Our peer-reviewed publications

BioAustralis Discovery Plates

TriTOX: A novel Trichomonas vaginalis assay platform for high-throughput screening of compound libraries

Alexander Y.F. Lam, Daniel Vuong, Aaron R. Jex, Andrew M. Piggott, Ernest Lacey and Samantha J. Emery-Corbin

International Journal for Parasitology: Drugs and Drug Resistance (2021).

ABSTRACT: Trichomonas vaginalis is a neglected urogenital parasitic protist that causes 170 million cases of trichomoniasis annually, making it the most prevalent non-viral, sexually transmitted disease. Trichomoniasis treatment relies on nitroheterocyclics, such as metronidazole. However, with increasing drug-resistance, there is an urgent need for novel anti-trichomonals. Little progress has been made to translate anti-trichomonal research into commercialised therapeutics, and the absence of a standardised compound-screening platform is the immediate stumbling block for drug-discovery. Herein, we describe a simple, cost-effective growth assay for T. vaginalis and the related Tritrichomonas foetus. Tracking changes in pH were a valid indicator of trichomonad growth (T. vaginalis and T. foetus), allowing development of a miniaturised, chromogenic growth assay based on the phenol red indicator in 96- and 384-well microtiter plate formats. The outputs of this assay can be quantitatively and qualitatively assessed, with consistent dynamic ranges based on Z′ values of 0.741 and 0.870 across medium- and high-throughput formats, respectively. We applied this high-throughput format within the largest pure-compound microbial metabolite screen (812 compounds) for T. vaginalis and identified 43 hit compounds. We compared these identified compounds to mammalian cell lines, and highlighted extensive overlaps between anti-trichomonal and anti-tumour activity. Lastly, observing nanomolar inhibition of T. vaginalis by fumagillin, and noting this compound has reported activity in other protists, we performed in silico analyses of the interaction of fumagillin with its molecular target methionine aminopeptidase 2 for T. vaginalis, Giardia lamblia and Entamoeba histolytica, highlighting potential for fumagillin as a broad-spectrum anti-protistal against microaerophilic protists. Together, this new platform will accelerate drug-discovery efforts, underpin drug-resistance screening in trichomonads, and contributing to a growing body of evidence highlighting the potential of microbial natural products as novel anti-protistals.

Conglobatin B      Conglobatin C

Conglobatins B–E: cytotoxic analogues of the C2-symmetric macrodiolide conglobatin

Heather J. Lacey, Thomas J. Booth, Daniel Vuong, Peter J. Rutledge, Ernest Lacey, Yit-Heng Chooi and Andrew M. Piggott

The Journal of antibiotics, 73(11), pp.756-765. (2020)

ABSTRACT: Chemical investigation of a previously unreported indigenous Australian Streptomyces strain MST-91080 has identified six novel analogues related to the oxazole-pendanted macrodiolide, conglobatin. Phylogenetic analysis of the 16S rRNA gene sequence identified MST-91080 as a species of Streptomyces, distinct from reported conglobatin producer, Streptomyces conglobatus ATCC 31005. Conglobatins B–E diverge from conglobatin through differing patterns of methylation on the macrodiolide skeleton. The altered methyl positions suggest a deviation from the published biosynthetic pathway, which proposed three successive methylmalonyl-CoA extender unit additions to the conglobatin monomer. Conglobatins B1, C1 and C2 exhibited more potent cytotoxic activity selectively against the NS-1 myeloma cell line (IC₅₀ 0.084, 1.05 and 0.45 µg ml⁻¹, respectively) compared with conglobatin (IC₅₀ 1.39 µg ml⁻¹).

Amycolatopsin A     Amycolatopsin B     Amycolatopsin C

Amycolatopsins A–C: antimycobacterial glycosylated polyketide macrolides from the Australian soil Amycolatopsis sp. MST-108494

Zeinab G Khalil, Angela A Salim, Daniel Vuong, Andrew Crombie, Ernest Lacey, Antje Blumenthal and Robert J Capon

The Journal of antibiotics, 70(12), pp.1097-1103. (2017)

ABSTRACT: A southern Australian soil isolate, Amycolatopsis sp. MST-108494, was subjected to a panel of fermentation and media optimization trials, supported by analytical chemical profiling, to detect and enhance production of a rare class of secondary metabolites. Chemical fractionation of two complementary fermentations yielded three new polyketides, identified by detailed spectroscopic analysis as the glycosylated macrolactones, amycolatopsins A (1), B (2) and C (3), closely related to the ammocidins and apoptolidins. Amycolatopsins 1 and 3 selectively inhibited growth of Mycobacterium bovis (BCG) and Mycobacterium tuberculosis (H37Rv) when compared with other Gram-positive or Gram-negative bacteria, with 3 exhibiting low levels of cytotoxicity toward mammalian cells. Thus, our data reveal promising structure activity relationship correlations where the antimycobacterial properties of amycolatopsins are enhanced by hydroxylation of the 6-Me (that is, 1 and 3), whereas mammalian cytotoxicity is decreased by hydrolysis of the disaccharide moiety (that is, 3).

Nanangenine A     Nanangenine B     Isonanangenine B     Nanangenine C     Nanangenine D     Nanangenine F     Nanangenine G     Nanangenine H

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

Heather J. Lacey, Cameron L. M. Gilchrist, Andrew Crombie, John A. Kalaitzis, Daniel Vuong, Peter J. Rutledge, Peter Turner, John I. Pitt, Ernest Lacey, Yit-Heng Chooi and Andrew M. Piggott

Beilstein journal of organic chemistry, 15(1), pp.2631-2643. (2019)

ABSTRACT: Chemical investigation of an undescribed Australian fungus, Aspergillus nanangensis, led to the identification of the nanangenines – a family of seven new and three previously reported drimane sesquiterpenoids. The structures of the nanangenines were elucidated by detailed spectroscopic analysis supported by single crystal X-ray diffraction studies. The compounds were assayed for in vitro activity against bacteria, fungi, mammalian cells and plants. Bioinformatics analysis, including comparative analysis with other acyl drimenol-producing Aspergilli, led to the identification of a putative nanangenine biosynthetic gene cluster that corresponds to the proposed biosynthetic pathway for nanangenines.

Banksialactone A

Banksialactones and Banksiamarins: Isochromanones and Isocoumarins from a new Australian Fungus Aspergillus banksianus

Nirmal K. Chaudhary, John I. Pitt, Ernest Lacey, Andrew Crombie, Daniel Vuong, Andrew M. Piggott and Peter Karuso

Journal of natural products, 81(7), pp.1517-1526. (2018)

ABSTRACT: Chemical investigation of an Australian fungus, Aspergillus banksianus, led to the isolation of the major metabolite banksialactone A (1), eight new isochromanones, banksialactones B–I (2–9), two new isocoumarins, banksiamarins A and B (10 and 11), and the reported compounds, clearanol I (12), dothideomynone A (13), questin (14), and endocrocin (15). The structures of 1–11 were established by NMR spectroscopic data analysis, and the absolute configurations were determined from optical rotations and ECD spectra in conjunction with TD-DFT calculations. The secondary metabolite profile of A. banksianus is unusual, with the 11 most abundant metabolites belonging to a single isochromanone class. Conjugation of 1 with endocrocin, 5-methylorsellinic acid, 3,5-dimethylorsellinic acid, mercaptolactic acid, and an unknown methylthio source gave rise to five unprecedented biosynthetic hybrids, 5–9. The isolated compounds were tested for cytotoxicity, antibacterial, and antifungal activities, with hybrid metabolites 7–9 displaying weak cytotoxic and antibiotic activities.

Unguinol     Nidulin     Nornidulin     Emeguisin A

Expanding antibiotic chemical space around the nidulin pharmacophore             

Mahmud T. Morshed, Daniel Vuong, Andrew Crombie, Alastair E. Lacey, Peter Karuso, Ernest Lacey and Andrew M. Piggott 

Organic & biomolecular chemistry, 16(16), pp.3038-3051. (2018)

ABSTRACT: Reinvestigating antibiotic scaffolds that were identified during the Golden Age of antibiotic discovery, but have long since been “forgotten”, has proven to be an effective strategy for delivering next-generation antibiotics capable of combatting multidrug-resistant superbugs. In this study, we have revisited the trichloro-substituted depsidone, nidulin, as a selective and unexploited antibiotic lead produced by the fungus Aspergillus unguis. Manipulation of halide ion concentration proved to be a powerful tool for modulating secondary metabolite production and triggering quiescent pathways in A. unguis. Supplementation of the culture media with chloride resulted in a shift in co-metabolite profile to dichlorounguinols and nornidulin at the expense of the non-chlorinated parent, unguinol. Surprisingly, only marginal enhancement of nidulin was observed, suggesting O-methylation may be rate-limiting. Similarly, supplementation of the media with bromide led to the production of the corresponding bromo-analogues, but also resulted in a novel family of depsides, the unguidepsides. Unexpectedly, depletion of chloride from the media halted the biosynthesis of the non-chlorinated parent compound, unguinol, and redirected biosynthesis to a novel family of ring-opened analogues, the unguinolic acids. Supplementation of the media with a range of unnatural salicylic acids failed to yield the corresponding nidulin analogues, suggesting the compounds may be biosynthesised by a single polyketide synthase. In total, 12 new and 11 previously reported nidulin analogues were isolated, characterised and assayed for in vitro activity against a panel of bacteria, fungi and mammalian cells, providing a comprehensive structure–activity profile for the nidulin scaffold.

Sydowinin B

Aspergillus Sydowii Marine Fungal Bloom in Australian Coastal Waters, Its Metabolites and Potential Impact on Symbiodinium Dinoflagellates

Aiko Hayashi, Andrew Crombie, Ernest Lacey, Anthony J. Richardson, Daniel Vuong, Andrew M. Piggott and Gustaaf Hallegraeff

Marine drugs, 14(3), p.59. (2016)

ABSTRACT: Dust has been widely recognised as an important source of nutrients in the marine environment and as a vector for transporting pathogenic microorganisms. Disturbingly, in the wake of a dust storm event along the eastern Australian coast line in 2009, the Continuous Plankton Recorder collected masses of fungal spores and mycelia (~150,000 spores/m³) forming a floating raft that covered a coastal area equivalent to 25 times the surface of England. Cultured A. sydowii strains exhibited varying metabolite profiles, but all produced sydonic acid, a chemotaxonomic marker for A. sydowii. The Australian marine fungal strains share major metabolites and display comparable metabolic diversity to Australian terrestrial strains and to strains pathogenic to Caribbean coral. Secondary colonisation of the rafts by other fungi, including strains of Cladosporium, Penicillium and other Aspergillus species with distinct secondary metabolite profiles, was also encountered. Our bioassays revealed that the dust-derived marine fungal extracts and known A. sydowii metabolites such as sydowic acid, sydowinol and sydowinin A adversely affect photophysiological performance (F_v/F_m) of the coral reef dinoflagellate endosymbiont Symbiodinium. Different Symbiodinium clades exhibited varying sensitivities, mimicking sensitivity to coral bleaching phenomena. The detection of such large amounts of A. sydowii following this dust storm event has potential implications for the health of coral environments such as the Great Barrier Reef.

ɛ-Rhodomycinone

Blanchaquinone:  A New Anthraquinone from an Australian Streptomyces sp.

Kumbicin C

Kumbicins A–D: bis-indolyl benzenoids and benzoquinones from an Australian soil fungus, Aspergillus kumbius

Heather J. Lacey, Daniel Vuong, John I. Pitt, Ernest Lacey and Andrew M. Piggott

Australian Journal of Chemistry, 69(2), pp.152-160. (2016)

A soil survey conducted in southern Queensland, Australia, identified a novel isolate belonging to the genus Aspergillus subgenus Circumdati section Circumdati, Aspergillus kumbius FRR6049. Cultivation and fractionation of secondary metabolites from A. kumbius revealed a unique chemotype comprising three new bis-indolyl benzenoids, kumbicins A–C, and a new bis-indolyl benzoquinone, kumbicin D, along with the previously reported compounds asterriquinol D dimethyl ether, petromurins C and D, aspochracin, its N-demethyl analogue JBIR-15, and neohydroxyaspergillic acid. The structures of kumbicins A–D were assigned by detailed spectroscopic analysis. Kumbicin C was found to inhibit the growth of mouse myeloma cells (IC50 0.74 μg mL–1) and the Gram-positive bacterium Bacillus subtilis (MIC 1.6 μg mL–1).

Burnettramic acid A     Burnettramic acid A aglycone

Discovery and heterologous biosynthesis of the burnettramic acids: Rare PKS-NRPS-derived bolaamphiphilic pyrrolizidinediones from an Australian Fungus, Aspergillus burnettii

Hang Li, Cameron L. M. Gilchrist, Heather J. Lacey, Andrew Crombie, Daniel Vuong, John I. Pit, Ernest Lacey, Yit-Heng Chooi, and Andrew M. Piggott

Organic letters, 21(5), pp.1287-1291. (2019)

ABSTRACT: The burnettramic acids are a new class of antibiotics from an Australian fungus Aspergillus burnettii. The rare bolaamphiphilic scaffold consists of β-d-mannose linked to a pyrrolizidinedione unit via a 26-carbon chain. The most abundant metabolite displayed potent in vitro antifungal activity. Comparative genomics identified the hybrid PKS-NRPS bua gene cluster, which was verified by heterologous pathway reconstitution in Aspergillus nidulans.

Platencin and platensimycin

Platencin and platensimycin are members of an exciting new class of antibiotics active against Gram positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE).  Platensimycin inhibits FabF, a bacterial enzyme required for the synthesis of fatty acids and thus inhibition of the formation of the bacterial cell membrane (Wang J. et al. Nature 2006; 441: 358 – 361).  It is more potent and has a wider spectrum of activity than linezolid, a novel synthetic oxazolidinone, used clinically to treat various Gram positive antibiotic resistant infections.  Platencin appears to have a broader mode of action, inhibiting both FabF and FabH sites.  

BioAustralis is the first commercial supplier of this product and its analogue, platencin, for in vitro laboratory research purposes. 

Liver X receptor antagonists

In 2002, Tangirala and co-workers identified Liver X receptors as targets for intervention in cardiovasular disease.  LXR alpha and LXR beta control transcription of genes critical to a range of biological functions, including regulation of high density lipoprotein cholesterol metabolism, hepatic cholesterol catabolism, and intestinal sterol absorption (Tangirala R.K. et al. Proc Natl Acad Sci U.S.A. 2002; 99(18): 11896-901).  In 2005, researchers from Merck isolated two new hexacyclic aromatic ketones, (-)-anthrabenzoxocinone and (-)-bischloroanthrabenzoxocinone ((-)-BABX), which exhibited binding to LXR alpha and inhibited Type II fatty acid synthesis (Kodali S. et al. JBC 2005; 280(2): 1669 – 1677, Herath R.K. et al. 2005; 68: 1437 – 1440).  BioAustralis is the first commercial supplier of BABX for in vitro laboratory research purposes.

Inhibitors of Heat Shock Protein 90

Hsp90 inhibitors are exciting intense interest as potential therapies in cancer, inflammatory diseases and neurodegenerative conditions – exemplified by Pfizer’s acquisition of Serenex Inc. in 2008.

Recently it was reported that the Hsp90 inhibitor, geldanamycin, has weak cytotoxic activity as a single agent, but it dramatically intensifies the cytotoxicity of doxorubicin and ICRF-193 in Jurkat and HL-60 cells.  These results suggest that abrogation of G2 checkpoint by geldanamycin may play a central role in sensitizing p53-negative tumor cells to DNA-damaging and decatenation-inhibiting agents (Sugimoto K. et al. Oncogene 2008; 27,:3091–3101).  Geldanamycin is also reported to augment the cytopathic effect of the measles virus in MDA-MB-231 (breast), SKOV3.IP (ovarian) and TE671 (rhabdomyosarcoma) cancer cell lines (Liu C. et al. Gene Therapy 2008; 15: 1024-1034).   

Hsp90 inhibitors:

• Geldanamycin
• Herbimycin A 
• Herbimycin C

 Other ansamacrolides sold by BioAustralis

• Ansatrienin A 
• Ansatrienin B
• Antibiotic TAN 420C
• Antibiotic TAN 420E