Armochaetoglasins A-I: Cytochalasan alkaloids from fermentation broth of Chaetomium globosum TW1-1 by feeding L-tyrosine

Marcytoglobosins A and B, Cytochalasans From a Marine Sponge Associated Chaetomium globosum 162105 Fungus

Two new cytochalasans, marcytoglobosins A (1) and B (2) were isolated from the marine sponge associated fungus Chaetomium globosum 162105, along with six known compounds (3-8). The complete structures of two new compounds were determined based on 1D/2D NMR and HR-MS spectroscopic analyses coupled with ECD calculations. All eight isolates were evaluated for their antibacterial activity. Among them, compounds 3-8 displayed antibacterial effects against Staphylococcus epidermidis, Bacillus thuringiensis, Pseudomonas syringae pv. Actinidiae, Vibrio alginolyticus, and Edwardsiella piscicida with minimum inhibitory concentration (MIC) values ranging from 10 to 25 μg/mL.

Marchaetoglobins A-D: Four Cytochalasans with Proangiogenic Activity from the Marine-Sponge-Associated Fungus Chaetomium globosum 162105

Four new cytochalasans, marchaetoglobins A-D (1-4), along with five known compounds (5-9), were isolated from the marine-sponge-associated fungus Chaetomium globosum 162105. Compounds 1-4 represent examples of 19,20-seco-chaetoglobosins, of which compound 1 is the first furan-containing cytochalasan. Their structures and absolute configurations were elucidated by extensive spectroscopic analyses and electronic circular dichroism calculations. Compounds 5, 8, and 9 displayed weak to moderate antibacterial activities against Bacillus thuringiensis, Edwardsiella piscicida, Vibrio alginolyticus, and Pseudomonas syringae pv. actinidiae with minimum inhibitory concentration values ranging from 5 to 25 μg/mL. In addition, compounds 2, 3, and 5 showed potent in vivo proangiogenic activity in transgenic zebrafish, comparable to the positive control.

Armochaetoglasins L and M, new cytochalasans from an arthropod-derived fungus Chaetomium globosum

Armochaetoglasins L (1) and M (2), two new cytochalasans, were isolated from the EtOAc extract of an arthropod-derived fungus Chaetomium globosum. Armochaetoglasin L (1) is a rare 19,20-seco-chaetoglobosin. Their structures were elucidated by NMR spectroscopy and comparison of their electronic circular dichroism (ECD) data. Compounds 1 and 2 were evaluated for anti-inflammatory activity against the NO production by using LPS-stimulated murine macrophage RAW264.7 cells and antibacterial activity against three drug-resistant microbial pathogens.

Chae-type cytochalasans from coculture of Aspergillus flavipes and Chaetomium globosum

Cocultivation of the high cytochalasan-producing fungi Aspergillus flavipes and Chaetomium globosum resulted in the isolation of 11 undescribed Chae-type cytochalasans. Their structures were determined by spectroscopic data and NMR data calculations. Asperchaetoglobin A (1) was the first Chae-type cytochalasan possessing an unprecedented nitrogen bridge between C-17 and C-20 to generate a surprising 5/6/12/5 multiple ring system; asperchaetoglobins B and C (2 and 3) displayed higher oxidation with an additional epoxide at the thirteen-member ring; asperchaetoglobin D (4) was the second Chae-type cytochalasin featuring a 5/6/12 tricyclic ring system. The cytotoxic activities against five human cancer cell lines and antibacterial activities against Staphylococcus aureus and Colon bacillus of selected compounds were evaluated in vitro.

Chaepseubakerins A-J, ten undescribed cytotoxic [11]-chaetoglobosins from an endophytic fungus Pseudeurotium bakeri

Ten previously unreported [11]-chaetoglobosins, chaepseubakerins A-J (1-10), were characterized from the solid rice-based culture of Pseudeurotium bakeri P1-1-1, an endophyte harbored in the roots of Macrocoma tenue subsp. sullivantii Vitt. (Orthotrichaceae). Their structures were determined by spectroscopic analysis, single-crystal X-ray diffraction (Cu Kα radiation), and chemical methods. Chaepseubakerin A (1) exhibited significant cytotoxic effects against seven human cancer cell lines, A549, A427, HCT116, HT-29, HeLa, HepG2, and MCF-7, with IC50 values of 2.9, 3.0, 4.0, 4.4, 7.1, 6.7, and 8.9 μM, respectively. Mechanistically, 1 induced G2/M cell cycle arrest and apoptosis in A549, Hela, and HCT116 cells in a dose dependent manner.

Caryophyllene Sesquiterpenes from a Chaetomium globosum Endophyte of the Canadian Medicinal Plant Empetrum nigrum

Punctaporonins T (1) and U (2), new caryophyllene sesquiterpenes, were isolated with three known punctaporonins, A (3), B (4), and C (5), from the endophytic fungus Chaetomium globosum (TC2-041). The structures and relative configurations of punctaporonins T and U were elucidated based on a combination of HRESIMS, 1D/2D NMR spectroscopic analysis, and X-ray diffraction analysis, while their absolute configuration is presumed to be consistent with the co-isolated 3-5 on biogenetic arguments. Compound 1 showed weak inhibitory activity against both Mycobacterium tuberculosis and Staphylococcus aureus.

Indoloquinazoline alkaloids with cardiomyocyte protective activity against cold ischemic injury from Aspergillus clavatonanicus

The arthropod-associated fungi have been demonstrated to be a remarkable producer of structurally captivating and bioactive secondary metabolites for drug discovery. In this study, eleven new indoloquinazoline alkaloids, namely aspergilloids A-K (1-11), along with five known congeners (12-16), were obtained from fungus Aspergillus clavatonanicus, which was isolated from the gut of a centipede collected in our Tongji campus. All these compounds were rarely defined by a 6/5/5 indolone ring system in conjugation with a five-membered spiral ring (1-5 and 10-16) or an opening five-membered spiral ring (6-9). Their structures were elucidated by widespread spectroscopic analyses, mainly including HRESIMS and 1D and 2D NMR data, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) data analyses. The cardiomyocyte protective activity assay revealed that compounds 1, 2, 5, 12-14, and 16 ameliorated cold ischemic injury at 48 h post cold ischemia (CI), and compounds 1, 5, and 14 prevented cold ischemia induced Ser9 dephosphorylation of GSK3β at 12 h post CI. Our current study highlights indoloquinazoline alkaloids as the first class of natural cardiomyocyte protective agents against cold ischemic injury, which furnishes promising lead molecules for the development of new cardioprotectants in heart transplantation medicine.

TRAIL-sensitizing Cytochalasins from the Endophytic Fungus Phoma multirostrata

Seven undescribed cytochalasins, multirostratins K - Q (2: -8: ), together with one known analogue, cytochalasin Z3 (1: ), were isolated from the culture of Phoma multirostrata XJ-2-1, an endophytic fungus obtained from the root of Parasenecio albus. Their structures with absolute configurations were determined by 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), electronic circular dichroism (ECD), single-crystal X-ray crystallography, and chemical methods. The structure of ascochalasin was revised from Δ ¹³ to Δ ²¹ by detailed analysis of the NMR data and by comparison with the data for 7: . In a TRAIL (tumor necrosis factor related apoptosis inducing ligand)-resistance-overcoming experiment, co-treatment of 2: or 6: with TRAIL reduced the cell viability of A549 cells by 30.3% and 27.5% at 10 µM, respectively.

Cytochalasan Alkaloids as TRAIL Sensitizers from an Endophytic Fungus Chaetomium sp

Two new cytochalasans with a rare 6/6/5/5/7 pentacyclic ring system, named chaetoconvosins C-D (1: -2: ), together with two known congeners (3: -4: ), were isolated from the fermentation of an endophytic fungus, Chaetomium sp. SG-01, harbored in the fibrous roots of Schisandra glaucescens Diels. Their structures including the absolute configuration were elucidated by extensive spectroscopic (HRESIMS, NMR, and ECD) and X-ray crystallographic analyses. The TRAIL-resistance-overcoming activity of 1: -4: in a TRAIL-resistant HT29 colorectal cancer cell line was evaluated, which revealed that co-treatment of 1: -4: at 50 µM with TRAIL (150 ng/mL) reduced the HT29 cell viability by 19.0%, 24.1%, 17.9%, and 15.5%, respectively, compared to treatment with 1: -4: alone.

Cytochalasans from the endophytic fungus Diaporthe ueckerae associated with the fern Pteris vittata

Six previously undescribed cytochalasans, ueckerchalasins A-E and 4'-hydroxycytochalasin J₃, together with eight known congeners, were isolated from solid cultures of the endophytic fungus Diaporthe ueckerae SC-J0123 which was originally isolated from the leaves of Pteris vittata L. Their structures were elucidated by extensive spectroscopic analysis, single-crystal X-ray diffraction, and theoretical simulations of ECD spectra and ¹³C NMR shifts. Ueckerchalasins A-C have a carbon-carbon bridge between C-14 and C-20, forming a rare 5/6/6/7-fused heterocyclic core. Ueckerchalasins C and D displayed selective activity against human carcinoma HeLa and HepG2 cells. Ueckerchalasins C was also active against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA).

Rubichaetoglobin A, a new cytochalasan alkaloid isolated from the plant endophytic fungus Chaetomium tectifimeti S104

Rubichaetoglobin A (1), a new cytochalasan alkaloid, together with nine closely related known ones (2-10), were isolated from the ethyl acetate extracts of the endophytic fungus Chaetomium tectifimeti S104 harbored in the root of Rubia podantha Diels. Their structures were elucidated based on comprehensive spectroscopic analysis. All isolated compounds were tested for cytotoxic, antibacterial, and nitric oxide inhibitory activities. The results showed that 2, 4, and 5 possessed moderate cytotoxicity against MDA-MB-231 cells with the IC₅₀ values of 19.14, 11.43, and 10.27 μM, respectively.

Cytochalasans and azaphilones: suitable chemotaxonomic markers for the Chaetomium species

The accurate taxonomic concept of the fungal Chaetomium species has been a hard work due to morphological similarity. Chemotaxonomy based on secondary metabolites is a powerful tool for taxonomical purposes, which could be used as an auxiliary reference to solve the problems encountered in the classification of Chaetomium. Among secondary metabolites produced by Chaetomium, cytochalasans and azaphilones exhibited a pattern of distribution and frequency of occurrence that establish them as chemotaxonomic markers for the Chaetomium species. This review attempted to elucidate the composition of the Chaetomium species and its relationship with classical taxonomy by summarizing the pattern of cytochalasans and azaphilones distribution and biosynthesis in the Chaetomium species. KEY POINTS: • Secondary metabolites from the genus Chaetomium are summarized. • Cytochalasans and azaphilones could be characteristic metabolites of the Chaetomium species. • Cytochalasans and azaphilones could be used to analyze for taxonomical purposes.

Secondary Metabolites of the Endophytic Fungus Chaetomium globosum Isolated From Coptis chinensis

A new steroid, chaetglotone (1), together with 3 known compounds (2-4), were isolated from Chaetomium globosum, which is an endophytic fungus isolated from the root of Coptis chinensis Franch . The new compound was characterized by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy and high-resolution electrospray ionization mass spectrometer. The relative configuration and absolute configuration of 1 were further determined via the DP4 + and Early Childhood Development protocols, separately.

Progress in the Chemistry of Cytochalasans

Cytochalasans are a group of fungal-derived natural products characterized by a perhydro-isoindolone core fused with a macrocyclic ring, and they exhibit a high structural diversity and a broad spectrum of bioactivities. Cytochalasans have attracted significant attention from the chemical and pharmacological communities and have been reviewed previously from various perspectives in recent years. However, continued interest in the cytochalasans and the number of laboratory investigations on these compounds are both growing rapidly. This contribution provides a general overview of the isolation, structural determination, biological activities, biosynthesis, and total synthesis of cytochalasans. In total, 477 cytochalasans are covered, including "merocytochalasans" that arise by the dimerization or polymerization of one or more cytochalasan molecules with one or more other natural product units. This contribution provides a comprehensive treatment of the cytochalasans, and it is hoped that it may stimulate further work on these interesting natural products.

Armochaetoglasins J and K: new cytochalasans from Chaetomium globosum

Two novel cytochalasans, armochaetoglasin J (1) and armochaetoglasin K (2), along with 14 known analogues (3-16) were isolated from Chaetomium globosum. Their structures were elucidated by HRESIMS, NMR spectroscopy, single-crystal X-ray crystallography, and ECD spectra. Armochaetoglasins J and K were found to be inactive against the HepG2, HT-29, K562, HL-60, and A549 cancer cell lines.

Cytochalasins from an endophytic fungus Phoma multirostrata XJ-2-1 with cell cycle arrest and TRAIL-resistance-overcoming activities

Nine new (1-9) and four known (10-13) [13]cytochalasins, along with three known 24-oxa[14]cytochalasins (14-16), were isolated from the culture of Phoma multirostrata XJ-2-1, an endophytic fungus obtained from the fibrous root of Parasenecio albus. Their structures were elucidated by interpretation of the nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS). The absolute configurations were assigned by single-crystal X-ray crystallography, modified Mosher's method, and by analysis of their experimental electronic circular dichroism (ECD) spectra. Compound 6 could induce cell cycle arrest at G2-phase in CT26 and A549 cells, and displayed moderate cytotoxicity against CT26 and A549 cell lines with IC₅₀ values of 6.03 and 5.04 μM, respectively. Co-treatment of 7-9, 13 and 16 with tumor necrosis factor related apoptosis inducing ligand (TRAIL) could significantly decrease the cell viability of A549, which revealed that cytochalasins could possibly be a new group of TRAIL sensitizers in lung cancer therapy.

Chemo-profiling of bioactive metabolites from Chaetomium globosum for biocontrol of Sclerotinia rot and plant growth promotion

Chaetomium globosum Kunze ex. Fries has been known to produce diverse bioactive metabolites, attracting researchers to exploit the biocontrol agent for plant disease management. However, distinct research gaps are visible regarding detail characterization of bioactive metabolites. Thus the current study has been planned to characterize volatile and nonvolatile compounds of most potential strain of C. globosum 5157. GC-MS analysis of hexane fraction revealed twenty-six volatile organic compounds, representing 65.5% of total components in which 3-octanone (21.4%) was found to be most abundant. UPLC-QTOF-MS/MS analysis of ethyl acetate and methanolic fractions resulted tentative characterization of fifteen and eleven metabolites, respectively. Among these, nine metabolites were isolated, purified and characterized using ¹H NMR and High resolution mass spectrometric analysis to delineate mass fragmentation pattern for the first time. Antifungal potential of hexane fraction exhibited high inhibitory action against Sclerotium rolfsii (139.2 μg mL^-1) whereas ethyl acetate fraction was highly effective against Sclerotinia sclerotiorum (112.1 μg mL^-1). Comparative assessment of C. globosum 5157 vis a vis Trichoderma harzianum A28 revealed promising effect of C. globosum 5157 with respect to antifungal properties and plant growth promotion of Brassica seedlings.

Generation of indole derivatives by an endophytic fungus Chaetomium sp. through feeding 1,2-dimethylindole

Through feeding 1,2-dimethylindole, two new bisindoles, chaetoindolone E and F (1 and 2) and five known indole derivatives (3-7) were isolated from the cultures of an endophytic fungus Chaetomium sp. The structures of these compounds were elucidated based on HR-MS, NMR and single-crystal X-ray crystallography. Compounds 1 and 2 were undescribed before, compounds 3-7 were first reported from natural sources, and NMR spectrums of compounds 4 and 5 were first reported. The cytotoxity of the bisindole compounds (1-3) was also tested.

Bioactivities and Future Perspectives of Chaetoglobosins

Chaetoglobosins belonging to cytochalasan alkaloids represent a large class of fungal secondary metabolites. To date, around 100 chaetoglobosins and their analogues have been isolated and identified over the years from a variety of fungi, mainly from the fungus Chaetomium globosum. Studies have found that chaetoglobosins possess a broad range of biological activities, including antitumor, antifungal, phytotoxic, fibrinolytic, antibacterial, nematicidal, anti-inflammatory, and anti-HIV activities. This review will comprehensively summarize the biological activities and mechanisms of action of nature-derived chaetoglobosins.

Reisolation and Configurational Reinvestigation of Cottoquinazolines E-G from an Arthropod-Derived Strain of the Fungus Neosartorya fischeri

The reported fumiquinazoline-related alkaloids cottoquinazolines E-G (1-3) were reisolated from solid cultures of the fungus Neosartorya fischeri, which was isolated from the medicinal arthropod Cryptotympana atrata. The unresolved issues regarding the absolute configurations (for cottoquinazolines E and F) prompted a reinvestigation of the configurations for all three compounds, as enabled by extensive spectroscopic methods, comparisons of experimental electronic circular dichroism data, and X-ray crystallography. In addition, cottoquinazoline F (2) showed significant antibacterial activity against ESBL-producing Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecalis with MIC values of 8, 32, 32, and 16 μg/mL, respectively.

Survey of natural products reported by Asian research groups in 2018

The new natural products reported in 2018 in peer-reviewed articles in journals with good reputations were reviewed and analyzed. The advances made by Asian research groups in the field of natural products chemistry in 2018 were summarized. Compounds with unique structural features and/or promising bioactivities originating from Asian natural sources were discussed based on their structural classification.