3) and
of a new orcinol-based dimer (4). Anomaloflavone (1) exhibit
significant activities with minimal inhibitory concentration values of
25 µg/mL against Staphylococcus aureus and
Mycobacterium smegmatis while failing to exert an antibacterial
activity against Pseudomonas aeruginosa, while being devoid of
cytotoxicity against SiHa cells.
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