Diterpene and flavonoid constituents of the newly identified Australian species Olearia fulgens

The phytochemistry and antimicrobial activity of the newly identified Australian plant Olearia fulgens A.R.Bean was examined. Antimicrobial TLC bioautography-guided isolation followed by NMR spectroscopy was used to identify the known compounds 8-O-β-D-xylopyranosyl-ent-8β-hydroxylabdan-15-oic acid (1) and pinocembrin (7), and new compounds 8-O-β-D-xylopyranosyl-ent-labdan-8β,15-diol (2) and ent-15-hydroxyclerod-3-en-17-oic acid (4a). Compounds without apparent activity in TLC bioautography included the previously undescribed ent-clerod-3-en-15,17-dioic acid (3a) and ent-cleroda-3,13-dien-15,17-dioic acid (5a), as well as known ent-8β-hydroxylabdan-15-oic acid (6) and penduletin (8). This is the first phytochemical and antibacterial study on this species of Olearia, showing it to be an abundant source of ent-labdanes and ent-clerodanes.