Seladoeflavones A-F, six novel flavonoids from Selaginella doederleinii

Six new flavonoids, seladoeflavones A-F (1-6), were isolated from the whole herbs of Selaginella doederleinii, together with one known flavonoid (7). Their structures including absolute configuration were characterized on the basis of extensive spectroscopic methods including NMR, HRMS, and electronic circular dichroism (ECD). All compounds consist of an aryl substituent at the C-3' position of naringenin or apigenin skeletons, and compounds 1 and 6 were identified as R configurations, which are uncommonly encountered in nature. A possible biosynthetic pathway was postulated. In addition, bioassay of the isolates revealed that 5-7 exhibited moderate cytotoxicity against three human cancer cell lines NCI-H460, A549, and K562 in vitro with IC₅₀ values ranging from 8.17 to 18.66μM.