Bysspectin A, an unusual octaketide dimer and the precursor derivatives from the endophytic fungus Byssochlamys spectabilis IMM0002 and their biological activities

An Update of Fungal Endophyte Diversity and Strategies for Augmenting Therapeutic Potential of their Potent Metabolites: Recent Advancement

Endophytic fungi represent a significant renewable resource for the discovery of pharmaceutically important compounds, offering substantial potential for new drug development. Their ability to address the growing issue of drug resistance has drawn attention from researchers seeking novel, nature-derived lead molecules that can be produced on a large scale to meet global demand. Recent advancements in genomics, metabolomics, bioinformatics, and improved cultivation techniques have significantly aided the identification and characterization of fungal endophytes and their metabolites. Current estimates suggest there are approximately 1.20 million fungal endophytes globally, yet only around 16% (190,000) have been identified and studied in detail. This underscores the vast untapped potential of fungal endophytes in pharmaceutical research. Research has increasingly focused on the transformation of bioactive compounds by fungal endophytes through chemical and enzymatic processes. A notable example is the anthraquinone derivative 6-O-methylalaternin, whose cytotoxic potential is enhanced by the addition of a hydroxyl group, sharing structural similarities with its parent compound macrosporin. These structure-bioactivity studies open up new avenues for developing safer and more effective therapeutic agents by synthesizing targeted derivatives. Despite the immense promise, challenges remain, particularly in the large-scale cultivation of fungal endophytes and in understanding the complexities of their biosynthetic pathways. Additionally, the genetic manipulation of endophytes for optimized metabolite production is still in its infancy. Future research should aim to overcome these limitations by focusing on more efficient cultivation methods and deeper exploration of fungal endophytes' genetic and metabolic capabilities to fully harness their therapeutic potential.

Purpurolide C-based microneedle promotes macrophage-mediated diabetic wound healing via inhibiting TLR4-MD2 dimerization and MYD88 phosphorylation

Delayed wound healing in diabetes is a global challenge, and the development of related drugs is a clinical problem to be solved. In this study, purpurolide C (PC), a small-molecule secondary metabolite of the endophytic fungus Penicillium purpurogenum, was found to promote diabetic wound healing. To investigate the key regulation targets of PC, in vitro RNA-seq, molecular docking calculations, TLR4-MD2 dimerization SDS-PAGE detection, and surface plasmon resonance (SPR) were performed, indicating that PC inhibited inflammatory macrophage activation by inhibiting both TLR4-MD2 dimerization and MYD88 phosphorylation. Tlr4 knockout in vivo attenuated the promotion effect of PC on wound healing. Furthermore, a delivery system consisting of macrophage liposome and GelMA-based microneedle patches combined with PC (PC@MLIP MN) was developed, which overcame the poor water solubility and weak skin permeability of PC, so that successfully punctured the skin and delivered PC to local tissues, and accurately regulated macrophage polarization in diabetic wound management. Overall, PC is an anti-inflammatory small molecule compound with a well-defined structure and dual-target regulation, and the PC@MLIP MN is a promising novel biomaterial for the management of diabetic wound.

New bysspectin A derivatives as potent inhibitors of human carboxylesterase 2A

Human carboxylesterase 2A (hCES2A), the most abundant carboxylesterase in the human gut, plays a crucial role in the metabolic clearance and activation of various ester-bearing drugs, environmental toxins and carcinogens. Inhibition of intestinal hCES2A can alleviate irinotecan-induced gut toxicity and modulate the oral bioavailability of hCES2A-substrate drugs. Bysspectin A, a natural product isolated from the endophytic fungus Byssochlamys spectabilis, has been identified as a highly selective hCES2A inhibitor. Herein, two sets of bysspectin A derivatives have been designed and synthesized, utilizing a Cu-catalyzed domino Sonogashira-cyclization as the key step. Following two rounds of structure activity relationship (SAR) studies and structural optimizations, compound 20w was identified as the most potent hCES2A inhibitor, with an IC50 value of 1.6 nM, an approximately 1000-fold improvement over bysspectin A. Further investigation showed that 20w potently inhibited hCES2A in a mixed inhibition manner, while this agent could also potently inhibit intracellular hCES2A in living cells and exhibited suitable metabolic stability. In summary, our findings demonstrate that a new bysspectin A derivative (20w) is a promising candidate for the development of clinically used hCES2A inhibitor.

Discovery of novel carboxylesterase 2 inhibitors for the treatment of delayed diarrhea and ulcerative colitis

Human carboxylesterase 2 (hCES2) is an enzyme that metabolizes irinotecan to SN-38, a toxic metabolite considered a significant source of side effects (lethal delayed diarrhea). The hCES2 inhibitors could block the hydrolysis of irinotecan in the intestine and thus reduce the exposure of intestinal SN-38, which may alleviate irinotecan-associated diarrhea. However, existing hCES2 inhibitors (except loperamide) are not used in clinical applications due to lack of validity or acceptable safety. Therefore, developing more effective and safer drugs for treating delayed diarrhea is urgently needed. This study identified a lead compound 1 with a novel scaffold by high-throughput screening in our in-house library. After a comprehensive structure-activity relationship study, the optimal compound 24 was discovered as an efficient and highly selective hCES2 inhibitor (hCES2: IC50 = 6.72 μM; hCES1: IC50 > 100 μM). Further enzyme kinetics study indicated that compound 24 is a reversible inhibitor of hCES2 with competitive inhibition mode (Ki = 6.28 μM). The cell experiments showed that compound 24 could reduce the level of hCES2 in living cells (IC50 = 6.54 μM). The modeling study suggested that compound 24 fitted very well with the binding pocket of hCES2 by forming multiple interactions. Notably, compound 24 can effectively treat irinotecan-induced delayed diarrhea and DSS-induced ulcerative colitis, and its safety has also been verified in subtoxic studies. Based on the overall pharmacological and preliminary safety profiles, compound 24 is worthy of further evaluation as a novel agent for irinotecan-induced delayed diarrhea.

An insight into endophytic antimicrobial compounds: an updated analysis

Resistance in micro-organisms against antimicrobial compounds is an emerging phenomenon in the modern era as compared to the traditional world which brings new challenges to discover novel antimicrobial compounds from different available sources, such as, medicinal plants, various micro-organisms, like, bacteria, fungi, algae, actinomycetes, and endophytes. Endophytes reside inside the plants without exerting any harmful impact on the host plant along with providing ample of benefits. In addition, they are capable of producing diverse antimicrobial compounds similar to their host, allowing them to serve as useful micro-organism for a range of therapeutic purposes. In recent years, a large number of studies on the antimicrobial properties of endophytic fungi have been carried out globally. These antimicrobials have been used to treat various bacterial, fungal, and viral infections in humans. In this review, the potential of fungal endophytes to produce diverse antimicrobial compounds along with their various benefits to their host have been focused on. In addition, classification systems of endophytic fungi as well as the need for antimicrobial production with genetic involvement and some of the vital novel antimicrobial compounds of endophytic origin can further be utilized in the pharmaceutical industries for various formulations along with the role of nanoparticles as antimicrobial agents have been highlighted.

The antimicrobial, antibiofilm, and wound healing properties of ethyl acetate crude extract of an endophytic fungus Paecilomyces sp. (AUMC 15510) in earthworm model

The endophytic fungus Paecilomyces sp. (AUMC 15510) was isolated from healthy stem samples of the Egyptian medicinal plant Cornulaca monacantha. We used GC-MS and HPLC analysis to identify the bioactive constituents of ethyl acetate crude extract of Paecilomyces sp. (PsEAE). Six human microbial pathogens have been selected to evaluate the antimicrobial activity of PsEAE. Our data showed that the extract has significant antimicrobial activity against all tested pathogens. However, the best inhibitory effect was observed against Bacillus subtilis ATCC 6633 and Pseudomonas aeruginosa ATCC 90274 with a minimum inhibitory concentration (MIC) of 3.9 μg/ml and minimum bactericidal concentration (MBC) of 15.6 μg/ml, for both pathogens. Also, PsEAE exerts a significant inhibition on the biofilm formation of the previously mentioned pathogenic strains. In addition, we evaluated the wound healing efficiency of PsEAE on earthworms (Lumbricus castaneus) as a feasible and plausible model that mimics human skin. Interestingly, PsEAE exhibited a promising wound healing activity and enhanced wound closure. In conclusion, Paecilomyces sp. (AUMC 15510) could be a sustainable source of antimicrobial agents and a potential therapeutic target for wound management.

Recent advances in natural phthalides: Distribution, chemistry, and biological activities

Phthalides, an important class of bioactive natural products, are widely distributed in plants, fungi, lichens, and liverworts. Amon them, n-butylphthalide, a phthalide monomer, has been approved to cure ischemic stroke. Owing to their good bioactivities in anti-microbial, anti-inflammatory, anti-tumor, anti-diabetic, and other aspects, a large number of researches have been conducted on phthalides from nature materials. In recent years, hundreds of novel natural phthalides were obtained. This review provides profiles of the advances in the distribution, chemistry, and biological activities of natural phthalides in 2016-2022.

Two New Nor-seco-Isodhilarane-Type Meroterpenoids from the Endophytic Fungus Penicillium purpurogenum

Two new nor-seco isodhilarane meroterpenoids (NSIMs), purpurogenolides F (1) and G (2), along with three known meroterpenoid analogs (3-5), were isolated from the cultures of an endophytic fungus, Penicillium purpurogenum. Structures and absolute configurations of the new NSIMs were determined based on extensive spectroscopic data analyses, including HR-ESI-MS, UV, IR, NMR chemical shift calculations together with DP4+ probability analysis, as well as ECD calculations. All the isolated meroterpenoids were assessed for their anti-inflammatory activities, and compound 4 exhibited moderate inhibitory activity against the nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW 264.7 cells with an IC₅₀ value of 20.85±2.31 μM.

Metabolites and novel compounds with anti-microbial or antiaging activities from Cordyceps fumosorosea

High-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) analysis revealed that there are 20 main components in spores and mycelia extract of Cordyceps fumosorosea strain RCEF 6672 including mannitol (1), uridine (2), adenine (3). N⁶-(2-hydroxyethyl)-adenosine (4). N⁶-(2-hydroxyethylacetate)-adenosine (5), fumosoroseanoside A (6) and B (7), ovalicin-4α-alcohol (8), 1-linoleoyl-sn-glycero-3-phosphocholine (9) and its isomer (10), fumosoroseain A (11) and its isomer (12), 5 non-ribosomal peptides (13 to 17) and 3 fatty acids (18 to 20). The compounds 5, 6, 7, 9 and 11 were prepared with preparative and semi-preparative HPLC and identified with 1D and 2D NMR. Compounds 4 and 5 were the first time identified from C. fumosorosea. Compounds 6, 7 and 11 are novel compounds. Compounds 6 and 7 showed antibacterial and antifungal activities, and 11 showed antiaging activity. All the secondary metabolites (4 to 8 and 11 to 17) have strong bioactivities indicating that the metabolites have pharmaceutical development potentiality.

Clarified small molecular metabolites of C. fumosorosea for the first time.

Identified three novel compounds with antimicrobial or antiaging activities.

The fungus has development potentiality for rich in bioactive metabolites.

Fungal Endophytes: A Potential Source of Antibacterial Compounds

Antibiotic resistance is becoming a burning issue due to the frequent use of antibiotics for curing common bacterial infections, indicating that we are running out of effective antibiotics. This has been more obvious during recent corona pandemics. Similarly, enhancement of antimicrobial resistance (AMR) is strengthening the pathogenicity and virulence of infectious microbes. Endophytes have shown expression of various new many bioactive compounds with significant biological activities. Specifically, in endophytic fungi, bioactive metabolites with unique skeletons have been identified which could be helpful in the prevention of increasing antimicrobial resistance. The major classes of metabolites reported include anthraquinone, sesquiterpenoid, chromone, xanthone, phenols, quinones, quinolone, piperazine, coumarins and cyclic peptides. In the present review, we reported 451 bioactive metabolites isolated from various groups of endophytic fungi from January 2015 to April 2021 along with their antibacterial profiling, chemical structures and mode of action. In addition, we also discussed various methods including epigenetic modifications, co-culture, and OSMAC to induce silent gene clusters for the production of noble bioactive compounds in endophytic fungi.

Cross-coupling reactions towards the synthesis of natural products

Cross-coupling reactions are powerful synthetic tools for the formation of remarkable building blocks of many naturally occurring molecules, polymers and biologically active compounds. These reactions have brought potent transformations in chemical and pharmaceutical disciplines. In this review, we have focused on the use of cross-coupling reactions such as Suzuki, Negishi, Heck, Sonogashira and Stille in the total synthesis of some natural products of recent years (2016-2020). A short introduction of mentioned cross-coupling reactions along with highlighted aspects of natural products has been stated in separate sections. Additionally, few examples of natural products via incorporation of more than one type of cross-coupling reaction have also been added to demonstrate the importance of these reactions in organic synthesis.

Diversity, Chemical Constituents, and Biological Activities of Endophytic Fungi Isolated From Ligusticum chuanxiong Hort

The objective of this study was to evaluate the diversity of endophytic fungi of different parts of Ligusticum chuanxiong Hort (CX) and further characterize their biological activities and identify chemical compounds produced by these endophytic fungi. A total of 21 endophytic fungi were isolated and identified from CX. Penicillium oxalicum, Simplicillium sp., and Colletotrichum sp. were identified as promising strains by the color reaction. Comparing different organic extracts of the three strains, it was observed that the ethyl acetate extract of Penicillium oxalicum and Simplicillium sp. and the n-butanol extract of Colletotrichum sp. showed significant antioxidant and antibacterial activities. The ethyl acetate extracts of Penicillium oxalicum had outstanding antioxidant and antibacterial effects, and its radical scavenging rates for ABTS and DPPH were 98.43 ± 0.006% and 90.11 ± 0.032%, respectively. At the same time, their IC₅₀ values were only 0.18 ± 0.02 mg/mL and 0.04 ± 0.003 mg/mL. The ethyl acetate extract of Penicillium oxalicum showed MIC value of only 0.5 mg/mL against Escherichia coli and Staphylococcus aureus. By liquid chromatography-mass spectrometry (LC-MS), we found that Penicillium oxalicum could produce many high-value polyphenols, such as hesperidin (36.06 μmol/g), ferulic acid (1.17 μmol/g), and alternariol (12.64 μmol/g), which can be a potential resource for the pharmaceutical industry. In conclusion, these results increase the diversity of CX endophytic fungi and the antioxidant and antibacterial activities of their secondary metabolites.

Effect of the compound bacterial agent on microbial community of the aerobic compost of food waste

In our study, we used 16SrRNA and ITS to investigate the microbial community composition and the effect of compound bacterial agent on the microbial community composition in the aerobic composting process of food waste (FW). At the bacterial level, the main phyla of Group A (compost naturally) were Proteobacteria and Firmicutes, and the main species were Pseudomonas_sp._GR7, Bacillus licheniformis and Pediococcus acidilactici. The main phyla of Group B (compost with compound bacterial agent) were Proteobacteria, Firmicutes and Streptophyta, and the main species were Klebsiella pneumoniae, Cronobacter sakazakii, Macrococcus caseolyticus, Enterococcus faecalis, Citrobacter freundii and Bacillus velezensis. It is worth noting that M. caseolyticus may be able to improve the effect of odour which is an important sensory index during aerobic composting. At the fungal level, the main phylum of both Groups A and B was Ascomycota, and the main species of Group A were Paecilomyces variotii, Byssochlamys spectabilis and Aspergillus fumigatus. The main species of Group B were Ogataea polymorpha and Millerozyma farinosa. Finally, the degradation rate of Group B was 81% that was about 15% higher than that of Group A, indicating that the compound bacterial agent could effectively improve the degradation rate and the composting process, while the low abundance of the compound bacterial agent in the composting process might be due to the small initial addition or the inhibition of other bacteria or fungi in the composting process.

Scalable Biomimetic Syntheses of Paeciloketal B, 1-epi-Paeciloketal B, and Bysspectin A

The first total synthesis of the benzannulated 5,5-spiroketal natural products paeciloketal B and 1-epi-paeciloketal B has been achieved in 10 linear steps employing a biomimetic spiroketalization. This approach also furnished the related natural product bysspectin A from the same putative biosynthetic precursor as the paeciloketals. Alternatively, bysspectin A could be accessed in only six steps using an improved route. This scalable and efficient synthesis affords insight into the biosynthesis of these natural products in nature.

Biological Activities of Some New Secondary Metabolites Isolated from Endophytic Fungi: A Review Study

Secondary metabolites isolated from plant endophytic fungi have been getting more and more attention. Some secondary metabolites exhibit high biological activities, hence, they have potential to be used for promising lead compounds in drug discovery. In this review, a total of 134 journal articles (from 2017 to 2019) were reviewed and the chemical structures of 449 new metabolites, including polyketides, terpenoids, steroids and so on, were summarized. Besides, various biological activities and structure-activity relationship of some compounds were aslo described.

Bioactivity-Guided Discovery of Human Carboxylesterase Inhibitors from the Roots of Paeonia lactiflora

In a continuing search for potential inhibitors against human carboxylesterases 1A1 and 2A1 (hCES1A1 and hCES2A1), an EtOAc extract of the roots of Paeonia lactiflora showed strong hCES inhibition activity. Bioassay-guided fractionation led to the isolation of 26 terpenoids including 12 new ones (1-5, 7-12, and 26). Among these, sesquiterpenoids 1 and 6, monoterpenoids 10, 11, and 13-15, and triterpenoids 18-20, 22, and 24-26 contributed to the hCES2A1 inhibition, in the IC₅₀ range of 1.9-14.5 μM, while the pentacyclic triterpenoids 18-26 were responsible for the potent inhibitory activity against hCES1A1, with IC₅₀ values less than 5.0 μM. The structures of all the compounds were elucidated using MS and 1D and 2D NMR data, and the absolute configurations of the new compounds were resolved via specific rotation, experimental and calculated ECD spectra, and single-crystal X-ray diffraction analysis. The structure-activity relationship analysis highlighted that the free HO-3 group in the pentacyclic triterpenoids is crucial for their potent inhibitory activity against hCES1A1.

Design, synthesis and biological evaluation of indanone-chalcone hybrids as potent and selective hCES2A inhibitors

Human carboxylesterase 2 (hCES2A), one of the major serine hydrolases distributed in the small intestine, plays a crucial role in hydrolysis of ester-bearing drugs. Accumulating evidence has indicated that hCES2A inhibitor therapy can modulate the pharmacokinetic and toxicological profiles of some important hCES2A-substrate drugs, such as the anticancer agent CPT-11. Herein, a series of indanone-chalcone hybrids are designed and synthesized to find potent and highly selective hCES2A inhibitors. Inhibition assays demonstrated that most indanone-chalcone hybrids displayed strong to moderate hCES2A inhibition activities. Structure-hCES2A inhibition activity relationship studies showed that introduction of a hydroxyl at the C4' site and introduction of an N-alkyl group at the C6 site were beneficial for hCES2A inhibition. Particularly, B7 (an N-alkylated 1-indanone-chalcone hybrid) exhibited the most potent inhibition on hCES2A and excellent specificity (this agent could not inhibit other human esterases including hCES1A and butyrylcholinesterase). Inhibition kinetic analyses demonstrated that B7 potently inhibited hCES2A-mediated FD hydrolysis in a mixed inhibition manner, with a calculated K_i value of 0.068 μM. Furthermore, B7 was capable of inhibiting intracellular hCES2A in living cells and displayed good metabolic stability. Collectively, our findings show that indanone-chalcone hybrids are good choices for the development of hCES2A inhibitors, while B7 is a promising candidate for the development of novel anti-diarrhea agents to ameliorate irinotecan-induced intestinal toxicity.

Basidiosins A and B: Cyclopentapeptides from the entomophthoralean fungus Basidiobolus meristosporus

Two new cyclopentapeptides, basidiosins A and B (1 and 2) were isolated from the mycelia extracts of entomophthoralean fungus Basidiobolus meristosporus RCEF 4516. The structures were determined based on spectroscopic methods, and the absolute config urations were assigned by Marfey's method on their acid hydrolyzates. Compounds 1 and 2 were identified as cyclo(L-Thr-L-Leu- L-Ile-D-Tyr-D-Thr) and cyclo(L-Thr-L-Leu-L-Val-D-Val-D-Ser), respectively. They were evaluated for the biological activities including antibacterial, antifungal and antioxidative activities. Furthermore, the biosynthetic pathway of 1 was proposed by bioinformatic analysis. This is the first study on the isolation of natural products from Basidiobolus fungus.

Diversity, Chemical Constituents and Biological Activities of Endophytic Fungi Isolated from Schinus terebinthifolius Raddi

Schinus terebinthifolius Raddi is a medicinal plant widely used for the treatment of various diseases. The secondary metabolites responsible for the pharmacological properties can be produced directly by the plant or by endophytic fungi. The objective of this study was to evaluate the diversity of endophytic fungi of different parts of S. terebinthifolius and to identify chemical compounds produced by endophytes and their antioxidant and antibacterial activities. For this, fruits, stem bark and roots were dried, ground and placed in fungal growth medium. The selected endophytes were grown and subjected to extraction with ethyl acetate. DPPH, FRAP, β-carotene bleaching and antimicrobial assays were performed. The phylogenetic tree was elaborated, encompassing 15 different species. The fungal extracts showed hydroxybenzoic acids and 1-dodecanol as predominant compounds. All fungal extracts exhibited antioxidant activity. The fungal extracts exhibited bactericidal and bacteriostatic activities against Gram-positive and Gram-negative bacterial ATCC strains and against methicillin-resistant nosocomial bacteria. Among the 10 endophytic fungi evaluated, the extract of the fungus Ochrocladosporium elatum showed higher phenolic content and exhibited higher antioxidant and antibacterial activities in all tests. Together, the results increase the known diversity of S. terebinthifolius endophytic fungi, secondary metabolites produced and their antioxidant and antibacterial activities.

Acid-base-sensitive allylic oxidation of 2-allylbenzoic acids to form phthalides

Allylic oxidation of 2-allylbenzoic acids to phthalides, instead of Wacker-type isocoumarins, was achieved with 1,2-bis(phenylsulfinyl)ethane palladium(ii) acetate (White catalyst) and oxygen in DMSO. The selective formation of 3-ethylidenephthalides or 3-vinylphthalides was controlled by the addition of acids or bases, and the reaction conditions were applied to substituted 2-allylbenzoic acids to generate corresponding phthalides selectively. Mechanistic studies, including the corresponding reaction of (E)-2-(1-propenyl)benzoic acid to 3-methylisocoumarin, isomerization reaction of 3-vinylphthalide to 3-ethylidenephthalide, and the kinetic isotope effect using 2-(1,1-d2-allyl)benzoic acid, revealed the competition between Wacker-type oxidation and allylic C-H cleavage, which is the key step to generating phthalides. A natural product, 3-ethyl-6-hydroxyphthalide, was prepared by this method.

Three new polyketides from the endophytic fungus Penicillium purpurogenum

Three new polyketides including two benzophenone derivatives, penibenzones A and B (1 and 2), and a new phthalide derivative, penibenzone C (3), along with six known compounds, were isolated from the solid-substrate cultures of the endophytic fungus Penicillium purpurogenum IMM003. Their structures were elucidated on the basis of spectroscopic data (UV, IR, HRESIMS, 1D and 2D NMR). All compounds were evaluated for inhibitory activity against pancreatic lipase, but none of them displayed activity.[Formula: see text].

Yanhusanines A-F, Isoquinoline-Derived Alkaloid Enantiomers from Corydalis yanhusuo and Their Biological Activity

Six new pairs of isoquinoline alkaloid enantiomers, designated as yanhusanines A-F (1-6), were isolated from an aqueous extract of Corydalis yanhusuo tubers. The structures of these enantiomers were elucidated via physicochemical analysis and a variety of spectroscopic methods. All compounds were resolved into their enantiomers via chiral-phase HPLC, and their configurations were determined by DP4+ NMR calculation methods, specific rotations, and comparison of experimental and calculated ECD spectra. Compounds 1-6 bear a rare 9-methyl moiety, and compound 1 possesses a rare 1-oxa-6-azaspiro[4.5]decane core containing an N-CHO group. Compounds (+)-2, (-)-2, (+)-4, (-)-4, (+)-5, (-)-5, (+)-6, and (-)-6 exhibited selective inhibitory activities against human carboxylesterase (hCE2), in the IC₅₀ value range of 2.0-13.2 μM.

Fusariumins C and D, two novel antimicrobial agents from Fusarium oxysporum ZZP-R1 symbiotic on Rumex madaio Makino

Bioassay-guided fractionation of the crude extract of fermentation broth of one symbiotic strain Fusarium oxysporum ZZP-R1 derived from coastal plant Rumex madaio Makino, one traditional Chinese medicine used as a treatment of inflammation and toxication, yielded two novel compounds, fusariumins C (1) and D (2). Chemical structures of 1 and 2 were respectively determined as one meroterpene with cyclohexanone moiety and a sesquiterpene ester with a conjugated triene and an unusual oxetene ring by a combination of spectroscopic methods, including 1D and 2D NMR, mass spectrometry, and optical rotation analysis, as well as by comparison with literature data. Bioassay results indicated that compound 1 displayed potent activity against Staphyloccocus aureus with an MIC value of 6.25 μM, and compound 2 had a moderate inhibitory effect on S. aureus with an MIC value of 25.0 μM. It was the first report that phytochemical investigation of Fusarium strain from R. madaio Makino led to isolation of new antimicrobial agents.

Purpurolide A, 5/5/5 Spirocyclic Sesquiterpene Lactone in Nature from the Endophytic Fungus Penicillium purpurogenum

Purpurolide A (1), an unprecedent sesquiterpene lactone with a rarely encountered 5/5/5 spirocyclic skeleton, along with two new 6/4/5/5 tetracyclic sesquiterpene lactones (2 and 3), were isolated from the cultures of the endophytic fungus Penicillium purpurogenum IMM003. The structures and absolute configurations of 1-3 were established by spectroscopic analysis, single-crystal X-ray diffraction, and calculations of the ¹³C NMR and ECD data. Compounds 1-3 showed significant inhibitory activity against pancreatic lipase.

Human carboxylesterases: a comprehensive review

Mammalian carboxylesterases (CEs) are key enzymes from the serine hydrolase superfamily. In the human body, two predominant carboxylesterases (CES1 and CES2) have been identified and extensively studied over the past decade. These two enzymes play crucial roles in the metabolism of a wide variety of endogenous esters, ester-containing drugs and environmental toxicants. The key roles of CES in both human health and xenobiotic metabolism arouse great interest in the discovery of potent CES modulators to regulate endobiotic metabolism or to improve the efficacy of ester drugs. This review covers the structural and catalytic features of CES, tissue distributions, biological functions, genetic polymorphisms, substrate specificities and inhibitor properties of CES1 and CES2, as well as the significance and recent progress on the discovery of CES modulators. The information presented here will help pharmacologists explore the relevance of CES to human diseases or to assign the contribution of certain CES in xenobiotic metabolism. It will also facilitate medicinal chemistry efforts to design prodrugs activated by a given CES isoform, or to develop potent and selective modulators of CES for potential biomedical applications.

Hot off the press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as tundrenone from Methylobacter tundripaludum.