Phomopsichin A-D; Four New Chromone Derivatives from Mangrove Endophytic Fungus Phomopsis sp. 33

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.

The hidden treasures in endophytic fungi: a comprehensive review on the diversity of fungal bioactive metabolites, usual analytical methodologies, and applications

This review provides a comprehensive overview of the key aspects of the natural metabolite production by endophytic fungi, which has attracted significant attention due to its diverse biological activities and wide range of applications. Synthesized by various fungal species, these metabolites encompass compounds with therapeutic, agricultural, and commercial significance. We delved into strategies and advancements aimed at optimizing fungal metabolite production. Fungal cultivation, especially by Aspergillus, Penicillium, and Fusarium, plays a pivotal role in metabolite biosynthesis, and researchers have explored both submerged and solid-state cultivation processes to harness the full potential of fungal species. Nutrient optimization, pH, and temperature control are critical factors in ensuring high yields of the targeted bioactive metabolites especially for scaling up processes. Analytical methods that includes High-Performance Liquid Chromatography (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS), Gas Chromatography-Mass Spectrometry (GC-MS), Nuclear Magnetic Resonance (NMR), and Mass Spectrometry (MS), are indispensable for the identification and quantification of the compounds. Moreover, genetic engineering and metabolic pathway manipulation have emerged as powerful tools to enhance metabolite production and develop novel fungal strains with increased yields. Regulation and control mechanisms at the genetic, epigenetic, and metabolic levels are explored to fine-tune the biosynthesis of fungal metabolites. Ongoing research aims to overcome the complexity of the steps involved to ensure the efficient production and utilization of fungal metabolites.

Phomopamide A, a cyclic pentadepsipeptide with α-glucosidase inhibition activity from the endophytic fungus Diaporthe sp

An undescribed cytotoxic cyclopeptide named phomopamide A (1) was isolated from Diaporthe sp., which is an endophytic fungus from Artemisia argyi. Phomopamide A (1) featured an pentadepsipeptide skeleton and composed of two Phe, one Val, one Leu, and one 2-hydroxyoctanoic acid units. The structure of this new compound was fully characterised on the basis of extensive spectroscopic analysis. Moreover, phomopamide A was evaluated for in vitro cyctotoxic and α-glucosidase inhibitory activity. As a result, phomopaminde A exhibited no cytotoxic activity against four tumour cell lines, while it showed a potent α-glucosidase inhibition effect with IC50 value of 62.35 µM.

Endophytic fungi: a potential source for drugs against central nervous system disorders

Neuroprotection is one of the important protection methods against neuronal cells and tissue damage caused by neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, and multiple sclerosis. Various bioactive compounds produced by medicinal plants can potentially treat central nervous system (CNS) disorders. Apart from these resources, endophytes also produce diverse secondary metabolites capable of protecting the CNS. The bioactive compounds produced by endophytes play essential roles in enhancing the growth factors, antioxidant defence functions, diminishing neuroinflammatory, and apoptotic pathways. The efficacy of compounds produced by endophytic fungi was also evaluated by enzymes, cell lines, and in vivo models. Acetylcholine esterase (AChE) inhibition is frequently used to assess in vitro neuroprotective activity along with cytotoxicity-induced neuronal cell lines. Some of drugs, such as tacrine, donepezil, rivastigmine, galantamine, and other compounds, are generally used as reference standards. Furthermore, clinical trials are required to confirm the role of these natural compounds in neuroprotection efficacy and evaluate their safety profile. This review illustrates the production of various bioactive compounds produced by endophytic fungi and their role in preventing neurodegeneration.

Anti-Alzheimer's Natural Products Derived from Plant Endophytic Fungi

Alzheimer's is the most common cause of dementia worldwide and seriously affects patients' daily tasks. Plant endophytic fungi are known for providing novel and unique secondary metabolites with diverse activities. This review focuses primarily on the published research regarding anti-Alzheimer's natural products derived from endophytic fungi between 2002 and 2022. Following a thorough review of the literature, 468 compounds with anti-Alzheimer's-related activities are reviewed and classified based on their structural skeletons, primarily including alkaloids, peptides, polyketides, terpenoids, and sterides. The classification, occurrences, and bioactivities of these natural products from endophytic fungi are summarized in detail. Our results provide a reference on endophytic fungi natural products that may assist in the development of new anti-Alzheimer's compounds.

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.

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.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

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.

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.

Xanthone-derived polyketides from the Thai mangrove endophytic fungus Phomopsis sp. xy21

Six new xanthone-derived polyketides, named phomoxanthones F-K (1-6), along with three known ones, were isolated from Phomopsis sp. xy21, which was isolated as an endophytic fungus from the Thai mangrove Xylocarpus granatum. Phomoxanthone F (1) represents the first xanthone-derived polyketide containing a 10a-decarboxylated benzopyranone nucleus that was substituted by a 4-methyldihydrofuran-2(3H)-one moiety at C10a. Phomoxanthones G (2) and H (3) are highly oxidized xanthone-derived polyketides containing a novel 5-methyl-6-oxabicyclo[3.2.1]octane motif. This is the first report of a C6-O-C12 bridge in xanthone-derived polyketides. Additionally, a plausible biogenetic pathway for these xanthone-derived polyketides is proposed.

Marine natural products

Covering: 2016. Previous review: Nat. Prod. Rep., 2017, 34, 235-294This review covers the literature published in 2016 for marine natural products (MNPs), with 757 citations (643 for the period January to December 2016) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1277 in 432 papers for 2016), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included.

Phochrodines A-D, first naturally occurring new chromenopyridines from mangrove entophytic fungus Phomopsis sp. 33

Four new chromenopyridine derivatives, phochrodines A-D (1-4), were identified from mangrove entophytic fungus Phomopsis sp. 33# by means of various modern chromatographic, spectroscopic and single crystal X-ray diffraction techniques. Compounds 1-4 with an unusual 5H-chromeno[4,3-b]pyridine skeleton were the first naturally occurring chromenopyridines. Their anti-inflammatory, antioxidant and cytotoxic activities were evaluated. 3 and 4 showed moderate inhibition of nitric oxide production with IC₅₀ values of 49.0 as well as 51.0μM, respectively. 4 had well ability to scavenge DPPH radical with IC₅₀ value of 34.0μM. The four had no cytotoxic activity for MDA-MB-435 breast cancer cells.

α-Glucosidase inhibitory and cytotoxic botryorhodines from mangrove endophytic fungus Trichoderma sp. 307

One new depsidone, botryorhodine H (1), together with three known analogues, botryorhodines C, D and G (2-4), were obtained from the mangrove endophytic fungus Trichoderma sp. 307 by co-culturing with Acinetobacter johnsonii B2. Structures were determined by 1D and 2D NMR analyses and high-resolution mass spectrum. Compounds 1-3 showed α-glucosidase inhibitory activity with IC₅₀ ranging from 8.1 to 11.2 μM, and compound 1 exhibited potent cytotoxicity against rat prolactinoma MMQ and rat pituitary adenoma GH3 cell lines (IC₅₀ = 3.09 and 3.64 μM).

Identification and Antifungal Activity of Compounds from the Mangrove Endophytic Fungus Aspergillus clavatus R7

Two new coumarin derivatives, 4,4′-dimethoxy-5,5′-dimethyl-7,7′-oxydicoumarin (1), 7-(γ,γ-dimethylallyloxy)-5-methoxy-4-methylcoumarin (2), a new chromone derivative, (S)-5-hydroxy-2,6-dimethyl-4H-furo[3,4-g]benzopyran-4,8(6H)-dione (5), and a new sterone derivative, 24-hydroxylergosta-4,6,8(14),22-tetraen-3-one (6), along with two known bicoumarins, kotanin (3) and orlandin (4), were isolated from an endophytic fungus Aspergillusclavatus (collection No. R7), isolated from the root of Myoporum bontioides collected from Leizhou Peninsula, China. Their structures were elucidated using 1D- and 2D- NMR spectroscopy, and HRESIMS. The absolute configuration of compound 5 was determined by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. Compound 6 significantly inhibited the plant pathogenic fungi Fusarium oxysporum, Colletotrichum musae and Penicillium italicum, compound 5 significantly inhibited Colletotrichum musae, and compounds 1, 3 and 4 greatly inhibited Fusarium oxysporum, showing the antifungal activities higher than those of the positive control, triadimefon.

Induction of Diverse Bioactive Secondary Metabolites from the Mangrove Endophytic Fungus Trichoderma sp. (Strain 307) by Co-Cultivation with Acinetobacter johnsonii (Strain B2)

Two new sesquiterpenes, microsphaeropsisin B (1) and C (2), and two new de-O-methyllasiodiplodins, (3R, 7R)-7-hydroxy-de-O-methyllasiodiplodin (4) and (3R)-5-oxo-de-O-methyllasiodiplodin (5), together with one new natural product (6) and twelve known compounds (3, 7-17), were isolated from the co-cultivation of mangrove endophytic fungus Trichoderma sp. 307 and aquatic pathogenic bacterium Acinetobacter johnsonii B2. Their structures, including absolute configurations, were elucidated by extensive analysis of spectroscopic data, electronic circular dichroism, Mo₂(AcO)₄-induced circular dichroism, and comparison with reported data. All of the isolated compounds were tested for their α-glucosidase inhibitory activity and cytotoxicity. New compounds 4 and 5 exhibited potent α-glucosidase inhibitory activity with IC₅₀ values of 25.8 and 54.6 µM, respectively, which were more potent than the positive control (acarbose, IC₅₀ = 703.8 µM). The good results of the tested bioactivity allowed us to explore α-glucosidase inhibitors in lasiodiplodins.

Chroman-4-one and pyrano[4,3-b]chromenone derivatives from the mangrove endophytic fungus Diaporthe phaseolorum SKS019

Seven new compounds: diaporchromanones A–D (1–4), (−)-phomopsichin A (5a), (+)-phomopsichin B (6a), and (±)-diaporchromone A (7), along with the known (+)-phomopsichin A (5b) and (−)-phomopsichin B (6b) were isolated from an endophytic fungus Diaporthe phaseolorum SKS019.