Three new highly-oxygenated metabolites from the endophytic fungus Cytospora rhizophorae A761

Carneusones A-F, Benzophenone Derivatives from Sponge-Derived Fungus Aspergillus carneus GXIMD00543

Six benzophenone derivatives, carneusones A-F (1-6), along with seven known compounds (7-13) were isolated from a strain of sponge-derived marine fungus Aspergillus carneus GXIMD00543. Their chemical structures were elucidated by detailed spectroscopic data and quantum chemical calculations. Compounds 5, 6, and 8 exhibited moderate anti-inflammatory activity on NO secretion using lipopolysaccharide (LPS)-induced RAW 264.7 cells with EC50 values of 34.6 ± 0.9, 20.2 ± 1.8, and 26.8 ± 1.7 μM, while 11 showed potent effect with an EC50 value of 2.9 ± 0.1 μM.

Benzophenones-natural metabolites with great Hopes in drug discovery: structures, occurrence, bioactivities, and biosynthesis

Fungi have protruded with enormous development in the repository of drug discovery, making them some of the most attractive sources for the synthesis of bio-significant and structural novel metabolites. Benzophenones are structurally unique metabolites with phenol/carbonyl/phenol frameworks, that are separated from microbial and plant sources. They have drawn considerable interest from researchers due to their versatile building blocks and diversified bio-activities. The current work aimed to highlight the reported data on fungal benzophenones, including their structures, occurrence, and bioactivities in the period from 1963 to April 2023. Overall, 147 benzophenones derived from fungal source were listed in this work. Structure activity relationships of the benzophenones derivatives have been discussed. Also, in this review, a brief insight into their biosynthetic routes was presented. This work could shed light on the future research of benzophenones.

Polyketones from the endophytic fungus Cytospora rhizophorae

Cytosporaphenones D (1) and E (2), two new polyketones, and one new natural product 1,7-dihydroxy-6-methyl-8-formylxanthone (3), along with four known compounds, were isolated from Cytospora rhizophorae, an endophytic fungus from Morinda officinalis. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction technique.

Fungal isolates influence the quality of Peucedanum praeruptorum Dunn

The symbiotic relationship between beneficial microorganisms and plants plays a vital role in natural and agricultural ecosystems. Although Peucedanum praeruptorum Dunn is widely distributed, its development is greatly limited by early bolting. The reason for early bolting in P. praeruptorum remains poorly characterized. We focus on the plant related microorganisms, including endophytes and rhizosphere microorganisms, by combining the traditional isolation and culture method with metagenomic sequencing technology. We found that the OTUs of endophytes and rhizosphere microorganisms showed a positive correlation in the whole growth stage of P. praeruptorum. Meanwhile, the community diversity of endophytic and rhizosphere fungi showed an opposite change trend, and bacteria showed a similar change trend. Besides, the microbial communities differed during the pre- and post-bolting stages of P. praeruptorum. Beneficial bacterial taxa, such as Pseudomonas and Burkholderia, and fungal taxa, such as Didymella and Fusarium, were abundant in the roots in the pre-bolting stage. Further, a strain belonging to Didymella was obtained by traditional culture and was found to contain praeruptorin A, praeruptorin B, praeruptorin E. In addition, we showed that the fungus could affect its effective components when it was inoculated into P. praeruptorum. This work provided a research reference for the similar biological characteristics of perennial one-time flowering plants, such as Saposhnikovia divaricate, Angelica sinensis and Angelica dahurica.

Bioactive polyketide derivatives from the endophytic fungus Phaeosphaeriopsis musa

Two undescribed phenolic derivatives musaones A and B, six undescribed γ-butyrolactone musaolides A-F, together with two undescribed cyclopentanone musaolides G and H were isolated from the solid culture of an endophytic strain Phaeosphaeriopsis musae M. Arzanlou & Crous (Phaeosphaeriaceae). Their structures were unambiguously elucidated by extensive spectral analyses. The absolute configurations of two diastereomers musaolides G and H were assigned by comparing their experimental and calculated ECD data. Moreover, the in vitro α-glucosidase inhibition and cytotoxic activities of isolated compounds (except musaolide D) were evaluated to understand their biological effects, wherein musaone B and musaolide F displayed promising α-glucosidase inhibition with IC₅₀ values of 37.3 ± 0.59 μM and 105.18 ± 2.76 μM respectively, compared to the positive control acarbose (24.99 ± 1.28 μM).

Antioxidant Aryl-Substituted Phthalan Derivatives Produced by Endophytic Fungus Cytospora rhizophorae

Six new phthalan derivatives cytorhizophins D-I (1-6) as well as three known derivatives cytorhizophin C, pestacin and rhizophol B were isolated from Cytospora rhizophorae. Among them, cytorhizophins D-E (1-2) and F-G (3-4) were two pairs of diastereoisomers, all of them featuring a 1-phenyl-1,3-dihydroisobenzofuran scaffold with a highly oxygenated O-linked isopentenyl unit. Besides, cytorhizophins H-I (5-6) represent the first examples of phthalide family with fascinating 6/6/6/5 tetracyclic ring system fusing as unprecedented furo [4,3,2-kl]xanthen-2 (10bH)-one skeleton. The structures of the new phthalan derivatives were extensively confirmed by detail spectroscopic analysis. The partial absolute configurations of compounds 1-6 were established through electronic circular dichroism (ECD) calculations. Moreover, compounds 1-4 showed remarkable antioxidant activities with EC₅₀ values ranging from 5.86 to 26.80 μM, which were better than or comparable to that of ascorbic acid (positive control).

The important role of P450 monooxygenase for the biosynthesis of new benzophenones from Cytospora rhizophorae

Benzophenones are polyketides with diverse biological activities. Novel cytotoxic benzophenones cytosporaphenones A-C and cytorhizins A-D, which contain a new skeleton, were previously extracted from endophytic fungus Cytospora rhizophorae A761. However, the mechanism for the biosynthesis of these compounds remains unknown. Cytosporaphenone A was assumed to be the precursor for the biosynthesis of cytorhizins A-D. In this study, we sequenced the genome of C. rhizophorae A761 and characterized a benzoate 4-monooxygenase cytochrome P450(BAM). CRISPR/Cas9-mediated gene knockout and overexpression studies in C. rhizophorae confirmed the vital function of BAM in the biosynthesis of cytosporaphenones and cytorhizins. Overexpression of BAM also enhanced the yield of cytosporaphenone A by 1.868 folds. The in vitro function and enzymatic properties of BAM were also described. This study demonstrates the important role of BAM for the biosynthesis of cytosporaphenone A and cytorhizins and is also the first to provide approaches for the CRISPR-Cas9-mediated gene deletion and gene overexpression studies in C. rhizophoarae, thus laying a foundation for the elucidation of the biosynthetic mechanism of cytorhizins and the discovery of new benzophenones mediated by BAM.Key points• The novel bam gene encoding BAM protein in C. rhizophorae was firstly deleted using CRIPSR/Cas9 system.• The in vitro oxidation function of novel BAM protein and enzymatic properties was characterized.• The over expression of bam gene enhanced the yield of cytosporaphone A in C. rhizophorae significantly.

Endophytic fungi: A treasure trove of novel anticancer compounds

Cancer is a multifactorial disease with a convoluted genesis and progression. The emergence of multidrug resistance to presently be offered drug and relapse is by far, the most critical concern to tackle this deteriorating disease. Henceforth, there is undeniably an inflated necessity for safe, promising, and less harmful new anticancer drugs. Natural compounds from various sources like plants, animals, and microorganisms have occupied a center stage in drug discovery due to their tremendous chemical diversity and potential as therapeutic agents. Endophytic microbes are symbiotically associated with plants and have been proven to produce novel or analogues of host bioactive metabolites exhibiting a variety of biological activities including anticancer activity. This review emphasizes on structurally diverse unprecedented anticancer natural compounds that have been reported exclusively from endophytic fungi from 2016 to 2020. It covers chemical nature of metabolites, its fungal source associated with terrestrial, as well as marine plants and anticancer activity based on their cytotoxicity profile against various cancer cell lines. Many of these fungal metabolites with promising anticancer activity can be used as lead molecules for in silico experiments and deserve special attention from scientists for further in vitro and clinical research.

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

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

Genome Sequence of Trichoderma lixii MUT3171, A Promising Strain for Mycoremediation of PAH-Contaminated Sites

Mono- and polycyclic aromatic hydrocarbons (PAHs) are widespread and recalcitrant pollutants that threaten both environmental and human health. By exploiting the powerful enzymatic machinery of fungi, mycoremediation in contaminated sites aims at removing a wide range of pollutants in a cost-efficient and environmentally friendly manner. Next-generation sequencing (NGS) techniques are powerful tools for understanding the molecular basis of biotransformation of PAHs by selected fungal strains, allowing genome mining to identify genetic features of biotechnological value. Trichoderma lixii MUT3171, isolated from a historically PAH-contaminated soil in Italy, can grow on phenanthrene, as a sole carbon source. Here, we report the draft genome sequence of T. lixii MUT3171 obtained with high-throughput sequencing method. The genome of T. lixii MUT3171 was compared with other 14 Trichoderma genomes, highlighting both shared and unique features that can shed a light on the biotransformation of PAHs. Moreover, the genes potentially involved in the production of important biosurfactants and bioactive molecules have been investigated. The gene repertoire of T. lixii MUT3171 indicates a high degrading potential and provides hints on putative survival strategies in a polluted environment.

Natural Products from Endophytic Fungi Associated with Rubiaceae Species

This review presents the chemical diversity and pharmacological properties of secondary metabolites produced by endophytic fungi associated with various genera of Rubiaceae. Several classes of natural products are described for these endophytes, although, this study highlights the importance of some metabolites, which are involved in antifungal, antibacterial, anti-protozoal activities; neurodegenerative diseases; cytotoxic activity; anti-inflammatory and antioxidant activity; and hyperglycemic control.

Metabolites from Two Dominant Thermophilic Fungal Species Thermomyces lanuginosus and Scytalidium thermophilum

Thermomyces lanuginosus and Scytalidium thermophilum are among the most ubiquitous thermophilic fungi in compost and soil. Chemical study on these two prevalent strains collected from Yunnan led to isolation of 23 metabolites, including one new metabolite, therlanubutanolide, and 15 known compounds, isolated from the YGP culture broth of Thermomyces lanuginosus and 7 known compounds isolated from Scytalidium thermophilum, respectively. Therlanubutanolide shared the quite similar features of the same carbon skeleton and saturation as natural hexadecanoic acids. This was the first reported discovery of such a lactone as natural occurring metabolite. All the compounds were reported for the first time from thermophilic fungi. Among them, N-[(2S,3R,4E,8E)-1,3-dihydroxy-9-methyloctadeca-4,8-dien-2-yl]acetamide was for the first time reported to be a naturally occurring metabolite and its NMR data was first provided in this study. A type of PKS-derived metabolites, three 3,4-dihydronaphthalen-1(2H)-ones, which were widely found in plant pathogenic fungi as phytotoxins and reported to have antimicrobial activity, were obtained from both dominant thermophilic fungi. The frequent occurrence of such PKS phytotoxins in these two thermophilic fungi might suggest particular ecological interest.

Dihydroisocoumarins produced by Diaporthe cf. heveae LGMF1631 inhibiting citrus pathogens

Citrus black spot (CBS) and post-bloom fruit drop (PFD), caused by Phyllosticta citricarpa and Colletotrichum abscissum, respectively, are two important citrus diseases worldwide. CBS depreciates the market value and prevents exportation of citrus fruits to Europe. PFD under favorable climatic conditions can cause the abscission of flowers, thereby reducing citrus production by 80%. An ecofriendly alternative to control plant diseases is the use of endophytic microorganisms, or secondary metabolites produced by them. Strain LGMF1631, close related to Diaporthe cf. heveae 1, was isolated from the medicinal plant Stryphnodendron adstringens and showed significant antimicrobial activity, in a previous study. In view of the potential presented by strain LGMF1631, and the absence of chemical data for secondary metabolites produced by D. cf. heveae, we decided to characterize the compounds produced by strain LGMF1631. Based on ITS, TEF1, and TUB phylogenetic analysis, strain LGMF1631 was confirmed to belong to D. cf. heveae 1. Chemical assessment of the fungal strain LGMF1631 revealed one new seco-dihydroisocoumarin [cladosporin B (1)] along with six other related, already known dihydroisocoumarin derivatives and one monoterpene [(-)-(1S,2R,3S,4R)-p-menthane-1,2,3-triol (8)]. Among the isolated metabolites, compound 5 drastically reduced the growth of both phytopathogens in vitro and completely inhibited the development of CBS and PFD in citrus fruits and flowers. In addition, compound 5 did not show toxicity against human cancer cell lines or citrus leaves, at concentrations higher than used for the inhibition of the phytopathogens, suggesting the potential use of (-)-(3R,4R)-cis-4-hydroxy-5-methylmellein (5) to control citrus diseases.

Four new metabolites from the endophytic fungus Diaporthe lithocarpus A740

One new benzophenone derivative, named tenllone I (1), two new eremophilane derivatives lithocarins B (2) and C (3), and a new monoterpentoid lithocarin D (4), together with two know compounds (5 and 6) were isolated from the endophytic fungus Diaporthe lithocarpus A740. All of the structures for these new compounds were fully characterized and established on the basis of extensive spectroscopic interpretation. In addition, all the isolated compounds were evaluated in vitro for their cytotoxic activity. Compounds 2, 3, and 5 showed weak inhibitory activities against tumor cell lines.

Two new metabolites from Daldinia eschscholtzii, an endophytic fungus derived from Pogostemon cablin

The chemical investigation of the mycelia of endophytic fungus Daldinia eschscholtzii A630, which was isolated from the medicinal plant Pogostemon cablin, resulted in the isolation of two new compounds, named eschscholin A (1), 3-ene-2-methyl-2H-1-benzopyran-5-ol (2), and one new natural product 3,5-dihydroxy-2-methyl-4H-chromen-4-one (3), along with seven known compounds. Their structures were fully characterized by means of detailed spectroscopic analysis, and in comparison with published data for known compounds. All of the isolated compounds (1-10) were evaluated for their antibacterial activities.

Cytotoxic triquinane-type sesquiterpenoids from the endophytic fungus Cerrena sp. A593

The culture broth of Cerrena sp. A593, which was isolated from Pogostemon cablin, showed potent cytotoxicity against several human tumor cell lines. The following chemical study resulted in the isolation of two new triquinane-type sesquiterpenoids, named cerrenins D (1) and E (2), along with two known compounds plerocybellone A (3) and chloriolin B (4). Their structures were fully assigned with the aid of extensive spectroscopic analysis (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, HRESIMS, and IR) and data from the literature. Moreover, cytotoxic activity in vitro of compounds 1-4 were evaluated against SF-268, MCF-7, NCI-H460, and HepG-2 tumor cell lines. The new compound 1 exhibited weak growth inhibitory activity against all the four tumor cell lines with IC₅₀ values of 41.01, 14.43, 29.67, 44.32 μM.

Cytorhizophins A and B, benzophenone-hemiterpene adducts from the endophytic fungus Cytospora rhizophorae

(±)-Cytorhizophin A and cytorhizophin B (2), novel benzophenone-hemiterpene conjugated hetero-dimers featuring an unprecedented 6/7/6/7 tetracyclic fused ring system.

Cytosporins A–D, novel benzophenone derivatives from the endophytic fungus Cytospora rhizophorae A761

Cytosporins A–D (1–4), hemiterpene-conjugated phenolics with an unprecedented benzo[b][1,5]dioxocane skeleton, were isolated from Cytospora rhizophorae A761.

Novel natural compounds from endophytic fungi with anticancer activity

Plant endophytes are microorganisms that live in healthy plant tissues in part or all of their life history without causing obvious symptoms of infection in the host plants. Endophytes, a new type of microbial resource that can produce a variety of biological constituents, have great values for research and broad prospects for development. This article reviewed the research and development progress of endophytic fungi with cytotoxic activity between 2014 and 2017, including endophytic fungi sources, microbial taxonomy, compound classification and cytotoxic activity. The results showed that the 109 strains of endophytic fungi belong to 3 phyla, 7 classes and 50 genera. The secondary metabolites mainly contained alkaloids, terpenes, steroids, polyketides, quinones, isocoumarins, esters etc. The results of this study provide references for the development of new antitumor drugs and endophytes resources.

Cerrenins A-C, cerapicane and isohirsutane sesquiterpenoids from the endophytic fungus Cerrena sp

One new cerapicane cerrenin A (1), and two new isohirsutane sesquiterpenoids cerrenins B and C (2 and 3), were isolated from the broth extract of Cerrena sp. A593. Cerrenin A featured a rare cage-like bicyclo[3.2.1]octane skeleton, and cerrenin B represented the rearranged triquinane-type sesquiterpenoid. Their structures were extensively elucidated by NMR spectroscopic analysis with the absolute configuration determined by X-ray crystallography and ECD calculations. The anti-cancer activity for all the compounds were evaluated, and their plausible biosynthetic relationships involving fascinating carbon skeleton rearrangements were also suggested.

Cytoskyrin C, an unusual asymmetric bisanthraquinone with cage-like skeleton from the endophytic fungus Diaporthe sp

Cytoskyrin C (1), a new bisanthraquinone with asymmetrically cytoskyrin type skeleton, together with a known symmetrical analogue (+)-epicytoskyrin (2), were isolated from an endophytic fungus ARL-09 (Diaporthe sp.). Cytoskyrin C (1) featured an asymmetrically cage-like structural motif arising from the dimerization of anthraquinone monomers by three carbon‑carbon bonds 9a/3', 3/9a' and 1/1'. The structure and absolute configuration of compound 1 were determined by spectroscopic analyses, ECD calculation and exciton chirality methods. Moreover, a plausible biogenetic pathway of 1-2 was predicted. Their cytotoxicities against SMMC-7721 cell as well as effects on NF-κB signaling pathway were evaluated. 2009 Elsevier Ltd. All rights reserved.

Two New Metabolites from the Endophytic Fungus Alternaria sp. A744 Derived from Morinda officinalis

Two new compounds isobenzofuranone A (1) and indandione B (2), together with eleven known compounds (3-13) were isolated from liquid cultures of an endophytic fungus Alternaria sp., which was obtained from the medicinal plant Morinda officinalis. Among them, the indandione (2) showed a rarely occurring indanone skeleton in natural products. Their structures were elucidated mainly on the basis of extensive spectroscopic data analysis. All of the compounds were evaluated with cytotoxic and α-glucosidase inhibitory activity assays. Compounds 11 and 12 showed significant inhibitory activities against four tumor cell lines; MCF-7, HepG-2, NCI-H460 and SF-268, with IC₅₀ values in the range of 1.91-9.67 μM, and compounds 4, 5, 9, 10, 12 and 13 showed excellent inhibitory activities against α-glucosidase with IC₅₀ values in the range of 12.05-166.13 μM.