A new stilbene from Oeceoclades maculata and chemophenetic significance

Abstract

Oeceoclades maculata Lindl. (Orchidaceae) is a terrestrial orchid species native to the African continent but widely distributed across the Americas, representing a rare example of an invasive orchid. A chemical investigation of specimens collected in Brazil led to the isolation and structural characterization of a previously unreported natural product, 2,3,2′,5′-tetramethoxy-4,3′-dihydroxy-stilbene (1), which has been named ingasine. Its structure was elucidated through 1D and 2D NMR spectroscopy, as well as HR-ESI-MS analysis. In addition to this novel compound, several previously described metabolites were identified, including cycloartane triterpenes and a phenanthrenoid. Dereplication studies allowed for the putative identification of flavonoids, stilbene, and alkaloids as the major compound classes. The antiproliferative activity of the crude extract and its fractions was evaluated against VERO cells and human cervical cancer HeLa cells. Furthermore, the chemophenetic relationships of the identified compounds within the Eulophiinae subtribe were analyzed and discussed.