Phomopchalasins A and B, Two Cytochalasans with Polycyclic-Fused Skeletons from the Endophytic Fungus Phomopsis sp. shj2

Cytochalasins and orsellinic acid derivatives with cytotoxicity from the soil-derived fungus Trichocladium asperum

Four undescribed cytochalasins (1-4), three undescribed orsellinic acid derivatives (5-7) and two known metabolites including methyl lecanorate (8) and methyl orsellinate (9) were isolated from the solid-state cultivation of a soil-derived fungus Trichocladium asperum SQ2-3 collected in Qinghai-Tibet Plateau. Their structures were elucidated by analysis of NMR (1D and 2D) and mass spectrometry data. The absolute configurations of 1-7 were assigned by a combination of the modified Mosher's method, microscale derivatization and Mo2(OAc)4-induced circular dichroism experiment. Compounds 1, 2, 3 and 6 showed significant cytotoxicity against HL-60, A3494, SMMC-7721, MDA-MB-231 and SW480 cell lines with IC50 values ranging from 4.74 to 15.84 μM, respectively. Meanwhile, compound 1 could obviously damage mitochondrial membrane potential and induce G2/M cell cycle arrest in A549 cells.

Diaporchalasins A-E, New Cytochalasins from the Endophytic Fungus Diaporthe sp. BMX12 Isolated from Aquilaria sinensis

Five new cytochalasins, diaporchalasins A-E (1-5), together with 14 known congeners (6-19) were isolated from the endophytic fungus Diaporthe sp. BMX12, which was isolated from the branches of Aquilaria sinensis. The structures of the new compounds were elucidated by extensive spectroscopic analyses including high-resolution electron spray ionization mass spectrometry (HR-ESI-MS) and nuclear magnetic resonance (NMR). Their absolute configurations were assigned by theoretical electronic circular dichroism (ECD) calculations. Compounds 11 and 12 featuring a keto carbonyl at C-21 displayed cytotoxicity toward K562, BEL-7402, SGC-7901, A549, and HeLa cell lines with IC50 values ranging from 4.4 to 47.4 μM.

Two new cytochalasins from the endophytic fungus Xylaria sp. GDGJ-77B

Two new open-chain cytochalasins, xylarchalasins A and B (1 and 2), together with six known analogues (3-8), were isolated from the endophytic fungus Xylaria sp. GDGJ-77B from the Chinese medicinal plant Sophora tonkinensis. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. Compound 2 displayed moderate antibacterial activities against Bacillus subtilis and Escherichia coli with MIC values of 25 and 12.5 μg/mL, respectively.

Ethnobotanical, Phytochemical, and Pharmacological Properties of the Subfamily Nepetoideae (Lamiaceae) in Inflammatory Diseases

Nepetoideae is the most diverse subfamily of Lamiaceae, and some species are well known for their culinary and medicinal uses. In recent years, there has been growing interest in the therapeutic properties of the species of this group regarding inflammatory illnesses. This study aims to collect information on traditional uses through ethnobotanical, pharmacological, and phytochemical information of the subfamily Nepetoideae related to inflammatory diseases. UNAM electronic resources were used to obtain the information. The analysis of the most relevant literature was compiled and organised in tables. From this, about 106 species of the subfamily are traditionally recognised to alleviate chronic pain associated with inflammation. Pharmacological studies have been carried out in vitro and in vivo on approximately 308 species belonging to the genera Salvia, Ocimum, Thymus, Mentha, Origanum, Lavandula, and Melissa. Phytochemical and pharmacological evaluations have been performed and mostly prepared as essential oil or high polarity extracts, whose secondary metabolites are mainly of a phenolic nature. Other interesting and explored metabolites are diterpenes from the abietane, clerodane, and kaurane type; however, they have only been described in some species of the genera Salvia and Isodon. This review reveals that the Nepetoideae subfamily is an important source for therapeutics of the inflammatory process.

Boerelasins A-D, Four Unprecedented Cytochalasins from the Endophytic Fungus Boeremia Exigua

Four undescribed cytochalasins (1-4) were isolated from the endophytic fungus Boeremia exigua. Structurally, boerelasin A (1) represents the first example of a cytochalasin with a rare 5/5 bicyclic carbon core. Boerelasin B (2) possesses an unprecedented 5/6/5/6/8 pentacyclic ring system. Boerelasin C (3), a derivative from the common biosynthetic intermediate to 1, is a macrocyclic ring-opening cytochalasin, and boerelasin D (4) contains an uncommon six-carbon alkyl acid side chain. The structures were elucidated based on spectroscopic methods, electronic circular dichroism, spin-spin coupling constants, and calculated nuclear magnetic resonance with DP4+ analysis. These compounds exhibited significant cytotoxicity against the tumor cells.

Apoptotic Janus-faced mycotoxins against thoracal and breast metastases

Abdominal organs (liver, kidney, spleen) are frequent targets of cancer cell invasion but their primary tumours are less known for their metastatic potential to other organs e.g. to the breast. Despite the known connection of the pathogenesis from breast cancer to liver metastasis, the study of the spread in the opposite direction has been neglected. The notion that breast cancer could be a metastasis besides being a primary tumour is based on rodents' tumour models upon implantation of tumour cells under the capsule of the kidney or under the Glisson's capsule of the liver of rats and mice. Tumour cells develop into a primary tumour at the site of subcutaneous implantation. The metastatic process starts with peripheral disruptions of blood vessels near the surface of primary tumours. Tumour cells released into the abdomen cross the apertures of the diaphragm, enter the thoracal lymph nodes and accumulate in parathymic lymph nodes. Abdominal colloidal carbon particles injected into the abdomen faithfully mimicked the migration of tumour cells and deposited in parathymic lymph nodes (PTNs). An explanation is provided why the connection between abdominal tumours and mammary tumours escaped attention, notably, parathymic lymph nodes in humans were referred to as internal mammary or parasternal lymph nodes. The apoptotic effect of Janus-faced cytotoxins is suggested to provide a new approach against the spread of abdominal primary tumours, and metastatic development.

Cytotoxic cytochalasans from cultures of the fungus Metarhizium brunneum TBRC-BCC 79240

Fourteen new cytochalasans, brunnesins A-N (1-14), along with eleven known compounds, were isolated from the culture extracts of the insect pathogenic fungus Metarhizium brunneum strain TBRC-BCC 79240. The compound structures were established by spectroscopy, X-ray diffraction analysis, and electronic circular dichroism. Compound 4 exhibited antiproliferative activity against all cell lines tested (mammalian), with 50% inhibition concentration (IC₅₀) values ranging from 2.09 to 16.8 μg mL^-1. Compounds 6 and 16 were shown to be bioactive only against non-cancerous Vero cells (IC₅₀ 4.03 and 0.637 μg mL^-1, respectively) whereas compounds 9 and 12 were bioactive only against NCI-H187 small-cell lung cancer cells (IC₅₀ 18.59 and 18.54 μg mL^-1, respectively). Compounds 7, 13, and 14 showed cytotoxicity against NCI-H187 and Vero cell lines with IC₅₀ values ranging from 3.98-44.81 μg mL^-1.

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.

New cytochalasans from an endophytic Xylaria species associated with Costa Rican Palicourea elata (Rubiaceae)

Four new leucine-derived cytochalasans, possessing a 5,6,5,8-ring (1) and a 5,6,11-ring core (2-4), were isolated from a cultivated endophytic fungus Xylaria sp. strain WH2D4 (Xylariaceae). This fungus was isolated from leaves of the neotropical tree species Palicourea elata (Sw.) Borhidi (Rubiaceae) collected in Costa Rica. The chemical structures were determined by employing IR, MS as well as 1D- and 2D-NMR experiments. The stereochemistry at C-15 of compound 4 was determined by quantum calculations. The isolated compounds did not affect germination and growth of Trichoderma reesei and the opportunistic human fungal pathogen T. longibrachiatum.

Five new secondary metabolites from an endophytic fungus Phomopsis sp. SZSJ-7B

Two previously undescribed lactones, phomolides A and B (1 and 2), and three new sesquiterpenoids, phomenes A-C (3-5), together with one known compound, colletotricholide A (6), were isolated from the endophytic fungus Phomopsis sp. SZSJ-7B. Their chemical structures, including the absolute configurations, were comprehensively established by extensive analyses of NMR, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism powered by theoretical calculations, and X-ray diffractions. Moreover, the cytotoxic and antibacterial activities of compounds 1-6 were also evaluated, and the results demonstrated that compound 2 showed significant antibacterial effects towards methicillin-resistant Staphylococcus aureus and S. aureus strains with minimum inhibitory concentration as low as 6.25 μg/ml, which was comparable to that of the clinical drug vancomycin. Moreover, all compounds showed no cytotoxic activity.

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.

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).

Epigenetic Manipulation Induced Production of Immunosuppressive Chromones and Cytochalasins from the Mangrove Endophytic Fungus Phomopsis asparagi DHS-48

A mangrove endophytic fungus Phomopsis asparagi DHS-48 was found to be particularly productive with regard to the accumulation of substantial new compounds in our previous study. In order to explore its potential to produce more unobserved secondary metabolites, epigenetic manipulation was used on this fungus to activate cryptic or silent genes by using the histone deacetylase (HDAC) inhibitor sodium butyrate and the DNA methyltransferase (DNMT) inhibitor 5-azacytidine (5-Aza). Based on colony growth, dry biomass, HPLC, and ¹H NMR analyses, the fungal chemical diversity profile was significantly changed compared with the control. Two new compounds, named phaseolorin J (1) and phomoparagin D (5), along with three known chromones (2–4) and six known cytochalasins (6–11), were isolated from the culture treated with sodium butyrate. Their structures, including their absolute configurations, were elucidated using a combination of detailed HRESIMS, NMR, and ECD and ¹³C NMR calculations. The immunosuppressive and cytotoxic activities of all isolated compounds were evaluated. Compounds 1 and 8 moderately inhibited the proliferation of ConA (concanavalin A)-induced T and LPS (lipopolysaccharide)-induced B murine spleen lymphocytes. Compound 5 exhibited significant in vitro cytotoxicity against the tested human cancer cell lines Hela and HepG2, which was comparative to the positive control adriamycin and fluorouracil. Our finding demonstrated that epigenetic manipulation should be an efficient strategy for the induction of new metabolites from mangrove endophytic fungi.

Immunosuppressive Cytochalasins from the Mangrove Endophytic Fungus Phomopsis asparagi DHS-48

Three new cytochalasins, phomoparagins A-C (1–3), along with five known analogs (4–8), were isolated from Phomopsis asparagi DHS-48, a mangrove-derived endophytic fungus. Their structures, including their absolute configurations, were elucidated using a combination of detailed HRESIMS, NMR, and ECD techniques. Notably, 1 possessed an unprecedented 5/6/5/8/5-fused pentacyclic skeleton. These compounds were tested for their inhibitory activity against concanavalin A (ConA)/lipopolysaccharide (LPS)-induced spleen lymphocyte proliferation and calcineurin (CN) enzyme. Several metabolites (2 and 4–6) exhibited fascinating inhibitory activities with a relatively low toxicity. Furthermore, 2 was demonstrated to inhibit ConA-stimulated activation of NFAT1 dephosphorylation and block NFAT1 translocation in vitro, subsequently inhibiting the transcription of interleukin-2 (IL-2). Our results provide evidence that 2 may, at least partially, suppress the activation of spleen lymphocytes via the CN/NFAT signaling pathway, highlighting that it could serve as an effective immunosuppressant that is noncytotoxic and natural.

Cytotoxic Bromine- and Iodine-Containing Cytochalasins Produced by the Mangrove Endophytic Fungus Phomopsis sp. QYM-13 Using the OSMAC Approach

Twelve new cytochalasins, phomopchalasins D-O (1-3, 5-12, and 14), including one brominated (2) and two iodinated cytochalasins (3 and 6), together with six known analogues (4, 13, and 15-18) were isolated from the mangrove-derived fungus Phomopsis sp. QYM-13 treated with 3% NaBr or 3% KI in potato liquid medium. Their structures and absolute configurations were established by extensive spectroscopic analysis (1D and 2D NMR, HRESIMS), electronic circular dichroism calculations, and a single-crystal X-ray diffraction experiment. Compounds 3 and 6 represent the first iodinated cytochalasins. Compounds 2, 15, 17, and 18 exhibited significant cytotoxicity against human cancer cell line MDA-MB-435 with IC₅₀ values ranging from 0.2 to 8.2 μM.

Cytochalasans from the Endophytic Fungus Phomopsis sp. shj2 and Their Antimigratory Activities

Cytochalasans from the endophytic fungi featured structure diversity. Our previous study has disclosed that cytochalasans from the endophytic fungus Phomopsis sp. shj2 exhibited an antimigratory effect. Further chemical investigation on Phomopsis sp. shj2 has led to the discovery of seven new cytochalasans (1–7), together with four known ones. Their structures were elucidated through extensive spectroscopic data interpretation and single-crystal X-ray diffraction analysis. Compounds 1–3 and 8–11 exhibited antimigratory effects against MDA-MB-231 in vitro with IC₅₀ values in the range of 1.01−10.42 μM.

Discovery of ent-Kaurane Diterpenoids, characteristic metabolites of Isodon species, from an Endophytic fungal strain Geopyxis sp. XY93 inhabiting Isodon parvifolia

Isogeopyxins A-C (1-3), three new diterpenoids with ent-kaurane, ent-pimarane, and ent-abietane scaffolds, respectively, along with six known ent-kauranoids, were isolated from the fermentation culture of Geopyxis sp. XY93 inhabiting the leaves of Isodon parvifolia. Their structures were elucidated by interpretation of spectroscopic data, and single crystal X-ray diffraction. It marks the first time that ent-kauranoids, characteristic metabolites of Isodon species, have been isolated from an associated endophytic fungus.

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).

Asperflavipines C–E and aspermichalasine A: three cytochalasan heterotetramers and an unusual cytochalasan monomer from Aspergillus micronesiensis

Asperflavipines C–E, three new cytochalasin heterotetramers, possessing a highly complex tetradecacyclic ring system with continuous bridged ring systems, and aspermichalasine A, possessing an unusual 5/6/5/8 ring system, were isolated.

Tf2O-Mediated Cyclization of 7-Enamides: Bioinspired Construction of Fused Eight-Membered Carbocyclic Enimines and Enones

In this paper, we document the construction of functionalized and fused eight-membered carbocycles by the triflic anhydride-mediated cyclization of 7-enamides. Taking advantage of the high electrophilicity of the nitrilium ion intermediates, generated in situ from secondary N-(2,6-dimethyl)anilides, the nonactivated, trisubstituted alkene-nitrilium cyclization reactions proceeded smoothly to afford nonconjugated β,γ-enimines (for fused 6/6/8 ring systems), conjugated α,β-enimines (for 6/5/8), or fused 5/8 ring systems in good yields. When the cyclization reactions were followed by one-pot acidic hydrolysis, the reaction led directly to the corresponding α,β-enones. For some substrates, the reaction afford an efficient access to pendent cyclic β,γ-enimines/enones.

Cytotoxic diaporindene and tenellone derivatives from the fungus Phomopsis lithocarpus

Nine new compounds, including five natural rarely-occurring 2, 3-dihydro-1H-indene derivatives named diaporindenes E-I (1-5), and four new benzophenone analogues named tenellones J-M (6-9) were isolated from the deep-sea sediment-derived fungus Phomopsis lithocarpus FS508. All the structures for these new compounds were fully characterized on the basis of spectroscopic data, NMR spectra, and ECD calculation and single-crystal X-ray diffraction analysis. The potential anti-tumor activities of compounds 1-9 against four tumor cell lines SF-268, MCF-7, HepG-2, and A549 were evaluated using the SRB method. Compound 7 exhibited cytotoxic activity against the SF-268 cell line with an IC₅₀ value of 11.36 μmol·L^-1.

Pentacyclic Cytochalasins and Their Derivatives from the Endophytic Fungus Phomopsis sp. xz-18

Eight new cytochalasins 1–8 and ten known analogs 9–18 were isolated from the endophytic fungus Phomopsis sp. xz-18. The planar structures of the cytochalasins were determined by HR-ESI-MS and NMR analysis. Compounds 1, 2, 9 and 10 were 5/6/6/7/5-fused pentacyclic cytochalasins; compounds 3 and 4 had conjugated diene structures in the macrocycle; and compound 6 had a β,γ-unsaturated ketone. The absolute configuration of 6 was confirmed for the first time by the octant rule. The acid-free purification process proved that the pentacyclic system was a natural biosynthetic product and not an acid-mediated intramolecular cyclized artifact. The new compounds did not exhibit activities against human cancer cell lines in cytotoxicity bioassays or antipathogenic fungal activity, but compounds 1, 3 and 4 showed moderate antibacterial activity in disk diffusion assays.

Alternariasin A, new pentacyclic cytochalasin from the fungus Alternaria alternate

Alternariasin A (1), one new cytochalasin possessing the benzo[4,5]indeno[2,1-d]isoindole-1,3,13(2H,3aH)-trione skeleton, and five known compounds 2-6 were isolated from the solid cultures of the Midui Glacier-derived fungus Alternaria alternata. Their structures were elucidated by NMR and MS spectroscopic analyses and by a comparison with data from the literature. The absolute configuration of 1 was assigned by combination of experimental and calculated electronic circular dichroism (ECD) spectra. Compound 1 displayed antibacterial activity against the S. aureus, B. subtilis and E. coli with MIC values of 16.7, 16.7 and 33.3 μΜ, respectively. While compound 3 showed potent cytotoxicity against a small panel of human tumour cell lines.

Z, Cubilla-Rios L. Structurally Uncommon Secondary Metabolites Derived from Endophytic Fungi

Among microorganisms, endophytic fungi are the least studied, but they have attracted attention due to their high biological diversity and ability to produce novel and bioactive secondary metabolites to protect their host plant against biotic and abiotic stress. These compounds belong to different structural classes, such as alkaloids, peptides, terpenoids, polyketides, and steroids, which could present significant biological activities that are useful for pharmacological or medical applications. Recent reviews on endophytic fungi have mainly focused on the production of novel bioactive compounds. Here, we focus on compounds produced by endophytic fungi, reported with uncommon bioactive structures, establishing the neighbor net and diversity of endophytic fungi. The review includes compounds published from January 2015 to December 2020 that were catalogued as unprecedented, rare, uncommon, or possessing novel structural skeletons from more than 39 different genera, with Aspergillus and Penicillium being the most mentioned. They were reported as displaying cytotoxic, antitumor, antimicrobial, antiviral, or anti-inflammatory activity. The solid culture, using rice as a carbon source, was the most common medium utilized in the fermentation process when this type of compound was isolated.

Bioinspired Network Analysis Enabled Divergent Syntheses and Structure Revision of Pentacyclic Cytochalasans

We accomplished the divergent total syntheses of ten pentacyclic cytochalasans (aspergillin PZ, trichodermone, trichoderones, flavipesines, and flavichalasines) from a common precursor aspochalasin D and revised the structures of trichoderone B, spicochalasin A, flavichalasine C, aspergilluchalasin based on structure network analysis of the cytochalasans biosynthetic pathways and DFT calculations. The key steps of the syntheses include transannular alkene/epoxyalkene and carbonyl-ene cyclizations to establish the C/D ring of pentacyclic aspochalasans. Our bioinspired approach to these pentacyclic cytochalasans validate the proposed biosynthetic speculation from a chemical view and provide a platform for the synthesis of more than 400 valuable cytochalasans bearing different macrocycles and amino-acid residues.

Four New Chromones from the Endophytic Fungus Phomopsis asparagi DHS-48 Isolated from the Chinese Mangrove Plant Rhizophora mangle

Four new chromones, phomochromenones D–G (1–4), along with four known analogues, diaporchromone A (5), diaporchromanone C (6), diaporchromanone D (7), and phomochromenone C (8), were isolated from the culture of Phomopsis asparagi DHS-48 from Chinese mangrove Rhizophora mangle. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configurations of 1 and 4 were assigned on the basis of experimental and calculated electronic circular dichroism (ECD) data, and those of enantiomers 2 and 3 were determined by a modified Mosher’s method and basic hydrolysis. To the best of our knowledge, phomochromenones D–F (1–4) possessing a 3-substituted-chroman-4-one skeleton are rarely found in natural sources. Diaporchromone A (5) showed moderate to weak immunosuppressive activity against T and/or B lymphocyte cells with IC₅₀ of 34 μM and 117 μM.

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.

Large-scale culture as a complementary and practical method for discovering natural products with novel skeletons

Covering: up to July 2020Fungal metabolites with diverse and novel scaffolds can be assembled from well-known biosynthetic precursors through various mechanisms. Recent examples of novel alkaloids (e.g., cytochalasans and diketopiperazine derivatives), terpenes (e.g., sesterterpenes and diterpenes) and polyketides produced by fungi are presented through case studies. We show that large-scale culture is a complementary and practical method for genome mining and OSMAC approaches to discover natural products of unprecedented skeletal classes from fungi. We also summarize the discovery strategies and challenges for characterizing these compounds.

Five new secondary metabolites from the fungus Phomopsis asparagi

Five new compounds, including a pair of diphenylcyclopentenone enantiomers (±)-phomopsisin A (1), a sesquiterpenoid 15-hydroxylithocarin A (2), a new diketopiperazine alkaloid prenylcyclotryprostatin A (3) and 7-hydroxy-cis-L(-)-3,6-dibenzyl-2,5-dioxopiperazine (6), along with five known compounds were isolated from the fungus Phomopsis asparagi. Their structures were elucidated on the basis of spectroscopic analyses (1D and 2D NMR), theoretical electronic circular dichroism (ECD) calculation, modified Mosher's method, and X-ray crystallography. The racemates of (±)-phomopsisin A showed inhibition on α-glucosidase with IC₅₀ of 30.07 ± 0.75 μM (positive control acarbose, 121 ± 2.7 μM).

Bioactive Secondary Metabolites of the Genus Diaporthe and Anamorph Phomopsis from Terrestrial and Marine Habitats and Endophytes: 2010-2019

The genus Diaporthe and its anamorph Phomopsis are distributed worldwide in many ecosystems. They are regarded as potential sources for producing diverse bioactive metabolites. Most species are attributed to plant pathogens, non-pathogenic endophytes, or saprobes in terrestrial host plants. They colonize in the early parasitic tissue of plants, provide a variety of nutrients in the cycle of parasitism and saprophytism, and participate in the basic metabolic process of plants. In the past ten years, many studies have been focused on the discovery of new species and biological secondary metabolites from this genus. In this review, we summarize a total of 335 bioactive secondary metabolites isolated from 26 known species and various unidentified species of Diaporthe and Phomopsis during 2010-2019. Overall, there are 106 bioactive compounds derived from Diaporthe and 246 from Phomopsis, while 17 compounds are found in both of them. They are classified into polyketides, terpenoids, steroids, macrolides, ten-membered lactones, alkaloids, flavonoids, and fatty acids. Polyketides constitute the main chemical population, accounting for 64%. Meanwhile, their bioactivities mainly involve cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, anti-algae, phytotoxic, and enzyme inhibitory activities. Diaporthe and Phomopsis exhibit their potent talents in the discovery of small molecules for drug candidates.

Six 19,20-epoxycytochalasans from endophytic Diaporthe sp. RJ-47

Two new cytochalasins, deacetyl-19-epi-cytochalasin P1 (1), deacetyl-19,20-epoxycytochalasin D (2) were isolated from the endophytic fungus Diaporthe sp. RJ-47, along with four known compounds deacetyl-5,6-dihydro-7-oxo-19,20-epoxycytochalasin C (3), 19,20-epoxycytochalasin Q (4), 19,20-epoxycytochalasin C (5) and deacetyl-19,20-epoxy cytochalasin C (6). Their structures were unambiguously elucidated on the basis of the comprehensive analysis of extensive spectroscopic data. The antimicrobial effects of these compounds were evaluated.

Lithocaldehydes A and B, polyketones from the deep sea-derived fungus Phomopsis lithocarpus FS508

Lithocaldehydes A (1) and B (2), a pair of novel diastereoisomers possessing an unprecedented 6/6/5/5/6 highly-fused ring system forming an earring-like skeleton, were isolated from the deep sea-derived fungus Phomopsis lithocarpus FS508. The structures of 1 and 2 were fully characterized and established through extensive spectroscopic interpretations and ECD calculations. Moreover, compounds 1 and 2 were shown to be promising antibiotics, exhibiting potent antifungal activities that are comparable to those of the positive control nystatin.

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.

Prospective Leads from Endophytic Fungi for Anti-Inflammatory Drug Discovery

A wide array of therapeutic effects has been exhibited by compounds isolated from natural sources. "Bio-actives of endophytic origin" is a recently explored area that came into recognition over the last 2 decades. Literature search on the secondary metabolites of endophytes have shown several pharmacologically active compounds especially anti-inflammatory compounds, which have been reviewed in the present paper. The article is structured based on the chemical classification of secondary metabolites. The compounds were identified to possess activity against a total of 16 anti-inflammatory targets. The most common targets involved were NO, TNF-α, and inhibition of total ROS. Further, the article gives a detailed insight into the compounds, their endophytic source, and anti-inflammatory target as well as potency. The contents of the article cover all the scientific reports published until Feb. 2019. Thus 118 compounds and 6 extracts have been reported to be obtained from endophytic sources showing anti-inflammatory activities. Amongst these, herbarin, periconianone A, and periconianone B were identified as the most potent compounds in terms of their IC₅₀ values against NO inhibition.

Arthrinins E-G, Three Botryane Sesquiterpenoids from the Plant Endophytic Fungus Arthrinium sp. HS66

Arthrinins E-G (1-3), three new sesquiterpenoids possessing non-isoprenoid botryane skeleton, were isolated from the fermentation of an endophytic fungus named Arthrinium sp. HS66 which colonized in the stems of Isodon xerophilus. Their structures were determined by extensive spectroscopic methods. Furthermore, the structure of 1 was unambiguously confirmed by X-ray diffraction, while those of 2 and 3 were verified through quantum chemical calculation of NMR data and ECD spectra.

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.

Fungi: outstanding source of novel chemical scaffolds

A large number of remarkable studies on the secondary metabolites of fungi have been conducted in recent years. This review gives an overview of one hundred and sixty-seven molecules with novel skeletons and their bioactivities that have been reported in seventy-nine articles published from 2013 to 2017. Our statistical data showed that endophytic fungi and marine-derived fungi are the major sources of novel bioactive secondary metabolites.

Extracting value: mechanistic insights into the formation of natural product artifacts – case studies in marine natural products

This review highlights the importance of valuing natural product handling artifacts, to open a new window into, and provide a unique perspective of, bioactive chemical space.

Cytochalasins from endophytic Diaporthe sp. GDG-118

The plant Sophora tonkinensis, possessed a range of active compounds, was traditionally used in the medicine of Chinese minorities. Endophytic fungi were isolated from this plant, of which the fungus Diaporthe sp. GDG-118 was fermented and extracted with methanol. The extract was screened by antifungal and antibacterial assays leading to the discovery of two new 21-acetoxycytochalasins (1-2) and five known cytochalasins (3-7). These two new compounds were elucidated by spectroscopic analyses, and further their absolute configurations were determined by the X-ray of compound 3 and comparing their experimental CD spectra. The antibacterial and antifungal effects of these compounds were evaluated. Compound 2 showed significant inhibitory activity against Bacillus anthraci and Escherichia coli with MIC value of 12.5 μg/mL, and 7 showed strong antifungal activity against Alternaria oleracea, Pestalotiopsis theae and Colletotrichum capsici with MIC values of 3.125, 1.56 and 1.56 μg/mL, respectively.

Anti-leishmanial and Anti-inflammatory Agents from Endophytes: A Review

Leishmaniases and chronic inflammatory diseases are the cause of millions of deaths in the world each year. The treatment of leishmaniasis is facing serious drawbacks particularly due to the limited number of effective medicines, the resistance, and the toxicity of available drugs. On the other hand, many drugs are used for the management of inflammatory disorders. However, the most commonly prescribed although efficient is highly toxic with multiples side effects. New leads compounds for the development of new anti-leishmanial and anti-inflammatory drugs are needed. Over the past decade, several studies on the potential of endophytes to produce bioactive metabolites have been reported. We are presenting in the present review the status of research from 2000 to 2019 on the anti-leishmanial and anti-inflammatory metabolites isolated from endophytes from diverse habitats. An emphasis was put on existing gaps in the literature to inspire and guide future investigations. We hope that this review will help accelerate the drug discovery against leishmaniases and inflammation-associated disorders.