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An investigation of ×19 soil samples collected under the auspices of the Australian citizen science initiative, Soils for Science, returned ×559 chemically dereplicated microbial isolates, of which ×54 exhibited noteworthy anthelmintic activity against either the heartworm Dirofilaria immitis microfilaria and/or the gastrointestinal parasite Haemonchus contortus L1-L3 larvae. Chemical (GNPS and UPLC-DAD) and cultivation (MATRIX) profiling prompted a detailed chemical investigation of Streptomyces sp. S4S-00196A10, which yielded new anthelmintic polyketide goondapyrones A-J ( 1 - 10 ), together with the known actinopyrones A ( 11 ) and C ( 12 ). Structures for 1 - 12 were assigned on the basis of detailed spectroscopic and chemical analysis, with preliminary structure activity relationship analysis revealing selected γ-pyrones >50-fold and >13-fold more potent than isomeric α-pyrones against D. immitis mf motility (e.g., EC 50 0.05 μM for 1 ; EC 50 2.7 μM for 5 ) and H. contortus L1-L3 larvae development (e.g., EC 50 0.58 μM for 1 ; EC 50 8.2 μM for 5 ), respectively.

There is a lack of new antibiotics to combat drug-resistant bacterial infections that increasingly threaten global health. The current pipeline of clinical-stage antimicrobials is primarily populated by "new and improved" versions of existing antibiotic classes, supplemented by several novel chemical scaffolds that act on traditional targets. The lack of fresh chemotypes acting on previously unexploited targets (the "holy grail" for new antimicrobials due to their scarcity) is particularly unfortunate as these offer the greatest opportunity for innovative breakthroughs to overcome existing resistance. In recognition of their potential, this review focuses on this subset of high value antibiotics, providing chemical structures where available. This review focuses on candidates that have progressed to clinical trials, as well as selected examples of promising pioneering approaches in advanced stages of development, in order to stimulate additional research aimed at combating drug-resistant infections.

The first total synthesis of the Australian marine tunicate fungus-derived cyclic peptide talarolide A ( 1 ) has confirmed the structure previously proposed on the basis of spectroscopic and chemical analyses and re-affirmed the importance of the unique hydroxamate H-bond bridge in ring conformer stabilization. The unexpected co-synthesis of atrop -talarolide A ( 8 ) revealed, for the first time, that hydroxamate H-bond bridging in the talarolide framework invokes non-canonical atropisomerism and that talarolides A ( 1 ), C ( 3 ), and D ( 4 ) all exist naturally as atropisomers. These discoveries raise the intriguing prospect that comparable functionalisation of other cyclic peptides, including those with commercial value, could provide ready access to new "unnatural atropisomeric" chemical space, with new and/or improved chemical and biological properties.

Subunit vaccines require an immunostimulant (adjuvant) and/or delivery system to induce immunity. However, currently, available adjuvants are either too dangerous in terms of side effects for human use (experimental adjuvants) or have limited efficacy and applicability. In this study, we examined the capacity of mannose-lipopeptide ligands to enhance the immunogenicity of a vaccine consisting of polyleucine(L 15 )-antigen conjugates anchored to liposomes. The clinically tested Group A Streptococcus (GAS) B-cell epitope, J8, combined with universal T helper PADRE (P) was used as the antigen. Six distinct mannose ligands were incorporated into neutral liposomes carrying L 15 PJ8. While induced antibody titers were relatively low, the ligand carrying mannose, glycine/lysine spacer, and two palmitic acids as liposomal membrane anchoring moieties (ligand 3), induced significantly higher IgG titers than non-mannosylated liposomes. The IgG titers were significantly enhanced when positively charged liposomes were employed. Importantly, the produced antibodies were able to kill GAS bacteria. Unexpectedly, the physical mixture of only ligand 3 and PJ8 produced self-assembled nanorods that induced antibody titers as high as those elicited by the lead liposomal formulation and antigen adjuvanted with the potent, but toxic, complete Freund's adjuvant (CFA). Antibodies produced upon immunization with PJ8 + 3 were even more opsonic than those induced by CFA + PJ8. Importantly, in contrast to CFA, ligand 3 did not induce observable adverse reactions or excessive inflammatory responses. Thus, we demonstrated that a mannose ligand, alone, can serve as an effective vaccine nanoadjuvant., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The revised structure, 2 , assigned to the title natural product has been prepared by chemical synthesis using a reaction sequence involving six simple steps starting from 2,3-dimethoxybenzaldehyde and proceeding via intermediates 8 , 12 , and 14 . A comparison of the NMR data acquired on synthetically derived compound 2 with those reported for the natural product reveals an excellent match. Preliminary biological screening of compound 2 along with analogues/precursors 7 , 9 , 10 , 11 , 13 , 14 , and 15 revealed that none exhibited antibacterial, antifungal or cytotoxic effects.

Quartzite caves located on table-top mountains (tepuis) in the Guyana Shield, are ancient, remote, and pristine subterranean environments where microbes have evolved peculiar metabolic strategies to thrive in silica-rich, slightly acidic and oligotrophic conditions. In this study, we explored the culturable fraction of the microbiota inhabiting the (ortho)quartzite cave systems in Venezuelan tepui (remote table-top mountains) and we investigated their metabolic and enzymatic activities in relation with silica solubilization and extracellular hydrolytic activities as well as the capacity to produce antimicrobial compounds. Eighty microbial strains were isolated with a range of different enzymatic capabilities. More than half of the isolated strains performed at least three enzymatic activities and four bacterial strains displayed antimicrobial activities. The antimicrobial producers Paraburkholderia bryophila CMB_CA002 and Sphingomonas sp. MEM_CA187, were further analyzed by conducting chemotaxonomy, phylogenomics, and phenomics. While the isolate MEM_CA187 represents a novel species of the genus Sphingomonas, for which the name Sphingomonas imawarii sp. nov. is proposed, P. bryophila CMB_CA002 is affiliated with a few strains of the same species that are antimicrobial producers. Chemical analyses demonstrated that CMB_CA002 produces ditropolonyl sulfide that has a broad range of activity and a possibly novel siderophore. Although the antimicrobial compounds produced by MEM_CA187 could not be identified through HPLC-MS analysis due to the absence of reference compounds, it represents the first soil-associated Sphingomonas strain with the capacity to produce antimicrobials. This work provides first insights into the metabolic potential present in quartzite cave systems pointing out that these environments are a novel and still understudied source of microbial strains with biotechnological potential., Competing Interests: Declaration of Competing Interest There is no conflict of interest among the authors., (Copyright © 2024. Published by Elsevier GmbH.)

A bioassay-guided chemical investigation of a bacterium, Streptomyces sp. CMB-MRB032, isolated from sheep feces collected near Bathurst, Victoria, Australia, yielded the known polyketide antimycins A4a ( 1 ) and A2a ( 2 ) as potent inhibitors of Dirofilaria immitis (heartworm) microfilaria (mf) motility (EC 50 0.0013-0.0021 µg/mL), along with the octapeptide surugamide A ( 3 ) and the new N -methylated analog surugamide K ( 4 ). With biological data suggesting surugamides may also exhibit activity against D. immitis , a GNPS molecular network analysis of a library of microbes sourced from geographically diverse Australian ecosystems identified a further five taxonomically and chemically distinct surugamide producers. Scaled-up cultivation of one such producer, Streptomyces sp. CMB-M0112 isolated from a marine sediment collected at Shorncliff, Qld, Australia, yielded 3 along with the new acyl-surugamides A1-A4 ( 5 - 8 ). Solid-phase peptide synthesis provided additional synthetic analogs, surugamides S1-S3 ( 9 - 11 ), while derivatization of 3 returned the semi-synthetic surugamide S4 ( 12 ) and acyl-surugamides AS1-AS3 ( 13 - 15 ). The natural acyl-surugamide A3 ( 7 ) and semi-synthetic acyl-surugamide AS3 ( 15 ) were shown to selectively inhibit D. immitis mf motility (EC 50 3.3-3.4 µg/mL), however, unlike antimycins 1 and 2 , were inactive against the gastrointestinal nematode Haemonchus contortus L1-L3 larvae (EC 50 > 25 µg/mL) and were not cytotoxic to mammalian cells (human colorectal carcinoma SW620, IC 50 > 30 µg/mL). A structure-activity relationship (SAR) study on the surugamides 3 - 15 revealed that selective acylation of the Lys 3 -ε-NH 2 correlates with anthelmintic activity.

Peptide-based vaccines can trigger highly specific immune responses, although peptides alone are usually unable to confer strong humoral or cellular immunity. Consequently, peptide antigens are administered with immunostimulatory adjuvants, but only a few are safe and effective for human use. To overcome this obstacle, herein a peptide antigen was lipidated to effectively anchor it to liposomes and emulsion. A peptide antigen B cell epitope from Group A Streptococcus M protein was conjugated to a universal T helper epitope, the pan DR-biding epitope (PADRE), alongside a lipidic moiety cholesterol. Compared to a free peptide antigen, the lipidated version (LP1) adopted a helical conformation and self-assembled into small nanoparticles. Surprisingly, LP1 alone induced the same or higher antibody titers than liposomes or emulsion-based formulations. In addition, antibodies produced by mice immunized with LP1 were more opsonic than those induced by administering the antigen with incomplete Freund's adjuvant. No side effects were observed in the immunized mice and no excessive inflammatory immune responses were detected. Overall, this study demonstrated how simple conjugation of cholesterol to a peptide antigen can produce a safe and efficacious vaccine against Group A Streptococcus - the leading cause of superficial infections and the bacteria responsible for deadly post-infection autoimmune disorders., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Subjecting the Australian marine-derived fungus Aspergillus noonimiae CMB-M0339 to cultivation profiling using an innovative miniaturized 24-well plate format (MATRIX) enabled access to new examples of the rare class of 2,6-diketopiperazines, noonazines A-C ( 1 - 3 ), along with the known analogue coelomycin ( 4 ), as well as a new azaphilone, noonaphilone A ( 5 ). Structures were assigned to 1 - 5 on the basis of a detailed spectroscopic analysis, and in the case of 1 - 2 , an X-ray crystallographic analysis. Plausible biosynthetic pathways are proposed for 1 - 4 , involving oxidative Schiff base coupling/dimerization of a putative Phe precursor. Of note, 2 incorporates a rare meta -Tyr motif, typically only reported in a limited array of Streptomyces metabolites. Similarly, a plausible biosynthetic pathway is proposed for 5 , highlighting a single point for stereo-divergence that allows for the biosynthesis of alternate antipodes, for example, the 7 R noonaphilone A ( 5 ) versus the 7 S deflectin 1a ( 6 ).

A chemical investigation of Australian soil-derived bacteria Actinomadura sp. S4S-00069B08 yielded eight new benzenoid ansamycins, goondansamycins A-H. Goondansamycins feature rare 1,4-benzoxazin-3-one or o -diamino- p -benzoquinone moieties and can exist as both aglycones or 9- O -α-glycosides of either d-rhodinose or d-amicetose. Structures were solved on the basis of detailed spectroscopy, including X-ray analysis.

Two novel meroterpenoids, alliisativins A and B ( 1 , 2 ) were discovered through a genome-based exploration of the biosynthetic gene clusters of the deep-sea-derived fungus Penicillium allii-sativi MCCC entry 3A00580. Extensive spectroscopic analysis, quantum calculations, chemical derivatization, and biogenetic considerations were utilized to establish their structures. Alliisativins A and B ( 1 , 2 ) possess a unique carbon skeleton featuring a drimane sesquiterpene with a highly oxidized polyketide. Noteworthily, alliisativin A ( 1 ) showed dual activity in promoting osteogenesis and inhibiting osteoclast, indicating an antiosteoporosis potential.

Investigation of the secondary metabolites of Streptomyces virginiae CMB-CA091 isolated from the quartz-rich (tepui) soil of a cave in Venezuela yielded two new dimeric phenazine glycosides, tepuazines A and B ( 1 and 2 ); three new monomeric phenazine glycosides, tepuazines C-E ( 3 - 5 ); and a series of known analogues, baraphenazine G ( 6 ), phenazinolin D ( 7 ), izumiphenazine C ( 8 ), 4-methylaminobenzoyl-l-rhamnopyranoside ( 9 ), and 2-acetamidophenol ( 10 ). Structures were assigned to 1 - 10 on the basis of detailed spectroscopic analysis and biosynthetic considerations, with 1 and 2 featuring a rare 2-oxabicyclo[3.3.1]nonane-like ring C/D bridge shared with only a handful of known Streptomyces natural products. We propose a plausible convergent biosynthetic relationship linking all known members of this structure class that provides a rationale for the observed ring C/D configuration.

We report on the use of n itric o xide- me diated t ranscriptional a ctivation (NOMETA) as an innovative means to detect and access new classes of microbial natural products encoded within silent biosynthetic gene clusters. A small library of termite nest- and mangrove-derived fungi and actinomyces was subjected to cultivation profiling using a miniaturized 24-well format approach (MATRIX) in the presence and absence of nitric oxide, with the resulting metabolomes subjected to comparative chemical analysis using UPLC-DAD and GNPS molecular networking. This strategy prompted study of Talaromyces sp. CMB-TN6F and Coccidiodes sp. CMB-TN39F, leading to discovery of the triterpene glycoside pullenvalenes A-D ( 1 - 4 ), featuring an unprecedented triterpene carbon skeleton and rare 6- O -methyl- N -acetyl-d-glucosaminyl glycoside residues. Structure elucidation of 1 - 4 was achieved by a combination of detailed spectroscopic analysis, chemical degradation, derivatization and synthesis, and biosynthetic considerations.

Mucosal vaccines are highly attractive due to high patient compliance and their suitability for mass immunizations. However, all currently licensed mucosal vaccines are composed of attenuated/inactive whole microbes, which are associated with a variety of safety concerns. In contrast, modern subunit vaccines use minimal pathogenic components (antigens) that are safe but typically poorly immunogenic when delivered via mucosal administration. In this study, we demonstrated the utility of various functional polymer-based nanostructures as vaccine carriers. A Group A Streptococcus (GAS)-derived peptide antigen ( PJ8 ) was selected in light of the recent global spread of invasive GAS infection. The vaccine candidates were prepared by either conjugation or physical mixing of PJ8 with rod-, sphere-, worm-, and tadpole-shaped polymeric nanoparticles. The roles of nanoparticle shape and antigen conjugation in vaccine immunogenicity were demonstrated through the comparison of three distinct immunization pathways (subcutaneous, intranasal, and oral). No additional adjuvant or carrier was required to induce bactericidal immune responses even upon oral vaccine administration.

The Australian roadside soil-derived fungus Penicillium shearii CMB-STF067 was prioritized for chemical investigation based on an SDA cultivation extract exhibiting both antibacterial properties and natural products with unprecedented molecular formulae (GNPS). Subsequent miniaturized 24-well plate cultivation profiling (MATRIX) identified red rice as optimal for the production of the target chemistry, with scaled-up cultivation, extraction and fractionation yielding four new xanthone-anthraquinone heterodimers, jugiones A-D ( 1 - 4 ), whose structures were assigned by detailed spectroscopic analysis and biosynthetic considerations. Of note, where 1 - 2 and 4 were active against the Gram-positive bacteria vancomycin-resistant Enterococcus faecalis (IC 50 2.6-3.9 μM) and multiple-drug-resistant clinical isolates of Staphylococcus aureus (IC 50 1.8-6.4 μM), and inactive against the Gram-negative bacteria Escherichia coli (IC 50 > 30 μM), the closely related analog 3 exhibited no antibacterial properties (IC 50 > 30 μM). Furthermore, where 1 was cytotoxic to human carcinoma (IC 50 9.0-9.8 μM) and fungal (IC 50 4.1 μM) cells, 2 and 4 displayed no such cytotoxicity (IC 50 > 30 μM), revealing an informative structure activity relationship (SAR). We also extended the SAR study to other known compounds of this heterodimer class, which showed that the modification of ring G can reduce or eliminate the cytotoxicity while retaining the antibacterial activity.

An integrated program of chemical profiling (GNPS) coupled with an expanded format 24-well-plate miniaturized cultivation profiling (MATRIX) utilizing traditional as well as grain/pulse and cereal media permitted rapid prioritization of Aspergillus terreus CMB-SWF012 as a source of unprecedented natural products. Scaled-up cultivation on rice and PDA yielded the rare tripeptides asterripeptides A-C ( 1 - 3 ), new indolo-sesquiterpene Michael adducts terreusides A and B ( 4 and 5 ), and known precursors asterresin A ( 6 ) and (+)-giluterrin ( 7 ). Structures for 1 - 7 were assigned by detailed spectroscopic and chemical analysis and biosynthetic considerations.

Covering literature to December 2022This review provides a comprehensive account of all natural products (500 compounds, including 17 semi-synthetic derivatives) described in the primary literature up to December 2022, reported to be capable of inhibiting the egg hatching, motility, larval development and/or the survival of helminths ( i.e. , nematodes, flukes and tapeworms). These parasitic worms infect and compromise the health and welfare, productivity and lives of commercial livestock ( i.e. , sheep, cattle, horses, pigs, poultry and fish), companion animals ( i.e. , dogs and cats) and other high value, endangered and/or exotic animals. Attention is given to chemical structures, as well as source organisms and anthelmintic properties, including the nature of bioassay target species, in vivo animal hosts, and measures of potency.

Marine fungi are prolific source for the discovery of structurally diverse and bioactive molecules. In our search for new anti-osteoporosis compounds from deep-sea-derived fungi, we prioritized a fungus whose extract exhibited moderate activity and rich chemical diversity. The investigation of this strain afforded a class of citrinins, including three new citrinin trimers, neotricitrinols A-C (1-3), and three known dimeric/monomeric precursors (4-6). Neotricitrinols A-C (1-3) feature a unique octacyclic carbon scaffold among the few reported citrinin trimers with their absolute configurations established by spectroscopic analysis, theoretical-statistical approaches (GIAO-NMR, TDDFT-ECD/ORD calculations), DP4+ probability analysis as well as biogenetic consideration. A plausible biosynthetic pathway linking 1-3 from the common intermediate metabolite penicitrinol A (4) was proposed. Biologically, neotricitrinol B (2) showed potential anti-osteoporosis activity by promoting osteoblastogenesis and inhibiting adipogenic differentiation on primary bone mesenchymal stem cells, while displaying no cytotoxicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Application of a miniaturized 24-well plate system for cultivation profiling (MATRIX) permitted optimization of the cultivation conditions for the marine-derived fungus Talaromyces sp. CMB-TU011, facilitating access to the rare cycloheptapeptide talarolide A ( 1 ) along with three new analogues, B-D ( 2 - 4 ). Detailed spectroscopic analysis supported by Marfey's analysis methodology was refined to resolve N -Me-l-Ala from N -Me-d-Ala, l- allo -Ile from l-Ile and l-Leu, and partial and total syntheses of 2 , and permitted unambiguous assignment of structures for 1 (revised) and 2 - 4 . Consideration of diagnostic ROESY correlations for the hydroxamates 1 and 3 - 4 , and a calculated solution structure for 1 , revealed how cross-ring H-bonding to the hydroxamate moiety influences (defines/stabilizes) the cyclic peptide conformation. Such knowledge draws attention to the prospect that hydroxamates may be used as molecular bridges to access new cyclic peptide conformations, offering the prospect of new biological properties, including enhanced oral bioavailability.

Untreated group A Streptococcus (GAS) can lead to a range of life-threatening diseases, including rheumatic heart disease. To date, no therapeutic or prophylactic vaccines are commercially available to treat or prevent GAS infection. Development of a peptide-based subunit vaccine offers a promising solution, negating the safety issues of live-attenuated or inactive vaccines. Subunit vaccines administer small peptide fragments (antigens), which are typically poorly immunogenic. Therefore, these peptide antigens require formulation with an immune stimulant and/or vaccine delivery platform to improve their immunogenicity. We investigated polyelectrolyte complexes (PECs) and polymer-coated liposomes as self-adjuvanting delivery vehicles for a GAS B cell peptide epitope conjugated to a universal T-helper epitope and a synthetic toll-like receptor 2-targeting moiety lipid core peptide-1 (LCP-1). A structure-activity relationship of cationic PEC vaccines containing different external PEI-coatings (poly(ethylenimine); 10 kDa PEI, 25 kDa PEI, and a synthetic mannose-functionalized 25 kDa PEI) formed vaccines PEC-1, PEC-2, and PEC-3, respectively. All three PEC vaccines induced J8-specific systemic immunoglobulin G (IgG) antibodies when administered intranasally to female BALB/c mice without the use of additional adjuvants. Interestingly, PEC-3 induced the highest antibody titers among all tested vaccines, with the ability to effectively opsonize two clinically isolated GAS strains. A comparative study of PEC-2 and PEC-3 with liposome-based delivery systems was performed subcutaneously. LCP-1 was incorporated into a liposome formulation (DPPC, DPPG and cholesterol), and the liposomes were externally coated with PEI (25 kDa; Lip-2) or mannosylated PEI (25 kDa; Lip-3). All liposome vaccines induced stronger humoral immune responses compared to their PEC counterparts. Notably, sera of mice immunized with Lip-2 and Lip-3 produced significantly higher opsonic activity against clinically isolated GAS strains compared to the positive control, P25-J8 emulsified with the commercial adjuvant, complete Freund's adjuvant (CFA). This study highlights the capability of a PEI-liposome system to act as a self-adjuvanting vehicle for the delivery of GAS peptide antigens and protection against GAS infection.

The need for new antibacterial drugs to treat the increasing global prevalence of drug-resistant bacterial infections has clearly attracted global attention, with a range of existing and upcoming funding, policy, and legislative initiatives designed to revive antibacterial R&D. It is essential to assess whether these programs are having any real-world impact and this review continues our systematic analyses that began in 2011. Direct-acting antibacterials (47), non-traditional small molecule antibacterials (5), and β-lactam/β-lactamase inhibitor combinations (10) under clinical development as of December 2022 are described, as are the three antibacterial drugs launched since 2020. Encouragingly, the increased number of early-stage clinical candidates observed in the 2019 review increased in 2022, although the number of first-time drug approvals from 2020 to 2022 was disappointingly low. It will be critical to monitor how many Phase-I and -II candidates move into Phase-III and beyond in the next few years. There was also an enhanced presence of novel antibacterial pharmacophores in early-stage trials, and at least 18 of the 26 phase-I candidates were targeted to treat Gram-negative bacteria infections. Despite the promising early-stage antibacterial pipeline, it is essential to maintain funding for antibacterial R&D and to ensure that plans to address late-stage pipeline issues succeed., (© 2023. The Author(s).)

In reviewing a selection of recent case studies from our laboratory, we revealed some lessons learned and benefits accrued from the application of mass spectrometry (MS/MS) molecular networking in the field of marine sponge natural products. Molecular networking proved pivotal to our discovery of many new natural products and even new classes of natural product, some of which were opaque to alternate dereplication and prioritization strategies. Case studies included the discovery of: (i) trachycladindoles, an exceptionally rare class of bioactive indole alkaloid previously only known from a single southern Australia sample of Trachycladus laevispirulifer ; (ii) dysidealactams, an unprecedented class of sesquiterpene glycinyl-lactam and glycinyl-imide from a Dysidea sp., a sponge genera often discounted as having been exhaustively studied; (iii) cacolides, an unprecedented family of sesterterpene α-methyl-γ-hydroxybutenolides from a Cacospongia sp., all too easily mischaracterized and deprioritized during dereplication as a well-known class of sponge sesterterpene tetronic acids; and (iv) thorectandrins, a new class of indole alkaloid which revealed unexpected insights into the chemical and biological properties of the aplysinopsins, one of the earliest and more extensively reported class of sponge natural products.

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 16 S 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.

Chemical analysis of cultures of a Queensland mud dauber wasp nest-derived fungus, Talaromyces sp. CMB-MW102, yielded the known dimeric oxaphenalenone duclauxin ( 1 ) along with a family of new 1-deoxy-d-glucosamine adducts, glyclauxins A-E ( 2 - 6 ). Despite 1D NMR spectra of 2 - 6 being compromised by broadening of selected resonances, structures inclusive of absolute configuration were assigned on the basis of detailed spectroscopic analysis and biogenetic considerations, as well as biomimetic semisynthesis and chemical interconversion. For example, exposure of duclauxin ( 1 ) to synthetic 1-deoxy-d-glucosamine yielded glyclauxin B ( 3 ), while on handling and storage, glyclauxins C ( 4 ) and D ( 5 ) (bearing a 7-OMe moiety) proved chemically labile and underwent quantitative transformation to glyclauxins B ( 3 ) and A ( 2 ), respectively. These latter observations on chemical reactivity and stability informed a proposed biogenetic relationship linking all known members of the extended duclauxin family. Notwithstanding their potential status as artifacts, the detection of glyclauxins B ( 3 ) and A ( 2 ) in a fresh CMB-MW102 culture extract confirmed their natural product status.

Fungal indole diterpenes (IDTs) occupy a valuable region of bioactive natural product chemical space, displaying potent and selective inhibition of therapeutically important ion channels and with potential application in the treatment of glaucoma, cancer, and neurodegenerative diseases, as well as insecticides and antivirals. We have employed an integrated workflow of analytical scale chemical profiling using GNPS (Global Natural Products Social molecular networking) and cultivation profiling (also known as "MATRIX" miniaturized microbioreactor) to detect, prioritize, optimize the production, isolate, characterize, and identify a new series of indole diterpenes, noonindoles G-L ( 7 - 12 ), from an Australian marine-derived fungus, Aspergillus noonimiae CMB-M0339. The first reported examples of IDT glycosides, the molecular structures for 7 - 12 , were assigned on the basis of detailed spectroscopic analysis and biosynthetic considerations.

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.

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., Competing Interests: The authors declare that they have no conflict of interest.

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., Competing Interests: The authors declare no conflict of interest.

Molecular network analysis of Streptomyces sp. CMB-MW079 detected rare phosphorylated natural products. Miniaturized cultivation profiling (MATRIX) established optimal conditions for the production, isolation, and identification of the polyketide δ-lactone phoslactomycin E ( 1 ) and new ester homologues, phoslactomycins J and K ( 2 and 3 ), as well as unprecedented heterocyclic analogues, the tetrahydrofuran cyclolactomycins A-D ( 4 - 7 ) and γ-lactone isocyclolactomycins A-C ( 8 - 10 ). We propose a biogenetic relationship linking these cometabolites with the known lactomycins A-C which were tentatively identified as minor cometabolites.

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.

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 Ca V 3.3 (IC 50 s DIM 2.09 µM; DIM-one 9.07 µM) while compound IX inhibited both Ca V 3.2 (6.68 µM) and Ca V 3.3 (IC 50 = 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 Ca 2+ current through Ca V 3.1 (IC 50 = 8.32 µM) and Ca V 3.3 (IC 50 = 9.63 µM), while IX partially blocked Ca V 3.2 and Ca V 3.3 inward Ca 2+ current. In contrast, DIM-one preferentially blocked Ca V 3.1 inward Ca 2+ current (IC 50 = 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., Competing Interests: The authors declare no conflicts of interest.

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 Streptomyces sp. CMB-PB041, supported by miniaturized cultivation profiling and molecular network analysis, led to the isolation and characterization of 13 new macrocyclic spirotetronates, glenthmycins A-M ( 1 - 13 ), with structures assigned by detailed spectroscopic analysis, chemical degradation and derivatization, and mechanistic and biosynthetic considerations. Hydrolysis of glenthmycin B ( 2 ) yielded the aglycone 14 , whose structure and absolute configuration were secured by X-ray analysis, along with the unexpected amino sugar residues glenthose lactams A ( 15 ) and B ( 16 ), with Mosher analysis of 15 facilitating assignment of absolute configurations of the amino sugar. While the glenthmycins proved to be acid stable, treatment of isomeric glenthmycins (i.e., 3 , 6 , and 8 ) with base catalyzed rapid intramolecular trans -esterification to regio-isomeric mixtures (i.e., 3 + 6 + 8 ). Exposure of 5 to base achieved the same intramolecular trans -esterification and was instrumental in detecting and tentatively identifying two additional minor co-metabolites, glenthmycins N ( 19 ) and O ( 20 ). A structure-activity relationship analysis carried out on 1 - 13 and the semisynthetic analogues 14 and 21 - 26 revealed a promising Gram +ve antibacterial pharmacophore, effective against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE), but with no detectable cytotoxicity to eukaryotic cells (i.e., fungal and human carcinoma). Of particular note, the semisynthetic analogue glenthmycin K 9-valerate ( 26 ) was unique among glenthmycins in potently inhibiting growth of the full panel of Gram +ve pathogens (IC 50 0.2-1.6 μM). We conclude with an observation that any future evaluation of the antibacterial potential of glenthmycins and related macrocyclic spirotetronates may do well to include important soil-derived Gram +ve pathogens, such as Bacillus anthrax , Clostridium botulinum , and Rhodococcus equi , the causative agents of anthrax, botulism, and livestock pneumonia.

Reconsideration of the spectroscopic data for penipacids A-E, first reported in 2013 as the acyclic amidines 1 - 5 from the South China deep sea sediment-derived fungus Penicillium paneum SD-44, prompted a total synthesis structure revision as the hydrazones 6 - 10 . This revision strongly supported the proposition that penipacids A-B ( 6 - 7 ) were artifact Schiff base adducts of the cryptic (undetected) natural product N -aminoanthranilic acid ( 11 ) with diacetone alcohol, induced by excessive exposure to acetone and methanol under acidic handling conditions. Likewise, the revised structures for penipacids C-D ( 8 - 9 ) and E ( 10 ) raise the possibility that they may also be artifact Schiff base adducts of 11 and the media constituents pyruvic acid and furfural, respectively. A review of the natural products literature revealed other Schiff base (hydrazone) natural products that might also be viewed as Schiff base adduct artifacts of 11 . Having raised the prospect that 11 is an undetected and reactive cryptic natural product, we went on to establish that 11 is not cytotoxic to a range of bacterial, fungal or mammalian (human) cell types. Instead, when added as a supplement to microbial cultivations, 11 can act as a chemical cue/transcriptional regulator, activating and/or enhancing the yield of biosynthetic gene clusters encoding for other natural product chemical defenses. This study demonstrates the value of challenging the structure and artifact status of natural products, as a window into the hidden world of cryptic and highly reactive natural products.

A library of fungi previously recovered from the gastrointestinal tract (GIT) of several fresh, commercially sourced Australian mullet fish was re-profiled for production of a rare class of phenylpropanoid piperazine alkaloids (chrysosporazines) using an integrated platform of; (i) miniaturized 24-well plate cultivation profiling (MATRIX), (ii) UPLC-DAD and UPLC-QTOF-MS/MS (GNPS) chemical profiling, and; (iii) precursor directed biosynthesis to manipulate in situ biosynthetic performance and outputs; to detect two new fungal producers of chrysosporazines. Chemical analysis of an optimized PDA solid phase cultivation of Aspergillus sp. CMB-F661 yielded the new regioisomeric chrysosporazine T ( 1 ) and U ( 2 ), while precursor directed cultivation amplified production and yielded the very minor new natural products azachrysosporazine T1 ( 3 ) and U1 ( 4 ), and the new unnatural analogues neochrysosporazine R ( 5 ) and S ( 6 ). Likewise, chemical analysis of an optimized M1 solid phase cultivation of Spiromastix sp. CMB-F455 lead to the GNPS detection of multiple chrysosporazines and brasiliamides, and the isolation and structure elucidation of chrysosporazine D ( 7 ) and brasiliamide A ( 8 ). Access to new chrysosporazine regioisomers facilitated structure activity relationship investigations to better define the chrysosporazine P-glycoprotein (P-gp) inhibitory pharmacophore, which is exceptionally potent at reversing doxorubrin resistance in P-gp over expressing colon carcinoma cells (SW600 Ad300).

Emerging evidence suggests that microbiome-host crosstalk regulates intestinal immune activity and predisposition to inflammatory bowel disease (IBD). NF-κB is a master regulator of immune function and a validated target for the treatment of IBD. Here, we identify five Clostridium strains that suppress immune-mediated NF-κB activation in epithelial cell lines, PBMCs, and gut epithelial organoids from healthy human subjects and patients with IBD. Cell-free culture supernatant from Clostridium bolteae AHG0001 strain, but not the reference C. bolteae BAA-613 strain, suppresses inflammatory responses and endoplasmic reticulum stress in gut epithelial organoids derived from Winnie mice. The in vivo responses to Clostridium bolteae AHG0001 and BAA-613 mirror the in vitro activity. Thus, using our in vitro screening of bacteria capable of suppressing NF-κB in the context of IBD and using an ex vivo organoid-based approach, we identify a strain capable of alleviating colitis in a relevant pre-clinical animal model of IBD., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Currently there is no approved vaccine to prevent and/or treat group A Streptococcus (GAS) infection. With increasing reports of GAS antibiotic resistance, vaccine adjuvants and targeted delivery systems which induce a strong immune response are a widely acknowledged unmet need. Through extensive structure-activity studies, we investigated a cyclic decapeptide physically mixed with a GAS B cell peptide epitope (J8), a universal T helper epitope (PADRE), and different synthetic lipidic moieties as a conceivable self-adjuvanting GAS vaccine. We explored the structure (orientation)-relationship of the chemically-conjugated B cell epitope and T helper epitope peptide as part of this physically-mixed vaccine. Following in vivo assessment in mice, these cyclic lipopeptide vaccines showed successful induction of J8-specific systemic IgG antibodies when administered subcutaneously without additional adjuvant. Interestingly, an exposed C-terminus of the GAS B cell epitope and a 16-carbon alpha-amino fatty acid lipid was required for strong immunoreactivity, capable of effectively opsonising multiple strains of clinically-isolated GAS bacteria. Physicochemical assessment proved the alpha helix structure of the GAS B cell epitope was retained, impacting particle self-assembly and vaccine immunoreactivity. This study showed the capability for a self-adjuvanting cyclic delivery system to act as a vehicle for the delivery of GAS peptide antigens to treat GAS infection., (Crown Copyright © 2022. Published by Elsevier B.V. All rights reserved.)

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 cm 2 (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., (© 2021 The Society for Applied Microbiology.)

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 and 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 naphthopyranoquinones disclose a new P-gp inhibitory pharmacophore capable of reversing doxorubicin resistance in P-gp overexpressing colon carcinoma cells.

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.

Upregulation of ATP binding cassette (ABC) transporter efflux pumps ( i.e. P-glycoprotein, P-gp) can impart multidrug resistance, rendering many chemotherapeutics ineffective and seriously limiting treatment regimes. While ABC transporters remain an attractive target for therapeutic intervention, the development of clinically useful small-molecule inhibitors has proved challenging. In this report, we describe the structure-activity relationship (SAR) analysis of a newly discovered P-gp inhibitory pharmacophore, phenylpropanoid piperazine chrysosporazines, produced by co-isolated marine-derived fungi. In the absence of any total syntheses, we apply an innovative precursor-directed biosynthesis strategy that successfully repurposed fungal biosynthetic output, allowing us to isolate, characterize, and identify the structurally diverse neochrysosporazines A-Q. SAR analysis utilizing all known (and new) neochrysosporazines, chrysosporazines, and azachrysosporazines, plus semi-synthetic analogues, established the key structure requirements for the P-gp inhibitory pharmacophore, and, in addition, identified non-essential sites that allow for the design of affinity and other conjugated probes.

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.

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 (IC 50 6.0 µM, MIC 99 13.9 µM), highlights the importance of the 2-OAc and 3-OAc moieties to the oxandrastin anti-VRE pharmacophore.

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.

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 (IC 50 37 nM to >30 μM).

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., (© 2021 Wiley-VHCA AG, Zurich, Switzerland.)