Sarglamides A–E, Indolidinoid–Monoterpenoid Hybrids with Anti-neuroinflammatory Activity from a Sarcandra Species

Sarglamides A-E (1-5), representing the first example of heterodimers of a trans-N-cinnamoylindolidinoid and α-phelladrene derivatives, were isolated from Sarcandra glabra subsp. brachystachys. Particularly, compounds 4 and 5 possess unprecedented cagelike 6/6/5/6/5- and 6/6/6/6/5-fused pentacyclic scaffolds, respectively. Their structures were established by spectroscopic analysis, X-ray crystallography, quantum-chemical calculations, and chemical conversions. Plausible biosynthetic pathways of 1-5 involving the coisolated enantiomers 6a and 6b were proposed. Compounds 3-7 showed inhibitory activity against lipopolysaccharide-induced inflammation in BV-2 microglial cells.