Jezananals A and B: two novel skeletal triterpene aldehydes from the stem bark of Picea jezoensis var. Jezoensis

Two novel skeletal triterpene aldehydes, jezananals A () and B () were isolated from the stem bark of Picea jezoensis var. jezoensis (Pinaceae). Their absolute stereo structures were determined to be 21β-hydroxy-3β-methoxy-16(15→14)abeo-13R,14S-serratan-15-al and the 3α-epimer, on the basis of spectral, single crystal X-ray analysis and chemical conversion. Compounds and are based on the unique 16(15→14)abeo-serratane skeleton. 3β-Methoxyserrat-14-en-21β-ol (), 3α-methoxyserrat-14-en-21β-ol (), and 14β,15β-epoxy-3β-methoxyserratan-21β-ol (), which is considered to be intermediates of compounds and , and showed strong inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) induction, while compounds and were inactive.