Trichodermanin A, a novel diterpenoid from endophytic fungus culture

Chemistry and biology of marine-derived Trichoderma metabolites

Marine-derived fungi of the genus Trichoderma have been surveyed for pharmaceuticals and agrochemicals since 1993, with various new secondary metabolites being characterized from the strains of marine animal, plant, sediment, and water origin. Chemical structures and biological activities of these metabolites are comprehensively reviewed herein up to the end of 2022 (covering 30 years). More than 70 strains that belong to at least 18 known Trichoderma species have been chemically investigated during this period. As a result, 445 new metabolites, including terpenes, steroids, polyketides, peptides, alkaloids, and others, have been identified, with over a half possessing antimicroalgal, zooplankton-toxic, antibacterial, antifungal, cytotoxic, anti-inflammatory, and other activities. The research is highlighted by the molecular diversity and antimicroalgal potency of terpenes and steroids. In addition, metabolic relevance along with co-culture induction in the production of new compounds is also concluded. Trichoderma strains of marine origin can transform and degrade heterogeneous molecules, but these functions need further exploration.

Enantioselective Syntheses of Wickerols A and B

The evolution of a successful strategy for the synthesis of the strained, cage-like antiviral diterpenoids wickerols A and B is described. Initial attempts to access the carbocyclic core were surprisingly challenging and in retrospect, presaged the many detours needed to ultimately arrive at the fully adorned wickerol architecture. In most cases, conditions to trigger desired outcomes with respect to both reactivity and stereochemistry were hard-won. The successful synthesis ultimately leveraged alkenes in virtually all productive bond-forming events. A series of conjugate addition reactions generated the fused tricyclic core, a Claisen rearrangement was used to install an otherwise unmanageable methyl-bearing stereogenic center, and a Prins cyclization closed the strained bridging ring. This final reaction proved enormously interesting because the strain of the ring system permitted diversion of the presumed initial Prins product into several different scaffolds.

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.

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.

Diterpenes Specially Produced by Fungi: Structures, Biological Activities, and Biosynthesis (2010–2020)

Fungi have traditionally been a very rewarding source of biologically active natural products, while diterpenoids from fungi, such as the cyathane-type diterpenoids from Cyathus and Hericium sp., the fusicoccane-type diterpenoids from Fusicoccum and Alternaria sp., the guanacastane-type diterpenoids from Coprinus and Cercospora sp., and the harziene-type diterpenoids from Trichoderma sp., often represent unique carbon skeletons as well as diverse biological functions. The abundances of novel skeletons, biological activities, and biosynthetic pathways present new opportunities for drug discovery, genome mining, and enzymology. In addition, diterpenoids peculiar to fungi also reveal the possibility of differing biological evolution, although they have similar biosynthetic pathways. In this review, we provide an overview about the structures, biological activities, evolution, organic synthesis, and biosynthesis of diterpenoids that have been specially produced by fungi from 2010 to 2020. We hope this review provides timely illumination and beneficial guidance for future research works of scholars who are interested in this area.

Endophytic Fungi: An Effective Alternative Source of Plant-Derived Bioactive Compounds for Pharmacological Studies

Plant-associated fungi (endophytic fungi) are a biodiversity-rich group of microorganisms that are normally found asymptomatically within plant tissues or in the intercellular spaces. Endophytic fungi promote the growth of host plants by directly producing secondary metabolites, which enhances the plant's resistance to biotic and abiotic stresses. Additionally, they are capable of biosynthesizing medically important "phytochemicals" that were initially thought to be produced only by the host plant. In this review, we summarized some compounds from endophyte fungi with novel structures and diverse biological activities published between 2011 and 2021, with a focus on the origin of endophytic fungi, the structural and biological activity of the compounds they produce, and special attention paid to the exploration of pharmacological activities and mechanisms of action of certain compounds. This review revealed that endophytic fungi had high potential to be harnessed as an alternative source of secondary metabolites for pharmacological studies.

Identification and Bioactivities of Secondary Metabolites Derived from Endophytic Fungi Isolated from Ethnomedicinal Plants of Tujia in Hubei Province: A Review

Tujia is a national minority, inhabiting in the mountainous Wuling area in China. Since 1978, Tujia medicine has been studied, summarized and developed, leading to numerous achievements by Chinese researchers, such as the publishing of approximately 30 monographs of Tujia medicine. These publications are focused on summarizing and improving the theory of Tujia medicine and developing clinical therapies from this system of medicine. The shortage of natural medicinal plants used in Tujia medicine has created the need to discover new resources to replace them and protect endangered natural plant species. Endophytic fungi are one of the conservation options, are considered a source of new bioactive natural products, and are a renewable and inexhaustible source of new drugs and agrochemicals. This review summarizes 260 compounds from endophytic fungi that have been previously isolated from the medicinal plants of Tujia. These compounds include steroids, terpenoids, meroterpenoids, polyketides, alkaloids, peptides, aliphatic compounds, aromatic compounds, and heterocyclic compounds.

Divergent Synthesis of Antiviral Diterpenes Wickerols A and B

Wickerols A and B are diterpene natural products that have a novel fused 6-5-6-6 ring framework and exhibit potent antiviral activity against the H1N1 type A influenza virus. Herein, we report a divergent synthesis of wickerols A and B in 16 and 15 steps, respectively, from commercial sitolactone. The key reactions of the synthesis are a SmI₂-mediated intramolecular ketone-allylic acetate reductive cyclization, a Claisen rearrangement, and an intramolecular alkylation/aldol reaction that rapidly assembled the compact tetracyclic core framework in a stereocontrolled manner. The work described herein allowed us to confirm the absolute configurations of wickerols A and B.

New Diterpenes with a Fused 6-5-6-6 Ring System Isolated from the Marine Sponge-Derived Fungus Trichoderma harzianum

New diterpenes, namely, trichodermanins F–H, with a fused 6-5-6-6 ring system were isolated from the fungus Trichoderma harzianum OUPS-111D-4 separated from a marine sponge Halichondria okadai. These chemical structures were elucidated by 1D and 2D NMR as well as high-resolution fast atom bombardment mass spectrometry (HRFABMS) spectral analyses. We established their absolute stereostructures by application of the modified Mosher’s method or circular dichroism (CD) spectroscopy. In addition, their cytotoxicities were assessed using several cancer cell lines, with 1 and 2 exhibiting modest activities.

Trichodermadiones A and B from the solid culture of Trichoderma atroviride S361, an endophytic fungus in Cephalotaxus fortunei

Chemical investigation on the solid rice culture of Trichoderma atroviride S361, an endophyte isolated from Cephalotaxus fortunei, has afforded a pair of novel N-furanone amide enantiomers, (-)-trichodermadione A (1a) and (+)-trichodermadione A (1b), and a new cyclohexenone sesquiterpenoid, trichodermadione B (2), together with six known secondary metabolites. Chiral separation of compound 1 was successfully performed on a Lux Cellulose-2 column. Their structures were elucidated by detailed spectroscopic analyses on the basis of NMR, HRMS, and ECD data, and the absolute configurations of the new compounds were determined by computational analyses of their electronic circular dichroism (ECD) spectra and Snatzke's method. Compounds 1a, 1b and 2 were also evaluated for their cytotoxicity against DU145 and PC3 cell lines, as well as inhibitory effects against the production of NO in LPS-stimulated RAW264.7 cells.

Trichodermanins C-E, New Diterpenes with a Fused 6-5-6-6 Ring System Produced by a Marine Sponge-Derived Fungus

Trichodermanins C–E (1–3), new diterpenes with a rare fused 6-5-6-6 ring system, have been isolated from a fungus Trichoderma harzianum OUPS-111D-4 separated from a piece of a marine sponge Halichondria okadai, and these chemical structures have been established by spectroscopic analyses using IR, MASS, HRFABMS, and NMR spectra. We established their absolute stereostructures by application of the modified Mosher’s method. In addition, 1 inhibited the growth of cancer cell lines potently.

The Terpenoid Biosynthesis Toolkit of Trichoderma

The widely used biotechnologically important fungi belonging to the genus Trichoderma are rich sources of secondary metabolites. Even though the genomes of several Trichoderma spp. have been published, and data are available on the genes involved in biosynthesis of non-ribosomal peptide synthetases and polyketide synthases, no genome-wide data are available for the terpenoid biosynthesis machinery in these organisms. In the present study, we have identified the genes involved in terpene biosynthesis in the genomes of three Trichoderma spp., viz., T. virens, T. atroviride and T. reesei. While the genes involved in the condensation steps are highly conserved across the three species, these fungi differed in the number and organization of terpene cyclases. T. virens genome harbours eleven terpene cyclases, while T. atroviride harbours seven, and T. reeseisix in their genomes; seven, three and two being part of putative secondary metabolism related gene clusters.

Fungal natural products in research and development

To date approximately 100 000 fungal species are known although far more than one million are expected. The variety of species and the diversity of their habitats, some of them less exploited, allow the conclusion that fungi continue to be a rich source of new metabolites. Besides the conventional fungal isolates, an increasing interest in endophytic and in marine-derived fungi has been noticed. In addition new screening strategies based on innovative chemical, biological, and genetic approaches have led to novel fungal metabolites in recent years. The present review focuses on new fungal natural products published from 2009 to 2013 highlighting the originality of the structures and their biological potential. Furthermore synthetic products based on fungal metabolites as well as new developments in the uses or the biological activity of known compounds or new derivatives are discussed.

Chemical Constituents from an Endophytic Fungus Chaetomium Globosum Z1

A new ergosterol, 15β-hydroxyl-(22 E,24 R)-ergosta-3,5,8,22-tetraen-one (1), along with three known ergosterols, two known cytochalasins, and two known azapholines were isolated from Chaetomium globosum Z1. The structures of these compounds were elucidated on the basis of spectroscopic methods (HR-ESI-MS, 1D NMR, and 2D NMR). Compound 6 showed significant cytotoxic activity against A-549 and MG-63 cell lines with IC50 values of 6.96 and 1.73 μg/mL, respectively.

Cytotoxic metabolites from Perenniporia tephropora, an endophytic fungus from Taxus chinensis var. mairei

Based on bioactivity-oriented isolation, the EtOAc extract of a culture broth of the endophytic fungus Perenniporia tephropora Z41 from Taxus chinensis var. mairei, with strong anti-Pyricularia oryzae activity, afforded a new sesquiterpenoid, perenniporin A (1), together with three known compounds, ergosterol (2), rel-(+)-(2aR,5R,5aR,8S,8aS,8bR)-decahydro-2,2,5,8-tetramethyl-2H-naphtho[1,8-bc]genfuran-5-ol (3), and albicanol (4). Their structures were elucidated by means of spectroscopic methods. All the isolated compounds and the EtOAc extract of P. tephropora Z41 (EPT) were evaluated for their cytotoxic activity against three human cancer cell lines (HeLa, SMMC-7721, and PANC-1). EPT demonstrated significant cytotoxicity with IC(50) values ranging from 2 to 15 μg/mL. Compound 2 was the most cytotoxic constituent against the tested cell lines with IC(50) values of 1.16, 11.63, and 11.80 μg/mL, respectively, while compounds 1, 3, and 4 exhibited moderate cytotoxicity with IC(50) values ranging from 6 to 58 μg/mL. We conclude that the endophytic fungus P. tephropora is a promising source of novel and cytotoxic metabolites.

Sesquiterpenoids from Trichoderma atroviride, an endophytic fungus in Cephalotaxus fortunei

Two new sesquiterpenoids, identified as (rel 1S, 3R, 4R, 7R)-3-[5-hydroxy-4-methylpent-3-enyl]-1, 3, 7-trimethyl-2-oxabicyclo [2, 2, 1] heptane (1) and (rel 1S, 3R, 4R, 7R)-3-[3, 4-dihydroxy-4-methylpentyl]-1, 3, 7-trimethyl-2-oxabicyclo [2, 2, 1] heptane (2), were isolated from cultures of Trichoderma atroviride (strain no. S361), an endophytic fungal strain residing in the bark of Cephalotaxus fortunei. The structures of compounds 1 and 2 were elucidated by detailed spectroscopic analyses on the basis of NMR, IR, and MS data. Both compounds 1 and 2 were potent inhibitors on NO production in LPS-stimulated RAW264.7 cells, with IC₅₀ values of 15.3 and 9.1μM, respectively.