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Rosenbergiella bacteria have been previously isolated predominantly from floral nectar and identified in metagenomic screenings as associated with bees. Here, we isolated three Rosenbergiella strains from the robust Australian stingless bee Tetragonula carbonaria sharing over 99.4% sequence similarity with Rosenbergiella strains isolated from floral nectar. The three Rosenbergiella strains (D21B, D08K, D15G) from T. carbonaria exhibited near-identical 16S rDNA. The genome of strain D21B was sequenced; its draft genome contains 3,294,717 bp, with a GC content of 47.38%. Genome annotation revealed 3236 protein-coding genes. The genome of D21B differs sufficiently from the closest related strain, Rosenbergiella epipactidis 2.1A, to constitute a new species. In contrast to R. epipactidis 2.1A, strain D21B produces the volatile 2-phenylethanol. The D21B genome contains a polyketide/non-ribosomal peptide gene cluster not present in any other Rosenbergiella draft genomes. Moreover, the Rosenbergiella strains isolated from T. carbonaria grew in a minimal medium without thiamine, but R. epipactidis 2.1A was thiamine-dependent. Strain D21B was named R. meliponini D21B, reflecting its origin from stingless bees. Rosenbergiella strains may contribute to the fitness of T. carbonaria.

Aims The control of Xanthomonas citri subsp. citri (X. citri), causal agent of citrus canker, relies heavily on integrated agricultural practices involving the use of copper-based chemicals. Considering the need for alternatives to control this disease and the potential of fungi from extreme environments as producers of bioactive metabolites, we isolated and identified a bioactive compound from Penicillium sp. CRM 1540 isolated from Antarctica marine sediment. Methods and Results The potential of compound as an antibacterial agent against X. citri was assessed through in vitro and greenhouse experiments. Molecular taxonomy indicates that this fungus is a possible new species of Penicillium. Results revealed 90% bacterial inhibition in vitro at 25 µg ml–1 and a decrease in 75.37% of citrus canker symptoms emergency in vivo in treated leaves of Citrus sinensis (L.) Osbeck considering the number of lesions per cm2 (p < 0.05) in comparison with the control. The structure of the active agent was identified as penicillic acid based on a detailed spectroscopic analysis. Conclusion Penicillic acid can be an alternative against citrus canker. Significance and Impact of Study Research into extremophile micro-organisms can identify molecules with biotechnological potential and alternatives to current agricultural practices.

Untreated or reoccurring group A Streptococcus (GAS) infection can lead to a number of post-infection complications, including rheumatic heart disease. There is no licenced vaccine for the treatment or prevention of GAS infection. We identified that a cyclic decapeptide plays a significant positive influence on the adjuvant activity of several lipid-antigen mixtures. Here, three synthetic vaccine components were synthesised: (1) J8-PADRE represents the GAS B cell antigen (J8) conjugated to the universal T helper epitope (PADRE); (2) a synthetic toll like receptor 2 (TLR2) ligand based on a C16 alkyl chain lipid moiety; and (3) a cyclic carrier deca-peptide. Previously, through structure-immune activity investigations, it was observed that a physical mixture of these three components had significantly higher IgG immune responses when compared to a fully conjugated vaccine construct. Expanding the scope of this structure-activity investigation, we show that the presence of the cyclic peptide is required for the induction of a strong, balanced Th1/Th2 immune response when compared with lipid and antigen only, and cyclic lipopeptide plus B/T cell antigen physical mixtures.

Intranasal vaccine administration can overcome the disadvantages of injectable vaccines and present greater efficiency for mass immunization. However, the development of intranasal vaccines is challenged by poor mucosal immunogenicity of antigens and the limited availability of mucosal adjuvants. Here, we examined a number of self-adjuvanting liposomal systems for intranasal delivery of lipopeptide vaccine against group A Streptococcus (GAS). Among them, two liposome formulations bearing lipidated cell-penetrating peptide KALA and a new lipidated chitosan derivative (oleoyl-quaternized chitosan, OTMC) stimulated high systemic antibody titers in outbred mice. The antibodies were fully functional and were able to kill GAS bacteria. Importantly, OTMC was far more effective at stimulating antibody production than the classical immune-stimulating trimethyl chitosan formulation. In a simple physical mixture, OTMC also enhanced the immune responses of the tested vaccine, without the need for a liposome delivery system. The adjuvanting capacity of OTMC was further confirmed by its ability to stimulate cytokine production by dendritic cells. Thus, we discovered a new immune stimulant with promising properties for mucosal vaccine development.

Calculations predict that testing of 5 000–10 000 molecules and >1 billion US dollars (£0.8 billion, £1=$1.2) are required for one single drug to come to the market. A solution to this problem is to establish more efficient protocols that reduce the high rate of re-isolation and continuous rediscovery of natural products during early stages of the drug development process. The study of ‘rare actinobacteria’ has emerged as a possible approach for increasing the discovery rate of drug leads from natural sources. Here, we define a simple genomic metric, defined as biosynthetic novelty index (BiNI), that can be used to rapidly rank strains according to the novelty of the subset of encoding biosynthetic clusters. By comparing a subset of high-quality genomes from strains of different taxonomic and ecological backgrounds, we used the BiNI score to support the notion that rare actinobacteria encode more biosynthetic gene cluster (BGC) novelty. In addition, we present the isolation and genomic characterization, focused on specialized metabolites and phenotypic screening, of two isolates belonging to genera Lentzea and Actinokineospora from a highly oligotrophic environment. Our results show that both strains harbour a unique subset of BGCs compared to other members of the genera Lentzea and Actinokineospora . These BGCs are responsible for potent antimicrobial and cytotoxic bioactivity. The experimental data and analysis presented in this study contribute to the knowledge of genome mining analysis in rare actinobacteria and, most importantly, can serve to direct sampling efforts to accelerate early stages of the drug discovery pipeline.

The Australian plant pasture-derived Streptomyces sp. CMB-PB042 yielded the unprecedented polycyclic C-aminoglycoside-pyranonaphthoquinone polyketides glenthamine A (1) and glenthimine A (2), the latter being a rare example of a naturally occurring imine, along with the spiropolyketide glenthol A (3), its hydrolysis artifact glenthol B (4), and the highly rearranged C-aminoglycoside-pyranonaphthoquinone glenthamide A (5). Structures including absolute configurations of 1-5 were assigned by spectroscopic analysis, chemical interconversion, and biosynthetic considerations.

A brown rice cultivation of Aspergillus sp. CMB-MRF324 yielded six new meroterpenes, millmerranones A-F (1-6), and four known analogues, terreulactones A-D (7-10). Millmerranone A (1) possesses a unique carbon skeleton bearing a rare cyclic carbonate and undergoes an unprecedented base mediated rearrangement to seco-millmerranone A (1a). We also report on an unexpected base rearrangement of 7 to 7a/b; a plausible biosynthetic relationship linking 1, 7, and 9; and acetylcholinesterase inhibitory properties (IC50 37 nM to >30 μM).

This study showcases the application of an integrated workflow of molecular networking chemical profiling (GNPS), together with miniaturized microbioreactor cultivation profiling (MATRIX) to successfully detect, dereplicate, prioritize, optimize the production, isolate, characterize, and identify a diverse selection of new chemically labile natural products from the Queensland sheep pasture soil-derived fungus

Analytical scale chemical/cultivation profiling prioritized the Australian marine-derived fungus

Peptide-based subunit vaccines include only minimal antigenic determinants, and, therefore, are less likely to induce allergic immune responses and adverse effects compared to traditional vaccines. However, peptides are weakly immunogenic and susceptible to enzymatic degradation when administered on their own. Hence, we designed polyelectrolyte complex (PEC)-based delivery systems to protect peptide antigens from degradation and improve immunogenicity. Lipopeptide (LCP-1) bearing J8 B-cell epitope derived from Group A Streptococcus (GAS) M-protein was selected as the model peptide antigen. In the pilot study, LCP-1 incorporated in alginate/cross-linked polyarginine-J8-based PEC induced high J8-specific IgG antibody titres. The PEC system was then further modified to improve its immune stimulating capability. Of the formulations tested, PEC-4, bearing LCP-1, alginate and cross-linked polylysine, induced the highest antibody titres in BALB/c mice following subcutaneous immunisation. The antibodies produced were more opsonic than those induced by mice immunised with other PECs, and as opsonic as those induced by antigen adjuvanted with powerful complete Freund’s adjuvant.

Molecular network analysis of

Peptide-based subunit vaccines include only minimal antigenic determinants, and, therefore, are less likely to induce allergic immune responses and adverse effects compared to traditional vaccines. However, peptides are weakly immunogenic and susceptible to enzymatic degradation when administered on their own. Hence, we designed polyelectrolyte complex (PEC)-based delivery systems to protect peptide antigens from degradation and improve immunogenicity. Lipopeptide (LCP-1) bearing J8 B-cell epitope derived from Group A

Peptide-based vaccines are composed of small, defined, antigenic peptide epitopes. They are designed to induce well-controlled immune responses. Multiple epitopes are often employed in these vaccines to cover strain variability of a pathogen. However, peptide epitopes cannot stimulate adequate immune responses on their own and require an adjuvant (immune stimulant) and/or delivery system. Here, we designed and synthesized a multiepitope vaccine candidate against Group A Streptococcus (GAS) composed of several B-cell epitopes (J8, PL1, and 88/30) derived from GAS M-protein, universal PADRE T-helper cell epitope, and a polyleucine self-adjuvanting unit. The vaccine components were conjugated together (using mercapto-maleimide and azide-alkyne Huisgen cycloaddition reactions) or delivered as a mixture. The conjugated multiepitope vaccine candidate self-assembled into small nanoparticles and chain-like aggregated nanoparticles (CLANs) that were able to induce the production of J8-, PL1-, and 88/30-specific antibodies in mice. The multiepitope conjugate and the physical mixture of conjugates bearing the individual epitopes produced similar nanoparticles and induced comparable immune responses. Hence, simple physical mixing can replace complex chemical conjugation to produce multiepitope nanoparticles with equivalent morphology and immunological efficacy. This greatly simplifies vaccine production.

Chemical cues produced by late-stage embryos of the cane toad (Rhinella marina) attract older conspecific larvae, which are highly cannibalistic and can consume an entire clutch. To clarify the molecular basis of this attraction response, we presented captive tadpoles with components present in toad eggs. As previously reported, attractivity arises from the distinctive toxins (bufadienolides) produced by cane toads, with some toxins (e.g., bufagenins) much stronger attractants than others (e.g., bufotoxins). Extracts of frozen toad parotoid glands (rich in bufagenins) were more attractive than were fresh MeOH extracts of the parotoid secretion (rich in bufotoxins), and purified marinobufagin was more effective than marinobufotoxin. Cardenolide aglycones (e.g., digitoxigenin) were active attractors, whereas C-3 glycosides (e.g., digoxin, oubain) were far less effective. A structure–activity relationship study revealed that tadpole attractant potency strongly correlated with Na+/K+ ATPase inhibitory activity, suggesting that tadpoles monitor and rapidly react to perturbations to Na+/K+ ATPase activity.

The natural product indole-3-carbinol (I3C) and its major digestive product 3,3′-diindolylmethane (DIM) have shown clinical promise in multiple forms of cancer including breast cancer. In this study, we explored the calcium channel activity of DIM, its synthetic derivative 3,3′-Diindolylmethanone (DIM-one) and related I3C and DIM-one analogs. For the first time, DIM, DIM-one and analog IX were identified as selective blockers for T-type CaV3.3 (IC50s DIM 2.09 µM; DIM-one 9.07 µM) while compound IX inhibited both CaV3.2 (6.68 µM) and CaV3.3 (IC50 = 3.05 µM) using a FLIPR cell-based assay to measure inhibition of T-type calcium channel window current. Further characterization of DIM by electrophysiology revealed it inhibited inward Ca2+ current through CaV3.1 (IC50 = 8.32 µM) and CaV3.3 (IC50 = 9.63 µM), while IX partially blocked CaV3.2 and CaV3.3 inward Ca2+ current. In contrast, DIM-one preferentially blocked CaV3.1 inward Ca2+ current (IC50 = 1.53 µM). The anti-proliferative activities of these compounds revealed that oxidation of the methylene group of DIM shifted the selectivity of DIMs from breast cancer cell line MCF-7 to colon cancer cell line HT-29.

Adjuvants and delivery systems are essential components of vaccines to increase immunogenicity against target antigens, particularly for peptide epitopes (poor immunogens). Emulsions, nanoparticles, and liposomes are commonly used as a delivery system for peptide-based vaccines. A Poly(hydrophobic amino acids) delivery system was previously conjugated to Group A Streptococcus (GAS)-derived peptide epitopes, allowing the conjugates to self-assemble into nanoparticles with self adjuvanting ability. Their hydrophobic amino acid tail also serves as an anchoring moiety for the peptide epitope, enabling it to be integrated into the liposome bilayer, to further boost the immunological responses. Polyleucine-based conjugates were anchored to cationic liposomes using the film hydration method and administered to mice subcutaneously. The polyleucine-peptide conjugate, its liposomal formulation, and simple liposomal encapsulation of GAS peptide epitope induced mucosal (saliva IgG) and systemic (serum IgG, IgG1 and IgG2c) immunity in mice. Polyleucine acted as a potent liposome anchoring portion, which stimulated the production of highly opsonic antibodies. The absence of polyleucine in the liposomal formulation (encapsulated GAS peptide) induced high levels of antibody titers, but with poor opsonic ability against GAS bacteria. However, the liposomal formulation of the conjugated vaccine was no more effective than conjugates alone self-assembled into nanoparticles.

Chemical investigation of Australian pasture plant-derived

Identifying the immunogenic moieties and their precise structure of carbohydrates plays an important role for developing effective carbohydrate-based subunit vaccines. This study assessed the structure-immunogenicity relationship of carbohydrate moieties of a single repeating unit of group A carbohydrate (GAC) present on the cell wall of group A Streptococcus (GAS) using a rationally designed self-adjuvanted lipid-core peptide, instead of a carrier protein. Immunological evaluation of fully synthetic glyco-lipopeptides (particle size: 300-500 nm) revealed that construct consisting of higher rhamnose moieties (trirhamnosyl-lipopeptide) was able to induce enhanced immunogenic activity in mice, and GlcNAc moiety was not found to be an essential component of immunogenic GAC mimicked epitope. Trirhamnosyl-lipopeptide also showed 75-97% opsonic activity against four different clinical isolates of GAS and was comparable to a subunit peptide vaccine (J8-lipopeptide) which illustrated 65-96% opsonic activity.

We report on the chemical analysis of a mud dauber wasp nest-associated fungus, Penicillium sp. CMB-MD22, leading to the discovery and structure elucidation of three known (1-3) and two new (4 and 5) anthrones, and a family of new and known bianthrones, neobulgarones 6-23. Detection and structure elucidation of 1-23 was supported by detailed spectroscopic analysis, as well as chemical (thermal) transformations, and global natural products social (GNPS) molecular networking. An empirical approach using HPLC retention times was effective at differentiating anti from syn bianthrone isomers, while a facile thermal equilibration was shown to favor anti over syn isomers. The neobulgarones 6-23 are natural products, and a crude extract rich in 6-23 exhibits selective antifungal activity against a co-isolated mud dauber wasp nest-associated fungus, suggestive of a possible ecological role as an antifungal chemical defense.

Peptide antigens have been widely used in the development of vaccines, especially for those against autoimmunity-inducing pathogens and cancers. However, peptide-based vaccines require adjuvant and/or a delivery system to stimulate desired immune responses. Here, we explored the potential of self-adjuvanting poly(hydrophobic amino acids) (pHAAs) to deliver peptide-based vaccine against Group A Streptococcus (GAS). We designed and synthesized self-assembled nanoparticles with a variety of conjugates bearing a peptide antigen (J8-PADRE) and polymerized hydrophobic amino acids to evaluate the effects of structural arrangement and pHAAs properties on a system's ability to induce humoral immune responses. Immunogenicity of the developed conjugates was also compared to commercially available human adjuvants. We found that a linear conjugate bearing J8-PADRE and 15 copies of leucine induced equally effective, or greater, immune responses than commercial adjuvants. Our fully defined, adjuvant-free, single molecule-based vaccine induced the production of antibodies capable of killing GAS bacteria.

Using a molecular networking guided strategy, chemical analysis of the Australian mullet fish gastrointestinal tract-derived fungus Amauroascus sp. CMB-F713 yielded a family of polyketide pyrones, amaurones A-I (1-9), featuring an unprecedented carbon skeleton. Structures were assigned to 1-9 by detailed spectroscopic analysis (including X-ray analysis of 1), biosynthetic considerations, and chemical interconversions. For example, the orthoacetate 5 was unstable when stored dry at room temperature, transforming to the monoacetates 2 and 3, while mild heating (40 °C) prompted quantitative conversion of 3 to 2, via an intramolecular trans-acetylation. Likewise, during handling, the monoacetate 1 was prone to intramolecular trans-acetylation, leading to an equilibrium mixture with the isomeric monoacetate amaurone J (10), confirmed when partial hydrolysis of the diacetate 2 yielded the monoacetates 1 and 10 and the triol amaurone K (11).

Cultivation profiling followed by chemical analysis of Streptomyces lincolnensis yielded four new isomeric bianthracenes, lincolnenins A-D (1-4), with relative stereostructures assigned on the basis of detailed spectroscopic analysis. Lincolnenins A (1) and B (2) exhibit restricted rotation about alternate bianthracene 9-9' and 9-8' bridges, respectively, and exist as single atropisomers, whereas C (3) and D (4) are thermally interconvertible atropisomers sharing a common 8-8' bianthracene bridge. Absolute configurations were assigned to 1-4 on the basis of diagnostic ROESY correlations and ECD calculations, whereas acid-mediated dehydration of 1 led to formation and revision of the absolute configuration of the biosynthetically related known Streptomyces antibiotic, setomimycin (5). Lincolnenin A (1) exhibited significant bactericidal activity against multiple susceptible and drug-resistant Gram-positive pathogens (MIC99 < 2.0 μM), including Mycobacterium tuberculosis H37Ra (MIC99 = 0.9 μM).

Reconsideration of the spectroscopic data for penipacids A-E, first reported in 2013 as the acyclic amidines

Group A Streptococcus (GAS) and GAS-related infections are a worldwide challenge, with no commercial GAS vaccine available. Polyethylenimine (PEI) attaches to the cells’ surface and delivers cargo into endosomal and cytosolic compartments. We hypothesized that this will confer mucosal adjuvant properties for peptide antigens against group A Streptococcus (GAS). In this study, we successfully demonstrated the development of PEI incorporated liposomes for the delivery of a lipopeptide-based vaccine (LCP-1) against GAS. Outbred mice were administrated with the vaccine formulations intranasally, and immunological investigation showed that the PEI liposomes elicited significant mucosal and systemic immunity with the production of IgA and IgG antibodies. Antibodies were shown to effectively opsonize multiple isolates of clinically isolated GAS. This proof-of-concept study showed the capability for PEI liposomes to act as a safe vehicle for the delivery of GAS peptide antigens to elicit immune responses against GAS infection, making PEI a promising addition to liposomal mucosal vaccines.

The polyketide enterocin is responsive to environmental stimuli, where mild heating promotes an equilibrium mixture of the isomeric acetals enterocins B and C, which subsequently undergo pseudo-chair-boat inversion to enterocin D. When exposed to aqueous base, enterocin is converted to the isomeric Michael acceptor enterocin F. These studies demonstrate that knowledge of environmental stimuli and associated artifacts is critical to understanding the chemical and ecological properties of enterocins and other classes of natural products.

The bioderived platform molecule levoglucosenone (LGO, 1) and its readily prepared pseudoenantiomer (iso-LGO, 2) have each been subjected to α-iodination reactions with the product halides then being engaged in palladium-catalyzed Ullmann cross-coupling reactions with various bromonitropyridines. The corresponding α-pyridinylated derivatives such as 11 and 24, respectively, are produced as a result. Biological screening of such products reveals that certain of them display potent and selective antimicrobial and/or cytotoxic properties. In contrast, the azaindoles obtained by reductive cyclization of compounds such as 11 and 12 are essentially inactive in these respects. Preliminary mode-of-action studies are reported.

A GNPS molecular networking approach mapped a library of 960 southern Australian marine sponges and prioritized Dysidea sp. (CMB-01171) for chemical investigation. Although the published natural pr...

Chemical analysis of the fungus Chrysosporium sp. CMB-F294 isolated from the gastrointestinal tract of a market-purchased specimen of Mugil mullet yielded eight new alkaloids, belonging to a rare class of phenylpropanoid piperazines. Chrysosporazines F–M (1–8) occur as an equilibrium mixture of acetamide rotamers and feature unprecedented carbocyclic and heterocyclic scaffolds. Structures inclusive of absolute configuration were assigned by detailed spectroscopic analysis, supported by biosynthetic considerations. Structure–activity relationship studies determined that selected chrysosporazines were promising noncytotoxic inhibitors of the multidrug resistance efflux pump P-glycoprotein (P-gp), capable of reversing doxorubicin resistance in P-gp-overexpressing human colon carcinoma cells (SW620 Ad300). Chrysosporazine F (1) was particularly noteworthy, with a 2.5 μM cotreatment inducing a doxorubicin gain in sensitivity (GS 14) > 2-fold that of the positive control verapamil (GS 6.1).

Chemical investigations into solid phase cultivations of an Australian sheep station pasture plant derived

Upregulation of ATP binding cassette (ABC) transporter efflux pumps (

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world’s most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage “If you don’t seek, you don’t find”. Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.

This study showcases the application of an integrated workflow of molecular networking chemical profiling (GNPS), together with miniaturized microbioreactor cultivation profiling (MATRIX) to successfully detect, dereplicate, prioritize, optimize the production, isolate, characterize, and identify a diverse selection of new chemically labile natural products from the Queensland sheep pasture soil-derived fungus Aspergillus sp. CMB-MRF324. More specifically, we report the new tryptamine enamino tripeptide aspergillamides E–F (7–8), dihydroquinoline-2-one aflaquinolones H–I (11–12), and prenylated phenylbutyrolactone aspulvinone Y (14), along with an array of known co-metabolites, including asterriquinones SU5228 (9) and CT5 (10), terrecyclic acid A (13), and aspulvinones N-CR (15), B (16), D (17), and H (18). Structure elucidation was achieved by a combination of detailed spectroscopic and chemical analysis, biosynthetic considerations, and in the case of 11, an X-ray crystallographic analysis.

The ethyl acetate extract of an ISP-2 agar cultivation of the wasp nest-associated fungus Penicillium sp. CMB-MD14 exhibited promising antibacterial activity against vancomycin-resistant enterococci (VRE), with a bioassay guided chemical investigation yielding the new meroterpene, oxandrastin A (1), the first andrastin-like metabolite with an extra oxygenation at C-2. A culture media optimisation strategy informed a scaled-up rice cultivation that yielded 1, together with three new oxandrastins B–D (2–4), two known andrastins C (5) and F (6), and a new meroterpene of the austalide family, isoaustalide F (7). Structures of 1–7 were assigned based on detailed spectroscopic analysis and chemical interconversion. A GNPS molecular networking analysis of the rice cultivation extract detected the known austalides B (8), H (9), and H acid (10), tentatively identified based on molecular formulae and co-clustering with 7. That the anti-VRE properties of the CMB-MD14 extract were exclusively attributed to 1 (IC50 6.0 µM, MIC99 13.9 µM), highlights the importance of the 2-OAc and 3-OAc moieties to the oxandrastin anti-VRE pharmacophore.

The ethyl acetate extract of an ISP-2 agar cultivation of the wasp nest-associated fungus Penicillium sp. CMB-MD14 exhibited promising antibacterial activity against vancomycin-resistant enterococci (VRE), with a bioassay guided chemical investigation yielding the new meroterpene, oxandrastin A (1), the first andrastin-like metabolite with an extra oxygenation at C-2. A culture media optimisation strategy informed a scaled-up rice cultivation that yielded 1, together with three new oxandrastins B–D (2–4), two known andrastins C (5) and F (6), and a new meroterpene of the austalide family, isoaustalide F (7). Structures of 1–7 were assigned based on detailed spectroscopic analysis and chemical interconversion. A GNPS molecular networking analysis of the rice cultivation extract detected the known austalides B (8), H (9), and H acid (10), tentatively identified based on molecular formulae and co-clustering with 7. That the anti-VRE properties of the CMB-MD14 extract were exclusively attributed to 1 (IC50 6.0 µM, MIC99 13.9 µM), highlights the importance of the 2-OAc and 3-OAc moieties to the oxandrastin anti-VRE pharmacophore.

The Australian plant pasture-derived

A brown rice cultivation of

Chemical investigations into solid phase cultivations of an Australian sheep station pasture plant-derived Streptomyces sp. CMB-PB042, yielded the rare enamine naphthopyranoquinones BE-54238A (1) and BE-54238B (2), together with four new analogues, glenthenamines B–D (4–6) and F (8), and two handling artifacts, glenthenamines A (3) and E (7). Single crystal X-ray analyses of 1–2 resolved configurational ambiguities in the scientific literature, while detailed spectroscopic analysis and biosynthetic considerations assigned structures inclusive of absolute configuration to 3–8. We propose a plausible sequence of biosynthetic transformations linking structural and configurational features of 1–8, and apply a novel Schiff base "fishing" approach to detect a key deoxyaminosugar precursor. These enamine naphthopyranoquinone disclose a new P-gp inhibitory pharmacophore capable of reversing doxorubicin resistance in P-gp overexpressing colon carcinoma cells.

Analytical scale chemical/cultivation profiling prioritized the Australian marine-derived fungus Aspergillus noonimiae CMB-M0339. Subsequent investigation permitted isolation of noonindoles A–F (5–10) and detection of eight minor analogues (i–viii) as new examples of a rare class of indole diterpene (IDT) amino acid conjugate, indicative of an acyl amino acid transferase capable of incorporating a diverse range of amino acid residues. Structures for 5–10 were assigned by detailed spectroscopic and X-ray crystallographic analysis. The metabolites 5–14 exhibited no antibacterial properties against G-ve and G+ve bacteria or the fungus Candida albicans, with the exception of 5 which exhibited moderate antifungal activity.

Chemical analysis of an M1 agar plate cultivation of a marine fish-gut-derived fungus, Chrysosporium sp. CMB-F214, revealed the known chrysosporazines A–D (11–14) in addition to a suite of very minor aza analogues 1–6. A microbioreactor (MATRIX) cultivation profiling analysis failed to deliver cultivation conditions that significantly improved the yields of 1–6, however, it did reveal that M2 agar cultivation produced the new natural product 15. A precursor-directed biosynthesis strategy adopting supplementation of a CMB-F214 M1 solid agar culture with sodium nicotinate enhanced production of otherwise inaccessible azachrysposorazines A1 (1), A2 (2), B1 (3), C1 (4), C2 (5) and D1 (6), in addition to four new chrysosporazines, chrysosporazines N–P (7–9) and spirochrysosporazine A (10). Structures inclusive of absolute configurations were assigned to 1–15 based on detailed spectroscopic and chemical analyses, and biosynthetic considerations. Non-cytotoxic to human carcinoma cells, azachrysosporazies 1–5 were capable of reversing doxorubicin resistance in P-glycoprotein (P-gp)-overexpressing human colon carcinoma cells (SW620 Ad300), with optimum activity exhibited by the C-2′ substituted analogues 3–5.

Chemical investigation on a Streptomyces sp. strain MS180069 isolated from a sediment sample collected from the South China Sea, yielded the new benzo[f]isoindole-dione alkaloid, bhimamycin J (1). The structure was determined by extensive spectroscopic analysis, including HRMS, 1D, 2D NMR, and X-ray diffraction techniques. A molecular docking study revealed 1 as a new molecular motif that binds with human angiotensin converting enzyme2 (ACE2), recently described as the cell surface receptor responsible for uptake of 2019-CoV-2. Using enzyme assays we confirm that 1 inhibits human ACE2 79.7 % at 25 µg/mL.

Chemical analysis of an M1 agar plate cultivation of a marine fish-gut-derived fungus, Chrysosporium sp. CMB-F214, revealed the known chrysosporazines A–D (11–14) in addition to a suite of very minor aza analogues 1–6. A microbioreactor (MATRIX) cultivation profiling analysis failed to deliver cultivation conditions that significantly improved the yields of 1–6; however, it did reveal that M2 agar cultivation produced the new natural product 15. A precursor-directed biosynthesis strategy adopting supplementation of a CMB-F214 M1 solid agar culture with sodium nicotinate enhanced production of otherwise inaccessible azachrysposorazines A1 (1), A2 (2), B1 (3), C1 (4), C2 (5) and D1 (6), in addition to four new chrysosporazines; chrysosporazines N–P (7–9) and spirochrysosporazine A (10). Structures inclusive of absolute configurations were assigned to 1–15 based on detailed spectroscopic and chemical analyses, and biosynthetic considerations. Non-cytotoxic to human carcinoma cells, azachrysosporazies 1–5 were capable of reversing doxorubicin resistance in P-glycoprotein (P-gp)-overexpressing human colon carcinoma cells (SW620 Ad300), with optimum activity exhibited by the C-2′ substituted analogues 3–5.

The termite nest-derived fungus Trichoderma virens CMB-TN16 cultivated on rice-based media produced seven new first-in-class trimeric sesquiterpenes, trivirensols A-G (11-17). Structures inclusive of absolute configurations were assigned by detailed spectroscopic analysis and biosynthetic considerations. Although trivirensols exhibit no cytotoxicity to mammalian carcinoma cells, selected examples are bacteriostatic against vancomycin-resistant Enterococcus faecalis (VRE). Structure-activity relationship (SAR) investigations combined with in situ chemical stability studies documented bacteriostatic activity for trivirensols A (11) and B (12) and the co-metabolite divirensols A (4), B (5), and G (10), all of which share a common terminal butenolide. Significantly, SAR studies also revealed bacteriostatic activity for trivirensols C (13) and G (17) and the co-metabolite divirensol C (6), all of which share a common hydrated butenolide terminal. Of note, when exposed to VRE cell cultures, the hydrated butenolides 6, 13, and 17 undergo rapid in situ dehydration to corresponding butenolides, suggesting hydrated butenolides are a pro-drug form of the butenolide VRE bacteriostatic pharmacophore.

Significance Agonists of the μ-opioid receptor (MOPr) are currently the gold standard for pain treatment. However, their therapeutic usage is greatly limited by side effects including respiratory depression, constipation, tolerance, and dependence. Functionally selective MOPr agonists that mediate their effects preferentially through G proteins rather than β-arrestin signaling are believed to produce fewer side effects. Here, we present the discovery of 3 unusual tetrapeptides with a unique stereochemical arrangement of hydrophobic amino acids from an Australian estuarine isolate of Penicillium species. Building on these natural templates we developed bilorphin, a potent and selective highly G protein-biased agonist of the MOPr. Further, through the addition of a simple sugar moiety, we generated bilactorphin that is an effective analgesic in vivo., An Australian estuarine isolate of Penicillium sp. MST-MF667 yielded 3 tetrapeptides named the bilaids with an unusual alternating LDLD chirality. Given their resemblance to known short peptide opioid agonists, we elucidated that they were weak (Ki low micromolar) μ-opioid agonists, which led to the design of bilorphin, a potent and selective μ-opioid receptor (MOPr) agonist (Ki 1.1 nM). In sharp contrast to all-natural product opioid peptides that efficaciously recruit β-arrestin, bilorphin is G protein biased, weakly phosphorylating the MOPr and marginally recruiting β-arrestin, with no receptor internalization. Importantly, bilorphin exhibits a similar G protein bias to oliceridine, a small nonpeptide with improved overdose safety. Molecular dynamics simulations of bilorphin and the strongly arrestin-biased endomorphin-2 with the MOPr indicate distinct receptor interactions and receptor conformations that could underlie their large differences in bias. Whereas bilorphin is systemically inactive, a glycosylated analog, bilactorphin, is orally active with similar in vivo potency to morphine. Bilorphin is both a unique molecular tool that enhances understanding of MOPr biased signaling and a promising lead in the development of next generation analgesics.