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

Abstract

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