Rosellichalasins A-H, cytotoxic cytochalasans from the endophytic fungus Rosellinia sp. Glinf021.

Eight new cytochalasans rosellichalasins A-H (1-8), as well as two new shunt metabolites rosellinins A (9) and B (10) before intramolecular Diels-Alder cycloaddition reaction in cytochalasan biosynthesis, along with nine known cytochalsans (11-19) were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata. Their structures were characterized by extensive analysis of 1D and 2D NMR as well as HRESIMS spectra and quantum chemical ECD calculations. The cytotoxic activities of these compounds were evaluated against four human cancer cell lines including HCT116, MDA-MB-231, BGC823, and PANC-1 with IC50 values ranging from 0.5 to 58.2 µM.

Novel 6/7/6 ring system diterpenoids and cytochalasins from the fungus Eutypella scoparia GZU-4-19Y and their anti-inflammatory activity.

Two new compounds eutyditerpenoid A (1) and seco-phenochalasin B (5), together with seven known compounds diaporthein A (2), aspergillon A (3), phenochalasin B (4), cytochalasins Z24 and Z25 (6 and 7), scoparasins A and B (8 and 9) were isolated from marine-derived Eutypella scoparia GZU-4-19Y. Among them, eutyditerpenoid A (1) with a rare 6/7/6 ring system possesing an anhydride moiety was the first example in the pimarane-type diterpenoids. Their structures were determined based on spectroscopic methods and the electronic circular dichroism (ECD) calculations. In the bioassays, all of the isolates were evaluated for their inhibitory activity against NO production induced by lipopolysaccharide in RAW 264.7 cells. Compounds 3 and 7 showed potent NO inhibition activity with IC50 values of 2.1 and 17.1 µM respectively, and the former also significantly suppressed the protein expression of iNOS and COX-2 at the concentration of 2.5 µM.

Specialized metabolites of the fungal genus Phomopsis: Structures, bioactivities and biosynthesis.

Fungi are important resources of novel bioactive compounds which have a high potential to be drug leads or candidates for further pharmacological applications. Phomopsis, a genus widely distributed in the environment, can produce various types of compounds including polyketides, alkaloids, terpenoids, cytochalasins, steroids and flavonoids. The metabolites of Phomopsis sp. showed diverse bioactivities such as antibacterial, anti-inflammatory, antimalarial, and so on, many of which may influence the physiological behaviour of the host plants. In this review, we focus on the chemical structures and biological activities of 183 specialized metabolites isolated from Phomopsis sp. in the decade (2013-2022). Moreover, the biosynthetic pathways of some typical components are summarized.

Unreported cytochalasins from an acid-mediated transformation of cytochalasin J isolated from Diaporthe cf. ueckeri.

Chemical investigation of an endophytic fungus herein identified as Diaporthe cf. ueckeri yielded four known compounds, named cytochalasins H and J and dicerandrols A and B. Reports of acid sensitivity within the cytochalasan family inspired an attempt of acid-mediated conversion of cytochalasins H and J, resulting in the acquisition of five polycyclic cytochalasins featuring 5/6/5/8-fused tetracyclic and 5/6/6/7/5-fused pentacyclic skeletons. Two of the obtained polycyclic cytochalasins constituted unprecedented analogues, for which the trivial names cytochalasins J4 and J5 were proposed, whereas the others were identified as the known phomopchalasin A, phomopchalasin D and 21-acetoxycytochalasin J3. The structures of the compounds were determined by extensive spectral analysis, namely HR-ESIMS, ESIMS and 1D/2D NMR. The stereochemistry of cytochalasins J4 and J5 was proposed using their ROESY data, biosynthetic and mechanistic considerations and by comparison of their ECD spectra with those of related congeners. All compounds except for cytochalasins H and J were tested for antimicrobial and cytotoxic activity. Cytochalasins J4 and J5 showed neither antimicrobial nor cytotoxic activity in the tested concentrations, with only weak antiproliferative activity observable against KB3.1 cells. The actin disruptive properties of all cytochalasins obtained in this study and of the previously reported cytochalasins RKS-1778 and phomopchalasin N were examined, and monitored by fluorescence microscopy using human osteo-sarcoma (U2-OS) cells. Compared to their precursor molecules (cytochalasins H and J), phomopchalasins A and D, 21-acetoxycytochalasin J3, cytochalasins J4 and J5 revealed a strongly reduced activity on the F-actin network, highlighting that the macrocyclic ring is crucial for bioactivity.

Rare cytochalasans isolated from the mangrove endophytic fungus Xylaria arbuscula.

Four new cytochalasans, arbuschalasins A-D (1-4), along with thirteen known analogues (5-17), were isolated from the solid rice medium of endophytic fungus Xylaria arbuscula. Arbuschalasins A-B feature a rare 5/6/6/6 fused ring system while arbuschalasin D was characterized as the first example of natural cytochalasans that possesses a 5/5/11 fused scaffold. The structures of 1-4 were assigned by spectroscopic data, with their absolute structures being determined by electronic circular dichroism (ECD) calculations. All of the isolates were evaluated against the human colorectal adenocarcinoma cell lines (HCT15). Compounds 6 and 7 showed significant inhibitory effects (IC50 values were 13.5 and 13.4 µM, respectively), being more active than those of the positive control, fluorouracil (103.1 µM).

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.

New Cytotoxic Cytochalasans from a Plant-Associated Fungus Chaetomium globosum kz-19.

Four new cytochalasans, phychaetoglobins A-D (1-4), together with twelve known cytochalasans (5-16), were isolated from a mangrove-associated fungus Chaetomium globosum kz-19. The new structures were elucidated on the basis of extensive 1D and 2D NMR, HR ESIMS spectroscopic analyses, and electronic circular dichroism (ECD) calculations. The absolute configuration of 2 was established by application of Mosher's method. Compounds 4-8 exhibited moderate cytotoxicities against A549 and HeLa cell lines with the IC50 values less than 20 µM.

Cytochalasans from endophytic fungus Diaporthe sp. SC-J0138.

Five new cytochalasans, diaporthichalasins D-H (1-5), along with five known cytochalasans (6-10) were isolated from solid cultures of the endophytic fungus Diaporthe sp. SC-J0138 isolated from the leaves of Cyclosorus parasiticus. Their structures were elucidated by analysis of spectroscopic data and theoretical calculations of electronic circular dichroism spectra. Compounds 1 and 5 showed noticeable cytotoxicity against human carcinoma A549, HeLa, and HepG2 cells. The structure-activity relationships in cytotoxicity were discussed for this group of compounds.

Flavipesines A and B and Asperchalasines E-H: Cytochalasans and Merocytochalasans from Aspergillus flavipes.

Flavipesines A and B (1 and 2) and asperchalasines E-H (3-6), two cytochalasans with an unusual ring system and four merocytochalasans possessing a 5/6/11/5/5/6 ring system, were isolated from Aspergillus flavipes, along with three related compounds (7-9). Their structures, including absolute configurations, were determined on the basis of data from HRESIMS, NMR, ECD, molecular modeling, and single-crystal X-ray diffraction. Flavipesines A and B (1 and 2) represent the first examples of cytochalasans possessing a 5/6/7/6 ring system with a C-18-O-C-21 bridge. Compounds 3, 7, and 9 show moderate inhibitory activities against isocitrate dehydrogenase 1 (IDH1). This is the first report on the IDH1 inhibitory activities of cytochalasans.

Cytotoxic cytochalasans from fungus Xylaria longipes.

Five new cytochalasans (1-5) were isolated from the rice fermentation of fungus Xylaria longipes, along with seven known compounds cytochalasin P (6), cytochalasin D (7), zygosporin D (8), 7-O-acetylcytochalasin D (9), cytochalasin C (10), 6,7-dihydro-7-oxo-cytochalasin C (11), and 6,7-dihydro-7-oxo-deacetylcytochalasin C (12). Their structures and absolute configurations were determined by extensive experimental spectroscopic methods as well as ECD calculation and GIAO 13C NMR calculation. The cytotoxicity of obtained compounds (1-12) was evaluated against human cancer cell lines HL-60, A549, SMMC-7721, MCF-7, and SW480. Compounds 6-8, 11, and 12 showed cytotoxicity with IC50 value ranging from 4.17-37.18 µM.

Cytotoxic 19,20-epoxycytochalasans from endophytic fungus Xylaria cf. curta.

Nine new 19,20-epoxycytochalasans (1-9) were isolated from the rice fermentation extracts of endophytic fungus Xylaria cf. curta, along with four known compounds 19,20-epoxycytochalasin C (10), 18-desoxy-19,20-epoxycytochalasin C (11), 19,20-epoxycytochalasin D (12) and 5,6-dihydro-7-oxo-19,20-epoxycytochalasin C (13). Their structures and absolute configurations were determined by 1D and 2D NMR, HRESIMS, X-ray diffraction and ECD calculation. The cytotoxicity of obtained compounds (1-13) was evaluated against human cancer cell lines HL-60, A549, SMMC-7721, MCF-7, and SW480. Remarkably, compound 10 showed significant specific cytotoxicity against HL-60 cell lines with IC50 value of 1.11 µM.

Cytochalasins and polyketides from the fungus Diaporthe sp. GZU-1021 and their anti-inflammatory activity.

Four new compounds: diaporthichalasins A-C (1-3) and biatriosporin N (7), along with six known compounds (4-6 and 8-10) were separated from the culture of the fungus Diaporthe sp. GZU-1021. The absolute configurations of 1-3 were determined by quantum chemical calculations, X-ray diffraction, and spectroscopic analysis. The structure of 4 was analyzed by X-ray crystallography analysis for the first time. All of the isolates were evaluated on the production of nitric oxide in lipopolysaccharide-induced microglial cells (RAW 264.7 cells). Compounds 5-10 exhibited significant inhibitory effects against nitric oxide production with IC50 values from 1.94 to 16.5 µM than positive control (indomethacin, IC50 = 29.7 µM). This is the first time tetrahydroxanthone dimer (10), as a novel carbon skeleton possessing NO inhibitory activity, was reported.

Cytotoxic seco-cytochalasins from an endophytic Aspergillus sp. harbored in Pinellia ternata tubers.

Six new seco-cytochalasins A-F (1-6), two new asperlactones G-H (7-8) along with three known cytochalasins (9-11) were isolated from the solid cultures of an endophytic fungus Aspergillus sp. Their structures were elucidated by comprehensive spectral analysis, and their absolute configurations were determined through Mo2(OCOCH3)4-induced electronic circular dichroism (ECD) spectra and Rh2(OCOCF3)4-induced ECD experiment. Compounds 5 and 6 were rare seco-cytochalasins possessing an α, ß-unsaturated furanone structure in their side-chains. These isolates exhibited cytotoxicity against human lung cancer A-549 cell line with IC50 values ranging from 7.8 to 70.2 µM. At the concentration of 16 µM, compound 4 also exerted a 3-fold enhancement of doxorubicin susceptibility on doxorubicin-resistant human breast cancer (MCF-7/DOX) cell line.

Diagnostic fragmentation filtering for the discovery of new chaetoglobosins and cytochalasins.

RATIONALE: Microbial natural products are often biosynthesized as classes of structurally related compounds that have similar tandem mass spectrometry (MS/MS) fragmentation patterns. Mining MS/MS datasets for precursor ions that share diagnostic or common features enables entire chemical classes to be identified, including novel derivatives that have previously been unreported. Analytical data analysis tools that can facilitate a class-targeted approach to rapidly dereplicate known compounds and identify structural variants within complex matrices would be useful for the discovery of new natural products. METHODS: A diagnostic fragmentation filtering (DFF) module was developed for MZmine to enable the efficient screening of MS/MS datasets for class-specific product ions(s) and/or neutral loss(es). This approach was applied to series of the structurally related chaetoglobosin and cytochalasin classes of compounds. These were identified from the culture filtrates of three fungal genera: Chaetomium globosum, a putative new species of Penicillium (called here P. cf. discolor: closely related to P. discolor), and Xylaria sp. Extracts were subjected to LC/MS/MS analysis under positive electrospray ionization and operating in a data-dependent acquisition mode, performed using a Thermo Q-Exactive mass spectrometer. All MS/MS datasets were processed using the DFF module and screened for diagnostic product ions at m/z 130.0648 and 185.0704 for chaetoglobosins, and m/z 120.0808 and 146.0598 for cytochalasins. RESULTS: Extracts of C. globosum and P. cf. discolor strains revealed different mixtures of chaetoglobosins, whereas the Xylaria sp. produced only cytochalasins; none of the strains studied produced both classes of compounds. The dominant chaetoglobosins produced by both C. globosum and P. cf. discolor were chaetoglobosins A, C, and F. Tetrahydrochaetoglobosin A was identified from P. cf. discolor extracts and is reported here for the first time as a natural product. The major cytochalasins produced by the Xylaria sp. were cytochalasin D and epoxy cytochalasin D. A larger unknown "cytochalasin-like" molecule with the molecular formula C38 H47 NO10 was detected from Xylaria sp. culture filtrate extracts and is a current target for isolation and structural characterization. CONCLUSIONS: DFF is an effective LC/MS data analysis approach for rapidly identifying entire classes of compounds from complex mixtures. DFF has proved useful in the identification of new natural products and allowing for their partial characterization without the need for isolation.

Antifungal activities of cytochalasins produced by Diaporthe miriciae, an endophytic fungus associated with tropical medicinal plants.

In the present study, we evaluated the antifungal potential of cytochalasins produced by Diaporthe taxa against phytopathogenic fungi. Using molecular methods, seven endophytic fungal strains from the medicinal plants Copaifera pubiflora and Melocactus ernestii were identified as Diaporthe miriciae, while two isolates were identified to the genus level (Diaporthe sp.). All crude extracts of Diaporthe species produced via solid-state fermentation were evaluated by 1H NMR analyses. Crude extracts of the isolates D. miriciae UFMGCB 6350, 7719, 7646, 7653, 7701, 7772, and 7770 and Diaporthe sp. UFMGCB 7696 and 7720 were demonstrated to produce highly functionalized compounds. The extracts of D. miriciae UFMGCB 7719 and 6350 were selected as representative Diaporthe samples and subjected to bioassay-directed fractionation to isolate cytochalasins H and J. Cytochalasins H and J were evaluated for activities against the fungal plant pathogens Colletotrichum fragariae, Colletotrichum gloeosporioides, Colletotrichum acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and Phomopsis viticola using microdilution broth assays. Cytochalasins H and J exhibited the most potent activities against the Phomopsis species tested. Our results showed that Diaporthe species were potential producers of different cytochalasins, which exhibit potential for controlling fungal diseases in planta and (or) maintaining antagonism.

New cytochalasin from Rosellinia sanctae-cruciana, an endophytic fungus of Albizia lebbeck.

AIM: To explore the potential of Rosellinia sanctae-cruciana an endophytic fungus associated with Albizia lebbeck for pharmaceutically important cytotoxic compounds. METHODS AND RESULTS: One novel cytochalasin, named jammosporin A (1) and four known analogues (2-5) were isolated from the culture of the endophytic fungus R. sanctae-cruciana, harboured from the leaves of the medicinal plant A. lebbeck. Their structures were elucidated by extensive spectroscopic analyses including one-dimensional and two-dimensional nuclear magnetic resonance data along with MS data and by comparison with literature reports. In preliminary screening the ethyl acetate extract of the fungal culture was tested for cytotoxic activity against a panel of four cancer cell lines (MOLT-4, A549, MIA PaCa-2 and MDA-MB-231), and found to be active against MOLT-4 with an IC50 value of 10 µg ml-1 . Owing to the remarkable cytotoxic activity of the extract the isolated compounds (1-5) were evaluated for their cytototoxicity against the MOLT-4 cell line by MTT assay. Interestingly, compounds 1-2, 4 and 5 showed considerable cytotoxic potential against the human leukaemia cancer cell line (MOLT-4) with IC50 values of 20·0, 10·0, 8·0 and 6·0 µmol l-1 , respectively, while compound 3 showed an IC50 value of 25 µmol l-1 . This is the first report of the existence of this class of secondary metabolites in R. sanctae-cruciana fungus. CONCLUSION: This study discovered a novel compound, named jammosporin A, isolated for the first time from R. sanctae-cruciana, an endophytic fungus of A. lebbeck with anticancer activity against the MOLT-4 cell line. SIGNIFICANCE AND IMPACT OF THE STUDY: Rosellinia sanctae-cruciana represents an interesting source of a new compound with bioactive potential as a therapeutic agent against a human leukaemia cancer cell line (MOLT-4).

Cytochalasin E in the lichen Pleurosticta acetabulum. Anti-proliferative activity against human HT-29 colorectal cancer cells and quantitative variability.

A biological screening of sixteen lichen extracts on human HT-29 colorectal cancer cells, led to the selection of Pleurosticta acetabulum, a lichen widely present in tree barks in Europe. Bioguided purification of the acetonic extract resulted in the isolation of cytochalasin E, a common fungal metabolite. This compound is responsible for the anti-proliferative activity of the extract. Its presence in lichens is reported here for the first time. LC-MS quantitation of cytochalasin E in different samples of P. acetabulum demonstrated quantitative variations of cytochalasin E production in the lichen and especially high concentrations in apothecia.

Antibacterial and cytotoxic cytochalasins from the endophytic fungus Phomopsis sp. harbored in Garcinia kola (Heckel) nut.

BACKGROUND: The continuous emergence of multidrug-resistant (MDR) bacteria drastically reduced the efficacy of our antibiotic armory and consequently, increased the frequency of therapeutic failure. The search for bioactive constituents from endophytic fungi against MDR bacteria became a necessity for alternative and promising strategies, and for the development of novel therapeutic solutions. We report here the isolation and structure elucidation of antibacterial and cytotoxic compounds from Phomopsis sp., an endophytic fungus associated with Garcinia kola nuts. METHODS: The fungus Phomopsis sp. was isolated from the nut of Garcinia kola. The crude extract was prepared from mycelium of Phomopsis sp. by maceration in ethyl acetate and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The isolated compounds were evaluated for their antibacterial and anticancer properties by broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide methods respectively. The samples were also tested spectrophotometrically for their hemolytic properties against human red blood cells. RESULTS: The fractionation of the crude extract afforded three known cytochalasins including 18-metoxycytochalasin J (1), cytochalasins H (2) and J (3) together with alternariol (4). The cytochalasin compounds showed different degrees of antibacterial activities against the tested bacterial pathogens. Shigella flexneri was the most sensitive microorganism while Vibrio cholerae SG24 and Vibrio cholerae PC2 were the most resistant. Ampicillin did not show any antibacterial activity against Vibrio cholerae NB2, Vibrio cholerae PC2 and Shigella flexneri at concentrations up to 512 µg/mL, but interestingly, these multi-drug resistant bacterial strains were sensitive to the cytochalasin metabolites. These compounds also showed significant cytotoxic properties against human cancer cells (LC50 = 3.66-35.69 µg/mL) with low toxicity to normal non-cancer cells. CONCLUSION: The three cytochalasin compounds isolated from the Phomopsis sp. crude extract could be a clinically useful alternative for the treatment of cervical cancer and severe infections caused by MDR Shigella and Vibrio cholerae.

Cytotoxic Cytochalasins and Other Metabolites from Xylariaceae sp. FL0390, a Fungal Endophyte of Spanish Moss.

Two new metabolites, 6-oxo-12-norcytochalasin D (1) and 4,5-di-isobutyl-2(1H)-pyrimidinone (2), together with seven known metabolites, cytochalasins D (3), Q (4), and N (5), 12-hydroxyzygosporin G (6), heptelidic acid chlorohydrin (7), (+)-heptelidic acid (8), and trichoderonic acid A (9), were isolated from Xylariaceae sp. FL0390, a fungal endophyte inhabiting Spanish moss, Tillandsia usneoides. Metabolite 1 is the first example of a 12-norcytochalasin. All metabolites, except 2 and 9, showed cytotoxic activity in a panel of five human tumor cell lines with IC50S of 0.2-5.0 µM.