Assessment of the toxicity of selected Australian native plant extracts using the Artemia franciscana nauplii bioassay
antibacterial, australian plants, medicinal plants, toxicity
I Cock. Assessment of the toxicity of selected Australian native plant extracts using the Artemia franciscana nauplii bioassay. The Internet Journal of Toxicology. 2007 Volume 5 Number 2.
Thirty nine methanolic extracts from twenty five Australian native plants were investigated for toxicity using the Artemia franciscana nauplii lethality bioassay and compared to the reference toxins potassium dichromate and Mevinphos. 7 extracts (18 %) showed marked lethality towards Artemia franciscana nauplii at 24 h, 11 extracts (28 %) at 48 h and 19 extracts (49 %) at 72 h. Of the positive controls, only Mevinphos displayed significant lethality at 24 h. Potassium dichromate treatment resulted in only approximately 10 % mortality at 24 h but induced 100% mortality by 48 h. Of the non-toxic extracts, A. aulacocarpa leaf, L. bracteata leaf, L. juniperium leaf and flower, S. australe leaf and B. celsissima leaf extracts have previously been shown to be good antibacterial agents, confirming their potential for antibiotic usage.
Financial support of this work was provided by the School of Biomolecular and Physical Sciences, Griffith University, Australia.
Plants have long been recognised as a valuable source of medicines for treating a variety of different diseases and complaints. Most, if not all civilisations, have used plants as medicines. The use of plant natural therapeutics in Asia is wide spread, being used in the treatment of numerous disorders including eczema, malaria and respiratory disorders . Africa also has a long history of medicinal plant use. For example,
As a result of its isolation, Australia has a variety of unique and distinctive flora not found elsewhere in the world. Australian Aborigines used a variety of plant medicines to help maintain their health prior to European settlement [7; 8]. More than 150 plants from nearly 60 widely varied botanical families were used by Australian Aborigines as antiseptic agents . Although there is enormous potential for the development of medicinal agents from Australian plants, much of our knowledge of the antimicrobial nature of Australian plants is anecdotal. Recent studies [9; 10; 11] have demonstrated the antibacterial and antifungal activity of extracts from a wide variety of Australian plants.
To be medically useful as antimicrobial agents, plant preparations should be non-toxic or of low toxicity to human cells . Limited information is available on the toxicity of antibacterial preparations from Australian plants. Recent studies have reported on the low toxicity of
Materials and Methods
Collection of Plant Samples
Plant samples were as previously described . Briefly,
Preparation of Crude Extracts
Plant samples were dried in a Sunbeam food dehydrator and the dried material was ground to a coarse powder. 1 g of each of the samples of dried plant material
Reference Toxins for Biological Screening
Potassium dichromate (K2Cr2O7) (AR grade, Chem-Supply, Australia) was prepared as a 1.6 mg/ml solution in distilled water and was serially diluted in artificial seawater for use in the
Artemia franciscana Nauplii Toxicity Screening
Toxicity was tested using the
Thirty nine samples from twenty five Australian native plant species were extracted in methanol and dried as previously described . The weight of the dried extracted material is recorded in table 1. The weight of dried extractable material varied across samples, ranging from 83 mg (
All extracts were diluted to 2000 µg/ml in artificial seawater for toxicity testing, resulting in a 1000 µg/ml concentration in the
An extra four extracts showed greater than 50 % mortality at 48 h compared to 24 h (
Ten plant extracts induced greater than 50% mortality by 48 h (
- indicates that LC50 values were unable to be obtained as no increase in mortality above seawater controls was evident.
A previous study from this laboratory  has reported on the antibacterial activity of methanolic extracts from some Australian native plants. That study indicated that
Likewise, studies within this laboratory  have also shown
Financial support for this work was provided by the School of Biomolecular and Physical Sciences, Griffith University, Australia.