Antimicrobial activity of some Australian plant species from the genus Eremophila

Abstract

Plant species of the genus Eremophila (Myoporaceae) are native to Australia and are known to produce a diverse range of unusual secondary compounds. The purpose of this research was to examine the antimicrobial activity of 72 Eremophila species most of which had not been the subject of any previous pharmacological testing. Organic extracts of Eremophila species were screened for antimicrobial activity against Gram-positive and Gram-negative bacteria and yeasts of medical importance. Extracts of a number of Eremophila species showed selective activity against Gram-positive bacteria with MICs for the most active species in the range of 16 to 62 microg/ml for Streptococcus species, and 62 to 250 microg/ml for standard strains of Staphylococcus aureus. Extracts with the greatest activity against standard strains were tested against 68 clinical isolates of multi-resistant methicillin-resistant S. aureus (mMRSA). The majority of the clinical isolates were susceptible to concentrations below 62.5 microg/ml for the extracts of E. drummondii, E. linearis, E. serrulata, E. acrida, E. neglecta, E. virens and a new undescribed species affiliated with E. prolata. The extract of E. virens inhibited growth of all 68 clinical mMRSA isolates at the minimum tested concentration of 31 microg/ml. This study has shown for the first time that a number of different Eremophila species manifest selective antibacterial activity against Gram-positive organisms which are important causes of human disease. It shows that there are several Eremophila species possessing interesting antibacterial activity besides those that have published traditional use. These may yield novel antibacterial compounds with potential to be used in biomedical applications.

Antibacterial spectrum and cytotoxic activities of serrulatane compounds from the Australian medicinal plant Eremophila neglecta

“…A broth microdilution assay was used to determine the MICs of serrulatane compounds against Gram‐negative and Gram‐positive strains based on previously published methods (Ndi et al. 2007a,c).…”

“…The interesting antibacterial activity of crude Eremophila extracts against Gram‐positive bacteria including antibiotic‐resistant strains (Palombo and Semple 2002; Ndi et al. 2007a) has led different groups to examine the active antibacterial components of these extracts.…”

Antimicrobial Properties of 8-Hydroxyserrulat-14-en-19-oic Acid for Treatment of Implant-Associated Infections

“…The large Australian plant genus Eremophila (Myoporaceae), of which a few species have been traditionally used by Aborigines to treat various ailments (9), is native to arid areas of Australia and produces unique secondary metabolites, among others nine classes of diterpenoids, including the most commonly occurring serrulatanes (10). Screening of organic extracts of Eremophila species revealed a selective effect against Gram-positive bacteria (11).…”

Policy lessons from practice: Australian bush products for commercial markets

“…To the surprise of many Aboriginal people with traditional connections to this genus, the chemistry of most Eremophila species has been investigated. Many species have been tested for their active ingredients by Australian and international scientists and findings are in the public domain (for example Ghisalberti 1994;Grice et al 2003;Ndi et al 2007;Owen and Palombo 2007;Pennacchio et al 1995).…”