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The escalating global crisis of bacterial resistance to antibiotics poses a threat to public health. Urgent measures are required to identify novel antibacterial treatments. Multidrug-resistant bacterial strains limit the effective therapeutic options available, raising concerns about a post-antibiotic era and a reduced ability to treat infections that were previously not classified as serious. Simultaneously, the threat of emerging infectious diseases, including zoonotic pathogens, underscores the need to develop effective antibiotics against these pathogens. Innovative approaches to antibiotic development, such as novel chemical scaffolds, combination therapies, antimicrobial peptides, and phage therapy, show promise but require the discovery of new antibacterial compounds. Desert and rainforest ecosystems, despite being disparate in climate and biodiversity, offer unique prospects for developing antibacterial compounds. Deserts, which are characterized by extreme aridity and temperature fluctuations, harbor plants and micro-organisms with specialized antibacterial defences honed through evolution. Conversely, rainforests, with their biodiversity and high humidity, are promising for the development of potential antibacterial compounds. To date, much natural product research aimed at discovery of new antibiotic compounds has focussed on rainforest plants due to the biodiversity of these ecosystems, and because plants develop chemical defences against microbes that are prevalent in those environments. In comparison, the search for new antimicrobial compounds from desert plants has been overshadowed, despite some noteworthy antibacterial activities in arid environment plants. This commentary discusses the comparative potential of desert and rainforest ecosystems as reservoirs of novel antibacterial agents and emphasises the importance of screening plants in both environments. [ABSTRACT FROM AUTHOR]

According to the World Health Organisation (WHO), diarrhoea is the second leading cause of death in children under the age of five. It is a common symptom associated with gastrointestinal bacterial infections. Many antibiotics have lost their efficacy due to the rapid emergence of Antimicrobial Resistant (AMR) bacterial pathogens. Traditional Ayurvedic medicinal plants are likely to play a significant role in the development of new effective and safe therapies in the fight against AMR in gastrointestinal bacteria. Recent research has reported the effectiveness of numerous different Ayurvedic medicines in the treatment of gastrointestinal infections. One example is Triphala, which is a polyherbal formulation consisting of an equal mixture of dried fruit powders from the three Ayurvedic plants Terminalia bellirica (Gaertn.) Roxb., Terminalia chebula Retz. and Emblica officinalis Linn. This review discusses the principles of Ayurveda and summarises the traditional use of Ayurvedic plants in the treatment of diarrhoea, dysentery, and stomach discomfort. [ABSTRACT FROM AUTHOR]

The genus Eremophila (family Scrophulariaceae) consists of approximately 200 species that are widely distributed in the semi-arid and arid regions of Australia. Multiple Eremophila spp. are used as traditional medicines by the First Australians in the areas in which they grow. They are used for their antibacterial, antifungal, antiviral, antioxidant, anti-diabetic, anti-inflammatory, and cardiac properties. Many species of this genus are beneficial against several diseases and ailments. The antibacterial properties of the genus have been relatively well studied, with several important compounds identified and their mechanisms studied. In particular, Eremophila spp. are rich in terpenoids, and the antimicrobial bioactivities of many of these compounds have already been confirmed. The therapeutic properties of Eremophila spp. preparations and purified compounds have received substantially less attention, and much study is required to validate the traditional uses and to highlight species that warrant further investigation as drug leads. The aim of this study is to review and summarise the research into the medicinal properties, therapeutic mechanisms, and phytochemistry of Eremophila spp., with the aim of focussing future studies into the therapeutic potential of this important genus. [ABSTRACT FROM AUTHOR]

Introduction: The development of bacterial strains that are resistant to multiple antibiotics has made the discovery of new antibiotics a priority for medical research. Examination of plants for new antimicrobial agents is an attractive prospect and numerous recent studies have screened plants for antibacterial activity. Despite this, Australian native plants have been relatively neglected. Heritiera actinophyllum (F.M.Bailey) Kosterm. is a rainforest tree that is native to eastern coastal regions of Australia. Material from this species has not yet been examined for antibacterial properties against human pathogens. Materials and Methods: The ability of H. actinophyllum leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: H. actinophyllum methanolic and aqueous extracts were ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were non-toxic or of low toxicity following 24 h exposure. Conclusion: The H. actinophyllum leaf extracts lacked growth inhibitory bioactivity against a panel of pathogenic bacteria and were nontoxic in the Artemia nauplii assay. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, and virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: The development of bacterial strains that are resistant to multiple antibiotics has made the discovery of new antibiotics a priority for medical research. Examination of plants for new antimicrobial agents is an attractive prospect and numerous recent studies have screened plants for antibacterial activity. Despite this, Australian native plants have been relatively neglected. Mirbelia oxylobioides F. Muell. is a native Australian shrub of the family Fabaceae. Very few studies have yet examined species for antibacterial properties against human pathogens. Methods: The ability of M. oxyloboides leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: M. oxyloboides methanolic and aqueous extracts were ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were non-toxic or of low toxicity following 24 h exposure. Conclusion: The M. oxyloboides leaf extracts lacked growth inhibitory bioactivity against a panel of pathogenic bacteria and were non-toxic in the Artemia nauplii assay. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: The recent development of extensively antibiotic resistant bacteria has necessitated the search for novel antibacterial compounds. An examination of aromatic plants and traditional medicines is an attractive option for drug discovery. Astrotrichia latifolia Benth. is a native Australia shrub that has yet to be tested for antibacterial activity. Methods: The ability of A. latifolia leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: A. latifolia leaf methanolic and aqueous extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were non-toxic in the Artemia nauplii bioassay following 24 h exposure. Conclusion: A. latifolia leaf extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

The First Australians had well-developed healing systems. Groote Eylandt inhabitants used a variety of plant species to treat diarrhoea and other gastrointestinal illnesses. This study was undertaken to test, identify, and evaluate traditional medicines to treat these conditions against gastrointestinal bacterial, protozoal, and viral pathogens, as well as against cancer cell proliferation. Six plant species (Buchanania obovata Engl., Casuarina equisetifolia L., Eucalyptus tetrodonta F. Muell., Planchonia careya (F. Muell.) R. Knuth, Terminalia carpentariae C. T. White, and Vigna vexillata (L.) A. Rich.) were selected from a survey of a panel of elders from the Warnindhilyagwa tribe and compared with the published literature. Decoctions prepared according to traditional methods were screened for growth inhibitory activity of a panel of diarrhoea-causing bacterial pathogens by disc diffusion and liquid dilution MIC assays. Inhibitory activity against the gastrointestinal protozoal parasite Giardia duodenalis and antiproliferative activity against human colorectal (Caco2) and cervical (HeLa) cancer cell lines were evaluated using MTS-based colorimetric cell proliferation assays. Preliminary antiviral screening was accomplished using an MS2 bacteriophage plaque reduction assay. Toxicity was evaluated using Artemia franciscana nauplii mortality and HDF cell viability bioassays. All traditional medicines tested inhibited bacterial growth, often with MIC values substantially <1000 μg/mL. T. carpentariae was particularly noteworthy, with MIC values of 230–350 μg/mL against Citrobacter freundii, Salmonella newport, Shigella sonnei, Staphylococcus aureus, and Staphylococcus epidermidis. This species also had MICs 450–950 μg/mL against all other bacterial pathogens. B. obovata Engl. and E. tetrodonta were also good inhibitors of bacterial growth, albeit with substantially higher MIC values than determined for T. carpentariae. The T. carpentariae decoction was also the best inhibitor of MS2 phage replication (IC50 = 427 μg/mL) and Caco2 and HeLa proliferation (IC50 values of 885 and 85 μg/mL, respectively). None of the extracts were particularly strong inhibitors of Giardia duodenalis growth. All decoctions were nontoxic in the Artemia nauplii and HDF cell viability bioassays, indicating their suitability for therapeutic use. [ABSTRACT FROM AUTHOR]

Introduction: Trachyspermum ammi leaves and seeds have been used as dietary supplements and to treat multiple pathogenic diseases in several traditional healing systems. Despite this, their therapeutic properties have been poorly studied. Methods: Chloroform, ethyl acetate, hexane, methanol and water extracts of T. ammi were prepared and tested and the activity was compared to that of standard antibiotics for their in vitro antibacterial activity against ten human bacterial pathogens. The antibacterial activity was studied by standard disc diffusion assays and the activity was recorded as zones of inhibition. Results: All T. ammi seed extracts were ineffective at inhibiting the growth of all of the gram-positive and gram-negative bacteria pathogens screened against. Conclusion: Despite their use in traditional healing systems to treat some pathogenic diseases, T. ammi seed extracts were completely ineffective bacterial growth inhibitors. However, these extracts were screened against a limited panel of bacteria and further testing against other pathogens is required. [ABSTRACT FROM AUTHOR]

Introduction: High antioxidant levels have been linked with multiple therapeutic properties, including antibacterial activity. Therefore, high antioxidant plant preparations are good targets for antibacterial testing. D. pruriens has high antioxidant capacity although it is yet to be tested for the ability to inhibit the growth of bacterial pathogens. Methods: The ability of D. pruriens fruit and leaf extracts to inhibit the growth of a panel of bacterial and fungal pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: All D. pruriens fruit and leaf extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria, as well as fungi. The extracts were non-toxic in the Artemia bioassay following 24 h exposure. Conclusion: Despite their high antioxidant capacity, D. pruriens fruit and leaf extracts were completely ineffective bacterial and fungal growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a family are known to possess therapeutic properties. The genus Pouteria (family Sapotaceae) has a long history of medicinal usage in many areas of the world. Many species are known to have therapeutic properties, several of which have well established antibacterial bioactivities. Methods: The ability of P. australis leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: P. australis methanolic and aqueous extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were nontoxic to Artemia nauplii following 24 hr exposure. Conclusion: Despite the taxonomic relationship with several bioactive Pouteria spp., P. australis leaf extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: The development of multi-antibiotic resistant strains of bacteria has necessitated the search for new, effective antibacterial therapies. B. collina and B. oblongifolia leaves were used by Australian Aborigines to treat bacterial infections. However, little research has been published on antibacterial activity of these species. Methods: The ability of B. collina and B. oblongifolia leaf extracts to inhibit the growth of gram-negative and gram-positive bacterial species was investigated by disc diffusion and growth time course assays. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The B. collina and B. oblongifolia leaf extracts were good inhibitors of the growth of both gram-positive and gram-negative bacteria. The B. collina and B. oblongifolia leaf extracts were particularly good inhibitors of A. faecalis growth (MICs of 225 and 486µg/mL respectively) and B. cereus growth (MICs of 515 and 875µg/mL respectively). The B. collina extract was also a good inhibitor of B. subtilis growth, whilst the B. oblongifolia extract was a moderate growth inhibitor (MIC values of 923 and 1250µg/mL respectively). A similar, trend was noted for Y. entercolitica growth inhition (MICs of 518 and 1136µg/mL respectively). Whilst MIC values were also determined against other bacterial species, they generally indicated low-moderate activity. The B. collina and B. oblongifolia leaf extracts were further investigated by growth time course assays against A. faecalis and B. cereus. Interestingly, both extracts showed significant growth inhibition within 1h of exposure against both bacterial species. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for the treatment of bacterial infections. Conclusion: The lack of toxicity of the B. collina and B. oblongifolia leaf extracts and their growth inhibitory bioactivity against multiple bacterial species indicate their potential in the development of new antibiotic chemotherapies. [ABSTRACT FROM AUTHOR]

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a genus are known to possess therapeutic properties. The genus Ficus has a long history of medicinal usage in many areas of the world. Many species are known to have therapeutic properties, several species of which have well established antibacterial bioactivities. Methods: The ability of F. racemosa leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: F. racemosa methanolic and aqueous extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were nontoxic or of low toxicity following 24 h exposure. Conclusion: Despite the close taxonomic relationship with several bioactive Ficus spp. and its therapeutic uses in traditional medicine, F. racemosa leaf extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a genus are known to possess therapeutic properties. The genus Eucalyptus has a long history of medicinal usage by the first Australians. Many species are known to have therapeutic properties, several species of which have well established antibacterial bioactivities. Methods: The ability of Eucalyptus grandis leaf and flower extracts to inhibit the growth of a panel of bacterial and fungal pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: E. grandis leaf and flower methanolic and aqueous extracts were completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria, as well as fungi. The extracts were nontoxic in the Artemia nauplii bioassay following 24 hr exposure. Conclusion: Despite the taxonomic relationship to several bioactive Eucalyptus spp., E. grandis leaf and flower extracts were completely ineffective bacterial and fungal growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: The development of bacterial strains that are resistant to multiple antibiotics has made the development of new antibiotics a priority for medical research. Traditional plant medicines are important leads for the discovery of new medicines. The family Agavaceae is widely used therapeutically in many areas of the world. Despite this, many members of this family are yet to be examined extensively for therapeutic properties. The species Cordyline rubra Otto and A. Dietr. was screened for antibacterial activity in this study. Methods: The ability of C. rubra leaf and fruit extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: Methanolic C. rubra leaf and fruit extracts were completely ineffective at inhibiting the growth of gram-positive and gramnegative panels of bacteria. The extracts were also non-toxic or of low toxicity following 24 h exposure. Conclusion: C. rubra leaf and fruit extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: The development of multi-antibiotic resistant strains of bacteria has necessitated the search for new effective antibacterial therapies. Several Grevillea spp. were used traditionally to treat pathogenic illness and are rich in phytocompounds with antibacterial activity. Despite this, the antibacterial activity of Australian Grevillea spp. extracts have not been extensively examined. Methods: The ability of G. juncifolia and G. robusta leaf and flower extracts to inhibit the growth of gram-negative and gram-positive bacterial species and some fungi was investigated by disc diffusion assays. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The G. juncifolia and G. robusta extracts were good inhibitors of the growth of both gram-positive and gram-negative bacteria yet were completely ineffective against all fungal species tested. The leaf extracts generally had better antibacterial activity than the flower extracts. The G. juncifolia leaf extract was a particularly good inhibitor of A. faecalis, P. fluorescens, Y. entercolitica and B. subtilis growth, with MIC values of 62, 533, 736 and 682µg/mL respectively. The G. robusta leaf extract was a potent inhibitor of B. cereus and B. subtilis growth (145 and 83µg/mL respectively). That extract was also a good inhibitor of A. faecalis, P. fluorescens, S. salford, S. aureus and S. epidermidis growth, albeit with substantially higher MIC values. In contrast, none of the extracts inhibited fungal growth. All extracts were determined to be non-toxic in the Artemia franciscana nauplii bioassay, indicating their safety for the treatment of bacterial infections. Conclusion: The lack of toxicity of the G. juncifolia and G. robusta extracts and their growth inhibitory bioactivity against grampositive and gram-negative bacteria indicate their potential in the development of new antibiotic chemotherapies. [ABSTRACT FROM AUTHOR]

Introduction: Xanthophyllum fragrans C.T. White is a rainforest tree that is native to north-eastern regions of Australia. X. fragrans leaf extracts were examined for the ability to inhibit the growth of Pseudomonas aeruginosa. Methods: The antimicrobial activity of a methanolic X. fragrans leaf extracts were investigated by disc diffusion and growth time course assays against P. aeruginosa. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanolic X. fragrans leaf extract was a potent inhibitor of P. aeruginosa growth (MICs of 430 and 1687µg/mL against the reference and clinical strains respectively). The aqueous X. fragrans leaf extract was also a moderate inhibitor of P. aeruginosa growth (MICs approximately 1000 and 2500µg/mL against the reference and clinical bacterial strains respectively). The antibacterial activities of the methanolic X. fragrans leaf extracts were further investigated using growth time course assays that showed significant growth inhibition in cultures of P. aeruginosa within 1 h of exposure. All extracts were determined to be non-toxic in the Artemia franciscana nauplii bioassay, indicating their safety for use in preventing diseases caused by these pathogens. Conclusion: The lack of toxicity of the X. fragrans leaf extracts and their growth inhibitory bioactivity against P. aeruginosa indicates their potential in the development of new therapies targeting this bacterium. [ABSTRACT FROM AUTHOR]

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a family are known to possess therapeutic properties. The family Laminaceae has a long history of medicinal usage globally. Many species are known to have therapeutic properties, several species of which have well established antibacterial bioactivities. Methods: The ability of Westringa fruticosa leaf and flower extracts to inhibit the growth of a panel of bacterial and fungal pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: W. fruticosa leaf methanolic and aqueous extracts were both completely ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria, as well as fungi. The extracts were non-toxic or of low toxicity in the Artemia bioassay following 24 h exposure. Conclusion: Despite the taxonomic relationship to several bioactive Laminaceae spp., W. fruticosa leaf and flower extracts were completely ineffective bacterial and fungal growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: Closely related plant species often share similar secondary metabolites and bioactivities and are therefore good targets for bioactivity testing when one or more species within a genus are known to possess therapeutic properties. The genus Piper has a long history of medicinal usage in many areas of the world. Many Piper spp. are known to have therapeutic properties and several have antibacterial bioactivities. Methods: The ability of P. novae-hollandiae leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: P. novae-hollandiae methanolic and aqueous extracts were completely ineffective at inhibiting the growth of panels of gram-positive and gram-negative bacteria. The extracts were nontoxic or of low toxicity to Artemia nauplii following 24 h exposure. Conclusion: Despite the close taxonomic relationship with several bioactive Piper spp. and its therapeutic use by first Australians, P. novae-hollandiae leaf extracts were completely ineffective bacterial growth inhibitors. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, virus and tumour cells is warranted. [ABSTRACT FROM AUTHOR]

Introduction: The development of multi-antibiotic resistant strains of bacteria has necessitated the search for new effective antibacterial therapies. Many Callistemon spp. were used traditionally to treat pathogenic illness and are rich in terpenoids with reported antibacterial activity. Despite this, the antibacterial activity of C. linearis leaf extracts has not been extensively examined. Methods: The ability of C. linearis leaf extracts to inhibit the growth of gram-negative and gram-positive bacterial species was investigated by disc diffusion and growth time course assays. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanolic and aqueous C. linearis leaf extracts were good inhibitors of the growth of gram-positive bacteria yet were completely ineffective against gram-negative bacteria. The methanolic extract was a particularly good inhibitor of B. cereus and S. pyogenes growth, with MIC values of 610 and 354µg/mL respectively. The aqueous extract was also a good inhibitor of these bacteria (MICs of 927 and 660µg/mL respectively). Whilst the extracts also inhibited the growth of S. aureus and S. epidermidis, the MIC values (in the range 1200-1500µg/mL) were indicative of moderate inhibitory activity. The methanolic extracts were further investigated by growth time course assays that showed significant growth inhibition within 1h of exposure. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for the treatment of gram-positive bacterial infections. Conclusion: The lack of toxicity of the C. linearis leaf extracts and their growth inhibitory bioactivity against the gram-positive bacteria indicate their potential in the development of new antibiotic chemotherapies. [ABSTRACT FROM AUTHOR]

Introduction: The development of multi-antibiotic resistant strains of bacteria has necessitated the search for new, effective antibacterial therapies. M. lauteriana was used by Australian Aborigines as a nutritious food. However, very little research has been published on this species and the antibacterial activity of M. lauteriana leaf extracts has not yet been reported. Methods: The ability of M. lauteriana leaf extracts to inhibit the growth of gram-negative and gram-positive bacterial species was investigated by disc diffusion and growth time course assays. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanolic and aqueous M. lauteriana leaf extracts were good inhibitors of the growth of both gram-positive and gram-negative bacteria. The methanolic extract was a particularly good inhibitor of K. pneumoniae and B. cereus growth, with MIC values of 728 and 515µg/mL respectively. The aqueous extract was also a good inhibitor of these bacteria (MICs of 953 and 860µg/mL respectively). Whilst the M. lauteriana leaf extracts also inhibited the growth of P. mirabilis, S. aureus and S. pyogenes, the MIC values (in the range 1000-2000µg/mL) were indicative of moderate inhibitory activity. The M. lauteriana leaf extracts were further investigated by growth time course assays against K. pneumoniae and B. cereus. Interestingly, both extracts showed significant growth inhibition within 1h of exposure against both bacterial species. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for the treatment of gram-positive bacterial infections. Conclusion: The lack of toxicity of the M. lauteriana leaf extracts and their growth inhibitory bioactivity against multiple bacteria indicate their potential in the development of new antibiotic chemotherapies. [ABSTRACT FROM AUTHOR]

Introduction: Streptococcus pyogenes is a gram positive pathogenic bacterium which causes a variety of diseases including streptococcal pharyngitis, impetigo and rheumatic heart disease. Many Brachychiton spp. have reported uses to treat pathogenic illness and are rich in flavonoids with reported antibacterial activity. Despite this, B. rupestris leaf extracts have not previously been examined for bacterial growth inhibitory properties. Methods: The ability of B. rupestris leaf extracts to inhibit the growth of S. pyogenes was investigated by disc diffusion and growth time course assays. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanolic and aqueous B. rupestris leaf extracts were potent inhibitors of S. pyogenes growth, with MIC values as low as 445µg/mL. The antibacterial activity of the methanolic and aqueous B. rupestris leaf extracts were further investigated by growth time course assays that showed significant growth inhibition within 1h of exposure. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for use in preventing S. pyogenes associated diseases caused by these pathogens. Conclusion: The lack of toxicity of the B. rupestris leaf extracts and their growth inhibitory bioactivity against S. pyogenes indicate their potential in the development of new therapies for rheumatic fever, pharyngitis, impetigo and other illnesses caused by this bacterium. [ABSTRACT FROM AUTHOR]

Introduction: Melodorum leichhardtii F.Muell. Benth. is a rainforest vine which is native to north-eastern rainforest regions of Australia. Melodorum spp. are rich in a variety of terpenoids with reported antibacterial activity. Despite this, M. leichhardtii leaf extracts have not previously been examined for bacterial growth inhibitory properties. Methods: The antimicrobial activity of a methanolic M. leichhardtii leaf extract was investigated by disc diffusion and growth time course assays against a panel of bacterial pathogens. The growth inhibitory activity was further quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanolic M. leichhardtii leaf extract was a potent inhibitor of Klebsiella pneumonia (MICs of 388µg/mL). The extract was also a low-moderate inhibitor of B. cereus growth (MICs 3678µg/mL) but was completely devoid of inhibitory activity against all other bacterial species tested. The antibacterial activity of the methanolic M. leichhardtii leaf extract was further investigated by growth time course assays that showed significant growth inhibition in cultures of K. pneumoniae and B. cereus within 1 h of exposure. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for use in preventing diseases caused by these pathogens. Conclusion: The lack of toxicity of the M. leichhardtii leaf extracts and their growth inhibitory bioactivity against K. pneumoniae and B. cereus indicate their potential in the development of new therapies targeting these bacteria. [ABSTRACT FROM AUTHOR]

Introduction: B. myrtifolia and S. anisatum are native Australian trees with uses as traditional medicines and bushfoods. Essential oils produced from leaves of these species have reputed antiseptic properties. Despite this, B. myrtifolia and S. anisatum leaf solvent extractions have not been rigorously examined for antibacterial properties against many pathogens. Methods: The antimicrobial activity of aqueous and methanolic leaf extracts of B. myrtifolia and S. anisatum was investigated by disc diffusion and growth time course assays against a panel of pathogenic bacteria. The growth inhibitory activity was quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Methanolic and aqueous B. myrtifolia and S. anisatum leaf extracts inhibited the growth of a wide range of bacterial species. Growth of both gram positive and gram negative bacteria was inhibited the B. myrtifolia and S. anisatum extracts to approximately the same extent. In general, S. anisatum extracts were more potent inhibitors of bacterial growth than were the B. myrtifolia extracts, and (with some noteable exceptions) the methanolic extracts were generally more potent than the aqueous extracts. The B. myrtifolia and S. anisatum extracts were particularly potent inhibitors of P. mirabilis growth, with MIC values as low as 105 µg/mL (aqueous S. anisatum extract). The antibacterial activity of the methanolic B. myrtifolia and S. anisatum extracts were further investigated by growth time course assays which showed significant growth inhibition in cultures of E. coli, K. pneumpniae and P. mirabilis within 1 h of exposure. All extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for internal use as well as for topical uses. Conclusions: The lack of toxicity of the B. myrtifolia and S. anisatum extracts and their growth inhibitory bioactivity against a panel of pathogenic bacteria partially validate Australian Aboriginal usage of these species as antiseptic agent and indicate their potential in the development of antiseptic agents. [ABSTRACT FROM AUTHOR]

Introduction: J. communis berry is a high antioxidant fruit which is used in several traditional medicinal systems to treat a variety of diseases including rheumatism, arthritis and gout. This study was undertaken to examine the inhibitory activity of J. communis berry extracts on the growth of several bacteria associated with autoimmune inflammatory disease, and to test their ability to block CaCo2 and HeLa cancer cell proliferation. Methods: J. Communis solvent extracts were prepared using solvents of varying polarity. The extracts were investigated by disc diffusion assay for the ability to inhibit the growth of a panel of pathogenic bacteria associated with autoimmune inflammatory diseases. Their MIC values were determined to quantify and compare their efficacies. Inhibitory activity against CaCo2 and HeLa human carcinoma cell lines was evaluated using an MTS colorimetric cell proliferation assay. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: The methanol, water and ethyl acetate J. communis berry extracts displayed moderate to potent growth inhibitory activity against bacterial triggers of rheumatoid arthritis, ankylosing spondylitis and multiple sclerosis. The methanol and water extracts displayed the broadest specificity, inhibiting the growth of all bacteria tested. The ethyl acetate extract also displayed antibacterial activity, inhibiting the growth of 9 of the 13 bacterial strains (69%). The ethyl acetate extract displayed the greatest potency, with MIC values substantially below 2000 µg/mL for all bacteria which it inhibited. It was most effective at inhibiting the growth of P. mirabilis, P. vulgaris and S. aureus, each with MIC's = 500 µg/mL. The methanol and water extracts also proved effective at blocking the proliferation of the colorectal cancer cell line CaCo2 and HeLa cervical cancer cell growth, with IC50 values in the 1300-2500 µg/mL range. All extracts were non-toxic in the Artemia nauplii bioassay. Conclusion: The lack of toxicity of the J. Communis berry extracts and their potent growth inhibitory bioactivity against bacteria and HeLa and CaCo2 carcinoma cells indicates their potential in the treatment and prevention of selected autoimmune inflammatory diseases and some cancers. [ABSTRACT FROM AUTHOR]

Anthrax is a zoonotic disease caused by the soil bacterium Bacillus anthracis. It has an extremely high mortality rate if untreated. Terminalia spp. have a long association with the treatment of various ailments, including bacterial infections although they have not been tested for the ability to inhibit the growth of B. anthracis. Methods: Solvent extracts were prepared using Terminalia spp. known to inhibit microorganism growth. The antibacterial potential of the extracts were investigated by disc diffusion assay to determine the growth inhibitory potential against an environmental strain of B. anthracis. Their MIC values were calculated to quantify and compare their relative efficacies. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Extracts prepared from several Indian Terminalia spp. displayed potent antibacterial activity in the disc diffusion assay against B. anthracis. The methanolic T. chebula fruit extract was particularly effective at inhibiting microbial growth, with MIC values against B. anthracis of 166 μg/mL (<2 μg impregnated in the disc). The aqueous T. chebula extract, as well as T. catappa and T. arjuna methanolic extracts, were also good growth inhibitors with MIC's generally <2500 μg/mL (<25 μg impregnated in the disc). All other plant extracts were either inactive or of only low inhibitory activity. None of the extracts were deemed toxic, with all recorded LC50 values substantially>1000 μg/mL. [ABSTRACT FROM AUTHOR]

Introduction: Anthrax is a zoonotic disease caused by the bacterium Bacillus anthracis. It is often fatal if left untreated. Many Australian plants have documented therapeutic properties as general antiseptics, inhibiting the growth of a wide variety of bacterial species. This study examines the ability of selected Australian plant extracts to inhibit B. anthracis growth. Methods: Solvent extracts were prepared using plants with documented ethnobotanical usage to treat bacterial infections, or published antibacterial activity. The extracts were investigated by disc diffusion assay for the ability to inhibit the growth of an environmental strain of B. anthracis. Their MIC values were determined to quantify and compare their efficacies. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Methanolic and aqueous extracts of Eucalyptus baileyana and Eucalyptus major displayed potent antibacterial activity in the disc diffusion assay against B. anthracis. The methanolic extracts were particularly potent with MIC values as low as 290 μg/mL (E. major methanolic extract). Tasmannia insipidia and Tasmannia stipitata extracts also inhibited B. anthracis growth, albeit with low efficacy. The E. baileyana and E. major methanolic leaf extracts as well as the E. baileyana aqueous leaf extract induced significant mortality in the Artemia fransiscana bioassay, with LC50 values substantially <1000 μg/mL, indicating the toxicity of these extracts. Conclusion: The potent inhibitory bioactivity of the E. baileyana and E. major extracts against B. anthracis demonstrate their potential as medicinal agents in the treatment and prevention of anthrax. However, their toxicity indicates that their use may be limited to the treatment of the cutaneous form of the disease, or for sterilisation of infected sites. [ABSTRACT FROM AUTHOR]

The author discusses the criteria in selecting plants for pharmacognostic studies. The author cites that plants with a documented history of usage by traditional healers is the best choice for a good start of research while own field observations of researchers are valuable in selecting a plant species for testing. The author also notes the importance of investigating species closely related to those plants that have medicinal properties and of random selection when selecting plant species.