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The phytochemical study of Cattleya intermedia (Orchidaceae) led to the isolation of two new stilbenoids and one new 9,10-dihydrophenanthrene, 4',5-dihydroxy-2',3-dimethoxy-dihydrostilbene ( 1 ), 3,6'-dihydroxy-4'-methoxy-dihydrostilbene ( 2 ) and 1,2,6-trihydroxy-3,8-dimethoxy-9,10-dihydrophenanthrene ( 3 ), named cattleymediol, cattleyol and phenanmediol, respectively, in addition to other five known compounds ( 4-8 ). The structural elucidations of the isolated compounds were carried out through the analyses of the one-dimensional 1 H, 1 ³C and NOE NMR spectra, and the 2D HSQC, HMBC, COSY and NOESY spectra, besides high-resolution mass spectrometry. In addition to this, the crude extract and its main fractions were analysed by ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-QTOF-MS/MS), leading to the putative identification of several other compounds, including flavonoids and organic acids derivatives. Finally, the main fractions of the crude extract, and the pure compounds cattleymediol ( 1 ) and lusiantridine ( 7 ), had their antiproliferative activities evaluated against human cancerous HeLa and non-cancerous VERO cells.

The phytochemical study of Laelia marginata (Lindl.) L. O. Williams (Orchidaceae) led to the isolation of a new natural product named crispoic acid (1), together with six other known compounds (2-7). The new natural product was identified as a dimer of eucomic acid and was structurally characterised based upon 1D and 2D NMR and HRMS data. Biological assays with plant crude extract, fractions and isolated compounds were performed against two human cancer cell lines (Hela and Siha), and the tropical parasites Trypanosoma cruzi and Leishmania (Leishmania) amazonensis. The phenantrenoid 9,10-dihydro-4-methoxyphenanthren-2,7-diol 2 was active against Hela and Siha cells (CC 50 5.86 ± 0.19 and 20.78 ± 2.72 μg/mL, respectively). Sub-lethal concentrations of the flavone rhamnazin 4 were not able to rescue the viability of the Vero cells infected by Zika virus.