Uncinatic acids A-C, three new carboxylated flavonoids from Selaginella uncinata

Three new carboxylated flavonoids, uncinatic acids A-C (1-3), were isolated from the whole herb of Selaginella uncinata. Their structures were established on the basis of extensive NMR analysis including 1D, 2D NMR experiments and HR-ESIMS techniques. All of them share the carboxylation structural characteristic. Compounds 1 and 2 belong to novel naturally occuring furanoflavonoids which is firstly reported in genus Selaginella. Such furanoflavonoids with dicarboxylic acid structrure have never been discovered before. In addition, the isolates were tested for their cytotoxicity against A549 and BGC-823 cell lines in vitro. (C) 2017 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.