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Many desired biobased chemicals exhibit a range of toxicity to microbial cell factories, making industry-level biomanufacturing more challenging. Separating microbial growth and production phases is known to be beneficial for improving production of toxic products. Here, we developed a novel synthetic carbon-responsive promoter for use in the rapidly growing, stress-tolerant yeast Kluyveromyces marxianus, by fusing carbon-source responsive elements of the native ICL1 promoter to the strong S. cerevisiae TDH3 or native NC1 promoter cores. Two hybrids, PIT350 and PIN450, were validated via EGFP fluorescence and demonstrated exceptional strength, partial repression during growth, and late phase activation in glucose- and lactose-based medium, respectively. Expressing the Gerbera hybrida 2-pyrone synthase (2-PS) for synthesis of the polyketide triacetic acid lactone (TAL) under the control of PIN450 increased TAL more than 50% relative to the native NC1 promoter, and additional promoter engineering further increased TAL titer to 1.39 g/L in tube culture. Expression of the Penicillium griseofulvum 6-methylsalicylic acid synthase (6-MSAS) under the control of PIN450 resulted in a 6.6-fold increase in 6-MSA titer to 1.09 g/L and a simultaneous 1.5-fold increase in cell growth. Finally, we used PIN450 to express the Pseudomonas savastanoi IaaM and IaaH proteins and the Salvia pomifera sabinene synthase protein to improve production of the auxin hormone indole-3-acetic acid and the monoterpene sabinene, respectively, both extremely toxic to yeast. The development of carbon-responsive promoters adds to the synthetic biology toolbox and available metabolic engineering strategies for K. marxianus, allowing greater control over heterologous protein expression and improved production of toxic metabolites.

SignificanceIn a polymicrobial battlefield where different species compete for nutrients and colonization niches, antimicrobial compounds are the sword and shield of commensal microbes in competition with invading pathogens and each other. The identification of an Escherichia coli-produced genotoxin, colibactin, and its specific targeted killing of enteric pathogens and commensals, including Vibrio cholerae and Bacteroides fragilis, sheds light on our understanding of intermicrobial interactions in the mammalian gut. Our findings elucidate the mechanisms through which genotoxins shape microbial communities and provide a platform for probing the larger role of enteric multibacterial interactions regarding infection and disease outcomes.

Polyketides have demonstrated their significance as therapeutics, industrial products, pesticides, and biological probes following intense study over the past decades. Tagging polyketides with a bioorthogonal functionality enables various applications such as diversification, quantification, visualization and mode-of-action elucidation. The terminal alkyne moiety, as a small, stable and highly selective clickable functionality, is widely adopted in tagging natural products. De novo biosynthesis of alkyne-tagged polyketides offers the unique advantage of reducing the background from feeding the biorthogonal moiety itself, leading to the accomplishment of in situ generation of a clickable functionality for bioorthogonal reactions. Here, we introduce several engineering strategies to apply terminal alkyne biosynthetic machinery, represented by JamABC, which produces a short terminal alkyne-bearing fatty acyl chain on a carrier protein, to functions with different downstream polyketide synthases (PKSs). Successful results in engineering type III and type I PKSs provide engineering guidelines and strategies that are applicable to additional PKSs to produce targeted alkyne-tagged metabolites for chemical and biological applications.

Streptomycetes are highly metabolically gifted bacteria with the abilities to produce bioproducts that have profound economic and societal importance. These bioproducts are produced by metabolic pathways including those for the biosynthesis of secondary metabolites and catabolism of plant biomass constituents. Advancements in genome sequencing technologies have revealed a wealth of untapped metabolic potential from Streptomyces genomes. Here, we report the largest Streptomyces pangenome generated by using 205 complete genomes. Metabolic potentials of the pangenome and individual genomes were analyzed, revealing degrees of conservation of individual metabolic pathways and strains potentially suitable for metabolic engineering. Of them, Streptomyces bingchenggensis was identified as a potent degrader of plant biomass. Polyketide, non-ribosomal peptide, and gamma-butyrolactone biosynthetic enzymes are primarily strain specific while ectoine and some terpene biosynthetic pathways are highly conserved. A large number of transcription factors associated with secondary metabolism are strain-specific while those controlling basic biological processes are highly conserved. Although the majority of genes involved in morphological development are highly conserved, there are strain-specific varieties which may contribute to fine tuning the timing of cellular differentiation. Overall, these results provide insights into the metabolic potential, regulation and physiology of streptomycetes, which will facilitate further exploitation of these important bacteria.

This document is an editorial published in the journal Frontiers in Plant Science. It discusses the topic of plant natural resins, specifically focusing on their formation mechanism and ecological significance. The editorial highlights the economic and medicinal importance of plant resins, as well as the exploitation and endangerment of the original wild plants that produce them. The document also mentions seven articles included in the edition, which cover various aspects of research on natural plant resins, including their formation dynamics, regulation mechanisms, main compounds, and interactions with plant microorganisms. [Extracted from the article]

Four new polyketides, namely furantides A–B (1–2), talamin E (3) and arugosinacid A (4), and two known polyketides were obtained from the mangrove-derived fungus Penicillium sp. HDN15-312 using the One Strain Many Compounds (OSMAC) strategy. Their chemical structures, including configurations, were elucidated by detailed analysis of extensive NMR spectra, HRESIMS and ECD. The DPPH radicals scavenging activity of 3, with an IC50 value of 6.79 µM, was better than vitamin C.

Background: Transforming waste and nonfood materials into bulk biofuels and chemicals represents a major stride in creating a sustainable bioindustry to optimize the use of resources while reducing environmental footprint. However, despite these advancements, the production of high-value natural products often continues to depend on the use of first-generation substrates, underscoring the intricate processes and specific requirements of their biosyntheses. This is also true for Streptomyces lividans, a renowned host organism celebrated for its capacity to produce a wide array of natural products, which is attributed to its genetic versatility and potent secondary metabolic activity. Given this context, it becomes imperative to assess and optimize this microorganism for the synthesis of natural products specifically from waste and nonfood substrates. Results: We metabolically engineered S. lividans to heterologously produce the ribosomally synthesized and posttranslationally modified peptide bottromycin, as well as the polyketide pamamycin. The modified strains successfully produced these compounds using waste and nonfood model substrates such as protocatechuate (derived from lignin), 4-hydroxybenzoate (sourced from plastic waste), and mannitol (from seaweed). Comprehensive transcriptomic and metabolomic analyses offered insights into how these substrates influenced the cellular metabolism of S. lividans. In terms of production efficiency, S. lividans showed remarkable tolerance, especially in a fed-batch process using a mineral medium containing the toxic aromatic 4-hydroxybenzoate, which led to enhanced and highly selective bottromycin production. Additionally, the strain generated a unique spectrum of pamamycins when cultured in mannitol-rich seaweed extract with no additional nutrients. Conclusion: Our study showcases the successful production of high-value natural products based on the use of varied waste and nonfood raw materials, circumventing the reliance on costly, food-competing resources. S. lividans exhibited remarkable adaptability and resilience when grown on these diverse substrates. When cultured on aromatic compounds, it displayed a distinct array of intracellular CoA esters, presenting promising avenues for polyketide production. Future research could be focused on enhancing S. lividans substrate utilization pathways to process the intricate mixtures commonly found in waste and nonfood sources more efficiently. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the anticancer properties of emestrin, a major constituent of Emericella nidulans ATCC 38163 through the induction of apoptosis in Huh-7 human hepatocellular carcinoma cells. In this study, this fungus was isolated from the fresh leaves of Ruprechtia salicifolia (Cham. & Schltdl.) C.A. Mey, and identified by morphology and 18S rDNA followed by large-scale fermentation in liquid biomalt broth medium. Epidithiodioxopiperazine derivative emestrin along with ten known metabolites were isolated and identified from the fungal extract. The cytotoxic assay revealed that emestrin had the strongest cytotoxicity against Huh-7 and A-549 cells with IC50 values of 4.89 and 6.3 lM, respectively. Using annexin V-FITC assay, treatment of Huh-7 cells with 4.89 mM for 24 h resulted in a significant increase in the percentage of early and late apoptosis (3.16% and 22.84%, respectively) compared to untreated cells. Additionally, Bax and bcl-2 protein levels were regulated, which induced apoptosis in treated cells. These results indicate that emestrin induces mitochondrial pathway to stimulate apoptosis and inhibits cell proliferation in hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

As life expectancy increases, the number of people affected by cancer is increasing. The available drugs still cause several adverse reactions, and it is important to look for less toxic drugs that act on resistant cancers. The present study evaluated the antitumor potential of acetogenins. Through a literature review, 44 acetogenins isolated from Annona muricata were selected and subjected to in silico studies to predict the physicochemical properties, pharmacokinetics (Preadmet and Admet lab), toxicity (Preadmet and Protox II) and molecular docking in caspase 3 (DockThor). For muricatacin, a literature review was carried out for antitumor activity and cytotoxicity. Only muricatacin met all physicochemical criteria, while all compounds showed high cutaneous and intestinal absorption (HIA), moderate permeability in Madin-Darby canine kidney and Caco2 cells, strongly bound plasma proteins, freely crossed the blood-brain barrier, inhibited CYP2C19, CYP2C9 and CYP3A4 and have an affinity for CYP3A4, being metabolized by it, an undesirable characteristic for antitumor drugs. All compounds were toxic in at least one model, while compound 28 was not carcinogenic in rats and mice. Compounds 13, 14, 15, 16, 17 and 28 were selected for molecular docking into Caspase 3. Docking showed hydrophobic interactions, hydrogen and covalent bonds performed to maintain the stability of caspase 3, and cis-uvariamicin IV stood out more through the energies and chemical bonds of this parameter. The chloroform fraction from the methanolic extract of the seeds showed activity against triple-negative breast cancer, both in vitro and in vivo, and only muricatacin has studies in which the antitumor activity was evaluated in vitro and showed to be very promising. In summary, muricatacin and cis-uvariamicin IV appear to be very promising as antitumors, especially cis-uvariamicin IV. [ABSTRACT FROM AUTHOR]

Enones are widely utilized linchpin functional groups in chemical synthesis and molecular biology. We herein report the direct conversion of boronic esters into enones using commercially available methoxyallene as a three‐carbon building block. Following boronate complex formation by reaction of the boronic ester with lithiated‐methoxyallene, protonation triggers a stereospecific 1,2‐migration before oxidation generates the enone. The protocol shows broad substrate scope and complete enantiospecificity is observed with chiral migrating groups. In addition, various electrophiles could be used to induce 1,2‐migration and give a much broader range of α‐functionalized enones. Finally, the methodology was applied to a 14‐step synthesis of the enone‐containing polyketide 10‐deoxymethynolide. [ABSTRACT FROM AUTHOR]

Koninginins X-Z (1–3), three novel polyketides, were isolated from the solid fermentation of the endophytic fungus Trichoderma koningiopsis SC-5. Their structures, including the absolute configurations, were comprehensively characterized by a combination of NMR spectroscopic methods, HRESIMS, 13C NMR, DFT GIAO 13C NMR, and electronic circular dichroism calculations as well as single crystal X-ray diffraction. In addition, all the compounds were evaluated for antifungal activity against Candida albicans. [ABSTRACT FROM AUTHOR]

The marine-derived fungal strains KMM 4718 and KMM 4747 isolated from sea urchin Scaphechinus mirabilis as a natural fungal complex were identified as Penicillium sajarovii and Aspergillus protuberus based on Internal Transcribed Spacer (ITS), partial β-tubulin (BenA), and calmodulin (CaM) molecular markers as well as an ribosomal polymerase two, subunit two (RPB2) region for KMM 4747. From the ethyl acetate extract of the co-culture, two new polyketides, sajaroketides A (1) and B (2), together with (2′S)-7-hydroxy-2-(2′-hydroxypropyl)-5-methylchromone (3), altechromone A (4), norlichexanthone (5), griseoxanthone C (6), 1,3,5,6-tetrahydroxy-8-methylxanthone (7), griseofulvin (8), 6-O-desmethylgriseofulvin (9), dechlorogriseofulvin (10), and 5,6-dihydro-4-methyl-2H-pyran-2-one (11) were identified. The structures of the compounds were elucidated using spectroscopic analyses. The absolute configurations of the chiral centers of sajaroketides A and B were determined using time-dependent density functional theory (TDDFT)-based calculations of the Electronic Circular Dichroism (ECD) spectra. The inhibitory effects of these compounds on urease activity and the growth of Staphylococcus aureus, Escherichia coli, and Candida albicans were observed. Sajaroketide A, altechromone A, and griseofulvin showed significant cardioprotective effects in an in vitro model of S. aureus-induced infectious myocarditis. [ABSTRACT FROM AUTHOR]

Malonyl-CoA is a precursor of fatty acids, polyketides, and bio-based chemicals with potential applications in medicine, antibiotics, and fuels. However, its low intracellular concentration and high cost have led to difficulties in research and production. To develop an efficient method for producing malonyl-CoA, we screened the acyl-CoA synthetase (ACS) gene from Streptomyces sp. using sequence-structure alignment. This protein contains conserved sequences and active sites for malonyl-CoA synthetases. The purified recombinant enzyme ACS was heterologously expressed in Escherichia coli BL21 and characterised. The results showed that it converted the substrates malonate and CoA into malonyl-CoA. Under the optimal conditions, the specific activity of the purified ACS was 32.3 U·mg−1 and the conversion rate reached 98.8%. In addition, when the cell-free extracts were used as catalysts, the highest yield of malonyl-CoA was obtained after 4 h, yielding 24.2 g·L−1 with a conversion rate of 90.3%. After the product was purified and vacuum freeze-dried, a solid powder of malonyl-CoA was obtained. This study characterised and identified a new ACS and optimised the reaction conditions to efficiently synthesise pure malonyl-CoA in vitro in high yield using enzyme-mediated methods. [Display omitted] • One new acyl-CoA synthetase (ACS) was mined and characterized. • ACS catalyze the synthesis of malonyl-CoA. • Malonyl-CoA received a high conversion rate (90.3%) and a high yield (24.2 g/L) with cell-free extracts catalyzed reaction. • Efficient malonyl-CoA synthesis on a 100-mL scale. [ABSTRACT FROM AUTHOR]

4-Hydroxy-2-pyrones are of interest as potential biorenewable molecules for a sustainable transition from biomass feedstock to valuable chemical products. This review focuses on the methodologies for the synthesis of 4-hydroxy-2-pyrones published over the last 20 years. These pyrones as polyketides are widespread in Nature and possess versatile bioactivity that makes them an attractive target for synthesis and modification. Biosynthetic paths of the pyrones are actively developed and used as biotechnological approaches for the construction of natural and unnatural polysubstituted 4-hydroxy-2-pyrones. The major synthetical methods are biomimetic and are based on the cyclization of tricarbonyl compounds. Novel chemical methods of de novo synthesis based on alkyne cyclizations using transition metal complexes and ketene transformations allow for straightforward access to 4-hydroxy-2-pyrones and have been applied for the construction of natural products. Possible directions for further pyrone ring modification are discussed. [ABSTRACT FROM AUTHOR]

Endophytic fungi produced attractive primary and secondary metabolites for industries, pharmacology, and biotechnology. The bioactive potential of HE19ct, identified as Penicillium brevicompactum according to ITS-BenA-caM, was addressed. Antimicrobial and antioxidant activities and secondary metabolite contents using four culture media in Agar-plate (ApF) and Submerged (SmF) fermentation were evaluated. Some plant growth-promoting (PGP) traits and their related genes were tested. HE19ct exhibited antimicrobial activity against Staphylococcus aureus , Enterococcus faecalis , Candida albicans , C. tropicalis , Fusarium sp., Geotrichum candidum , and Alternaria sp. All cultures showed DPPH scavenging activity and phenolic compounds, where ethyl acetate extract of SmF with malt extract showed higher activity and SmF/ApF with potato-dextrose exhibited higher yield, respectively. HE19ct solubilized tricalcium-phosphate and produced siderophore, endoglucanase, proteinase, and amylase. It enhanced the alfalfa's germination at 15 °C, root development, and phenols production at 15 and 24 °C. Phenols, tannins, anthraquinones, triterpenoids/steroids, and alkaloids production were detected depending on culture media. Polyketide synthase type I gene (PksI), subtilisin-like protease prb 1 (Pbr), and siderophore D (sidD) were PCR-amplified. Finally, HE19CT could be a promising source of interesting bioactive compounds for pharmacology and agriculture mainly in extreme conditions, then metabolomic and functional genetic research must be performed to support their appropriate application. • P. brevicompactum HE19ct exhibits wide antimicrobial activity in different methods. • HE19ct yields antioxidants, phenols, and other secondary metabolites. • HE19ct has some plant growth-promoting traits and enhances the growth of "alfalfa". [ABSTRACT FROM AUTHOR]

Background: Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense race 4 (Foc4), is the most lethal disease of bananas in Asia. Methods: To better understand the defense response of banana to Fusarium wilt, the transcriptome and metabolome profiles of the roots from resistant and susceptible bananas inoculated with Foc4 were compared. Results: After Foc4 inoculation, there were 172 and 1,856 differentially expressed genes (DEGs) in the Foc4-susceptible variety (G1) and Foc4-resistant variety (G9), respectively. In addition, a total of 800 DEGs were identified between G1 and G9, which were mainly involved in the oxidation-reduction process, cell wall organization, phenylpropanoid biosynthesis, and lipid and nitrogen metabolism, especially the DEGs of Macma4_08_g22610, Macma4_11_g19760, and Macma4_03_g06480, encoding non-classical arabinogalactan protein; GDSL-like lipase; and peroxidase. In our study, G9 showed a stronger and earlier response to Foc4 than G1. As the results of metabolomics, lipids, phenylpropanoids and polyketides, organic acids, and derivatives played an important function in response to Fusarium wilt. More importantly, Macma4_11_g19760 might be one of the key genes that gave G9 more resistance to Foc4 by a lowered expression and negative regulation of lipid metabolism. This study illustrated the difference between the transcriptomic and metabolomic profiles of resistant and susceptible bananas. These results improved the current understanding of host-pathogen interactions and will contribute to the breeding of resistant banana plants. [ABSTRACT FROM AUTHOR]

Main conclusion: The present investigation profoundly asserted the catalytic potential of plant-based aldo-ketoreductase, postulating its role in polyketide biosynthesis and providing new insights for tailored biosynthesis of vital plant polyketides for therapeutics. Plants hold great potential as a future source of innovative biocatalysts, expanding the possibilities within chemical reactions and generating a variety of benefits. The aldo–keto reductase (AKR) superfamily includes a huge collection of NAD(P)H-dependent oxidoreductases that carry out a variety of redox reactions essential for biosynthesis, detoxification, and intermediary metabolism. The present study involved the isolation, cloning, and purification of a novel aldo-ketoreductase (AvAKR) from the leaves of Aloe vera (Aloe barbadensis Miller) by heterologous gene expression in Escherichia coli based on the unigene sequences of putative ketoreductase and cDNA library screening by oligonucleotide hybridization. The in-silico structural analysis, phylogenetic relationship, and molecular modeling were outranged to approach the novelty of the sequence. Additionally, agroinfiltration of the candidate gene tagged with a green fluorescent protein (GFP) was employed for transient expression in the Nicotiana benthamiana to evaluate the sub-cellular localization of the candidate gene. The AvAKR preferred cytoplasmic localization and shared similarities with the known plant AKRs, keeping the majority of the conserved active-site residues in the AKR superfamily enzymes. The enzyme facilitated the NADPH-dependent reduction of various carbonyl substrates, including benzaldehyde and sugars, proclaiming a broad spectrum range. Our study successfully isolated and characterized a novel aldo-ketoreductase (AvAKR) from Aloe vera, highlighting its versatile NADPH-dependent carbonyl reduction proficiency therewith showcasing its potential as a versatile biocatalyst in diverse redox reactions. [ABSTRACT FROM AUTHOR]

After cooling to 0 °C, DIPEA (1.55 mL, 8.87 mmol), HOBt (679 mg, 4.43 mmol) and EDC•HCl (850 mg, 4.43 mmol) were added and the reaction solution was stirred at room temperature overnight. 50 Preparation of Alcohol 11: To a solution of amide 10 (1.19 g, 2.47 mmol) in anhydrous dichloromethane (15 mL) was added dropwise a solution of TFA (951 L, 12.3 mmol) in anhydrous dichloromethane (10 mL) at 0 °C. Keywords: boronic esters; Matteson homologation; natural products; peptides; stereoselective synthesis EN boronic esters Matteson homologation natural products peptides stereoselective synthesis 2159 2164 6 10/31/23 20231127 NES 231127 Graph Emericellamide A and B are two cyclic lipopeptides that were isolated from the marine-derived fungus I Emericella sp. i by Fenical et al. in 2007 (Figure 1). The solution was washed with KHSO 4 solution (1 M), saturated NaHCO 3 solution, and saturated NaCl solution, the organic phase was dried over MgSO 4 and concentrated under reduced pressure. [Extracted from the article]

Mupirocin is a clinically important antibiotic produced by a trans‐AT Type I polyketide synthase (PKS) in Pseudomonas fluorescens. The major bioactive metabolite, pseudomonic acid A (PA−A), is assembled on a tetrasubstituted tetrahydropyran (THP) core incorporating a 6‐hydroxy group proposed to be introduced by α‐hydroxylation of the thioester of the acyl carrier protein (ACP) bound polyketide chain. Herein, we describe an in vitro approach combining purified enzyme components, chemical synthesis, isotopic labelling, mass spectrometry and NMR in conjunction with in vivo studies leading to the first characterisation of the α‐hydroxylation bimodule of the mupirocin biosynthetic pathway. These studies reveal the precise timing of hydroxylation by MupA, substrate specificity and the ACP dependency of the enzyme components that comprise this α‐hydroxylation bimodule. Furthermore, using purified enzyme, it is shown that the MmpA KS0 shows relaxed substrate specificity, suggesting precise spatiotemporal control of in trans MupA recruitment in the context of the PKS. Finally, the detection of multiple intermodular MupA/ACP interactions suggests these bimodules may integrate MupA into their assembly. [ABSTRACT FROM AUTHOR]

Docosahexaenoic acid (DHA) and selenium (Se) are nutrients that confer several health benefits to both humans and animals. Widespread use of DHA in milk powder and health products requires large-scale mass production via Schizochytrium sp., while Se intended for human consumption is produced as organic Se via yeast. However, producing these nutrients on an industrial scale is constrained by various factors. We found that supplementing Schizochytrium sp. with Na2SeO3 (0.5 mg/L) improves its biomass and DHA production and also provides organic Se. De novo assembled transcriptome and biochemical indicators showed that Na2SeO3 promotes forming acetyl coenzyme A and L-cysteine via the glycerol kinase and cysteine synthase pathways, promoting DHA synthesis through the polyketide synthase pathway. However, high doses of Na2SeO3 (5 mg/L) limited the biomass of Schizochytrium sp. and DHA content. This study provided a theoretical basis for the simultaneous production of organic Se and DHA via Schizochytrium sp. [ABSTRACT FROM AUTHOR]

β-Amino acid-containing macrolactams represent a structurally diverse group of bioactive natural products derived from polyketides; however we are currently lacking a comprehensive overview about their abundance across bacterial families and the underlying biosynthetic diversity. In this study, we employed a targeted β-amino acid-specific homology-based multi-query search to identify potential bacterial macrolactam producers. Here we demonstrate that approximately 10% of each of the identified actinobacterial genera harbor a biosynthetic gene cluster (BGC) encoding macrolactam production. Based on our comparative study, we propose that mutations occurring in specific regions of polyketide synthases (PKS) are the primary drivers behind the variation in macrolactam ring sizes. We successfully validated two producers of ciromicin A from the genus Amycolatopsis, revised the composition of the biosynthetic gene cluster region mte of macrotermycins, and confirmed the ciromicin biosynthetic pathway through heterologous expression. Additionally, network-based metabolomic analysis uncovered three previously unreported macrotermycin congeners from Amycolatopsis sp. M39. The combination of targeted mining and network-based analysis serves as a powerful tool for identifying macrolactam producers and our studies will catalyze the future discovery of yet unreported macrolactams. β-Amino acid-containing macrolactams are a known natural product family exhibiting structural and functional diversity, however, the natural chemical space of this family remains underexplored. Here, the authors use a targeted β-amino acid-specific homology-based multi-query search to identify their potential microbial producers, explore the variation of their biosynthetic gene clusters, heterologously produce ciromicin A, and identify new macrotermycin derivatives. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: We report an efficient and convergent strategy for the total synthesis of UCS1025A and its diastereomer tetra‐epi‐UCS1025A. UCS1025A is a representative member of the naturally occurring pyrrolizidinone polyketides, from which members with potent antibacterial, antifungal, and anticancer activities have been identified. Our approach features a tandem carbonylative Stille cross coupling and Diels‐Alder reaction to forge a key C—C bond and build the trans‐decalin system. This tandem process utilizes carbon monoxide as a one‐carbon linchpin to stitch a vinyl triflate and a vinylstannane together and form the desired enone moiety for the subsequent intramolecular Diels‐Alder cyclization. Our synthesis also provides a versatile approach for the synthesis of other related pyrrolizidinone‐containing polyketides. [ABSTRACT FROM AUTHOR]

(±)-Hypecurvone A (1) and B (2), two new undescribed phenyl polyketides, along with seven known analogues (3–9) were isolated from the whole plant of Hypericum curvisepalum. Chiral separation of 1 and 2 yielded two pairs of enantiomers 1a/1b and 2a/2b, respectively. The structures of these compounds were elucidated by extensive spectroscopic analyses and ECD spectra simulations. All isolates exhibited moderate cytotoxicity against human hepatocellular carcinoma SMMC-7721 cells, and compound 3 also showed weak cytotoxicity toward MGC-803 cells. The cytotoxicity of these compounds was found to be related to enhanced mitochondria-mediated apoptosis and inhibition of the G2/M phase of the cell cycle. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: We report an efficient and convergent strategy for the total synthesis of UCS1025A and its diastereomer tetra‐epi‐UCS1025A. UCS1025A is a representative member of the naturally occurring pyrrolizidinone polyketides, from which members with potent antibacterial, antifungal, and anticancer activities have been identified. Our approach features a tandem carbonylative Stille cross coupling and Diels‐Alder reaction to forge a key C—C bond and build the trans‐decalin system. This tandem process utilizes carbon monoxide as a one‐carbon linchpin to stitch a vinyl triflate and a vinylstannane together and form the desired enone moiety for the subsequent intramolecular Diels‐Alder cyclization. Our synthesis also provides a versatile approach for the synthesis of other related pyrrolizidinone‐containing polyketides. [ABSTRACT FROM AUTHOR]

Incorporating enzymatic reactions into natural product synthesis can significantly improve synthetic efficiency and selectivity. In contrast to the increasing applications of biocatalytic functional‐group interconversions, the use of enzymatic C−C bond formation reactions in natural product synthesis is underexplored. Herein, we report a concise and efficient approach for the synthesis of [7.7]paracyclophane natural products, a family of polyketides with diverse biological activities. By using enzymatic Friedel–Crafts alkylation, cylindrocyclophanes A and F and merocyclophanes A and D were synthesized in six to eight steps in the longest linear sequence. This study demonstrates the power of combining enzymatic reactions with contemporary synthetic methodologies and provides opportunities for the structure–activity relationship studies of [7.7]paracyclophane natural products. [ABSTRACT FROM AUTHOR]

The pluramycin family of natural products has diverse substituents at the C2 position, which are closely related to their biological activity. Therefore, it is important to understand the biosynthesis of C2 substituents. In this study, we describe the biosynthesis of C2 moieties in Streptomyces sp. W2061, which produces kidamycin and rubiflavinone C-1, containing anthrapyran aglycones. Sequence analysis of the loading module (Kid13) of the PKS responsible for the synthesis of these anthrapyran aglycones is useful for confirming the incorporation of atypical primer units into the corresponding products. Kid13 is a ketosynthase-like decarboxylase (KSQ)-type loading module with unusual dual acyltransferase (AT) domains (AT1-1 and AT1-2). The AT1-2 domain primarily loads ethylmalonyl-CoA and malonyl-CoA for rubiflavinone and kidamycinone and rubiflavinone, respectively; however, the AT1-1 domain contributed to the functioning of the AT1-2 domain to efficiently load ethylmalonyl-CoA for rubiflavinone. We found that the dual AT system was involved in the production of kidamycinone, an aglycone of kidamycin, and rubiflavinone C-1 by other shared biosynthetic genes in Streptomyces sp. W2061. This study broadens our understanding of the incorporation of atypical primer units into polyketide products. [ABSTRACT FROM AUTHOR]

Invasive fungal infections present a significant risk to human health. The current arsenal of antifungal drugs is hindered by drug resistance, limited antifungal range, inadequate safety profiles, and low oral bioavailability. Consequently, there is an urgent imperative to develop novel antifungal medications for clinical application. This comprehensive review provides a summary of the antifungal properties and mechanisms exhibited by natural polyketides, encompassing macrolide polyethers, polyether polyketides, xanthone polyketides, linear polyketides, hybrid polyketide non-ribosomal peptides, and pyridine derivatives. Investigating natural polyketide compounds and their derivatives has demonstrated their remarkable efficacy and promising clinical application as antifungal agents. [ABSTRACT FROM AUTHOR]

Dinoflagellates make up the second largest marine group of marine unicellular eukaryotes in the world ocean and comprise both heterotrophic and autotrophic species, encompassing a wide genetic and chemical diversity. They produce a plethora of secondary metabolites that can be toxic to other species and are mainly used against predators and competing species. Dinoflagellates are indeed often responsible for harmful algal bloom, where their toxic secondary metabolites can accumulate along the food chain, leading to significant damages to the ecosystem and human health. Secondary metabolites from dinoflagellates have been widely investigated for potential biomedical applications and have revealed multiple antimicrobial, antifungal, and anticancer properties. Species from the genus Amphidinium seem to be particularly interesting for the production of medically relevant compounds. The present review aims at summarising current knowledge on the diversity and the pharmaceutical properties of secondary metabolites from the genus Amphidinium. Specifically, Amphidinium spp. produce a range of polyketides possessing cytotoxic activities such as amphidinolides, caribenolides, amphidinins, and amphidinols. Potent antimicrobial properties against antibiotic-resistant bacterial strains have been observed for several amphidinins. Amphidinols revealed instead strong activities against infectious fungi such as Candida albicans and Aspergillus fumigatus. Finally, compounds such as amphidinolides, isocaribenolide-I, and chlorohydrin 2 revealed potent cytotoxic activities against different cancer cell lines. Overall, the wide variety of antimicrobial, antifungal, and anticancer properties of secondary metabolites from Amphidinium spp. make this genus a highly suitable candidate for future medical applications, spanning from cancer drugs to antimicrobial products that are alternatives to currently available antibiotic and antimycotic products. [ABSTRACT FROM AUTHOR]

Transcriptomic studies have revealed that fungal pathogens of plants activate the expression of numerous biosynthetic gene clusters (BGC) exclusively when in presence of a living host plant. The identification and structural elucidation of the corresponding secondary metabolites remain challenging. The aim was to develop a polycistronic system for heterologous expression of fungal BGCs in Saccharomyces cerevisiae. Here we adapted a polycistronic vector for efficient, seamless and cost-effective cloning of biosynthetic genes using in vivo assembly (also called transformation-assisted recombination) directly in Escherichia coli followed by heterologous expression in S. cerevisiae. Two vectors were generated with different auto-inducible yeast promoters and selection markers. The effectiveness of these vectors was validated with fluorescent proteins. As a proof-of-principle, we applied our approach to the Colletochlorin family of molecules. These polyketide secondary metabolites were known from the phytopathogenic fungus Colletotrichum higginsianum but had never been linked to their biosynthetic genes. Considering the requirement for a halogenase, and by applying comparative genomics, we identified a BGC putatively involved in the biosynthesis of Colletochlorins in C. higginsianum. Following the expression of those genes in S. cerevisiae , we could identify the presence of the precursor Orsellinic acid, Colletochlorins and their non-chlorinated counterparts, the Colletorins. In conclusion, the polycistronic vectors described herein were adapted for the host S. cerevisiae and allowed to link the Colletochlorin compound family to their corresponding biosynthetic genes. This system will now enable the production and purification of infection-specific secondary metabolites of fungal phytopathogens. More widely, this system could be applied to any fungal BGC of interest. • Polycistronic plasmids developed for heterologous expression in S. cerevisiae. • Colletochlorin family of molecules linked to its biosynthetic gene cluster. • Engineered yeast overproduced molecules up to 35-fold relative to native producer. [ABSTRACT FROM AUTHOR]

Lilium davidii var. unicolor (Lanzhou lily) is rich in nutrients, making it an important economic plant widely used in the fields of food and medicine. In this study, potted lily bulbs were treated with nutrient solutions containing K+ and nutrient solutions without K+ (CK and KT). The contents of nutrients in lily bulbs at different stages after treatment were compared. It was found that the application of potassium fertilizers increased the content of total phenols, flavonoids, and flavanols in lily bulbs and the antioxidant activity in the bulbs. Simultaneously, the study observed that potassium fertilizers could impact the accumulation of polysaccharides and saponins. Furthermore, employing non-targeted metabolomics, the secondary metabolites of mature Lanzhou lily bulbs were scrutinized both with and without potassium fertilization (KT and CK). A total of 607 metabolites were identified, including 573 in positive ion mode and 34 in negative ion mode. These metabolites were classified into 13 categories at the superclass level, with lipids and lipid molecules (37.93%), organic acids and their derivatives (16.52%), organic oxygen compounds (14.88%), and phenylpropanoids and polyketides (13.61%) being the most prominent. Differential metabolite enrichment analysis between the experimental and control groups showed that the differential metabolites were mainly concentrated in metabolic pathways related to amino acid biosynthesis, such as arginine and proline metabolism, beta-alanine metabolism, alanine, aspartate, and glutamate metabolism. Additionally, it was found that the application of potassium fertilizer increased the accumulation of amino acids in Lanzhou lily bulbs. Overall, this study provides a theoretical reference for the development of nutrients and efficient cultivation techniques for L. davidii var. unicolor bulbs. [ABSTRACT FROM AUTHOR]

An Aspergillus fumigatus KMM 4631 strain was previously isolated from a Pacific soft coral Sinularia sp. sample and was found to be a source of a number of bioactive secondary metabolites. The aims of this work are the confirmation of this strain' identification based on ITS, BenA, CaM, and RPB2 regions/gene sequences and the investigation of secondary metabolite profiles of Aspergillus fumigatus KMM 4631 culture and its co-cultures with Penicillium hispanicum KMM 4689, Amphichorda sp. KMM 4639, Penicillium sp. KMM 4672, and Asteromyces cruciatus KMM 4696 from the Collection of Marine Microorganisms (PIBOC FEB RAS, Vladivostok, Russia). Moreover, the DPPH-radical scavenging activity, urease inhibition, and cytotoxicity of joint fungal cultures' extracts on HepG2 cells were tested. The detailed UPLC MS qTOF investigation resulted in the identification and annotation of indolediketopiperazine, quinazoline, and tryptoquivaline-related alkaloids as well as a number of polyketides (totally 20 compounds) in the extract of Aspergillus fumigatus KMM 4631. The metabolite profiles of the co-cultures of A. fumigatus with Penicillium hispanicum, Penicillium sp., and Amphichorda sp. were similar to those of Penicillium hispanicum, Penicillium sp., and Amphichorda sp. monocultures. The metabolite profile of the co-culture of A. fumigatus with Asteromyces cruciatus differed from that of each monoculture and may be more promising for the isolation of new compounds. [ABSTRACT FROM AUTHOR]

Two new cyclopiane diterpenes and a new cladosporin precursor, together with four known related compounds, were isolated from the marine sediment-derived fungus Penicillium antarcticum KMM 4670, which was re-identified based on phylogenetic inference from ITS, BenA, CaM, and RPB2 gene regions. The absolute stereostructures of the isolated cyclopianes were determined using modified Mosher's method and quantum chemical calculations of the ECD spectra. The isolation from the natural source of two biosynthetic precursors of cladosporin from a natural source has been reported for the first time. The antimicrobial activities of the isolated compounds against Staphylococcus aureus, Escherichia coli, and Candida albicans as well as the inhibition of staphylococcal sortase A activity were investigated. Moreover, the cytotoxicity of the compounds to mammalian cardiomyocytes H9c2 was studied. As a result, new cyclopiane diterpene 13-epi-conidiogenone F was found to be a sortase A inhibitor and a promising anti-staphylococcal agent. [ABSTRACT FROM AUTHOR]

Background: Oxytetracycline which is derived from Streptomyces rimosus, inhibits a wide range of bacteria and is industrially important. The underlying biosynthetic processes are complex and hinder rational engineering, so industrial manufacturing currently relies on classical mutants for production. While the biochemistry underlying oxytetracycline synthesis is known to involve polyketide synthase, hyperproducing strains of S. rimosus have not been extensively studied, limiting our knowledge on fundamental mechanisms that drive production. Results: In this study, a multiomics analysis of S. rimosus is performed and wild-type and hyperproducing strains are compared. Insights into the metabolic and regulatory networks driving oxytetracycline formation were obtained. The overproducer exhibited increased acetyl-CoA and malonyl CoA supply, upregulated oxytetracycline biosynthesis, reduced competing byproduct formation, and streamlined morphology. These features were used to synthesize bhimamycin, an antibiotic, and a novel microbial chassis strain was created. A cluster deletion derivative showed enhanced bhimamycin production. Conclusions: This study suggests that the precursor supply should be globally increased to further increase the expression of the oxytetracycline cluster while maintaining the natural cluster sequence. The mutagenized hyperproducer S. rimosus HP126 exhibited numerous mutations, including large genomic rearrangements, due to natural genetic instability, and single nucleotide changes. More complex mutations were found than those typically observed in mutagenized bacteria, impacting gene expression, and complicating rational engineering. Overall, the approach revealed key traits influencing oxytetracycline production in S. rimosus, suggesting that similar studies for other antibiotics could uncover general mechanisms to improve production. [ABSTRACT FROM AUTHOR]

Keywords: amphidinolides; polyketides; total synthesis; Suzuki cross-coupling; epoxides; protecting groups EN amphidinolides polyketides total synthesis Suzuki cross-coupling epoxides protecting groups 2017 2021 5 10/09/23 20231024 NES 231024 Graph Amphidinolide U is a moderately cytotoxic macrolide isolated from dinoflagellates of an I Amphidinium i species, with reported IC SB 50 sb values on L1210 and KB cell lines of 12 and 20 g/mL, respectively. 1994, 107 24 Ley, S V. Tackett, M N. Maddess, M L. Anderson, J C. Brennan, P E. Cappi, M W. Heer, J P. Helgen, C. Kori, M. Kouklovsky, C. Marsden, S P. Norman, J. Osborn, D P. Palomero, M. Á. Pavey, J B. J. Pinel, C. Robinson, L A. Schnaubelt, J. Scott, J S. Spilling, C D. Watanabe, H. Wesson, K E. Willis, M C. Chem. Eur. J. 2009, 15: 2874 25 Cid, M B. Pattenden, G. Synlett. Chem. 2006, 71: 5826 20 Mihelich, E D. Daniels, K. Eickhoff, D J. J. Am. Chem. Soc. 1981, 103: 7690 21 Corey, E J. Fuchs, P L. Tetrahedron Lett. Int. Ed. 2001, 40: 4544 29 Berthold, D. Breit, B. Chem. Eur. J. 2018, 24: 16770 30 Geist, E. Kirschning, A. Schmidt, T. Nat. [Extracted from the article]

Rice false smut (RFS) caused by Villosiclava virens (anamorph: Ustilaginoidea virens) has become one of the most destructive fungal diseases to decrease the yield and quality of rice grains. An albino strain LN02 was isolated from the white RFS balls collected in the Liaoning Province of China in 2019. The strain LN02 was considered as a natural albino mutant of V. virens by analyzing its phenotypes, internal transcribed spacer (ITS) conserved sequence, and biosynthesis gene clusters (BGCs) for secondary metabolites. The total assembled genome of strain LN02 was 38.81 Mb, which was comprised of seven nuclear chromosomes and one mitochondrial genome with an N50 value of 6,326,845 bp and 9339 protein-encoding genes. In addition, the genome of strain LN02 encoded 19 gene clusters for biosynthesis of secondary metabolites mainly including polyketides, terpenoids and non-ribosomal peptides (NRPs). Four sorbicillinoid metabolites were isolated from the cultures of strain LN02. It was found that the polyketide synthase (PKS)-encoding gene uspks1 for ustilaginoidin biosynthesis in strain LN02 was inactivated due to the deletion of four bases in the promoter sequence of uvpks1. The normal uvpks1 complementary mutant of strain LN02 could restore the ability to synthesize ustilaginoidins. It demonstrated that deficiency of ustilaginoidin biosynthesis is the cause of albinism for RFS albino strain LN02, and V. virens should be a non-melanin-producing fungus. This study further confirmed strain LN02 as a white phenotype mutant of V. virens. The albino strain LN02 will have a great potential in the development and application of secondary metabolites. The physiological and ecological functions of ustilaginoidins in RFS fungus are needed for further investigation. [ABSTRACT FROM AUTHOR]

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Verticillium wilt is a soil-borne fungal disease that affects olive trees (Olea europaea) and poses a serious threat to their cultivation. The causal agent of this disease is Verticillium dahliae, a pathogen that is difficult to control with conventional methods. Therefore, there is a need to explore alternative strategies for the management of Verticillium wilt. In this study, we aimed to isolate and characterize actinobacteria from the rhizosphere of olive trees that could act as potential biocontrol agents against V. dahliae. We selected a Streptomyces sp. OR6 strain based on its in vitro antifungal activity and its ability to suppress the pathogen growth in soil samples. We identified the main active compound produced by this strain as albocycline, a macrolide polyketide with known antibacterial properties and some antifungal activity. Albocycline was able to efficiently suppress the germination of conidiospores. To our knowledge, this is the first report of albocycline as an effective agent against V. dahliae. Our results suggest that Streptomyces sp. OR6, or other albocycline-producing strains, could be used as a promising tool for the biological control of Verticillium wilt. [ABSTRACT FROM AUTHOR]

The first total synthesis of (−)‐5‐deoxyenterocin has been accomplished starting from pentane‐1,3,5‐triol (16 steps in the longest linear sequence, 0.2 % overall yield). (−)‐Menthone served as the source of chirality to distinguish the enantiotopic hydroxymethyl groups of the substrate. Key steps of the synthesis include two aldol reactions to either end of the C5‐skeleton, a diastereoselective hydroxylation reaction and a biomimetic twofold intramolecular aldol reaction as the final step. Although this step suffered from geometrical constraints and was low yielding (10 %), enough synthetic material could be secured to substantiate the relative and absolute configuration of the natural product. Additional experiments were directed toward a C−H functionalization at carbon atom C5. Despite the fact that several protocols could be successfully applied to (3aR)‐(+)‐sclareolide as model substrate, (−)‐5‐deoxyenterocin withstood any selective functionalization. [ABSTRACT FROM AUTHOR]

Monensin A is a prototypical natural polyether polyketide antibiotic. It acts by binding a metal cation and facilitating its transport across the cell membrane. Biosynthesis of monensin A involves construction of a polyene polyketide backbone, subsequent epoxidation of the alkenes, and, lastly, formation of cyclic ethers via epoxide-opening cyclization. MonCI, a flavin-dependent monooxygenase, is thought to transform all three alkenes in the intermediate polyketide premonensin A into epoxides. Our crystallographic study has revealed that MonCI's exquisite stereocontrol is due to the preorganization of the active site residues which allows only one specific face of the alkene to approach the reactive C(4a)-hydroperoxyflavin moiety. Furthermore, MonCI has an unusually large substrate-binding cavity that can accommodate premonensin A in an extended or folded conformation which allows any of the three alkenes to be placed next to C(4a)-hydroperoxyflavin. MonCI, with its ability to perform multiple epoxidations on the same substrate in a stereospecific manner, demonstrates the extraordinary versatility of the flavin-dependent monooxygenase family of enzymes. MonCI, a flavin-dependent monooxygenase, transforms all three C = C groups in the polyene substrate into epoxides during monensin A biosynthesis. Here, the authors present the structural basis for this enzyme's regio- and stereoselective epoxidation activity. [ABSTRACT FROM AUTHOR]

Hispidin is an important styrylpyrone produced by Sanghuangporus sanghuang. To analyze hispidin biosynthesis in S. sanghuang, the transcriptomes of hispidin-producing and non-producing S. sanghuang were determined by Illumina sequencing. Five PKSs were identified using genome annotation. Comparative analysis with the reference transcriptome showed that two PKSs (ShPKS3 and ShPKS4) had low expression levels in four types of media. The gene expression pattern of only ShPKS1 was consistent with the yield variation of hispidin. The combined analyses of gene expression with qPCR and hispidin detection by liquid chromatography-mass spectrometry coupled with ion-trap and time-of-flight technologies (LCMS-IT-TOF) showed that ShPKS1 was involved in hispidin biosynthesis in S. sanghuang. ShPKS1 is a partially reducing PKS gene with extra AMP and ACP domains before the KS domain. The domain architecture of ShPKS1 was AMP-ACP-KS-AT-DH-KR-ACP-ACP. Phylogenetic analysis shows that ShPKS1 and other PKS genes from Hymenochaetaceae form a unique monophyletic clade closely related to the clade containing Agaricales hispidin synthase. Taken together, our data indicate that ShPKS1 is a novel PKS of S. sanghuang involved in hispidin biosynthesis. [ABSTRACT FROM AUTHOR]

Plant endophytic fungi are reservoirs of novel bioactive natural products, which may be used directly or indirectly to treat numerous diseases. However, it is difficult to rapidly obtain the natural products of interest from enormous endogenic fungi by conventional chemical extraction and separation methods when the overall biosynthetic potential is unknown. There is a lack of systematic studies on the biosynthetic and metabolic potential of endophytic fungi of Salvia miltiorrhiza. Therefore, untargeted metabolomics and metagenomic binning technology were used in this study to analyze the biosynthetic potential of endophytic fungi isolated from S. miltiorrhiza, including 47 species and 166 strains of 24 genera. Metabolomics analysis showed that 3016 metabolites were annotated, involving multiple primary and secondary metabolic pathways. A total of 12 genera and 443 KEGG pathways were annotated in the metagenomic, involving the biosynthesis of amino acids, saccharides, lipids, terpenoids, alkaloids, and polyketides. At the genus level, the biosynthesis and differences of amino acids, saccharides, alkaloids, terpenoids, phenolic acids and polyketides by endophytic fungi of S. miltiorrhiza were revealed. It provides a basis for quickly searching specific active substances from the endophytic fungi of S. miltiorrhiza and enhancing host plant productivity. [ABSTRACT FROM AUTHOR]

Panax notoginseng (Burk.) F.H. Chen is a species of the Araliaceae family that inhabits southwestern China, Burma, and Nepal. It is cultivated on a commercial scale in Yunnan province, China, owing to its significance in traditional Chinese medicine. Panax notoginseng roots are usually yellow-white (HS); however, purple roots (ZS) have also been reported. The majority of P. notoginseng research has concentrated on the identification and production of natural chemicals in HS; however, there is little to no information about the composition of ZS. Using UPLC-MS/MS, we investigated the global metabolome profile of both ZS- and HS-type roots and discovered 834 metabolites from 11 chemical groups. There were 123 differentially accumulated metabolites (DAM) in the HS and ZS roots, which were classified as lipids and lipid-like molecules, polyketides, organoheterocyclic chemicals, and organooxygen compounds. We investigated the associated compounds in the DAMs because of the importance of anthocyanins in color and saponins and ginsenosides in health benefits. In general, we discovered that pigment compounds such as petunidin 3-glucoside, delphinidin 3-glucoside, and peonidin-3-O-beta-galactoside were more abundant in ZS. The saponin (eight compounds) and ginsenoside (26 compounds) content of the two varieties of roots differed as well. Transcriptome sequencing revealed that flavonoid and anthocyanin production genes were more abundant in ZS than in HS. Similarly, we found differences in gene expression in genes involved in terpenoid production and related pathways. Overall, these findings suggest that the purple roots of P. notoginseng contain varying amounts of ginsenosides and anthocyanins compared to roots with a creamy yellow color. [ABSTRACT FROM AUTHOR]

Glutarimide-containing polyketides exhibiting potent antitumor and antimicrobial activities were encoded via conserved module blocks in various strains that favor the genomic mining of these family compounds. The bioinformatic analysis of the genome of Burkholderia gladioli ATCC 10248 showed a silent trans-AT PKS biosynthetic gene cluster (BGC) on chromosome 2 (Chr2C8), which was predicted to produce new glutarimide-containing derivatives. Then, the silent polyketide synthase gene cluster was successfully activated via in situ promoter insertion and heterologous expression. As a result, seven glutarimide-containing analogs, including five new ones, gladiofungins D-H (3–7), and two known gladiofungin A/gladiostatin (1) and 2 (named gladiofungin C), were isolated from the fermentation of the activated mutant. Their structures were elucidated through the analysis of HR-ESI-MS and NMR spectroscopy. The structural diversities of gladiofungins may be due to the degradation of the butenolide group in gladiofungin A (1) during the fermentation and extraction process. Bioactivity screening showed that 2 and 4 had moderate anti-inflammatory activities. Thus, genome mining combined with promoter engineering and heterologous expression were proved to be effective strategies for the pathway-specific activation of the silent BGCs for the directional discovery of new natural products. [ABSTRACT FROM AUTHOR]

A new series of 20 benzofuran based sulphonamides was synthesized from salicylaldehyde and ortho-vanillin. Synthesized compounds (VIIIa–VIIIt) were characterized using FT-IR (Fourier-transform infrared spectroscopy), 1H-NMR (Proton nuclear magnetic resonance) and Mass spectroscopic studies. All 20 compounds were subjected to in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv strains. Compounds (VIIIj), (VIIIi), (VIIIo) and (VIIId) were found to exhibit lower MICs (the minimum inhibitory concentrations) as 13, 18, 17 and 19 µg/mL respectively. To predict plausible modes of binding of these compounds, we carried out molecular docking analysis against a target type III polyketide synthase PKS18 from M. tuberculosis (PDB ID: 1TED). [ABSTRACT FROM AUTHOR]

Objectives: Annona muricata, also known as graviola, is traditionally used for the treatment of a range of disorders including cancer. Interest in A. muricata use has increased in recent years. This study investigated the quality and safety of a selection of commercially available A. muricata leaf products. Methods: Seven commercially available products were purchased via online shopping sites. Each product was assessed for quality indicators including weight variation, quantification of the bioactive constituent annonacin, presence of annonaceous acetogenins and contaminants. The samples were evaluated by thin-layer chromatography, high-performance liquid chromatography, liquid chromatography–mass spectroscopy, low-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Microbial analysis was carried out in accordance with the British Pharmacopoeia. Heavy metals were analysed by inductive coupled plasma mass spectrometry. Key findings: Of the seven products analysed, one product contained less than half of the content stated on the label. The labelled dosage recommendation varied between products. There was a high variation in annonacin concentration (1.05–3.09 mg/g) and the presence of annonaceous acetogenins. One of the products was found to have a total aerobic microbial count above the United States Pharmacopoeia limit. Conclusions: The variation in the indicators of quality and safety of commercially available A. muricata leaf products tested have implications for clinicians and people living with cancer who use these herbal products. [ABSTRACT FROM AUTHOR]

New symmetric aryl-substituted derivatives of acetogenins were synthesized using the Ti-catalyzed homo-cyclomagnesiation of aryl-substituted 1,2-dienes at the key step. Ruthenium catalyzed oxidative cyclization of symmetric aryl-substituted 1Z,5Z-dienes was used to synthesize diols and ketols containing a tetrahydrofuran fragment. Diastereoselective reduction of ketols with L-selectride yielded target diols. In addition, by oxidation of ketols with Dess—Martin periodinane, diketones were synthesized in high yields. [ABSTRACT FROM AUTHOR]

Two undescribed α-pyrone-containing polyketide derivatives designated aurovertins V (1) and W (2), and a known analogue (3), were isolated from the fungus Aspergillus aureoterreus. Their structures including the absolute configuration were elucidated on the basis of extensive spectroscopic methods and theoretical ECD calculation. Compound 1 is the first example of aurovertins with a 7R configuration, whereas 2 comprises a S configuration for C-6 and a Z geometry of the double bond Δ8. Both 1 and 2 showed no cytotoxicity against human cancer cell lines HL-60, SU-DHL-2 and U266) at the concentration of 20.0 μM. [ABSTRACT FROM AUTHOR]

Objective: The aim of this research was the isolation, structure elucidation and evaluation of the bioactivity of natural products produced by an Aureobasidium pullulans fungal endophyte of the medicinal plant Thuja occidentalis. Methods: The natural products were isolated from an extract of A. pullulans culture broth by reversed-phase chromatography and their structures were elucidated based on analysis of HRESIMS and 1D/2D NMR data. The absolute configurations of the compounds were assigned by comparison of their electronic circular dichroism (ECD) and optical rotatory dispersion (ORD) data with values obtained for Boltzmann-weighted conformer ensembles calculated by density functional theory. Results/Conclusion: Two new C11-polyketides, aureobasidol A (1) and B (2), were isolated from the A. pullulans extract. Both polyketides showed selective but weak inhibitory activity against Mycobacterium tuberculosis in vitro. [ABSTRACT FROM AUTHOR]