The genus Diaporthe: a rich source of diverse and bioactive metabolites

IMA Genome - F19 : A genome assembly and annotation guide to empower mycologists, including annotated draft genome sequences of Ceratocystis pirilliformis, Diaporthe australafricana, Fusarium ophioides, Paecilomyces lecythidis, and Sporothrix stenoceras

The pace at which Next Generation Sequence data is being produced continues to accelerate as technology improves. As a result, such data are increasingly becoming accessible to biologists outside of the field of bioinformatics. In contrast, access to training in the methods of genome assembly and annotation are not growing at a similar rate. In this issue, we report on a Genome Assembly Workshop for Mycologists that was held at the Forestry and Agricultural Biotechnology Institute (FABI) at the University of Pretoria, South Africa and make available the 12 draft genome sequences emanating from the event. With the aim of making the process of genome assembly and annotation more accessible to biologists, we provide a step-by-step guide to both genome assembly and annotation, intended to encourage and empower mycologists to use genome data in their research.

Diaporaustalides A-L, Austalide Meroterpenoids from a Plant Endophytic Diaporthe sp

Twelve new austalide meroterpenoids (1-12) were isolated from the endophytic fungus Diaporthe sp. XC1211. Their structures were elucidated by extensive spectroscopic analysis. The absolute configurations of compounds 1, 3, 4, and 6 were established by single-crystal X-ray diffraction, whereas those for the others were established by experimental electronic circular dichroism (ECD) data analysis. Compounds 1-12 represent a rare class of austalides with a 24α-CH3. Compounds 2 and 5 demonstrated potent proliferation inhibitory effects against LPS-induced B cells with IC50 values of 6.7 (SI = 3.6) and 3.8 (SI > 13) μM, respectively. Compounds 2 and 5 decreased the secretion of IL-6 in LPS-induced B cells in a dose-dependent manner.

Metabolomics insights into the polyketide-lactones produced by Diaporthe caliensis sp. nov., an endophyte of the medicinal plant Otoba gracilipes

IMPORTANCE

The integration of metabolomics-based approaches into the discovery pipeline has enabled improved mining and prioritization of prolific secondary metabolite producers such as endophytic fungi. However, relying on automated untargeted analysis tools might lead to misestimation of the chemical complexity harbored in these organisms. Our study emphasizes the importance of isolation and structure elucidation of the respective metabolites in addition to deep metabolome analysis for the correct interpretation of untargeted metabolomics approaches such as molecular networking. Additionally, it encourages the further exploration of endophytic fungi from traditional medicinal plants for the discovery of natural products.

Physiological mechanism of action and partial separation of herbicide-active compounds from the Diaporthe sp. extract on Amaranthus tricolor L

Thirteen fungi that produce compounds with herbicidal activities were isolated, identified, and extracted under the assumption that the mechanism of action occurs during seed exposure to the extract. The extracts from all the fungal strains considerably decreased the growth parameters of Amaranthus tricolor L. The EC010 strain extracts showed the greatest effect. Through ITS region gene sequencing methods, the isolated EC010 was identified as a genus of Diaporthe. The results showed a significant (p < 0.05) inhibitory effect of 91.25% on germination and a decrease in shoot and root length by 91.28% and 95.30%, respectively. The mycelium of Diaporthe sp. was extracted using sequential extraction techniques for the partial separation of the herbicidal fraction. According to the bioassay activities, the EtOAc fraction showed the highest inhibitory activity. The osmotic stress of the A. tricolor seeds was studied. Although the extract increased the accumulation of proline and soluble protein, the treated seeds showed lower imbibition. While the activity of α-amylase was dramatically decreased after treatment. A cytogenetic assay in the treated Allium cepa L. root revealed a decrease in the mitotic index, an altered mitotic phase index, and a promotion of mitotic abnormalities. Accordingly, the Diaporthe sp. may serve as a potential herbicidal compound resource.

Four new endophytic species of Diaporthe (Diaporthaceae, Diaporthales) isolated from Cameroon

The genus Diaporthe (Diaporthaceae, Diaporthales) is a large group of fungi frequently reported as phytopathogens, with ubiquitous distribution across the globe. Diaporthe have traditionally been characterized by the morphology of their ana- and teleomorphic state, revealing a high degree of heterogeneity as soon as DNA sequencing was utilized across the different members of the group. Their relevance for biotechnology and agriculture attracts the attention of taxonomists and natural product chemists alike in context of plant protection and exploitation for their potential to produce bioactive secondary metabolites. While more than 1000 species are described to date, Africa, as a natural habitat, has so far been under-sampled. Several endophytic fungi belonging to Diaporthe were isolated from different plant hosts in Cameroon over the course of this study. Phylogenetic analyses based on DNA sequence data of the internal transcribed spacer region and intervening 5.8S nrRNA gene, and partial fragments of the calmodulin, beta-tubulin, histone and the translation elongation factor 1-α genes, demonstrated that these isolates represent four new species, i.e. D.brideliae, D.cameroonensis, D.pseudoanacardii and D.rauvolfiae. Moreover, the description of D.isoberliniae is here emended, now incorporating the morphology of beta and gamma conidia produced by two of our endophytic isolates, which had never been documented in previous records. Moreover, the paraphyletic nature of the genus is discussed and suggestions are made for future revision of the genus.

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

From a fresh root of Trema guineensis (Ulmaceae), endophytic fungi were isolated, among which a taxon belonging to the new species Diaporthe cameroonensis. This strain was fermented in shake flask batch cultures and the broth was extracted with ethyl acetate. From the crude extract, a hemiketal polyketide 1, and an acetylated alternariol 2 were isolated, along with fifteen known secondary metabolites. Their structures were established by extensive NMR spectroscopy and mass spectrometry analyses, as well as by comparison with literature data of their analogs.

Study on secondary metabolites of endophytic fungus Diaporthe sp. AC1 induced by tryptophan analogs

Small molecule-induced fermentation of the endophytic fungus Diaporthe sp. AC1 originated from Artemisia argyi was executed to investigate its secondary metabolites. It was fermented in a culture medium containing 5-hydroxytryptophan (5-HTP), 1-methyl-L-tryptophan (1-MT), and tryptamine (TA), respectively. The antibacterial activities of crude extracts against pathogenic bacteria and pathogenic fungi were determined by using the Oxford cup method, while the cytotoxicity of crude extracts against cancer cells was determined by using the MTT method. The results showed that the secondary metabolites of Diaporthe sp. AC1 induced by 1-MT exhibited optimal antibacterial activity and tumor cytotoxicity. The induction conditions of 1-MT were optimized, and the antibacterial activities and tumor cytotoxicity of crude extracts under different induction conditions were investigated. As indicated, the optimal moment for 1-MT addition was before inoculation and its optimal concentration was 0.25 mM. Under these conditions, Diaporthe sp. AC1 was fermented and approximately 12 g of crude extracts was obtained. The crude extracts were then separated and purified to acquire nine monomer compounds, including three new compounds (1-3) and six known compounds (4-9). The antibacterial activities of the compounds against pathogenic bacteria and pathogenic fungi were investigated by using the microdilution method, while their cytotoxicity against cancer cells was analyzed by using the MTT method. The results demonstrated that Compound 1 exhibited moderate antibacterial activities against Verticillium dahlia, Fusarium graminearum, and Botrytis cinerea, as well as a low inhibitory activity against Listeria monocytogenes. Nevertheless, Compound 1 showed significant cytotoxicity against five cancer cells, with IC50 ranging from 12.26 to 52.52 μM. Compounds 2 and 3 exhibited negligible biological activity, while other compounds showed detectable inhibitory activities against pathogenic bacteria and cancer cells.

In Vitro Evaluation of Antiviral Activities of Funicone-like Compounds Vermistatin and Penisimplicissin against Canine Coronavirus Infection

Recent studies have demonstrated that 3-O-methylfunicone (OMF), a fungal secondary metabolite from Talaromyces pinophilus belonging to the class of funicone-like compounds, has antiviral activity against canine coronaviruses (CCoV), which causes enteritis in dogs. Herein, we selected two additional funicone-like compounds named vermistatin (VER) and penisimplicissin (PS) and investigated their inhibitory activity towards CCoV infection. Thus, both compounds have been tested for their cytotoxicity and for antiviral activity against CCoV in A72 cells, a fibrosarcoma cell line suitable for investigating CCoV. Our findings showed an increase in cell viability, with an improvement of morphological features in CCoV-infected cells at the non-toxic doses of 1 μM for VER and 0.5 μM for PS. In addition, we observed that these compounds caused a strong inhibition in the expression of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor which is activated during CCoV infection. Our results also showed the alkalinization of lysosomes in the presence of VER or PS, which may be involved in the observed antiviral activities.

Cytochalasans and Their Impact on Actin Filament Remodeling

The eukaryotic actin cytoskeleton comprises the protein itself in its monomeric and filamentous forms, G- and F-actin, as well as multiple interaction partners (actin-binding proteins, ABPs). This gives rise to a temporally and spatially controlled, dynamic network, eliciting a plethora of motility-associated processes. To interfere with the complex inter- and intracellular interactions the actin cytoskeleton confers, small molecular inhibitors have been used, foremost of all to study the relevance of actin filaments and their turnover for various cellular processes. The most prominent inhibitors act by, e.g., sequestering monomers or by interfering with the polymerization of new filaments and the elongation of existing filaments. Among these inhibitors used as tool compounds are the cytochalasans, fungal secondary metabolites known for decades and exploited for their F-actin polymerization inhibitory capabilities. In spite of their application as tool compounds for decades, comprehensive data are lacking that explain (i) how the structural deviances of the more than 400 cytochalasans described to date influence their bioactivity mechanistically and (ii) how the intricate network of ABPs reacts (or adapts) to cytochalasan binding. This review thus aims to summarize the information available concerning the structural features of cytochalasans and their influence on the described activities on cell morphology and actin cytoskeleton organization in eukaryotic cells.

Unprecedented Antimicrobial and Cytotoxic Polyketides from Cultures of Diaporthe africana sp. nov

Four unprecedented polyketides named isoprenylisobenzofuran B (2), isoprenylisobenzofuran C₁/C₂ (3), diaporisoindole F₁/F₂ (4), and isochromophilonol A₁/A₂ (7) were isolated from ethyl acetate extracts of the newly described endophytic fungus Diaporthe africana. Additionally, the previously reported cyclic depsipeptide eucalactam B (1) was also identified, along with the known compounds diaporisoindole A/B (5), tenellone B (6) and beauvericin (8). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures 1-8 were determined by a detailed analysis of their spectral data, namely high-resolution electrospray ionization mass spectrometry (HR-ESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, as well as electronic circular dichroism (ECD) spectra. In addition, chemical methods such as Marfey's analysis were also employed to determine the stereochemistry in compound 1. All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds 3-8 were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, 3-5 displayed cytotoxic effects (22.0 ≤ IC₅₀ ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds 6-8 inhibited the growth of seven mammalian cancer cell lines with IC₅₀ ranging from 17.7 to 49.5 µM (6), 0.9 to 12.9 µM (7) and 1.9 to 4.3 µM (8).

Secondary metabolites from endophytic fungi: Production, methods of analysis, and diverse pharmaceutical potential

The synthesis of secondary metabolites is a constantly functioning metabolic pathway in all living systems. Secondary metabolites can be broken down into numerous classes, including alkaloids, coumarins, flavonoids, lignans, saponins, terpenes, quinones, xanthones, and others. However, animals lack the routes of synthesis of these compounds, while plants, fungi, and bacteria all synthesize them. The primary function of bioactive metabolites (BM) synthesized from endophytic fungi (EF) is to make the host plants resistant to pathogens. EF is a group of fungal communities that colonize host tissues' intracellular or intercellular spaces. EF serves as a storehouse of the above-mentioned bioactive metabolites, providing beneficial effects to their hosts. BM of EF could be promising candidates for anti-cancer, anti-malarial, anti-tuberculosis, antiviral, anti-inflammatory, etc. because EF is regarded as an unexploited and untapped source of novel BM for effective drug candidates. Due to the emergence of drug resistance, there is an urgent need to search for new bioactive compounds that combat resistance. This article summarizes the production of BM from EF, high throughput methods for analysis, and their pharmaceutical application. The emphasis is on the diversity of metabolic products from EF, yield, method of purification/characterization, and various functions/activities of EF. Discussed information led to the development of new drugs and food additives that were more effective in the treatment of disease. This review shed light on the pharmacological potential of the fungal bioactive metabolites and emphasizes to exploit them in the future for therapeutic purposes.

Two new fungal genera (Diaporthales) found on Dipterocarpaceae in Thailand

Diaporthales is a species-rich order of fungi that includes endophytes, saprobes, and pathogens associated with forest plants and crops. They may also occur as parasites or secondary invaders of plant tissues injured or infected by other organisms or inhabit living animal and human tissues, as well as soil. Meanwhile, some severe pathogens wipe out large-scale cultivations of profitable crops, timber monocultures, and forests. Based on morphological and phylogenetic analyses of combined ITS, LSU, tef1-α, and rpb2 sequence data, generated using maximum likelihood (ML), maximum parsimony (MP), and MrBayes (BI), we introduce two new genera of Diaporthales found in Dipterocarpaceae in Thailand, namely Pulvinaticonidioma and Subellipsoidispora. Pulvinaticonidioma is characterized by solitary, subglobose, pycnidial, unilocular conidiomata with the internal layers convex and pulvinate at the base; hyaline, unbranched, septate conidiophores; hyaline, phialidic, cylindrical to ampulliform, determinate conidiogenous cells and hyaline, cylindrical, straight, unicellular, and aseptate conidia with obtuse ends. Subellipsoidispora has clavate to broadly fusoid, short pedicellate asci with an indistinct J- apical ring; biturbinate to subellipsoidal, hyaline to pale brown, smooth, guttulate ascospores that are 1-septate and slightly constricted at the septa. Detailed morphological and phylogenetic comparisons of these two new genera are provided in this study.

Linoleic acid from the endophytic fungus Diaporthe sp. HT-79 inhibits the growth of Xanthomonas citri subsp. citri by destructing the cell membrane and producing reactive oxygen species (ROS)

Citrus canker disease caused by Xanthomonas citri subsp. citri (Xac) severely influences the quality and quantity of citrus fruits. The current management of this disease mainly relies on the application of copper-associated chemicals, which poses a threat to human health and the environment. The present study isolated an endophytic fungus HT-79 from the healthy navel orange tree, whose crude fermentation product significantly inhibited the growth of Xac. The strain HT-79 was identified as a species of the Diaporthe genus. The petroleum ether extract (PEE) of the crude fermentation product of HT-79 exhibited remarkable activity against Xac with a MIC (minimum inhibitory concentration) value of 0.0625 mg/mL, significantly better than the positive control CuSO₄ (MIC = 0.125 mg/mL). Bioassay-guided isolation of PEE resulted in the discovery of one highly potent anti-Xac subfraction, namely fraction 5 (MIC = 0.0156 mg/mL). Gas chromatography-mass spectrometry (GC-MS) analysis revealed that fraction 5 mainly consisted of palmitic acid (18.17%), ethyl palmitate (15.66%), linoleic acid (6.80%), oleic acid (18.32%), ethyl linoleate (21.58%), ethyl oleate (15.87%), and ethyl stearate (3.60%). Among these seven compounds, linoleic acid (MIC = 0.0078 mg/mL) was found to be the most potent against Xac, followed by oleic acid (MIC = 0.0156 mg/mL), while all others were less pronounced than CuSO₄. Linoleic acid highly inhibited the growth of Xac via the destruction of the cell membrane and overproduction of reactive oxygen species (ROS). A preliminary in vivo experiment revealed that linoleic acid was effective in the control of citrus canker disease.

Diaporpyrone E, an undescribed α-pyrone from the endophytic fungus Diaporthe sp. CB10100

An undescribed α-pyrone diaporpyrone E (1), and three known nucleotides, 5'-O-acetyl uridine (2), 5'-O-acetyl thymidine (3), and adenine (4), were identified from Diaporthe sp. CB10100, an endophytic fungus isolated from the medicinal plant Sinomenium acutum. The structure of 1 was determined by extensive analysis of its HRMS, 1D and 2D NMR spectroscopic data, as well as electronic circular dichroism calculations and comparison. The in vitro cytotoxic and antibacterial assays of 1 revealed that it has a 30.2% inhibitory effect on HepG2 cells at 50 μM, while no antibacterial activities against Staphylococcus aureus and Klebsiella pneumoniae at 64 μg/mL.

Pioneering Metabolomic Studies on Diaporthe eres Species Complex from Fruit Trees in the South-Eastern Poland

Fungi from the genus Diaporthe have been reported as plant pathogens, endophytes, and saprophytes on a wide range of host plants worldwide. Their precise identification is problematic since many Diaporthe species can colonize a single host plant, whereas the same Diaporthe species can inhabit many hosts. Recently, Diaporthe has been proven to be a rich source of bioactive secondary metabolites. In our initial study, 40 Diaporthe isolates were analyzed for their metabolite production. A total of 153 compounds were identified based on their spectroscopic properties-Ultraviolet-visible and mass spectrometry. From these, 43 fungal metabolites were recognized as potential chemotaxonomic markers, mostly belonging to the drimane sesquiterpenoid-phthalide hybrid class. This group included mainly phytotoxic compounds such as cyclopaldic acid, altiloxin A, B, and their derivatives. To the best of our knowledge, this is the first report on the metabolomic studies on Diaporthe eres species complex from fruit trees in the South-Eastern Poland. The results from our study may provide the basis for the future research on the isolation of identified metabolites and on their bioactive potential for agricultural applications as biopesticides or biofertilizers.

Mycotoxin Contamination in Hazelnut: Current Status, Analytical Strategies, and Future Prospects

Hazelnuts represent a potential source of mycotoxins that pose a public health issue due to their increasing consumption as food ingredients worldwide. Hazelnuts contamination by mycotoxins may derive from fungal infections occurring during fruit development, or in postharvest. The present review considers the available data on mycotoxins detected in hazelnuts, on fungal species reported as infecting hazelnut fruit, and general analytical approaches adopted for mycotoxin investigation. Prompted by the European safety regulation concerning hazelnuts, many analytical methods have focused on the determination of levels of aflatoxin B1 (AFB1) and total aflatoxins. An overview of the available data shows that a multiplicity of fungal species and further mycotoxins have been detected in hazelnuts, including anthraquinones, cyclodepsipeptides, ochratoxins, sterigmatocystins, trichothecenes, and more. Hence, the importance is highlighted in developing suitable methods for the concurrent detection of a broad spectrum of these mycotoxins. Moreover, control strategies to be employed before and after harvest in the aim of controlling the fungal contamination, and in reducing or inactivating mycotoxins in hazelnuts, are discussed.

Unreported cytochalasins from an acid-mediated transformation of cytochalasin J isolated from Diaporthe cf. ueckeri

Chemical investigation of an endophytic fungus herein identified as Diaporthe cf. ueckeri yielded four known compounds, named cytochalasins H and J and dicerandrols A and B. Reports of acid sensitivity within the cytochalasan family inspired an attempt of acid-mediated conversion of cytochalasins H and J, resulting in the acquisition of five polycyclic cytochalasins featuring 5/6/5/8-fused tetracyclic and 5/6/6/7/5-fused pentacyclic skeletons. Two of the obtained polycyclic cytochalasins constituted unprecedented analogues, for which the trivial names cytochalasins J₄ and J₅ were proposed, whereas the others were identified as the known phomopchalasin A, phomopchalasin D and 21-acetoxycytochalasin J₃. The structures of the compounds were determined by extensive spectral analysis, namely HR-ESIMS, ESIMS and 1D/2D NMR. The stereochemistry of cytochalasins J₄ and J₅ was proposed using their ROESY data, biosynthetic and mechanistic considerations and by comparison of their ECD spectra with those of related congeners. All compounds except for cytochalasins H and J were tested for antimicrobial and cytotoxic activity. Cytochalasins J₄ and J₅ showed neither antimicrobial nor cytotoxic activity in the tested concentrations, with only weak antiproliferative activity observable against KB3.1 cells. The actin disruptive properties of all cytochalasins obtained in this study and of the previously reported cytochalasins RKS-1778 and phomopchalasin N were examined, and monitored by fluorescence microscopy using human osteo-sarcoma (U2-OS) cells. Compared to their precursor molecules (cytochalasins H and J), phomopchalasins A and D, 21-acetoxycytochalasin J₃, cytochalasins J₄ and J₅ revealed a strongly reduced activity on the F-actin network, highlighting that the macrocyclic ring is crucial for bioactivity.

Diaporthe species associated with the maritime grass Festuca rubra subsp. pruinosa

Festuca rubra subsp. pruinosa is a perennial grass growing in sea cliffs where plants are highly exposed to salinity and marine winds, and often grow in rock fissures where soil is absent. Diaporthe species are one of the most abundant components of the root microbiome of this grass and several Diaporthe isolates have been found to produce beneficial effects in their host and other plant species of agronomic importance. In this study, 22 strains of Diaporthe isolated as endophytes from roots of Festuca rubra subsp. pruinosa were characterized by molecular, morphological, and biochemical analyses. Sequences of the nuclear ribosomal internal transcribed spacers (ITS), translation elongation factor 1-α (TEF1), beta-tubulin (TUB), histone-3 (HIS), and calmodulin (CAL) genes were analyzed to identify the isolates. A multi-locus phylogenetic analysis of the combined five gene regions led to the identification of two new species named Diaporthe atlantica and Diaporthe iberica. Diaporthe atlantica is the most abundant Diaporthe species in its host plant, and Diaporthe iberica was also isolated from Celtica gigantea, another grass species growing in semiarid inland habitats. An in vitro biochemical characterization showed that all cultures of D. atlantica produced indole-3-acetic acid and ammonium, and the strains of D. iberica produced indole 3-acetic acid, ammonium, siderophores, and cellulase. Diaporthe atlantica is closely related to D. sclerotioides, a pathogen of cucurbits, and caused a growth reduction when inoculated in cucumber, melon, and watermelon.

Endophytic Diaporthe as Promising Leads for the Development of Biopesticides and Biofertilizers for a Sustainable Agriculture

Plant pathogens are responsible for causing economic and production losses in several crops worldwide, thus reducing the quality and quantity of agricultural supplies. To reduce the usage of chemically synthesized pesticides, strategies and approaches using microorganisms are being used in plant disease management. Most of the studies concerning plant-growth promotion and biological agents to control plant diseases are mainly focused on bacteria. In addition, a great portion of registered and commercialized biopesticides are bacterial-based products. Despite fungal endophytes having been identified as promising candidates for their use in biological control, it is of the utmost importance to develop and improve the existing knowledge on this research field. The genus Diaporthe, encompasses plant pathogens, saprobes and endophytes that have been screened for secondary metabolite, mainly due to their production of polyketides and a variety of unique bioactive metabolites with agronomic importance. Some of these metabolites exhibit antifungal and antibacterial activity for controlling plant pathogens, and phytotoxic activity for the development of potential mycoherbicides. Moreover, species of Diaporthe are reported as promising agents in the development of biofertilizers. For this reason, in this review we summarize the potential of Diaporthe species to produce natural products with application in agriculture and describe the benefits of these fungi to promote their host plant's growth.

Dereplication of Cytochalasans and Octaketides in Cytotoxic Extracts of Endophytic Fungi from Casearia arborea (Salicaceae)

Endophytes have been shown to be a source of novel drug prototypes. The Casearia genus is known for presenting cytotoxic clerodane diterpenes; however, there are few reports on secondary metabolites produced by its fungal microbiota. Thus, in the present study endophytic fungi obtained from the fresh leaves of C. arborea were grown in potato dextrose broth and rice to perform a secondary metabolite prospection study. The cytotoxic profile of the crude extracts at 10 µg/mL was determined by a colorimetric assay on tumor cell lines. The endophytes producing cytotoxic extracts were identified through phylogenetic analysis and belong to Diaporthe and Colletotrichum species. Metabolites present in these extracts were organized in molecular networking format based on HRMS-MS, and a dereplication process was performed to target compounds for chromatographic purification. Metabolic classes, such as lipids, peptides, alkaloids, and polyketides were annotated, and octaketide and cytochalasin derivatives were investigated. Cytochalasin H was purified from the cytotoxic Diaporthe sp. CarGL8 extract and its cytotoxic activity was determined on human cancer cell lines A549, MCF-7, and HepG2. The data collected in the present study showed that molecular networking is useful to understand the chemical profile of complex matrices to target compounds, minimizing the cost and time spent in purification processes.

Whole-Genome Sequence Data for the Holotype Strain of Diaporthe ilicicola, a Fungus Associated with Latent Fruit Rot in Deciduous Holly

Diaporthe ilicicola is a newly described fungal species that is associated with latent fruit rot in deciduous holly. This announcement provides a whole-genome assembly and annotation for this plant pathogen, which will inform research on its parasitism and identification of gene clusters involved in the production of bioactive metabolites.

Bioactive Monoterpenes and Polyketides from the Ascidian-Derived Fungus Diaporthe sp. SYSU-MS4722

There has been a tremendous increase in the rate of new terpenoids from marine-derived fungi being discovered, while new monoterpenes were rarely isolated from marine-derived fungi in the past two decades. Three new monoterpenes, diaporterpenes A–C (1–3), and one new α-pyrones, diaporpyrone A (6), along with nine known polyketides 4, 5, and 7–13 were isolated from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were elucidated based on extensive spectroscopic analyses (1D and 2D NMR and HR-ESIMS). The absolute configurations of 1 and 3 were identified by an X-ray crystallographic diffraction experiment using Cu-Ka radiation, and those of compound 2 were assigned by calculating NMR chemical shifts and ECD spectra. It afforded an example of natural epimers with different physical properties, especially crystallization, due to the difference in intermolecular hydrogen bonding. Compounds 9, 10, and 13 showed moderate total antioxidant capacity (0.82 of 9; 0.70 of 10; 0.48 of 13) with Trolox (total antioxidant capacity: 1.0) as a positive control, and compounds 5 and 7 showed anti-inflammatory activity with IC₅₀ values of 35.4 and 40.8 µM, respectively (positive control indomethacin: IC₅₀ = 35.8 µM).

New polyketides from the liquid culture of Diaporthebreyniae sp. nov. (Diaporthales, Diaporthaceae)

During the course of a study on the biodiversity of endophytes from Cameroon, a fungal strain was isolated. A multigene phylogenetic inference using five DNA loci revealed that this strain represents an undescribed species of Diaporthe, which is introduced here as D.breyniae. Investigation into the chemistry of this fungus led to the isolation of two previously undescribed secondary metabolites for which the trivial names fusaristatins G (7) and H (8) are proposed, together with eleven known compounds. The structures of all of the metabolites were established by using one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) spectroscopic data in combination with High-Resolution ElectroSpray Ionization Mass Spectrometry (HR-ESIMS) data. The absolute configuration of phomopchalasin N (4), which was reported for the first time concurrently to the present publication, was determined by analysis of its Rotating frame Overhauser Effect SpectroscopY (ROESY) spectrum and by comparison of its Electronic Circular Dichroism (ECD) spectrum with that of related compounds. A selection of the isolated secondary metabolites were tested for antimicrobial and cytotoxic activities, and compounds 4 and 7 showed weak antifungal and antibacterial activity. On the other hand, compound 4 showed moderate cytotoxic activity against all tested cancer cell lines with IC₅₀ values in the range of 5.8-45.9 µM. The latter was found to be less toxic than the other isolated cytochalasins (1-3) and gave hints in regards to the structure-activity relationship (SAR) of the studied cytochalasins. Fusaristatin H (8) also exhibited weak cytotoxicity against KB3.1 cell lines with an IC₅₀ value of 30.3 µM. Graphical abstract.

Bioprospecting of fungal endophytes from Oroxylum indicum (L.) Kurz with antioxidant and cytotoxic activity

Oroxylum indicum (L.) Kurz, a medicinal plant, shows numerous pharmacological properties which may be attributed to the bioactive compounds produced by O. indicum or due to associated endophytes. In the present study, leaf of O. indicum was evaluated for the presence of associated fungal endophytes, and antioxidant and cytotoxic activities of bioactive compounds produced from them. Using culture-dependent approach, eight fungal endophytes belonging to five different genera were identified. Two endophytes Daldinia eschscholtzii and Ectophoma multirostrata have been reported for the first time from the leaf of O. indicum plant. High-performance thin-layer chromatography (HPTLC) of ethyl acetate (EA) extract of isolated fungal endophytes showed a distinct fingerprinting profile in EA extract of Colletotrichum gloeosporioides. Among identified endophytes, EA extract of C. gloeosporioides showed significant antioxidant activity against DPPH free radical, superoxide anion radical, nitric oxide radical and hydroxyl radical with EC₅₀ values of 22.24±1.302 μg/mL, 67.46±0.576 μg/mL, 80.10±0.706 μg/mL and 61.55±1.360 μg/mL, respectively. EA extract of C. gloeosporioides exhibited potential cytotoxicity against HCT116, HeLa and HepG2 cancer cell lines with IC₅₀ values of 76.59 μg/mL, 176.20 μg/mL and 1750.70 μg/mL, respectively. A comparative HPTLC fingerprinting and the antioxidant activity of C. gloeosporioides associated with two different hosts (leaf of O. indicum and dead twigs of other plant) showed that C. gloeosporioides produces bioactive compounds in a host-dependent manner.

Interaction of the Fungal Metabolite Harzianic Acid with Rare-Earth Cations (La3+, Nd3+, Sm3+, Gd3+)

Rare-earth elements are emerging contaminants of soil and water bodies which destiny in the environment and effects on organisms is modulated by their interactions with natural ligands produced by bacteria, fungi and plants. Within this framework, coordination by harzianic acid (H₂L), a Trichoderma secondary metabolite, of a selection of tripositive rare-earth cations Ln³⁺ (Ln³⁺ = La³⁺, Nd³⁺, Sm^3+, and Gd³⁺) was investigated at 25 °C, and in a CH₃OH/0.1 M NaClO₄ (50/50 w/w) solvent, using mass spectrometry, circular dichroism, UV-Vis spectrophotometry, and pH measurements. Experimental data can be satisfactorily explained by assuming, for all investigated cations, the formation of a mono-complex (LnL⁺) and a bis-complex (LnL₂^-). Differences were found between the formation constants of complexes of different Ln³⁺ cations, which can be correlated with ionic radius. Since gadolinium is the element that raises the most concern among lanthanide elements, its effects on organisms at different levels of biological organization were explored, in the presence and absence of harzianic acid. Results of ecotoxicological tests suggest that harzianic acid can decrease gadolinium biotoxicity, presumably because of complex formation with Gd³⁺.

Extracts of Amazonian Fungi With Larvicidal Activities Against Aedes aegypti

The global increase in diseases transmitted by the vector Aedes aegypti, new and re-emerging, underscores the need for alternative and more effective methods of controlling mosquitoes. Our aim was to identify fungal strains from the Amazon rain forest that produce metabolites with larvicidal activity against Aedes aegypti. Thirty-six fungal strains belonging to 23 different genera of fungi, isolated from water samples collected in the state of Amazonas, Brazil were cultivated. The liquid medium was separated from the mycelium by filtration. Medium fractions were extracted with ethyl acetate and isopropanol 9:1 volume:volume, and the mycelia with ethyl acetate and methanol 1:1. The extracts were vacuum dried and the larvicidal activity was evaluated in selective bioassays containing 500 μg/ml of the dried fungal extracts. Larval mortality was evaluated up to 72 h. None of the mycelium extracts showed larvicidal activity greater than 50% at 72 h. In contrast, 15 culture medium extracts had larvicidal activity equal to or greater than 50% and eight killed more than 90% of the larvae within 72 h. These eight extracts from fungi belonging to seven different genera (Aspergillus, Cladosporium, Trichoderma, Diaporthe, Albifimbria, Emmia, and Sarocladium) were selected for the determination of LC₅₀ and LC₉₀. Albifimbria lateralis (1160) medium extracts presented the lowest LC₅₀ value (0.268 μg/ml) after 24 h exposure. Diaporthe ueckerae (1203) medium extracts presented the lowest value of LC₉₀ (2.928 μg/ml) at 24 h, the lowest values of LC₅₀ (0.108 μg/ml) and LC₉₀ (0.894 μg/ml) at 48 h and also at 72 h (LC₅₀ = 0.062 μg/ml and LC₉₀ = 0.476 μg/ml). Extracts from Al. lateralis (1160) and D. ueckerae (1203) showed potential for developing new, naturally derived products, to be applied in integrated vector management programs against Ae. aegypti.

Evaluation of the Antibacterial Activity of Crude Extracts Obtained From Cultivation of Native Endophytic Fungi Belonging to a Tropical Montane Rainforest in Colombia

Bioactive secondary metabolite production from endophytic fungi has gained a recurring research focus in recent decades as these microorganisms represent an unexplored biological niche for their diverse biotechnological potential. Despite this focus, studies involving tropical endophytes remain scarce, particularly those isolated from medicinal plants of these ecosystems. In addition, the state of the art of the pharmaceutical industry has experienced stagnation in the past 30years, which has pushed pathogenic infections to get one step ahead, resulting in the development of resistance to existing treatments. Here, five fungal endophytes were isolated from the medicinal plant Otoba gracilipes (Myristicaceae), which corresponded to the genera Xylaria and Diaporthe, and screened to demonstrate the promissory potential of these microorganisms for producing bioactive secondary metabolites with broad-spectrum antibacterial activities. Thus, the evaluation of crude organic extracts obtained from the mycelia and exhaust medium allowed the elucidation of Xylaria sp. and Diaporthe endophytica potential toward providing crude extracellular extracts with promising bioactivities against reference strains of Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923), according to the determined half-maximum inhibitory concentration (IC₅₀) with values down to 3.91 and 10.50mg/ml against each pathogen, respectively. Follow-up studies provided insights into the polarity nature of bioactive compounds in the crude extracts through bioactivity guided fractionation using a polymeric resin absorbent alternative extraction procedure. In addition, evaluation of the co-culturing methods demonstrated how this strategy can enhance endophytes biosynthetic capacity and improve their antibacterial potential with a 10-fold decrease in the IC₅₀ values against both pathogens compared to the obtained values in the preliminary evaluations of Xylaria sp. and D. endophytica crude extracts. These results support the potential of Colombian native biodiversity to provide new approaches concerning the global emergence of antibiotics resistance and future production of undiscovered compounds different from the currently used antibiotics classes and simultaneously call for the value of preserving native habitats due to their promising ecosystemic applications in the biotechnological and pharmaceutical industries.

Plant associated fungal endophytes as a source of natural bioactive compounds

Endophytes are a potent source of bioactive compounds that mimic plant-based metabolites. The relationship of host plant and endophyte is significantly associated with alteration in fungal colonisation and the extraction of endophyte-derived bioactive compounds. Screening of fungal endophytes and their relationship with host plants is essential for the isolation of bioactive compounds. Numerous bioactive compounds with antioxidant, antimicrobial, anticancer, and immunomodulatory properties are known to be derived from fungal endophytes. Bioinformatics tools along with the latest techniques such as metabolomics, next-generation sequencing, and metagenomics multilocus sequence typing can potentially fill the gaps in fungal endophyte research. The current review article focuses on bioactive compounds derived from plant-associated fungal endophytes and their pharmacological importance. We conclude with the challenges and opportunities in the research area of fungal endophytes.

Endophytes of Brazilian Medicinal Plants With Activity Against Phytopathogens

Plant diseases caused by phytopathogens are responsible for significant crop losses worldwide. Resistance induction and biological control have been exploited in agriculture due to their enormous potential. In this study, we investigated the antimicrobial potential of endophytic fungi of leaves and petioles of medicinal plants Vochysia divergens and Stryphnodendron adstringens located in two regions of high diversity in Brazil, Pantanal, and Cerrado, respectively. We recovered 1,304 fungal isolates and based on the characteristics of the culture, were assigned to 159 phenotypes. One isolate was selected as representative of each phenotype and studied for antimicrobial activity against phytopathogens. Isolates with better biological activities were identified based on DNA sequences and phylogenetic analyzes. Among the 159 representative isolates, extracts from 12 endophytes that inhibited the mycelial growth (IG) of Colletotrichum abscissum (≥40%) were selected to expand the antimicrobial analysis. The minimum inhibitory concentrations (MIC) of the extracts were determined against citrus pathogens, C. abscissum, Phyllosticta citricarpa and Xanthomonas citri subsp. citri and the maize pathogen Fusarium graminearum. The highest activity against C. abscissum were from extracts of Pseudofusicoccum stromaticum CMRP4328 (IG: 83% and MIC: 40 μg/mL) and Diaporthe vochysiae CMRP4322 (IG: 75% and MIC: 1 μg/mL), both extracts also inhibited the development of post-bloom fruit drop symptoms in citrus flowers. The extracts were promising in inhibiting the mycelial growth of P. citricarpa and reducing the production of pycnidia in citrus leaves. Among the isolates that showed activity, the genus Diaporthe was the most common, including the new species D. cerradensis described in this study. In addition, high performance liquid chromatography, UV detection, and mass spectrometry and thin layer chromatography analyzes of extracts produced by endophytes that showed high activity, indicated D. vochysiae CMRP4322 and P. stromaticum CMRP4328 as promising strains that produce new bioactive natural products. We report here the capacity of endophytic fungi of medicinal plants to produce secondary metabolites with biological activities against phytopathogenic fungi and bacteria. The description of the new species D. cerradensis, reinforces the ability of medicinal plants found in Brazil to host a diverse group of fungi with biotechnological potential.

Anti-inflammatory dihydroxanthones from a Diaporthe species

In a search for anti-inflammatory compounds from fungi inhibiting the promoter activity of the small chemokine CXCL10 (Interferon-inducible protein 10, IP-10) as a pro-inflammatory marker gene, the new dihydroxanthone methyl (1R, 2R)-1,2,8-trihydroxy-6-(hydroxymethyl)-9-oxo-2,9-dihydro-1H-xanthene-1-carboxylate (2) and the previously described dihydroxanthone AGI-B4 (1) were isolated from fermentations of a Diaporthe species. The structures of the compounds were elucidated by a combination of one- and two-dimensional NMR spectroscopy, mass spectrometry, and calculations using density functional theory (DFT). Compounds 1 and 2 inhibited the LPS/IFNγ induced CXCL10 promoter activity in transiently transfected human MonoMac6 cells in a dose-dependent manner with IC₅₀ values of 4.1 µM (±0.2 µM) and 1.0 µM (±0.06 µM) respectively. Moreover, compounds 1 and 2 reduced mRNA levels and synthesis of pro-inflammatory mediators such as cytokines and chemokines in LPS/IFNγ stimulated MonoMac6 cells by interfering with the Stat1 and NFκB pathway.

Molecular Identification and Antimicrobial Activity of Foliar Endophytic Fungi on the Brazilian Pepper Tree (Schinus terebinthifolius) Reveal New Species of Diaporthe

The presence of endophytes promotes the biosynthesis of secondary plant metabolites. In this study, endophytic fungi were isolated from Schinus terebinthifolius to investigate their diversity and antimicrobial activity. A total of 272 endophytic fungi was obtained. These belonged to nine different genera: Alternaria, Colletotrichum, Diaporthe, Epicoccum, Fusarium, Pestalotiopsis, Phyllosticta, Xylaria, and Cryptococcus. Notably, Diaporthe foliorum was introduced as a new species, with accompanying morphological descriptions, illustrations, and a multigene phylogenetic analysis (using ITS, TEF1, TUB, HIS, and CAL). Among the 26 fungal morphotypes evaluated for antimicrobial activity, five strains had inhibitory effects against pathogenic microorganisms. Xylaria allantoidea CMRP1424 extracts showed antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Diaporthe terebinthifolii CMRP1430 and CMRP1436 showed antimicrobial activity against E. coli, P. aeruginosa, S. aureus, and C. albicans. Meanwhile, D. foliorum CMRP1321 and D. malorum CMRP1438 extracts inhibited C. albicans alone. Three classes of chemical compounds were identified in D. foliorum CMRP1438 extracts: ferric chloride, potassium hydroxide, and vanillin-sulfuric acid. In conclusion, the endophytic isolates were able to produce bioactive agents with pharmaceutical potential as antibacterial and antifungal agents. As such, they may provide fresh leads in the search for new, biological sources of drug therapies.

Bioactive potential evaluation and purification of compounds from an endophytic fungus Diaporthe longicolla, a resident of Saraca asoca (Roxb.) Willd

An endophytic fungus (L3), isolated from the leaf tissues of Saraca asoca was identified as D. longicolla by microscopic and molecular methods. The crude extracts of D. longicolla revealed to harbor seven compounds in GC-MS analysis which was subjected to a thin layer chromatography (TLC) for purification and separation of bioactive ingredients. The partially purified fraction from TLC displayed the presence of 2-tridecene (Z) (RT-14.50), 5-tridecene (E) (RT-16.65) and 2,4-di-tert-butylphenol (RT-13.92) in GC-MS. High-performance liquid chromatography (HPLC) was performed to further purify the constituents which led to the collection of 2,4-di-tert-butyl phenol (RT-2.34) with excellent antioxidant activity and antibacterial activity against methicillin resistance Staphylococcus aureus (MRSA).

Bioactive α-Pyrone Derivatives from the Endophytic Fungus Diaporthe sp. CB10100 as Inducible Nitric Oxide Synthase Inhibitors

Inducible nitric oxide synthase (iNOS) produces NO from l-arginine and plays critical roles in inflammation and immune activation. Selective and potent iNOS inhibitors may be potentially used in many indications, such as rheumatoid arthritis, pain, and neurodegeration. In the current study, five new compounds, including a dibenzo-α- pyrone derivative ellagic acid B (5) and four α-pyrones diaporpyrone A-D (9-12), together with three known compounds (6-8), were isolated from the endophytic fungus Diaporthe sp. CB10100. The structures of these new natural products were unambiguously elucidated using NMR, HRESIMS or electronic circular dichroism calculations. Ellagic acid B (5) features a tetracyclic 6/6/6/6 ring system with a fused 2H-chromene, which is different from ellagic acid (4) with a fused 2H-chromen-2-one. Both 2-hydroxy-alternariol (6) and alternariol (7) reduced the expression of iNOS at protein levels in a dose-dependent manner, using a lipopolysaccharide (LPS)-induced RAW264.7 cell models. Also, they decreased the protein expression levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6 and monocyte chemotactic protein 1. Importantly, 6 and 7 significantly reduced the production of NO as low as 10 μM in LPS-induced RAW264.7 cells. Molecular docking of 6 and 7 to iNOS further suggests that both of them may interact with iNOS. Our study suggests that 6 and 7, as well as the alternariol scaffold may be further developed as potential iNOS inhibitors.

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review

Endophytic microbes are microorganisms that colonize the intracellular spaces within the plant tissues without exerting any adverse or pathological effects. Currently, the world population is facing devastating chronic diseases that affect humans. The resistance of pathogens to commercial antibiotics is increasing, thus limiting the therapeutic potential and effectiveness of antibiotics. Consequently, the need to search for novel, affordable and nontoxic natural bioactive compounds from endophytic fungi in developing new drugs with multifunction mechanisms to meet human needs is essential. Fungal endophytes produce invaluable bioactive metabolic compounds beneficial to humans with antimicrobial, anticancer, antidiabetic, anti-inflammatory, antitumor properties, etc. Some of these bioactive compounds include pestacin, taxol, camptothecin, ergoflavin, podophyllotoxin, benzopyran, isopestacin, phloroglucinol, tetrahydroxy-1-methylxanthone, salidroside, borneol, dibenzofurane, methyl peniphenone, lipopeptide, peniphenone etc. Despite the aforementioned importance of endophytic fungal metabolites, less information is available on their exploration and pharmacological importance. Therefore, in this review, we shall elucidate the fungal bioactive metabolites from medicinal plants and their pharmacological potential.

Metabolites with Anti-Inflammatory Activity from the Mangrove Endophytic Fungus Diaporthe sp. QYM12

One new diterpenoid, diaporpenoid A (1), two new sesquiterpenoids, diaporpenoids B–C (2,3) and three new α-pyrone derivatives, diaporpyrones A–C (4–6) were isolated from an MeOH extract obtained from cultures of the mangrove endophytic fungus Diaporthe sp. QYM12. Their structures were elucidated by extensive analysis of spectroscopic data. The absolute configurations were determined by electronic circular dichroism (ECD) calculations and a comparison of the specific rotation. Compound 1 had an unusual 5/10/5-fused tricyclic ring system. Compounds 1 and 4 showed potent anti-inflammatory activities by inhibiting the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced RAW264.7 cells with IC₅₀ values of 21.5 and 12.5 μM, respectively.

Fungal endophytes in Peperomia obtusifolia and their potential as inhibitors of chickpea fungal pathogens

Chickpea (Cicer arietinum L., Fabaceae) is the second most important legume after common bean (Phaseolus vulgaris L., Fabaceae) and third in production among the legumes grains worldwide. Ascochyta blight and Fusarium wilt are among the main fungal infections which cause the major losses of chickpea crop. In this work we report the phyto-pathogen controlling properties of 24 endophyte Phomopsis/Diaporthe isolates on the chickpea fungal pathogens Ascochyta rabiei, Fusarium oxysporum and Fusarium solani. The Phomopsis/Diaporthe strains were isolated amongst a total of 62 endophytic fungi from the aerial parts of the herbaceous perennial American plant Peperomia obtusifolia (Piperaceae) along with Fusarium, Septoria, Colletotrichum, Alternaria and Roussoella genera among others. Phomopsis/Diaporthe isolates were identified as Diaporthe infecunda (12 isolates), Diaporthe sackstoni (1 isolate), Diaporthe cf. brasiliensis (4 isolates) and Phomopsis cf. tuberivora (7 isolates). All the Phomopsis/Diaporthe strains antagonized A. rabiei strain AR2 with a mean of inhibition (% I) of 86.59 ± 1.49% in dual cultures. The metabolic characterization of the Phomopsis/Diaporthe strains showed groups in three clusters which were in agreement with the taxonomic identification. Bioautographic evaluation of organic extracts showed that those of D. cf. brasiliensis and D. infecunda were better as inhibitors. Strain Po 45 was one of the most active (cluster 1, 96.87% I), and its ethyl acetate extract inhibited A. rabiei growth in a bioautographic assay until at least 10 μg/mm applied showing a specific chromatographic band as the responsible of the A. rabiei inhibition.

Draft Genome Sequence of Diaporthe sp. Strain HANT25, an Endophytic Fungus Producing Mycoepoxydiene

Diaporthe sp. strain HANT25 is an endophytic fungus that produces mycoepoxydiene, a rare bioactive natural compound. Here, we report the genome sequence of Diaporthe sp. HANT25, comprising 55.3 Mb in 80 scaffolds. The genome sequence should enhance understanding of the biology and bioactive compound production potential of the genus Diaporthe.

Diversity and Antimicrobial Activity of Endophytic Fungi Isolated from Chloranthus japonicus Sieb in Qinling Mountains, China

The plant Chloranthus japonicus Sieb is known for its anticancer properties and mainly distributed in China, Japan, and Korea. In this study, we firstly investigated the diversity and antimicrobial activity of the culturable endophytic fungi from C. japonicus. A total of 332 fungal colonies were successfully isolated from 555 tissue segments of the medicinal plant C. japonicus collected from Qinling Mountains, China. One hundred and thirty representative morphotype strains were identified according to ITS rDNA sequence analyses and were grouped into three phyla (Ascomycota, Basidiomycota, Mucoromycota), five classes (Dothideomycetes, Sordariomycetes, Eurotiomycetes, Agaricomycetes, Mucoromycetes), and at least 30 genera. Colletotrichum (RA, 60.54%) was the most abundant genus, followed by Aspergillus (RA, 11.75%) and Diaporthe (RA, 9.34%). The Species Richness Index (S, 56) and the Shannon-Wiener Index (H', 2.7076) indicated that C. japonicus harbored abundant fungal resources. Thirteen out of 130 endophytic fungal ethyl acetate extracts exhibited inhibitory activities against at least one pathogenic bacterium or fungus. Among of these, F8158, which was identified as Trichoderma cf. harzianum, exhibited good antagonistic capacities (the percent inhibition of mycelial growth ranged from 47.72~88.18) for different pathogens and has a potential application in biological control. In addition, it is noteworthy that the strain F8157 (Thanatephorus cucumeris, an opportunistic pathogen) showed antibacterial and antifungal activity, which is reported firstly in this study, and should be investigated further. Taken together, these results indicated that the endophytic fungi from C. japonicus may be of potential interest in screening bio-control agents and discovering of new bioactive compounds.

Discovery of a new species of the Hypoxylon rubiginosum complex from Iran and antagonistic activities of Hypoxylon spp. against the Ash Dieback pathogen, Hymenoscyphus fraxineus, in dual culture

During a survey of xylarialean fungi in Northern Iran, several specimens that showed affinities to the Hypoxylonrubiginosum complex were collected and cultured. A comparison of their morphological characters, combined with a chemotaxonomic study based on high performance liquid chromatography, coupled with diode array detection and mass spectrometry (HPLC-DAD/MS) and a multi-locus phylogeny based on ITS, LSU, rbp2 and tub2 DNA sequences, revealed a new species here described as Hypoxylonguilanense. In addition, Hypoxylonrubiginosumsensu stricto was also encountered. Concurrently, an endophytic isolate of the latter species showed strong antagonistic activities against the Ash Dieback pathogen, Hymenoscyphusfraxineus, in a dual culture assay in our laboratory. Therefore, we decided to test the new Iranian fungi for antagonistic activities against the pathogen, along with several cultures of other Hypoxylon species that are related to H.rubiginosum. Our results suggest that the antagonistic effects of Hypoxylon spp. against Hym.fraxineus are widespread and that they are due to the production of antifungal phomopsidin derivatives in the presence of the pathogen.

Isolation and Characterization of Antifungal Metabolites from the Melia azedarach-Associated Fungus Diaporthe eucalyptorum

Two biosynthetically related new metabolites, eucalyptacid A (1) and eucalactam B (2), along with six known compounds (3-8), eugenitol (3), cytosporone C (4), 4-hydroxyphenethyl alcohol (5), 1-(4-hydroxyphenyl)ethane-1,2-diol (6), N-(2-hydroxy-2-phenylethyl)acetamide (7), and phomopene (8), were isolated from the solid rice cultures of the endophytic fungus Diaporthe eucalyptorum KY-9 that had been isolated from Melia azedarach. Also, two further new derivatives (2a, 2b) were prepared from 2. The structures were elucidated by exhaustive analysis of NMR and ESIMS data and chemical methods such as Marfey's protocol. Compound 1 was identified as a rare polyketide fatty acid, (8E)-3,5,11-trihydroxy-2,10,12-trimethyltetradecenoic acid, and 2 was determined to be the first cyclic depsipeptide containing the same fatty acid unit as 1 and a Gly-Gly-Thr tripeptide chain. Its N-terminal end is N-acylated by an 11-hydroxy fatty acid with a branch alkyl chain of 14:1. The 11-hydroxyl group connects to the carboxylic group of the C-terminal amino acid to form a 22-membered lactone ring. A hypothetical biosynthetic pathway for the new polyketides is proposed. The isolated compounds were assayed for their inhibition against four plant pathogenic fungi, Alternaria solani, Botrytis cinerea, Fusarium solani, and Gibberella saubinettii. Compounds 1, 4, 6, and 7 exhibited antifungal activities against Alternaria solani, with minimal inhibitory concentration (MIC) values from 6.25 to 50 μM. Thus, strain KY-9 represents an untapped source for the development of biological control agents to prevent the infection of pathogenic fungus A. solani.

Molecular Characterization of Diaporthe Species Associated With Hazelnut Defects

Fungi of the genus Diaporthe have been reported as the main causative agent of hazelnut defects in the Caucasus area. This study aimed to define which fungal species are present in defective hazelnuts grown in Turkey and confirm the role of Diaporthe spp. Seven hazelnut orchards were selected, with each one located in a different Turkish Province (Düzce, Giresun, Ordu, Samsun, Sakarya, Trabzon, and Zonguldak), and hazelnuts were collected at early and full ripening. Fungal isolation and identification were performed at the genus level based on morphological characteristics. Several genera were isolated, with Diaporthe spp. being among the prevalent. This was the only genus with increasing incidence from early to full ripening, and incidence at full ripening was positively correlated both with internal (ρ = 0.86) and visible defects (ρ = 0.81), which confirmed its role as the key causative agent of hazelnut defects. The correlation of defect occurrence with rainfall, reported in previous study, was not confirmed, possibly due to the low defect incidence. A total of 86 Diaporthe monosporic strains isolated from Turkish hazelnut samples, together with 33 strains collected in the Caucasus region and 6 from Italy, were analyzed with a multi-locus phylogeny based on three genomic loci (ITS, EF1-α, and tub). The results showed that Diaporthe strains can be grouped into 7 distinct clades, with a majority of Turkish strains (95%) being placed into a single clade related with D. eres. These samples were organized into several sub-clades, which indicates the existence of genetically diverse sub-populations.

Antifungal Activities of Volatile Secondary Metabolites of Four Diaporthe Strains Isolated from Catharanthus roseus

Four endophytic fungi were isolated from the medicinal plant, Catharanthus roseus, and were identified as Diaporthe spp. with partial translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB), histone H3 (HIS), calmodulin (CAL) genes, and rDNA internal transcribed spacer (ITS) region (TEF1-TUB-HIS--CAL-ITS) multigene phylogeny suggested for species delimitation in the Diaporthe genus. Each fungus produces a unique mixture of volatile organic compounds (VOCs) with an abundant mixture of terpenoids analyzed by headspace solid-phase microextraction (SPME) fiber-GC/MS. These tentatively-detected terpenes included α-muurolene, β-phellandrene, γ-terpinene, and α-thujene, as well as other minor terpenoids, including caryophyllene, patchoulene, cedrene, 2-carene, and thujone. The volatile metabolites of each isolate showed antifungal properties against a wide range of plant pathogenic test fungi and oomycetes, including Alternaria alternata, Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium graminearum, and Phytophthora cinnamomi. The growth inhibition of the pathogens varied between 10% and 60% within 72 h of exposure. To our knowledge, the endophytic Diaporthe-like strains are first reported from Catharanthus roseus. VOCs produced by each strain of the endophytic Diaporthe fungi were unique components with dominant monoterpenes comparing to known Diaporthe fungal VOCs. A discussion is presented on the inhibitive bioactivities of secondary metabolites among endophytic Diaporthe fungi and this medicinal plant.