Enantiomeric Pairs of Meroterpenoids from Rhododendron Fastigiatum

Five pairs of optically pure meroterpenoid enantiomers（1 a/1 b?5 a/5 b） and two known compounds（6 and 7） were isolated from Rhododendron fastigiatum. Compounds 1 a/1 b?5 a/5 b were resolved from naturally scalemic mixtures by chiral HPLC. Their structures were elucidated by spectroscopic methods, X-ray crystallographic experiments, and ECD analyses. Compounds 1 a/1 b, 2 a/2 b, 3 b, 4 a/4 b, and 5 a/5 b were new meroterpenoids with different polycyclic systems. Two enantiomeric pairs（2 a/2 b and 3 a/3 b）, 6, and 7 exhibited inhibitory effects on protein tyrosine phosphatase 1 B（PTP1 B） in vitro.