Constituents of Polygala flavescens ssp. flavescens and their activity as inhibitors of human lactate dehydrogenase

Four new flavonol glycosides (1-4), two oligosaccharides (5-6), one α-ionone (7), and three triterpenoid saponins (8-10), together with four known secondary metabolites (11-14), were isolated from the aerial parts of Polygala flavescens ssp. flavescens. All structures were elucidated on the basis of their spectroscopic and spectrometric data. The isolates were assayed for their inhibitory activity against isoform 5 of human lactate dehydrogenase and compound 11 (3,6'-di-O-sinapoylsucrose) showed an IC50 value of 90.4 µM. Modeling studies were carried out to suggest the putative interaction mode of compound 11 in the enzyme active site.