Bactericidal and cyclooxygenase inhibitory diterpenes from Eremophila sturtii Qian Liu a , David Harrington b , James L. Kohen b , Subramanyam Vemulpad c , Joanne F. Jamie a, * a Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia b Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia c Department of Health and Chiropractic, Macquarie University, Sydney, NSW 2109, Australia Received 19 January 2006; received in revised form 4 April 2006 Available online 8 June 2006 Abstract Two serrulatane diterpenes, 3,8-dihydroxyserrulatic acid (1) and serrulatic acid (2), have been isolated from Eremophila sturtii through bioassay-guided fractionation. These compounds inhibit the inflammation pathway enzymes cyclooxygenase 1 and 2, and exhi- bit bactericidal activity against Staphylococcus aureus. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Eremophila sturtii; Myoporaceae; Antibacterial; Cyclooxygenase; Lipoxygenase; Serrulatane diterpene 1. Introduction Eremophila R. Br. is a genus in the Myoporaceae family and is restricted to Australia (Cribb and Cribb, 1981; Ghi- salberti, 1995). Eremophila species are known to the Aus- tralian Aboriginal people as fuchsia bushes or dogwood, and are important to them as medicines (Low, 1990). These plants have been used by the Aboriginal people for colds, fever, sores, wounds, headaches, scabies, and general mal- aise (Barr et al., 1988; Latz, 1995; Cribb and Cribb, 1981). Although various biological activities such as antibacterial, antiviral, neurological, cardioactive and anti-inflammatory activities have been reported for extracts of Eremophila species (Palombo and Semple, 2001, 2002; Semple et al., 1998; Pennacchio et al., 2005; Rogers et al., 2000, 2001, 2002; Sweeney et al., 2001), only a few bioactive compo- nents have been characterised (Shah et al., 2004; Pennac- chio et al., 1996). Eremophila sturtii R. Br. (known as turpentine bush, kerosene bush, or turpentine emu bush) is a sticky shrub typically about 2 m high with narrow and cylindrical leaves and small, hairy, white, pink or mauve flowers (Latz, 1995; Cribb and Cribb, 1981). Decoctions of E. sturtii leaves have been used by the Australian Aboriginal people of the Northern Territory to wash sores and cuts (Smith, 1991). Through interviews with Murawari elders in northern New South Wales, the authors recorded a similar use of decoctions of crushed leaves of E. sturtii ‘as a disinfectant’ to treat skin infections. These medicinal uses by the North- ern Territory and New South Wales Aboriginal communi- ties suggested that E. sturtii possesses antimicrobial and/or anti-inflammatory properties. Antibacterial activity against the Gram positive bacterium Bacillus cereus has been reported for ethanol extracts of the leaves of E. sturtii at a concentration of 1 mg/ml (Palombo and Semple, 2001), but none of its bioactive compounds have been described. In this paper we report the bioassay-guided isolation and structure elucidation of two novel bioactive serrulatic acids (1 and 2) from the leaves of E. sturtii. 0031-9422/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.phytochem.2006.04.014 * Corresponding author. Tel.: +61 2 9850 8283; fax: +61 2 9850 8313. E-mail address: joanne.jamie@mq.edu.au (J.F. Jamie). www.elsevier.com/locate/phytochem Phytochemistry 67 (2006) 1256–1261 PHYTOCHEMISTRY