New diterpenoid glucosides from Siegesbeckia pubescens

Five new diterpenoids isolated from Siegesbeckia pubescens, pubesides A~E, were established as ent-2a,15,16-trihydroxypimar-8(14)-en-2-O-b-D-glucopyranoside (1), ent-15,16,19-trihydroxypimar-8(14)-en-19-O-b-D-glucopyranoside (2), b-D-glucopyranosyl-ent-15,16-dihydroxypimar-8(14)-en-19-oiclate (3), ent-2-oxo-15,16,19-trihydroxypimar-8(14)-en-19-O-b-D-gluco-pyranoside (4), ent-2-oxo-15,16,19-trihydroxypimar-8(14)-en-19-O-b-D-glucopyranoside-15,16-acetonide (5) by 1D and 2D NMR techniques.