Secondary metabolites from an endophytic fungus Trichoderma erinaceum with antimicrobial activity towards Pythium ultimum

Fusarium begoniae metabolites: a promising larvicidal, pupicidal potential, histopathological alterations and detoxifications enzyme profiles of medically important mosquito vector Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi

Endophytic fungal molecules have the potential to be a cost-effective chemical source for developing eco-friendly disease-controlling pharmaceuticals that target mosquito-borne illnesses. The primary aims of the study were to identify the fungus Fusarium begoniae larvicidal ability against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi. The ethyl acetate extract demonstrated lethal concentrations that kill 50% of exposed larvae (LC50) and 90% of exposed larvae (LC90) for the 1st to 4th instar larvae of An. stephensi (LC50 = 54.821, 66.525, 68.250, and 73.614; LC90 = 104.56, 138.205, 150.415, and 159.466 μg/mL), Cx. quinquefasciatus (LC50 = 64.981, 36.505, 42.230, and 36.514; LC90 = 180.46, 157.105, 140.318, and 153.366 μg/ mL), and Ae. aegypti (LC50 = 74.890, 33.607, 52.173, and 26.974; LC90 = 202.56, 162.205, 130.518, and 163.286 μg/mL). Mycelium metabolites were evaluated for their pupicidal activity towards Ae. aegypti (LC50 = 80.669, LC90 = 119.904), Cx. quinquefasciatus (LC50 = 70.569, LC90 = 109.840), and An. stephensi (LC50 = 73.269, LC90 = 110.590 μg/mL). The highest larvicidal activity was recorded at 300 µg/mL, with 100% mortality against first and second-instar larvae of Cx. quinquefasciatus. Metabolite exposure to larvae exhibited several abnormal behavioral changes. The exposure to F. begoniae metabolite, key esterases such as acetylcholinesterase, α-and-β-carboxylesterase, and acid and alkaline phosphatase activity significantly decreased compared to control larvae. The outcomes of the histology analysis revealed that the mycelium metabolites-treated targeted larvae had a disorganized abdominal mid and hindgut epithelial cells. The is first-hand information on study of ethyl-acetate-derived metabolites from F. begoniae tested against larvae and pupae of Ae. aegypti, Cx. quinquefasciatus and An. stephensi. Bio-indicator toxicity findings demonstrate that A. nauplii displayed no mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04061-z.

Endophytic Fungi Volatile Organic Compounds as Crucial Biocontrol Agents Used for Controlling Fruit and Vegetable Postharvest Diseases

Fruits and vegetables are an important part of the human diet, but during transportation and storage, microbial pathogens attack and spoil fruits and vegetables, causing huge economic losses to agriculture. Traditionally used chemical fungicides leave chemical residues, leading to environmental pollution and health risks. With the emphasis on food safety, biocontrol agents are attracting more and more attention due to their environmental friendliness. Endophytic fungi are present in plant tissues and do not cause host disease. The volatile organic compounds (VOCs) they produce are used to control postharvest diseases due to their significant antifungal activity, as well as their volatility, safety and environmental protection characteristics. This review provides the concept and characterization of endophytic fungal VOCs, concludes the types of endophytic fungi that release antifungal VOCs and their biological control mechanisms, as well as focuses on the practical applications and the challenges of applying VOCs as fumigants. Endophytic fungal VOCs can be used as emerging biocontrol resources to control postharvest diseases that affect fruits and vegetables.

Chemical Constituents and Anticancer Activities of Marine-Derived Fungus Trichoderma lixii

The fungal genus Trichoderma is a rich source of structurally diverse secondary metabolites with remarkable pharmaceutical properties. The chemical constituents and anticancer activities of the marine-derived fungus Trichoderma lixii have never been investigated. In this study, a bioactivity-guided investigation led to the isolation of eleven compounds, including trichodermamide A (1), trichodermamide B (2), aspergillazine A (3), DC1149B (4), ergosterol peroxide (5), cerebrosides D/C (6/7), 5-hydroxy-2,3-dimethyl-7-methoxychromone (8), nafuredin A (9), and harzianumols E/F (10/11). Their structures were identified by using various spectroscopic techniques and compared to those in the literature. Notably, compounds 2 and 5-11 were reported for the first time from this species. Evaluation of the anticancer activities of all isolated compounds was carried out. Compounds 2, 4, and 9 were the most active antiproliferative compounds against three cancer cell lines (human myeloma KMS-11, colorectal HT-29, and pancreas PANC-1). Intriguingly, compound 4 exhibited anti-austerity activity with an IC50 of 22.43 μM against PANC-1 cancer cells under glucose starvation conditions, while compound 2 did not.

Synergistic Combination of NAPROC-13 and NMR 13C DFT Calculations: A Powerful Approach for Revising the Structure of Natural Products

This article describes the structure revision of nine triterpenoids that have been reported corresponding to the same 13C NMR data set. In addition, 13C NMR calculation shows that some chemical shift assignments must be swapped. Our analysis improves the fit between the experimental and calculated data. Correcting misassigned structures and correctly assigning each signal is essential for elucidating new structurally related compounds. Furthermore, the ambiguity of several compounds, the structure of which differs in the literature and the Sci-Finder database, has been eliminated. Misassigned structures were found by chemical shift searches in NAPROC-13, and the results provide two or more different compounds with the same 13C NMR data. The process to determine the correct, most likely structural proposal in agreement with the experimental 13C NMR data was carried out by DFT calculations.

Endophytic fungi mediates production of bioactive secondary metabolites via modulation of genes involved in key metabolic pathways and their contribution in different biotechnological sector

Endophytic fungi stimulate the production of an enormous number of bioactive metabolites in medicinal plants and affect the different steps of biosynthetic pathways of these secondary metabolites. Endophytic fungi possess a number of biosynthetic gene clusters that possess genes for various enzymes, transcription factors, etc., in their genome responsible for the production of secondary metabolites. Additionally, endophytic fungi also modulate the expression of various genes responsible for the synthesis of key enzymes involved in metabolic pathways of such as HMGR, DXR, etc. involved in the production of a large number of phenolic compounds as well as regulate the expression of genes involved in the production of alkaloids and terpenoids in different plants. This review aims to provide a comprehensive overview of gene expression related to endophytes and their impact on metabolic pathways. Additionally, this review will emphasize the studies done to isolate these secondary metabolites from endophytic fungi in large quantities and assess their bioactivity. Due to ease in synthesis of secondary metabolites and their huge application in the medical industry, these bioactive metabolites are now being extracted from strains of these endophytic fungi commercially. Apart from their application in the pharmaceutical industry, most of these metabolites extracted from endophytic fungi also possess plant growth-promoting ability, bioremediation potential, novel bio control agents, sources of anti-oxidants, etc. The review will comprehensively shed a light on the biotechnological application of these fungal metabolites at the industrial level.

Differences and biocontrol potential of haustorial endophytic fungi from Taxillus Chinensis on different host plants

BACKGROUND

To explore the community composition and diversity of the endophytic fungi in Taxillus chinensis, samples of the parasites growing on seven different hosts, Morus alba, Prunus salicina, Phellodendron chinense, Bauhinia purpurea, Dalbergia odorifera, Diospyros kaki and Dimocarpus longan, were isolated. The strains were identified by their morphological characteristics and their internal transcribed spacer (ITS) sequences.

RESULTS

150 different endophytic fungi were isolated from the haustorial roots of the seven hosts with a total isolation rate of 61.24%. These endophytic fungi were found to belong to 1 phylum, 2 classes, 7 orders, 9 families, 11 genera and 8 species. Among of them, Pestalotiopsis, Neopestalotiopsis and Diaporthe were the dominant genera, accounting for 26.67, 17.33 and 31.33% of the total number of strains, respectively. Diversity and similarity analyses showed that the endophytic fungi isolated from D. longan (H'=1.60) had the highest diversity index. The highest richness indexes were found in M. alba and D. odorifera (both 2.23). The evenness index of D. longan was the highest (0.82). The similarity coefficient of D. odorifera was the most similar to D. longan and M. alba (33.33%), while the similarity coefficient of P. chinense was the lowest (7.69%) with M. alba and D. odorifera. Nine strains showed antimicrobial activities. Among them, Pestalotiopsis sp., N. parvum and H. investiens showed significant antifungal activity against three fungal phytopathogens of medicinal plants. At the same time, the crude extracts from the metabolites of the three endophytic fungi had strong inhibitory effects on the three pathogens. Pestalotiopsis sp., N. parvum and H. investiens had the strongest inhibitory effects of S. cucurbitacearum, with inhibitory rates of 100%, 100% and 81.51%, respectively. In addition, N. parvum had a strong inhibitory effect on D. glomerata and C. cassicola, with inhibitory rates of 82.35% and 72.80%, respectively.

CONCLUSIONS

These results indicate that the species composition and diversity of endophytic fungi in the branches of T. chinensis were varied in the different hosts and showed good antimicrobial potential in the control of plant pathogens.

Efficacy of the biocontrol agent Trichoderma hamatum against Lasiodiplodia theobromae on macadamia

Macadamia (Macadamia integrifolia) trees are an important source of revenue in rainforest ecosystems. Their nuts are rich in vitamins, minerals, fiber, antioxidants, and monounsaturated oils. The fungus Lasiodiplodia theobromae, however, is a major disease problem, causing kernel rot and other disease symptoms. In the present study, a dual confrontation assay was used to evaluate the inhibitory effect of an endophytic strain of Trichoderma hamatum C9 from macadamia root against L. theobromae. Volatiles and cell-free culture filtrate of T. hamatum were also used to assess their antifungal activity against L. theobromae. Results suggested that T. hamatum exhibited a significant inhibitory effect against L. theobromae in vitro. Further results of a biocontrol assay indicated that a spray treatment of T. hamatum conidial suspension significantly decreased the size of lesions caused by artificially inoculated L. theobromae on macadamia leaves, as well as the disease index in young trees inoculated with L. theobromae, relative to sterile water controls. Collectively, our findings indicate that T. hamatum C9 represents a potential biocontrol agent that can be used to manage L. theobromae on macadamia.