Chemical and Pharmacological Potential of , an Endemic Endangered Plant from Cuba.

Britton (Polygonaceae) is an endemic and critically endangered plant that only grows in Camagüey, a province of Cuba. In this study, a total of 13 compounds were identified in a methanolic leaf extract, employing a dereplication of the UHPLC-HRMS data by means of feature-based molecular networking (FBMN) analysis in the Global Natural Products Social Molecular Network (GNPS), together with the interpretation of the MS/MS data and comparison with the literature. The major constituents were glucuronides and glycosides of myricetin and quercetin, as well as epichatechin-3--gallate, catechin, epicatechin and gallic acid, all of them being reported for the first time in leaves. The leaf extract was also tested against various microorganisms, and it showed a strong antifungal effect against ATCC B59630 (azole-resistant) (IC 2.1 µg/mL) and ATCC B66663 (IC 4.1 µg/mL) with no cytotoxicity (CC > 64.0 µg/mL) on MRC-5 SV2 cells, determined by the resazurin assay. Additionally, the extract strongly inhibited COX-1 and COX-2 enzyme activity using a cell-free experiment in a dose-dependent manner, being significantly more active on COX-1 (IC 4.9 µg/mL) than on COX-2 (IC 10.4 µg/mL). The constituents identified as well as the pharmacological activities measured highlight the potential of leaves, increasing the interest in the implementation of conservation strategies for this species.