Three new diterpenes and two new sesquiterpenoids from the endophytic fungus Trichoderma koningiopsis A729

Diterpenoids with Antibacterial Activities from the Fungus Trichoderma harzianum

A new fusicoccane diterpenoid, harziaderma A (1), two novel harziane diterpenoids, harzianones G and H (2 and 3), one revised harziane diterpenoid (4), and two known diterpenoids (5 and 6) were isolated from the fungus Trichoderma harzianum and established via NMR, HRESIMS, Mo2(OAc)4-induced circular dichroism (ICD) and electronic circular dichroism (ECD) calculations. It is worth noting that compound 1 represents the first instance of a fusicoccane-type diterpenoid derived from T. harzianum. The structure of furanharzianone B was revised to 4 via careful spectroscopic analyses. Additionally, compounds 2 and 5 could suppress the overall growth of the foodborne bacterial pathogen Bacillus cereus. Compound 4 showed a moderate suppressive impact on NO generation in lipopolysaccharide (LPS)-treated RAW 264.7 cells. The discoveries from the current study not only expanded the structural variety of diterpenoids isolated from T. harzianum but also laid a robust foundation for the development of harziane diterpenoids as anti-foodborne pathogen agents.

Pararorine A, isoindolinone alkaloid from the endophytic fungus Paramyrothecium roridum and its anti-tumor activity

Pararorine A, a new isoindolinone alkaloid was isolated from Paramyrothecium roridum, an endophytic fungus from the medicinal plant Gynochthodes officinalis (F.C. How) Razafim. & B. Bremer. The structure of this compound was elucidated by extensive spectroscopic (UV, IR, MS, and NMR) analyses. In addition, the antitumor activity of pararorine A was evaluated against SF-268, MCF-7, HepG2, and A549 tumor cell lines. The results revealed that pararorine A exhibited potent antitumor activities with the IC50 values ranging from 1.69 to 8.95 μM. Moreover, the tumor cell inhibitory activity of pararorine A was evidenced by promoting cytochrome C release and cell cycle arrest as well as the induction of apoptosis by the up-regulation of the protein expressions of JNK and Bax through PARP-cleavage and caspase 3-cleavage.

Irpexols A-C, xanthone derivatives from the endophyte fungus Irpex laceratus A878

Three new xanthone derivatives irpexols A-C (1-3) and five known xanthones including three dimeric ones were successfully isolated from Irpex laceratus A878, an endophytic fungus of the family Irpicaceae from the medicinal plant Pogostemon cablin (Blanco) Bentham (Lamiaceae). The structures of these compounds were elucidated by extensive spectroscopic analyses including ultraviolet-visible spectroscopy (UV), infrared spectroscopy (IR), mass spectrometry (MS), and nuclear magnetic resonance (NMR). All of the three new compounds (1-3) share a de-aromatic and highly‑oxygenated xanthone skeleton. In addition, the cytotoxic activity of compounds 1-8 were evaluated against SF-268, MCF-7, HepG2, and A549 tumor cell lines. The results revealed that compound 6 showed moderate cytotoxic activity with the IC50 values ranging from 24.83 to 45.46 μM, while the IC50 values of the positive control adriamycin was ranging from 1.11 to 1.44 μM.

Exploring the Biomedical Potential of Terpenoid Alkaloids: Sources, Structures, and Activities

Terpenoid alkaloids are recognized as a class of compounds with limited numbers but potent biological activities, primarily derived from plants, with a minor proportion originating from animals and microorganisms. These alkaloids are synthesized from the same prenyl unit that forms the terpene skeleton, with the nitrogen atom introduced through β-aminoethanol, ethylamine, or methylamine, leading to a range of complex and diverse structures. Based on their skeleton type, they can be categorized into monoterpenes, sesquiterpenes, diterpenes, and triterpene alkaloids. To date, 289 natural terpenoid alkaloids, excluding triterpene alkaloids, have been identified in studies published between 2019 and 2024. These compounds demonstrate a spectrum of biological activities, including anti-inflammatory, antitumor, antibacterial, analgesic, and cardioprotective effects, making them promising candidates for further development. This review provides an overview of the sources, chemical structures, and biological activities of natural terpenoid alkaloids, serving as a reference for future research and applications in this area.

Secondary metabolites isolated from Trichoderma hamatum b-3 and their fungicidal activity

An undescribed trichodenone derivative (1), two new diketopiperazines (3 and 4) along with a bisabolane analog (2) were isolated from Trichoderma hamatum b-3. The structures of the new findings were established through comprehensive analyses of spectral evidences in HRESIMS, 1D and 2D NMR, Marfey's analysis as well as comparisons of ECD. The absolute configuration of 2 was unambiguously confirmed by NMR, ECD calculation and Mo2(AcO)4 induced circular dichroism. Compounds 1-4 were tested for their fungicidal effects against eight crop pathogenic fungi, among which 1 showed 51% inhibition against Sclerotinia sclerotiorum at a concentration of 50 μg/mL.

Discovery of Diverse Sesquiterpenoids from Crossiella cryophila through Genome Mining and NMR Tracking

Terpenoids, the largest and most structurally diverse natural product family, are predominantly found in fungi and plants, with bacterial terpenoids forming a minor fraction. Here, we established an efficient platform that integrates genome mining and NMR-tracking for prioritizing strains and tracking bacterial terpenoids. By employing this platform, we selected Crossiella cryophila for a comprehensive investigation of its capacity for terpenoid production, resulting in the characterization of 15 sesquiterpenoids. These compounds comprise nine new sesquiterpenoids (1-9), along with six known analogs (10-15), which are categorized into five distinctive carbon skeletons: bicyclogermacrane, maaliane, cadinane, eudesmane, and nor-eudesmane. Their chemical structures were determined through a combination of spectroscopic analysis, single-crystal X-ray diffraction, and quantum chemical calculations. Notably, the absolute configurations of compounds 1, 2, 5-7, 9, and 13-15 were determined via single-crystal X-ray diffraction analyses. The selected compounds were evaluated for their anticancer, antimicrobial, and anti-inflammatory bioactivities; however, none of these compounds displayed any significant bioactivity. This study enriches the repertoire of bacterial terpenoids, offers a practical process for prioritizing strains for bacterial terpenoids discovery, and establishes a foundation for exploring terpenoid biosynthesis.

Koningipyridines A and B, two nitrogen-containing polyketides from the fungus Trichoderma koningiopsis SC-5

Two novel koninginin derivatives, koningipyridines A and B (1 and 2), along with four known compounds (3-6) were isolated from the EtOAc extract of the endophytic fungus Trichoderma koningiopsis SC-5. Among them, koningipyridine A featured an unprecedented pentacyclic ketal skeleton with the formation of a fascinating 6/6/5/6/5 fused ring system and shared a characteristic pyridine core, which represents the first example of nitrogen-containing koninginin-type natural product. Moreover, koningipyridine B was the first member in the koninginin family sharing a unique 6/6/5 dihydropyridine skeleton, and it was suggested to be the critical biosynthetic precursor of koningipyridine A. The structures of 1 and 2 were elucidated by the interpretation of 1D and 2D NMR spectroscopy, HRESIMS data, as well as theoretical calculations of 13C NMR and electronic circular dichroism (ECD). Moreover, all isolates were screened for antimicrobial activities against Staphylococcus aureus, MRSA, and Escherichia coli as well as the cytotoxic effects against three cancer cell lines (A549, Hela, and HepG2).

Koninginins X-Z, Three New Polyketides from Trichoderma koningiopsis SC-5

Koninginins X-Z (1-3), three novel polyketides, were isolated from the solid fermentation of the endophytic fungus Trichoderma koningiopsis SC-5. Their structures, including the absolute configurations, were comprehensively characterized by a combination of NMR spectroscopic methods, HRESIMS, 13C NMR, DFT GIAO 13C NMR, and electronic circular dichroism calculations as well as single crystal X-ray diffraction. In addition, all the compounds were evaluated for antifungal activity against Candida albicans.

Structures and Biological Activities of Secondary Metabolites from the Trichoderma genus (Covering 2018-2022)

Trichoderma, a genus with more than 400 species, has a long history of use as an industrial bioreactor, biofertilizer, and biocontrol agent. It is considered a significant source of secondary metabolites (SMs) that possess unique structural features and a wide range of bioactivities. In recent years, numerous secondary metabolites of Trichoderma, including terpenoids, polyketides, peptides, alkaloids, and steroids, have been identified. Most of these SMs displayed antimicrobial, cytotoxic, and antifungal effects. This review focuses on the structural diversity, biological activities, and structure-activity relationships (SARs) of the SMs isolated from Trichoderma covered from 2018 to 2022. This study provides insights into the exploration and utilization of bioactive compounds from Trichoderma species in the agriculture or pharmaceutical industry.

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.

Alkyl aromatic derivatives from the endophytic fungus Cytospora rhizophorae

Two new alkylresorcinols named herein 5'-methoxy-integracins A-B (1-2), two new monomeric alkyl aromatic derivatives 3-(7-hydroxyheptyl)-5-methoxyphenol (5) and 7-(3,5-dihydroxyphenyl) heptyl acetate (6), along with four known compounds including integracins A-B (3-4), 2,4-dihydroxy-6-(8-hydroxyoctyl) benzene (7), and cytosporone B (8) were isolated from the endophytic fungus Cytospora rhizophorae A761. The structures of the four new compounds were elucidated by NMR, HRESIMS data, and electronic circular dichroism (ECD) calculations, whereas the compounds 1 and 2 were disclosed as a class of the natural rare-occurring dimeric alkylresorcinol derivatives. Moreover, the bioassays of the new compounds clarified that compound 1 was a potent inhibitor for the α-glucosidase, and compound 2 showed relatively good activity against the tumor cell lines. It is worth mentioning that the known compound integracin B (4) was first reported to display significant antibacterial activity against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) with MIC values of 6.25 μg ml^-1.

Trichoderma species from plant and soil: An excellent resource for biosynthesis of terpenoids with versatile bioactivities

BACKGROUND

Trichoderma species are rich source of bioactive secondary metabolites. In the past decades, a series of secondary metabolites were reported from different Trichoderma fungi, among which terpenoids possessing versatile structural diversities and extensive pharmacological activities are one of the particularly important categories.

AIM OF REVIEW

The review aims to summarize the terpenoids isolated from Trichoderma species regarding their structural diversities, biological activities, and promising biosynthetic potentials.

KEY SCIENTIFIC CONCEPTS OF REVIEW

So far, a total of 253 terpenoids, including 202 sesquiterpenes, 48 diterpenes, 2 monoterpenes and 1 meroterpenoid, were isolated and identified from Trichoderma species between 1948 and 2022. Pharmacological investigations of Trichoderma terpenoids mainly focused on their antibacterial activities, antifungal activities, inhibitory activities on marine plankton species and cytotoxic activities, indicating that Trichoderma species are important microbial agents for drug discovery and environmentally friendly agrochemicals development. Intriguing chemistry and enzymology involved in the biosynthesis of Trichoderma terpenoids were also presented to facilitate further precise genome mining-guided novel structure discovery. Taken together, the abundance of novel skeletons, bioactivities and biosynthetic potentials presents new opportunities for drug and agrochemicals discovery, genome mining and enzymology exploration from Trichoderma species. The work will provide references for the profound study of terpenoids derived from Trichoderma, and facilitate further studies on Trichoderma species in the areas of chemistry, medicine, agriculture and microbiology.

Neocucurbols A-H, Phomactin Diterpene Derivatives from the Marine-Derived Fungus Neocucurbitaria unguis-hominis FS685

Neocucurbols A-D (1-4) are diterpene derivatives that possess a complex 6/6/5/5/6 polycyclic ring system with a characteristic tetrahedrofuran bridge ring skeleton. Neocucurbols E-H (5-8) are diterpenes that feature a 6/8/6 tricyclic ring system. Their structures were unambiguously determined by detailed spectroscopic analyses, X-ray diffractions studies, and ECD calculations. All compounds (1-8) were evaluated for in vitro antimicrobial and cytotoxic activities.

Altereporenes A-E, five epoxy octa-hydronaphthalene polyketides produced by an endophytic fungus Alternaria sp. YUD20002

Five previously undescribed epoxy octa-hydronaphthalene polyketides, altereporenes A-E (1-5) were isolated from rice culture of the endophytic fungus Alternaria sp. YUD20002 derived from the tubers of Solanum tuberosum. Their structures were determined on the basis of comprehensive spectroscopic analyses, while the absolute configurations were elucidated by the comparison of experimental and calculated specific rotations. Meanwhile, the antimicrobial, cytotoxic, anti-inflammatory and acetylcholinesterase inhibitory activities of compounds 1-5 were also investigated.

Identification of Two Fungal Pathogens Responsible for Liriodendron chinense × tulipifera Black Spot and Screening of Trichoderma sp. for Disease Control

Liriodendron chinense × tulipifera black spot is a newly discovered disease that causes yellowing and early shedding of leaves, affecting the growth of Liriodendron trees, and significantly reducing their ornamental value as a garden species. The pathogen responsible for this disease, and how it can be prevented and controlled, are not clear. In this study, the occurrence of this disease was first investigated according to Koch's postulates, and the primary pathogens causing Liriodendron black spot were determined to be Colletotrichum gloeosporioides and Alternaria alternata. Biocontrol strains antagonistic to these two pathogens were then screened from the leaf microorganisms of L. chinense × tulipifera, and a preliminary investigation of the biological control of Liriodendron black spot was performed. Through the screening of antagonistic microorganisms on the leaf surface of L. chinense × tulipifera, the strain Trichoderma koningiopsis T2, which displayed strong antagonism against C. gloeosporioides and A. alternata, was obtained. The T2 strain could inhibit the growth of the two pathogens via three mechanisms: hyperparasitism, volatile and nonvolatile metabolite production, and environmental acidification. The biocontrol experiments in the greenhouse and field showed that initial spraying with a T. koningiopsis T2 spore suspension followed by the two pathogens resulted in the lowest disease incidence. These results confirmed the black spot pathogens of L. chinense × tulipifera, clarified the antagonistic mechanism of T. koningiopsis T2 against the two pathogens, and provided a theoretical basis and technical support for the biological control of the disease.

Bioactive terpenoids derived from plant endophytic fungi: An updated review (2011-2020)

Plant endophytes have been considered as novel sources of naturally occurring compounds with various biological activities, including cytotoxic, antimicrobial, anti-inflammatory, anticancer, herbicides, antileishmanial and antioxidant. A variety of specialised products, comprising terpenoids, alkaloids, polyketides, phenolic compounds, coumarins, and quinone derivatives have been reported from various strains. An increasing number of products, especially terpenoids, are being isolated from endophytes. Herein, the isolated new terpenoids from plant endophytic fungi, their hosts, as well as biological activities, from January 2011 until the end of 2020 are reviewed. In this period, 516 terpenoids are classified into monoterpenes (5), sesquiterpenes (299), diterpenes (76), sesterterpens (22), meroterpenes (83), triterpenes (29), and other terpenoids (2), were isolated from different plant endophytic fungi species.

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).

Antimicrobial Diterpenes: Recent Development From Natural Sources

Antimicrobial resistance has been posing an alarming threat to the treatment of infectious diseases over the years. Ineffectiveness of the currently available synthetic and semisynthetic antibiotics has led the researchers to discover new molecules with potent antimicrobial activities. To overcome the emerging antimicrobial resistance, new antimicrobial compounds from natural sources might be appropriate. Secondary metabolites from natural sources could be prospective candidates in the development of new antimicrobial agents with high efficacy and less side effects. Among the natural secondary metabolites, diterpenoids are of crucial importance because of their broad spectrum of antimicrobial activity, which has put it in the center of research interest in recent years. The present work is aimed at reviewing recent literature regarding different classes of natural diterpenes and diterpenoids with significant antibacterial, antifungal, antiviral, and antiprotozoal activities along with their reported structure-activity relationships. This review has been carried out with a focus on relevant literature published in the last 5 years following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 229 diterpenoids from various sources like plants, marine species, and fungi are summarized in this systematic review, including their chemical structures, classification, and significant antimicrobial activities together with their reported mechanism of action and structure-activity relationships. The outcomes herein would provide researchers with new insights to find new credible leads and to work on their synthetic and semisynthetic derivatives to develop new antimicrobial agents.

The diterpenoid alkaloids

The diterpenoid alkaloids are a family of extremely important natural products that have long been a research hotspot due to their myriad of intricate structures and diverse biological properties. This chapter systematically summarizes the past 11 years (2009-2019) of studies on the diterpenoid alkaloids, including the "so-called" atypical ones, covering the classification and biogenetic relationships, phytochemistry together with 444 new alkaloids covering 32 novel skeletons and the corrected structures, chemical reactions including conversion toward toxoids, synthetic studies, as well as biological activities. It should be noted that the synthetic studies, especially the total syntheses of various diterpenoid alkaloids, are for the first time reviewed in this treatise. This chapter, in combination with our four previous reviews in volumes 42, 59, 67, and 69, will present to the readers a more completed and updated profile of the diterpenoid alkaloids.

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).

Fungal Endophytes: A Potential Source of Antibacterial Compounds

Antibiotic resistance is becoming a burning issue due to the frequent use of antibiotics for curing common bacterial infections, indicating that we are running out of effective antibiotics. This has been more obvious during recent corona pandemics. Similarly, enhancement of antimicrobial resistance (AMR) is strengthening the pathogenicity and virulence of infectious microbes. Endophytes have shown expression of various new many bioactive compounds with significant biological activities. Specifically, in endophytic fungi, bioactive metabolites with unique skeletons have been identified which could be helpful in the prevention of increasing antimicrobial resistance. The major classes of metabolites reported include anthraquinone, sesquiterpenoid, chromone, xanthone, phenols, quinones, quinolone, piperazine, coumarins and cyclic peptides. In the present review, we reported 451 bioactive metabolites isolated from various groups of endophytic fungi from January 2015 to April 2021 along with their antibacterial profiling, chemical structures and mode of action. In addition, we also discussed various methods including epigenetic modifications, co-culture, and OSMAC to induce silent gene clusters for the production of noble bioactive compounds in endophytic fungi.

Endophytic Fungal Terpenoids: Natural Role and Bioactivities

Endophytic fungi are a highly diverse group of fungi that intermittently colonize all plants without causing symptoms of the disease. They sense and respond to physiological and environmental changes of their host plant and microbiome. The inter-organism interactions are largely driven by chemical networks mediated by specialized metabolites. The balance of these complex interactions leads to healthy and strong host plants. Endophytic strains have particular machinery to produce a plethora of secondary metabolites with a variety of bioactivities and unknown functions in an ecological niche. Terpenoids play a key role in endophytism and represent an important source of bioactive molecules for human health and agriculture. In this review, we describe the role of endophytic fungi in plant health, fungal terpenoids in multiple interactions, and bioactive fungal terpenoids recently reported from endophytes, mainly from plants used in traditional medicine, as well as from algae and mangroves. Additionally, we highlight endophytic fungi as producers of important chemotherapeutic terpenoids, initially discovered in plants. Despite advances in understanding endophytism, we still have much to learn in this field. The study of the role, the evolution of interactions of endophytic fungi and their terpenoids provide an opportunity for better applications in human health and agriculture.

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

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

Sesquiterpenoids Specially Produced by Fungi: Structures, Biological Activities, Chemical and Biosynthesis (2015-2020)

Fungi are widely distributed in the terrestrial environment, freshwater, and marine habitat. Only approximately 100,000 of these have been classified although there are about 5.1 million characteristic fungi all over the world. These eukaryotic microbes produce specialized metabolites and participate in a variety of ecological functions, such as quorum detection, chemical defense, allelopathy, and maintenance of symbiosis. Fungi therefore remain an important resource for the screening and discovery of biologically active natural products. Sesquiterpenoids are arguably the richest natural products from plants and micro-organisms. The rearrangement of the 15 high-ductility carbons gave rise to a large number of different skeletons. At the same time, abundant structural variations lead to a diversification of biological activity. This review examines the isolation, structural determination, bioactivities, and synthesis of sesquiterpenoids that were specially produced by fungi over the past five years (2015-2020).

The chemical diversity, the attractant, anti-acetylcholinesterase, and antifungal activities of metabolites from biocontrol Trichoderma harzianum uncovered by OSMAC strategy

Eight new compounds (1-8) were discovered from Trichoderma harzianum associated with edible mushroom by the one strain many compounds (OSMAC) strategy. Triharzianin A (1) is the first naturally scaffold characterized by a C₁₃-prostaglandin skeleton. The configurations of 1-3, and 5 were determined by the Mosher's method, experimental and calculated ECD spectra, and plausible biosynthesis of stereospecific epoxidation. Most compounds indicated obvious feeding attractant activities to silkworm with attraction rates at 30-90%. Compound 7 showed anti-acetylcholinesterase (anti-AChE) activity with a ratio of 29% at a concentration of 50 μM for insecticidal potential. So 2,​3-​dialkylchromone (7) had potential of chemical entrapment and killing of insects. Compounds 2, 3 and 7-11 showed antifungal activities against Aspergillus fumigates, and Trichoderma sp. from mushroom with MICs ≤ 300 μM. The four fermentation extracts also indicated obvious feeding attractant activities to silkworm for the activities brought by active metabolites from T. harzianum. The material base of biocontrol induced by the interaction of host-fungal symbiont can be investigated by the antifungal metabolites against pathogen fungi.

A review: Research progress on microplastic pollutants in aquatic environments

The ubiquitous problems of microplastics in waters are receiving global attention as microplastics can harm aquatic organisms, and finally can accumulate in the human body through biological chain amplification. In addition, microplastics act as a carrier capable of carrying heavy metals, organics, which form complex pollutants. These new combinations of pollutants, once ingested by aquatic organisms, are amplified through the food chain and can have unpredictable ramifications for aquatic organisms and human beings. Therefore, human beings are not only the source of plastic pollution, but also the sink of microplastic pollution. Therefore, this study reviews the source and distribution of microplastics, and their combined ability with heavy metals, antibiotics, and persistent organic pollutants in aquatic environments. Furthermore, it describes the interaction between aquatic organisms and microplastics. Finally, some suggestions are put forward to promote the sustainable application of microplastics. This work provides theoretical guidance for combining microplastics with other pollutants in water, and the accumulation of microplastics in food chain.

New alkaloids from the diversity-enhanced extracts of an endophytic fungus Aspergillus flavus GZWMJZ-288

Three new alkaloids (1-3) together with four previously reported compounds (4-7) were identified from the extracts and the diversity-enhanced extracts of the fermentation broth of the endophytic fungus, Aspergillus flavus GZWMJZ-288 associated with Garcinia multiflora. The structures of new compounds were respectively determined as 19-amino-19-dehydroxy 5-epi-α-cyclopiazonic acid (1), 2-hydroxymethyl-5-(3-oxobutan-2-yl)aminopyran-4(4H)-one (2) and 4-amino-2-hydroxymethylpyridin-5-ol (3) by spectroscopic analysis, ECD calculation and X-ray single crystal diffraction. Compounds 1 and 4 with 19-enamine were dynamic equilibrium of Z- and E- isomers in the solution but favored in Z- isomers in the solid state, while compound 7 with 19-enol was favored in Z- isomer in the solution but a mixture of Z- and E- isomers in solid state. This phenomenon could be explained by the quantum-mechanical energies calculations. Among the isolated compounds 1-7, compounds 1, 4 and 7 with a rare 1,3,4,5-tetrahydro-1-azaacenaphtho[3,4-c]pyrrolizidine skeleton showed α-glucosidase inhibitory activity with the IC₅₀ values of 41.97 ± 0.97, 232.57 ± 11.45 and 243.95 ± 3.36 μM, respectively, and the binding modes were performed by silico docking studies.

Combined Comparative Genomics and Gene Expression Analyses Provide Insights into the Terpene Synthases Inventory in Trichoderma

Trichoderma is a fungal genus comprising species used as biocontrol agents in crop plant protection and with high value for industry. The beneficial effects of these species are supported by the secondary metabolites they produce. Terpenoid compounds are key players in the interaction of Trichoderma spp. with the environment and with their fungal and plant hosts; however, most of the terpene synthase (TS) genes involved in their biosynthesis have yet not been characterized. Here, we combined comparative genomics of TSs of 21 strains belonging to 17 Trichoderma spp., and gene expression studies on TSs using T. gamsii T6085 as a model. An overview of the diversity within the TS-gene family and the regulation of TS genes is provided. We identified 15 groups of TSs, and the presence of clade-specific enzymes revealed a variety of terpenoid chemotypes evolved to cover different ecological demands. We propose that functional differentiation of gene family members is the driver for the high number of TS genes found in the genomes of Trichoderma. Expression studies provide a picture in which different TS genes are regulated in many ways, which is a strong indication of different biological functions.

Endophytic Trichoderma Species Isolated from Persea americana and Cinnamomum verum Roots Reduce Symptoms Caused by Phytophthora cinnamomi in Avocado

Avocado root rot caused by the oomycete Phytophthora cinnamomi is a severe disease that affects avocado production in Mexico and worldwide. The use of biological control agents such as Trichoderma species isolated from places where the disease is always present, represents an efficient alternative to reduce losses. Thus, the objective of this research was to evaluate the biocontrol ability of 10 endophytic Trichoderma spp. strains against P. cinnamomi tested both in vitro and in the greenhouse. The endophytic Trichoderma spp. were recovered from Persea americana and Cinnamomum verum roots, isolated and purified on potato-dextrose-agar medium. Ten strains were identified by phylogenetic reconstruction of the internal transcribed spacer region of rDNA sequences as T. asperellum (T-AS1, T-AS2, T-AS6, and T-AS7), T. harzianum (T-H3, T-H4, and T-H5), T. hamatum (T-A12), T. koningiopsis (T-K8 and T-K11), and P. cinnamomi (CPO-PCU). In vitro dual-culture assay, the percentage of inhibition of radial growth (PIRG) between Trichoderma spp. and P. cinnamomi strains was measured according to the Bell's scale. PIRG results indicated that T-AS2 reached the highest value of 78.32%, and T-H5 reached the lowest value of 38.66%. In the greenhouse, the infection was evaluated according to the percentage of disease incidence. Plants with the lowest incidence of dead by avocado root rot were those whose seedlings were inoculated with T-AS2 and T-AS7, resulting in only 5% death by root rot caused by P. cinnamomi. The disease incidence of seedlings with wilt symptoms and death decreased more than 50% in the presence of Trichoderma spp. Relying on the results, we conclude that T. asperellum and T. harzianum contribute to the biocontrol of soil-borne pathogenic oomycete P. cinnamomi.

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.

Progress on Terpenoids With Biological Activities Produced by Plant Endophytic Fungi in China Between 2017 and 2019

Plant endophytic fungi are an important part of plant microecosystems and a natural resource for human survival and development. Various bioactive natural products produced by plant endophytic fungi show promising prospects in biopharmacy, agricultural production, and industrial fermentation. Terpenoids, the most numerous and structurally diverse natural products from endophytic fungi, possess a broad range of biological activities and huge potential for drug development. It is critically significant for ecological and economic benefits to develop their activities. This paper utilized literature analysis to summarize 200 terpenoids with biological activities that are derived from plant endophytic fungi in China between 2017 and 2019. Among them, sesquiterpenoids were the most important kind of terpenoids, and Trichoderma and Aspergillus species were main terpenoid-producing plant endophytic fungi. Furthermore, these terpenoids displayed multifarious biological activities, including antimicrobial, antipathogenic, and anti-inflammatory activities, as well as cytotoxicity, antitumor agents, and enzyme inhibition.

Isolation, diversity, and antimicrobial activity of fungal endophytes from Rohdea chinensis (Baker) N.Tanaka (synonym Tupistra chinensis Baker) of Qinling Mountains, China

Endophytic fungi have been emerged as fruitful resources for producing structurally fascinating and biologically active secondary metabolites. However, endophytic fungi from medicinal plants of Qinling Mountains–the most important natural climatic boundary between the subtropical and warm temperate zones of China with an astonishingly high level of biodiversity–have rarely been explored as potential sources of novel fungal species and active secondary metabolites. In this study, a total of 371 fungal colonies were successfully isolated from 510 tissue segments of the medicinal Tupistra chinensis Baker collected from Qinling Mountains, China. Roots of T. chinensis Baker are used as a folk medicine to ameliorate pharyngitis and treat rheumatic diseases. A total of 100 representative morphotype strains were identified according to ITS rDNA sequence analyses and were grouped into three phyla (Ascomycota, Basidiomycota, Mucoromycota), seven classes (Dothideomycetes, Sordariomycetes, Eurotiomycetes, Microbotryomycetes, Agaricomycetes, Leotiomycetes, Mortierellomycetes), and at least 35 genera. The genera of Collectotrichum (IF, 29.92%), Fusarium (IF, 8.36%), Aspergillus (IF, 8.09%), and Dactylonectria (IF, 5.39%) were most frequently isolated from the tissues of T. chinensis Baker. The Species Richness Index (S, 65) and the Shannon-Wiener Index (H′, 3.7914) indicated that T. chinensis Baker harbored abundant fungal resources. Moreover, five isolates were potential new taxa because of low similarity of ITS sequences ranged from 95.09%∼96.61%. Fifteen out of 100 endophytic fungal ethyl acetate extracts exhibited inhibitory activities against at least one pathogenic bacterium or fungus. Two important lead compounds produced by two stains (F8047 and F8075) with high antimicrobial activities were identified using high performance liquid chromatography (HPLC) and ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC–QTOF MS) analyses. In addition, it was noteworthy that the strain F8001, which may be a potential new species, showed antimicrobial activity and should be investigated further. Overall, these results indicated that the endophytic fungi from T. chinensis Baker could be exploited as a novel source of bioactive compounds.

Recent progress of antibacterial natural products: Future antibiotics candidates

The discovery of novel antibacterial molecules plays a key role in solving the current antibiotic crisis issue. Natural products have long been an important source of drug discovery. Herein, we reviewed 256 natural products from 11 structural classes in the period of 2016-01/2020, which were selected by SciFinder with new compounds or new structures and MICs lower than 10 μg/mL or 10 μM as criterions. This review will provide some effective antibacterial lead compounds for medicinal chemists, which will promote the antibiotics research based on natural products to the next level.

Photeroids A and B, unique phenol–sesquiterpene meroterpenoids from the deep-sea-derived fungus Phomopsis tersa

Photeroids A (1) and B (2), two structurally fascinating meroterpenoids, were isolated from the deep-sea-derived fungus Phomopsis tersa FS441.

Phomeroids A and B: two novel cytotoxic meroterpenoids from the deep-sea-derived fungus Phomopsis tersa FS441

Phomeroids A (1) and B (2), two novel meroterpenoids representing two types of skeletons, together with one known homologous analogue (3) were isolated from the deep-sea-derived fungus Phomopsis tersa FS441.

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.

Tersone A-G, New Pyridone Alkaloids from the Deep-Sea Fungus Phomopsis tersa

Four phenylfuropyridone racemates, (±)-tersones A-C and E (1–3, 5), one phenylpyridone racemate, (±)-tersone D (4), one new pyridine alkaloid, tersone F (6), single new phenylfuropyridone, tersone G (7) and two known analogs 8 and 9 were isolated from the deep-sea fungus Phomopsis tersa. Their structures and absolute configurations were characterized on the basis of comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments, and electronic circular dichroism (ECD) calculations. Moreover, compounds 1–9 were evaluated for in vitro antimicrobial and cytotoxic activity. Compounds 5b and 8b exhibited antibacterial activity against S. aureus with the MIC value of 31.5 μg/mL, while compound 5b showed cytoxic activities against SF-268, MCF-7, HepG-2 and A549 cell lines with IC₅₀ values of 32.0, 29.5, 39.5 and 33.2 μM, respectively.