Chaetominine, a cytotoxic alkaloid produced by endophytic Chaetomium sp. IFB-E015

Diverse bioactive secondary metabolites from Aspergillus terreus: antimicrobial, anticancer, and anti-SARS-CoV-2 activity studies

Owing to its high interest as prolific source of diverse bioactive compounds referred in our previous research work, we have scaled-up the fermentation of the marine Aspergillus terreus LGO13 on a liquid culture medium to isolate and identify the very minor/further promising bioactive secondary metabolites and to study their antibacterial, cytotoxic, and antiviral properties. Twenty-three known bioactive metabolites, including the recently discovered microbial natural product N-benzoyl-tryptophan (1), were obtained herein. Their structures were determined using HR-ESI-MS 1D/2D NMR spectroscopy and data from the literature. The biological properties of the microbial extract and the resulting compounds were examined using a set of microorganisms, cervix carcinoma KB-3-1, nonsmall cell lung cancer (NSCLC) A549, and coronavirus (SARS-CoV-2), respectively. Molecular docking (MD) simulations were used to investigate the potential targets of the separated metabolites as anti-SARS-CoV-2 drugs. According to the current study, a viral protein that may be the target of anticovid drugs is a papain-like protease (PLpro), and chaetominine (2) appears to be a viable choice against this protein. We evaluated the antiviral efficacy of chaetominine (2), fumitremorgin C (6), and azaspirofuran A (9) against SARS-CoV-2 based on MD data. Chaetominine (2) and azaspirofuran A (9) displayed intermediate selectivity indices (SI = 6.6 and 3.2, respectively), while fumitremorgin C (6) displayed a high selectivity index (SI = 19.77). These findings show that fumitremorgin C has promising antiviral action against SARS-CoV-2.

Novel Alkaloids from Aspergillus fumigatus VDL36, an Endophytic Fungus Associated with Vaccinium dunalianum

Eleven alkaloids (1-11) including seven new ones, 1-7, were isolated from the solid fermentation of Aspergillus fumigatus VDL36, an endophytic fungus isolated from the leaves of Vaccinium dunalianum Wight (Ericaceae), a perennial evergreen shrub distributed across the Southwest regions of China, Myanmar, and Vietnam. Their structures were elucidated on the basis of extensive spectroscopic methods. The isolates were evaluated for in vitro antifungal activities against five phytopathogenic fungi (Fusarium oxysporum, Coriolus versicolor, Fusarium solani, Botrytis cinerea, Fusarium graminearum). As a result, the new compounds fumigaclavine I (1), 13-ethoxycyclotryprostatin A (5), 13-dehydroxycyclotryprostatin A (6), and 12β-hydroxy-13-oxofumitremorgin C (7) exhibited antifungal activities with MIC values of 7.8-62.5 μg/mL which were comparable to the two positive controls ketoconazole (MIC = 7.8-31.25 μg/mL) and carbendazim (MIC = 1.95-7.8 μg/mL). Furthermore, compounds 1 and 5 demonstrated potent protective and curative effects against the tomato gray mold in vivo. Preliminary structure-activity relationships of the tested indole diketopiperazine alkaloids indicate that the introduction of a substituent group at position C-13 enhances their biological activities.

A New Quinazolinone Alkaloid along with Known Compounds with Seed-Germination-Promoting Activity from Rhodiola tibetica Endophytic Fungus Penicillium sp. HJT-A-6

A new quinazolinone alkaloid named peniquinazolinone A (1), as well as eleven known compounds, 2-(2-hydroxy-3-phenylpropionamido)-N-methylbenzamide (2), viridicatin (3), viridicatol (4), (±)-cyclopeptin (5a/5b), dehydrocyclopeptin (6), cyclopenin (7), cyclopenol (8), methyl-indole-3-carboxylate (9), 2,5-dihydroxyphenyl acetate (10), methyl m-hydroxyphenylacetate (11), and conidiogenone B (12), were isolated from the endophytic Penicillium sp. HJT-A-6. The chemical structures of all the compounds were elucidated by comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS. The absolute configuration at C-13 of peniquinazolinone A (1) was established by applying the modified Mosher's method. Compounds 2, 3, and 7 exhibited an optimal promoting effect on the seed germination of Rhodiola tibetica at a concentration of 0.01 mg/mL, while the optimal concentration for compounds 4 and 9 to promote Rhodiola tibetica seed germination was 0.001 mg/mL. Compound 12 showed optimal seed-germination-promoting activity at a concentration of 0.1 mg/mL. Compared with the positive drug 6-benzyladenine (6-BA), compounds 2, 3, 4, 7, 9, and 12 could extend the seed germination period of Rhodiola tibetica up to the 11th day.

Exploring the synthetic potential of epoxide ring opening reactions toward the synthesis of alkaloids and terpenoids: a review

Epoxides are oxygen containing heterocycles which are significantly employed as crucial intermediates in various organic transformations. They are considered highly reactive three-membered heterocycles due to ring strain and they undergo epoxide ring opening reactions with diverse range of nucleophiles. Epoxide ring-opening reactions have gained prominence as flexible and effective means to obtain various functionalized molecules. These reactions have garnered substantial attention in organic synthesis, driven by the need to comprehend the synthesis of biologically and structurally important organic compounds. They have also found applications in the synthesis of complex natural products. In this review article, we have summarized the implementation of epoxide ring opening reactions in the synthesis of alkaloids and terpenoids based natural products reported within the last decade (2014-2023).

Endophytic fungi as a potential source of anti-cancer drug

Endophytes are considered one of the major sources of bioactive compounds used in different aspects of health care including cancer treatment. When colonized, they either synthesize these bioactive compounds as a part of their secondary metabolite production or augment the host plant machinery in synthesising such bioactive compounds. Hence, the study of endophytes has drawn the attention of the scientific community in the last few decades. Among the endophytes, endophytic fungi constitute a major portion of endophytic microbiota. This review deals with a plethora of anti-cancer compounds derived from endophytic fungi, highlighting alkaloids, lignans, terpenes, polyketides, polyphenols, quinones, xanthenes, tetralones, peptides, and spirobisnaphthalenes. Further, this review emphasizes modern methodologies, particularly omics-based techniques, asymmetric dihydroxylation, and biotic elicitors, showcasing the dynamic and evolving landscape of research in this field and describing the potential of endophytic fungi as a source of anticancer drugs in the future.

Chemical Constituents and Bioactivities of the Plant-Derived Fungus Aspergillus fumigatus

A new bergamotane sesquiterpenoid, named xylariterpenoid H (1), along with fourteen known compounds (2-15), were isolated from the crude extract of Aspergillus fumigatus, an endophytic fungus isolated from Delphinium grandiflorum L. Their structures were elucidated mainly by extensive analyses of NMR and MS spectroscopic data. In addition, the screening results of antibacterial and cytotoxic activities of compounds 1-15 showed that compound 4 displayed antibacterial activities against Staphylococcus aureus and MRSA (methicillin-resistant S. aureus) with an MIC value of 3.12 µg/mL.

Rhodium-Catalyzed Allylic Addition as an Atom-Efficient Approach in Total Synthesis

ConspectusFinding efficient synthetic methods for the asymmetric synthesis of complex molecules has always been of interest to organic chemists. Creating and controlling the stereochemistry of stereogenic centers bearing branched allylic moieties in organic molecules using a catalytic process is an attractive and successful method for the synthesis of several natural products and medicinally important compounds. Remarkable progress toward their synthesis has been achieved via transition-metal catalysis, especially in the case of allylic substitution and allylic C-H oxidation chemistry. However, for allylic substitution the preinstallation of a leaving group is essential, and for allylic C-H oxidation, stoichiometric amounts of oxidant are required. Besides that, the control of regioselectivity with these methods is often problematic because the linear product can be produced as a major isomer. Our research group has developed a regioselective, enantioselective, and atom economic route toward the more valuable branched product via a Rh-catalyzed coupling of easily accessible alkynes or the double-bond isomeric allenes with pronucleophiles. It was demonstrated that, using this new approach, it is possible to add different pronucleophiles to alkynes or allenes to form branched allylic moieties through C-C and C-heteroatom bond formation. Since new organic reactions offer new opportunities in chemical synthesis and the benchmark for new synthetic methods is their application in target-oriented synthesis, we have demonstrated several successful syntheses of natural products and medicinally relevant targets. For example, in the total syntheses of Quercuslactones, Helicascolides A-C, Epothilone D, Homolargazole, and Thailandepsin B, the Rh-catalyzed hydro-oxycarbonylation of allenes was used as key step via C-O bond formation. Remarkably, the Rh-catalyzed C2-symmetric dimerization strategy was used to synthesize the complex molecules Clavosolide A and Vermiculine, leading to an extreme increase in structural complexity within a single step. For the total syntheses of Centrolobine, Pitavastatin, and Rosuvastatin, C-O bond formation was achieved through the addition of a hydroxy function to the allene moiety. The potential of the addition of nitrogen pronucleophiles to allenes was demonstrated in the total syntheses of Cusparein, Angusterein, Cermicin C, Senepodin G, Homoproline, Pipecolinol, Coniceine, Coniine, Ruxolitinib, Sitagliptin, Abacavir, Glucokinase activators, and Chaetominine. All of these examples testify to the wide applicability of the Rh-catalyzed addition of pronucleophiles to allenes or alkynes in target-oriented synthesis, and in this Account we summarize our contribution.

Using alternative SMILES representations to identify novel functional analogues in chemical similarity vector searches

Chemical similarity searches are a widely used family of in silico methods for identifying pharmaceutical leads. These methods historically relied on structure-based comparisons to compute similarity. Here, we use a chemical language model to create a vector-based chemical search. We extend previous implementations by creating a prompt engineering strategy that utilizes two different chemical string representation algorithms: one for the query and the other for the database. We explore this method by reviewing search results from nine queries with diverse targets. We find that the method identifies molecules with similar patent-derived functionality to the query, as determined by our validated LLM-assisted patent summarization pipeline. Further, many of these functionally similar molecules have different structures and scaffolds from the query, making them unlikely to be found with traditional chemical similarity searches. This method may serve as a new tool for the discovery of novel molecular structural classes that achieve target functionality.

Pyripyropene U, a new alkaloid from the sponge-derived fungus Aspergillus sp. SCSIO41420

One new alkaloid, named pyripyropene U (1), and six known natural products (2-7) were obtained from the marine sponge-derived fungus Aspergillus sp. SCSIO41420. Their structures were determined by detailed nuclear magnetic resonance (NMR) and mass spectroscopic (MS) analyses, while the absolute configurations of the new compound were unambiguously confirmed by theoretical electronic circular dichroism (ECD) calculation. Those natural products were evaluated in the antimicrobial tests against various fungi and bacteria, and 7 possessed obvious inhibitory activity against Staphylococcus aureus ATCC 29213.

Two new Aspera chaetominines A and B, and a new derivative of terrein, isolated from marine sponge associated fungus Aspergillus versicolour SCSIO XWS04 F52

Two new alkaloids, Aspera chaetominines A (1) and B (2), a new derivative (3) of terrein, and together with 11 known compounds (4-14) were isolated from marine sponge Callyspongia sp. -derived fungus Aspergillus versicolour SCSIO XWS04 F52, which was identified on the basis of morphology and ITS sequence analysis. The planar structures of 1-3 were determined by spectroscopic (1H, 13C NMR, HSQC, HMBC, and 1H-1H COSY), and MS analysis. Compounds 1 and 2 showed cytotoxic activity against leukaemia K562 and colon cancer cells SW1116 with IC50 7.5 to 12.5 μM, and also compounds 1 and 2 exhibited significant protection against H1N1 virus-induced cytopathogenicity in MDCK cells with IC50 values of 15.5 and 24.5 μM, respectively.

A new benzophenone derivative from Aspergillus fumigatus WJ-131

A new benzophenone derivative, 8'-hydroxymonomethylsulochrin (1), together with eighteen known compounds (2-19) were produced by the endophytic fungus Aspergillus fumigatus WJ-131, isolated from the stem of Gardenia jasminoides. The structure of 1 was determined by extensive spectroscopic analysis and X-ray crystallography. Under the condition of concentration of 20.0 μM, the splenic lymphocytes proliferation rates of compounds 1 and 7 induced by LPS were 39.4% and 38.1% (LPS, the splenic lymphocytes cell proliferation rates of 21.3%), and the splenic lymphocytes proliferation rate of compounds 7 induced by ConA is 44.6% (ConA, the splenic lymphocytes proliferation rates of 28.9%). Therefore, compounds 1 and 7 promoted the proliferation of ConA/LPS-stimulated splenic lymphocytes at 20.0 μM in vitro. In addition, compound 1 showed weak antibacterial activity against Fusarium oxysporum.

Nickel-Catalyzed Hydroamination and Hydroalkoxylation of Enelactams with Unactivated Amines and Alcohols

Nickel-catalyzed hydroamination and hydroalkoxylation of enelactams with unactivated amines and alcohols are reported. This method showed good functional group tolerance and delivered the corresponding hydrofunctionalized products in good to excellent yields (≤98%). Furthermore, an intramolecular hydroalkoxylation of an enelactam was also realized, giving a cyclization product in a good yield. Mechanistic studies indicated that tBuI acts as a hydride donor and radical precursor, which is crucial for the success of the reaction.

Fungal BGCs for Production of Secondary Metabolites: Main Types, Central Roles in Strain Improvement, and Regulation According to the Piano Principle

Filamentous fungi are one of the most important producers of secondary metabolites. Some of them can have a toxic effect on the human body, leading to diseases. On the other hand, they are widely used as pharmaceutically significant drugs, such as antibiotics, statins, and immunosuppressants. A single fungus species in response to various signals can produce 100 or more secondary metabolites. Such signaling is possible due to the coordinated regulation of several dozen biosynthetic gene clusters (BGCs), which are mosaically localized in different regions of fungal chromosomes. Their regulation includes several levels, from pathway-specific regulators, whose genes are localized inside BGCs, to global regulators of the cell (taking into account changes in pH, carbon consumption, etc.) and global regulators of secondary metabolism (affecting epigenetic changes driven by velvet family proteins, LaeA, etc.). In addition, various low-molecular-weight substances can have a mediating effect on such regulatory processes. This review is devoted to a critical analysis of the available data on the "turning on" and "off" of the biosynthesis of secondary metabolites in response to signals in filamentous fungi. To describe the ongoing processes, the model of "piano regulation" is proposed, whereby pressing a certain key (signal) leads to the extraction of a certain sound from the "musical instrument of the fungus cell", which is expressed in the production of a specific secondary metabolite.

NBS-induced intramolecular annulation reactions for the divergent synthesis of fused- and spirocyclic indolines

An NBS-induced intramolecular annulation of 3-(1H-indol-3-yl)-N-alkoxypropanamide is described. The reactions proceed well and quickly under mild conditions with the help of a base. It was found that C2-substituents on the indole ring in 3-(1H-indol-3-yl)-N-alkoxypropanamide have a great influence upon the reaction. By using C2-methyl- and C2-phenyl-3-(1H-indol-3-yl)-N-alkoxypropanamide as templates, practical protocols for the divergent synthesis of fused- and spirocyclic indoline compounds were studied and established.

Merging Alkene Isomerization Enables Difunctionalization of Cyclic Enamines toward Ring-Fused Aminal Synthesis

Here we report a Pd-catalyzed isomerization of alicyclic allyl amine to achieve the unprecedented α,β-difunctionalization of synthetically inaccessible trisubstituted cyclic enamine. The dual role of in situ formed enamine intermediate allows for the intermolecular formal [4 + 2] reaction with acrylamide or isatoic anhydride to simultaneously construct the C-C bond and C-N bond, thus realizing the expedient construction of [4.3.0]-aminal with excellent diastereoselectivity and high atom economy.

Diastereoselective Access to Triazolo[1,2-a]indolines via a Bio-Inspired Oxidative Cyclization of NH-Indoles

Establishing three-dimensional chemicals by using the C₂-C₃ π bond of indoles has always been a research hotspot in organic synthesis; however, employing the oxidative C₂-C₃ π bond of indoles to generate imine which would lead to the N₁-C₂ π bond cyclization under metal-free conditions is still rare. Here, we report a bio-inspired synthesis of triazolo[1,2-a]indolines by the oxidative cyclization between NH-indoles and azomethine imines with 3,3-dimethyldioxirane as the sole oxidant under metal-free and mild conditions. This finding represents an elegant instance of tri-functionalization of NH-indoles, which provides rapid access to a broad range of triazolo[1,2-a]indolines with tetrahydroisoquinolines in one single step. Up to 86% yield and above 20:1 dr value are observed. The radical mechanism and proton migration process have been speculated.

Anti-inflammatory alkaloids from the cold-seep-derived fungus Talaromyces helicus SCSIO41311

One new natural alkaloid, chaetominine B (1), together with twenty known compounds was isolated from the South China Sea cold-seep-derived fungus Talaromyces helicus SCSIO41311. Their structures were elucidated on the basis of nuclear magnetic resonance spectrum (NMR), mass spectrometry (MS) and ECD calculation, as well as comparing with previous literatures. Among them, twelve compounds showed potent NO inhibitory activities and two of them, azaspirofurans A (13) and fumiquinones B (21), exhibited NO inhibitory effects more than the positive control eicosapentaenoic acid (EPA) with IC₅₀ values of 9.65 and 15.54 μM, respectively. Moreover, compound 13 attenuated LPS-induced imbalance of cytokines release such as TNF-α, IL-1β, IL-4, and IL-10. Additionally, the NMR data and absolute configuration of compound 20 were first reported.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03237-9.

Discovery of Anti-MRSA Secondary Metabolites from a Marine-Derived Fungus Aspergillus fumigatus

Methicillin-resistant Staphylococcus aureus (MRSA), a WHO high-priority pathogen that can cause great harm to living beings, is a primary cause of death from antibiotic-resistant infections. In the present study, six new compounds, including fumindoline A–C (1–3), 12β, 13β-hydroxy-asperfumigatin (4), 2-epi-tryptoquivaline F (17) and penibenzophenone E (37), and thirty-nine known ones were isolated from the marine-derived fungus Aspergillus fumigatus H22. The structures and the absolute configurations of the new compounds were unambiguously assigned by spectroscopic data, mass spectrometry (MS), electronic circular dichroism (ECD) spectroscopic analyses, quantum NMR and ECD calculations, and chemical derivatizations. Bioactivity screening indicated that nearly half of the compounds exhibit antibacterial activity, especially compounds 8 and 11, and 33–38 showed excellent antimicrobial activities against MRSA, with minimum inhibitory concentration (MIC) values ranging from 1.25 to 2.5 μM. In addition, compound 8 showed moderate inhibitory activity against Mycobacterium bovis (MIC: 25 μM), compound 10 showed moderate inhibitory activity against Candida albicans (MIC: 50 μM), and compound 13 showed strong inhibitory activity against the hatching of a Caenorhabditis elegans egg (IC₅₀: 2.5 μM).

Bioactive Compounds from Terrestrial and Marine-Derived Fungi of the Genus Neosartorya †

Fungi comprise the second most species-rich organism group after that of insects. Recent estimates hypothesized that the currently reported fungal species range from 3.5 to 5.1 million types worldwide. Fungi can grow in a wide range of habitats, from the desert to the depths of the sea. Most develop in terrestrial environments, but several species live only in aquatic habitats, and some live in symbiotic relationships with plants, animals, or other fungi. Fungi have been proved to be a rich source of biologically active natural products, some of which are clinically important drugs such as the β-lactam antibiotics, penicillin and cephalosporin, the immunosuppressant, cyclosporine, and the cholesterol-lowering drugs, compactin and lovastatin. Given the estimates of fungal biodiversity, it is easy to perceive that only a small fraction of fungi worldwide have ever been investigated regarding the production of biologically valuable compounds. Traditionally, fungi are classified primarily based on the structures associated with sexual reproduction. Thus, the genus Neosartorya (Family Trichocomaceae) is the telemorphic (sexual state) of the Aspergillus section known as Fumigati, which produces both a sexual state with ascospores and an asexual state with conidiospores, while the Aspergillus species produces only conidiospores. However, according to the Melbourne Code of nomenclature, only the genus name Aspergillus is to be used for both sexual and asexual states. Consequently, the genus name Neosartorya was no longer to be used after 1 January 2013. Nevertheless, the genus name Neosartorya is still used for the fungi that had already been taxonomically classified before the new rule was in force. Another aspect is that despite the small number of species (23 species) in the genus Neosartorya, and although less than half of them have been investigated chemically, the chemical diversity of this genus is impressive. Many chemical classes of compounds, some of which have unique scaffolds, such as indole alkaloids, peptides, meroterpenes, and polyketides, have been reported from its terrestrial, marine-derived, and endophytic species. Though the biological and pharmacological activities of a small fraction of the isolated metabolites have been investigated due to the available assay systems, they exhibited relevant biological and pharmacological activities, such as anticancer, antibacterial, antiplasmodial, lipid-lowering, and enzyme-inhibitory activities.

Identification of Antibacterial Metabolites from Endophytic Fungus Aspergillus fumigatus, Isolated from Albizia lucidior Leaves (Fabaceae), Utilizing Metabolomic and Molecular Docking Techniques

The rapid spread of bacterial infection caused by Staphylococcus aureus has become a problem to public health despite the presence of past trials devoted to controlling the infection. Thus, the current study aimed to explore the chemical composition of the extract of endophytic fungus Aspergillus fumigatus, isolated from Albizia lucidior leaves, and investigate the antimicrobial activity of isolated metabolites and their probable mode of actions. The chemical investigation of the fungal extract via UPLC/MS/MS led to the identification of at least forty-two metabolites, as well as the isolation and complete characterization of eight reported metabolites. The antibacterial activities of isolated metabolites were assessed against S. aureus using agar disc diffusion and microplate dilution methods. Compounds ergosterol, helvolic acid and monomethyl sulochrin-4-sulphate showed minimal inhibitory concentration (MIC) values of 15.63, 1.95 and 3.90 µg/mL, respectively, compared to ciprofloxacin. We also report the inhibitory activity of the fungal extract on DNA gyrase and topoisomerase IV, which led us to perform molecular docking using the three most active compounds isolated from the extract against both enzymes. These active compounds had the required structural features for S. aureus DNA gyrase and topoisomerase IV inhibition, evidenced via molecular docking.

Alkaloids and Colon Cancer: Molecular Mechanisms and Therapeutic Implications for Cell Cycle Arrest

Cancer is the second most fatal disease worldwide, with colon cancer being the third most prevalent and fatal form of cancer in several Western countries. The risk of acquisition of resistance to chemotherapy remains a significant hurdle in the management of various types of cancer, especially colon cancer. Therefore, it is essential to develop alternative treatment modalities. Naturally occurring alkaloids have been shown to regulate various mechanistic pathways linked to cell proliferation, cell cycle, and metastasis. This review aims to shed light on the potential of alkaloids as anti-colon-cancer chemotherapy agents that can modulate or arrest the cell cycle. Preclinical investigated alkaloids have shown anti-colon cancer activities and inhibition of cancer cell proliferation via cell cycle arrest at different stages, suggesting that alkaloids may have the potential to act as anticancer molecules.

Putative Anticancer Compounds from Plant-Derived Endophytic Fungi: A Review

Endophytic fungi are microorganisms that exist almost ubiquitously inside the various tissues of living plants where they act as an important reservoir of diverse bioactive compounds. Recently, endophytic fungi have drawn tremendous attention from researchers; their isolation, culture, purification, and characterization have revealed the presence of around 200 important and diverse compounds including anticancer agents, antibiotics, antifungals, antivirals, immunosuppressants, and antimycotics. Many of these anticancer compounds, such as paclitaxel, camptothecin, vinblastine, vincristine, podophyllotoxin, and their derivatives, are currently being used clinically for the treatment of various cancers (e.g., ovarian, breast, prostate, lung cancers, and leukemias). By increasing the yield of specific compounds with genetic engineering and other biotechnologies, endophytic fungi could be a promising, prolific source of anticancer drugs. In the future, compounds derived from endophytic fungi could increase treatment availability and cost effectiveness. This comprehensive review includes the putative anticancer compounds from plant-derived endophytic fungi discovered from 1990 to 2020 with their source endophytic fungi and host plants as well as their antitumor activity against various cell lines.

Antitubercular metabolites from the marine-derived fungus strain Aspergillus fumigatus MF029

During the systematic screening of bioactive compounds from our marine natural product library, crude extract of the marine-derived fungus strain Aspergillus fumigatus MF029 exhibited moderate bioactivities against Bacillus subtilis, Staphylococcus aureus, methicillin-resistant S. aureus, and Mycobacterium bovis bacillus Calmette-Guérin (BCG). Further chemical investigation resulted in the identification of two new compounds, chaetominine A (1) and sphingofungin I (2), together with four known compounds, emodin (3), chaetominine (4), sphingofungin D (5) and trypacidin (6). Trypacidin displayed potential antitubercular activity with MIC value of 1.25 μg/mL.

Electrophilically Activated Nitroalkanes in Synthesis of 3,4-Dihydroquinozalines

Nitroalkanes activated with polyphosphoric acid serve as efficient electrophiles in reactions with various nucleophilic amines. Strategically placed second functionality allows for the design of annulation reactions enabling preparation of various heterocycles. This strategy was employed to develop an innovative synthetic approach towards 3,4-dihydroquinazolines from readily available 2-(aminomethyl)anilines.

Alkaloids from endophytic fungus Aspergillus fumigatus HQD24 isolated from the Chinese mangrove plant Rhizophora mucronata

Chemical investigation of endophytic fungus Aspergillus fumigatus HQD24, isolated from the flower of Rhizophora mucronata led to the isolation of eight alkaloids, including pyripyropene A (1), 1,11-dideacetyl-pyripyropene A (2), pyripyropene E (3), chaetominine (4), tryptoquivaline J (5), fumitremorgin C (6), 1-acetyl-β-carboline (7), and nicotinic acid (8). Their structures were unambiguously elucidated on the basis of extensive spectroscopic data and comparison with the data of literature. Compound 2 was known as a synthetic product and isolated as a natural product for the first time. The immunosuppressive and cytotoxic activities of all isolated compounds were evaluated.

Three new unsaturated fatty acids from marine-derived fungus Aspergillus sp. SCAU150

Four unsaturated fatty acid derivatives including three new pantheric acids (1-3), together with three known polyketides (5-7), were isolated from a culture broth of the marine-derived fungus Aspergillus sp. SCAU150. Their complete structures were determined by NMR and HRESIMS data analyses. The antifungal activity of the isolated compounds above was evaluated and 2 was found to show moderated activity toward the phytopathogenic fungus Fusarium solani bio-80814 with an inhibition zone diameter of 6 mm under 5 µg/disc.

Cascade C–N bond cleavage of amides/intramolecular amination reactions: an atom economical way to α-cabolin-4-ones

A novel one-pot procedure for the synthesis of 2,3-disubstituted α-carbolin-4-ones through successive C–N bond cleavage and intramolecular amination reactions involving a 1,2-acyl migration has been developed.

Antibiotics from Extremophilic Micromycetes

Extremophilic microorganisms, which are capable of functioning normally at extremely high or low temperatures, pressure, and in other environmental conditions, have been in the focus of microbiologists' attention for several decades due to the biotechnological potential of enzymes inherent in extremophiles. These enzymes (also called extremozymes) are used in the production of food and detergents and other industries. At the same time, the inhabitants of extreme econiches remained almost unexplored for a long time in terms of the chemistry of natural compounds. In recent years, the emergence of new antibiotic-resistant strains of pathogens, which affect humans and animals has become a global problem. The problem is compounded by a strong slowdown in the development of new antibiotics. In search of new active substances and scaffolds for medical chemistry, researchers turn to unexplored natural sources. In recent years, there has been a sharp increase in the number of studies on secondary metabolites produced by extremophiles. From the discovery of penicillin to the present day, micromycetes, along with actinobacteria, are one of the most productive sources of antibiotic compounds for medicine and agriculture. Many authors consider extremophilic micromycetes as a promising source of small molecules with an unusual mechanism of action or significant structural novelty. This review summarizes the latest (for 2018-2019) experimental data on antibiotic compounds, which are produced by extremophilic micromycetes with various types of adaptation. Active metabolites are classified by the type of structure and biosynthetic origin. The data on the biological activity of the isolated metabolites are summarized.

4-(3H)-quinazolinones N-3 substituted with a five membered heterocycle: A promising scaffold towards bioactive molecules

The quinazolinone nucleus represents, among the class of fused heterocycles, a very important scaffold to obtain molecules with biological activities. A review of literature revealed how such kind of fused heterocycles, coming from natural or synthetic source, are associated with a wide range of biological activities. This review is mainly directed towards the 4-(3H)-quinazolinones N-3 substituted with a five membered heterocycle in which all the possible combinations of nitrogen, sulfur and oxygen atoms are present.

Genome-Inspired Chemical Exploration of Marine Fungus Aspergillus fumigatus MF071

The marine-derived fungus Aspergillus fumigatus MF071, isolated from sediment collected from the Bohai Sea, China, yielded two new compounds 19S,20-epoxy-18-oxotryprostatin A (1) and 20-hydroxy-18-oxotryprostatin A (2), in addition to 28 known compounds (3-30). The chemical structures were established on the basis of 1D, 2D NMR and HRESIMS spectroscopic data. This is the first report on NMR data of monomethylsulochrin-4-sulphate (4) and pseurotin H (10) as naturally occurring compounds. Compounds 15, 16, 20, 23, and 30 displayed weak antibacterial activity (minimum inhibitory concentration: 100 μg/mL). Compounds 18 and 19 exhibited strong activity against S. aureus (minimum inhibitory concentration: 6.25 and 3.13 μg/mL, respectively) and E. coli (minimum inhibitory concentration: 6.25 and 3.13 μg/mL, respectively). A genomic data analysis revealed the putative biosynthetic gene clusters ftm for fumitremorgins, pso for pseurotins, fga for fumigaclavines, and hel for helvolinic acid. These putative biosynthetic gene clusters fundamentally underpinned the enzymatic and mechanistic function study for the biosynthesis of these compounds. The current study reported two new compounds and biosynthetic gene clusters of fumitremorgins, pseurotins, fumigaclavines and helvolinic acid from Aspergillus fumigatus MF071.

Base-promoted Lewis acid catalyzed synthesis of quinazoline derivatives

A one-pot protocol has been developed for the synthesis of quinazolinones from amide-oxazolines with TsCl via a cyclic 1,3-azaoxonium intermediate and 6π electron cyclization in the presence of a Lewis acid and base. The process is operationally simple and has a broad substrate scope. This method provides a unique strategy for the construction of quinazolinones.

Visible-light-induced selectivity controllable synthesis of diamine or imidazoline derivatives by multicomponent decarboxylative radical coupling reactions

A visible-light-induced and photoredox-catalyzed three-component selectivity controllable synthesis of vicinal diamines and imidazoles from readily available starting materials under mild reaction conditions has been realized.

Cp*Co(III)-Catalyzed Regioselective C2 Amidation of Indoles Using Acyl Azides

A cobalt-catalyzed C2-selective amidation of indoles using acyl azides has been accomplished. Isotope experiments suggest that C-H activation is reversible. The use of sustainable Co catalysis, functional group diversity, substrate scope, and regioselectivity are the important practical features.

Griseofulvin Derivatives: Synthesis, Molecular Docking and Biological Evaluation

Background:

Griseofulvin - a mold metabolite produced by Penisilium griseofulvum is known as an antifungal drug.

Objective:

Thus, the goal of this paper is the design and synthesis of new griseofulvin derivatives and evaluation of their antifungal activity.

Methods:

Forty-two new compounds were synthesized using classical methods of organic synthesis and evaluated for their antimicrobial activity by microdilution method.

Results:

All forty-two new compounds exhibited very good activity against eight tested micromycetes with MIC ranging from 0.0075-0.055 mg/ml and MFC from 0.02-024 mg/ml. All compounds exhibited better activity than reference drugs ketoconazole (7-42 times) and bifonazole (3-16 fold). The most promising was compound 15. The most sensitive fungal was found to be T. viride, while the most resistant, as was expected, was A. fumigatus. It should be mentioned that most of compounds exhibited better activity than griseofulvin.

:

The molecular docking studies revealed that the most active compound have the same hydrophobic and H-bonding interactions with Thr276 residue observed for griseofulvin forming 3 hydrogen bonds while griseofulvin only one. In general, the molecular docking results coincide with experimental.

Conclusion:

Forty-two giseofulvin derivatives were designed, synthesized and evaluated for antimicrobial activity. These derivatives revealed good antifungal activity, better than reference drugs ketoconazole, bifonazole, and griseofulvin as well.

Biomimetic Enantioselective Total Synthesis of (-)-Robustanoids A and B and Analogues

We report a step-economical, enantioselective total synthesis of (-)-robustanoid B and (-)-robustanoid A and four novel natural product-like compounds. Our strategy relied on our biosynthetic hypothesis and on a novel complexity generation methodology, namely, the one-pot hydroxylative double cyclization reaction. The latter consists of a modified 3,3-dimethyldioxirane-triggered epoxidation-epoxide-ring-opening cyclization reaction cascade and Trost's regioselectivity umpolung methodology ("anti-Michael addition").

New α-pyrones from an endophytic fungus, Hypoxylon investiens J2

Four new α-pyrones, hypotiens A–D (1–4), were isolated from a fungal endophyte, Hypoxylon investiens J2, harbored in the medicinal plant Blumea balsamifera. Their structures were determined through detailed HRMS and NMR spectroscopic data. Compounds 1–4 are new α-pyrone derivatives containing an unusual dimethyl substitution in the highly unsaturated side chain. Their plausible biosynthetic pathway was discussed. Biological assay indicated that compounds 1–4 showed no antimicrobial, quorum sensing inhibitory, and cytotoxic activities. The specific side chain in α-pyrone derivatives 1–4 might be responsible for the weak pharmacological activities.

Four new α-pyrones, hypotiens A–D (1–4), were isolated from a fungal endophyte, Hypoxylon investiens J2, harbored in the medicinal plant Blumea balsamifera.