Screening of secondary metabolites and antioxidant potential of endophytic fungus Penicillium citrinum and host Digitaria bicornis by spectrophotometric and electrochemical methods

Pharmacological properties of biomimetic synthesized silver nanoparticles from endophytic fungus Coniothyrium chaingmaiense: KUMBMDBT-25

In this study, the endophytic fungus Coniothyrium chaingmaiense-KUMBMDBT-25 was isolated from the healthy stem of Euphorbia tirucalli, mass cultivated by submerged fermentation, and extracted using ethyl acetate as a solvent. The extract was subjected to GC-MS analysis. The synthesized Con-AgNPs were characterized through various bioanalytical methods. The synthesis was confirmed by Bio- spectrophotometry, which showed an absorption peak at 404 nm. FTIR analysis verified the reduction and capping of Con-AgNPs, displaying peaks corresponding to various functional groups. SEM-EDAX and HR-TEM examinations revealed that the Con-AgNPs were spherical, and EDAX analysis confirmed the presence of silver atoms at 3 keV. XRD studies revealed the crystalline structure of Con-AgNPs. DLS and Zeta potential tests determined the size and stability of the synthesized Con-AgNPs, which were 65.81 nm. The Con-AgNPs demonstrated strong antibacterial activity against P. aeruginosa (14.06 ± 0.11 mm, 10 mg/mL) and effective antifungal activity against A. flavus (13.03 ± 0.05 mm, 10 mg/mL). Con-AgNPs exhibited notable biological attributes, including a cytotoxic effect of up to 38.82% and 19.15% at 200 µg/mL in an MTT assay measuring cell viability. Additionally, the nanoparticles demonstrated significant anti-inflammatory effects in both in vitro and in vivo studies, validating the biological and pharmacological potential of Con-AgNPs.

Role of grass endophytic fungi as a natural resource of bioactive metabolites

Grass endophytic fungi have garnered increasing attention as a prolific source of bioactive metabolites with potential application across various fields, including pharmaceticals agriculture and industry. This review paper aims to synthesize knowledge on the diversity, isolation, and bioactivity of metabolites produced by grass endophytic fungi. Additionally, this approach aids in the conservation of rare and endangered plant species. Advanced analytical techniques such as high-performance liquid chromatography, liquid chromatograpy-mass spectrometry and gas chromatography are discussed as critical tools for metabolite identification and characterization. The review also highlights significant bioactive metabolites discovered to date, emphasizing their antimicrobial, antioxidant, and insecticidal activities and plant growth regulation properties. Besides address the challenges and future prospects in harnessing grass endophytic fungi for sustainable biotenological applications. By consolidating recent advancements and identifying agaps in the current research, this paper provides a comprehensive overview of the potential grass endophytic fungi as a valuable resource for novel bioactive compounds.

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.

Promising drought and salinity tolerance features of Nigrospora species existing as endophytes in Oryza sativa

In this study, we report the discovery of novel Nigrospora species isolated from the extensively cultivated PUSA 44 rice variety in Punjab, India. Out of the 120 isolates examined, 6.6% and 5% isolates exhibited tolerance to high salinity and drought stress. Isolates 6OSFR2e and 7OSFS3a exhibited the highest indole acetic acid and gibberellic acid production, with 268.32 ± 08.10 and 25.72 ± 0.04 µg/mL. Additionally, isolates 7OSFS3a, 6OSFR2e and 6OSFL4c had highest antioxidant potential with IC50 345.45 ± 11.66, 391.58 ± 10.66, and 474.529 ± 11.08 µg/mL. The isolates 6OSFR2e and 6OSFL4c also exhibited phosphate solubilisation with a PI of 1.06 ± 0.00 and 1.04 ± 0.02. The highest cellulase and laccase production with EI 1.24 ± 0.00 and 1.16 ± 0.00 was observed by isolates 6OSFR2e and 6OSFL4c. Promising results were observed in the case of ammonia production. The isolates belonged to the same phylum, Ascomycota and were identified as Nigrospora zimmermanii (6OSFR2e) and Nigrospora oryzae (7OSFS3a), and Nigrospora sphaerica (6OSFL4c) using morpho-taxonomic and molecular identification. The present study provides a critical insight into the characteristics of these Nigrospora species, which could be used to develop a bio-consortium for the rejuvenation of PUSA-44 cultivation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03679-9.

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.

Eco-friendly synthesized silver nanoparticles from endophytic fungus Phyllosticta owaniana: KUMBMDBT-32 and evaluation of biomedical properties

The primary objective of the current investigation was the biosynthesis of Phy-AgNPs by the endophytic fungus Phyllosticta owaniana (extracted from Abrus precatorius) and the evaluation of the secondary metabolites from the ethyl acetate extract of P. owaniana cultivated by submerged fermentation. Utilizing bioanalytical strategies, Phy-AgNPs were characterized. The UV-visible spectrophotometer analysis revealed an absorption spectrum with a peak at 420 nm, thus validating the Phy-AgNPs synthesis. The FTIR analysis revealed peaks correlating to various potential functional groups, suggesting that Phy-AgNPs have been reduced and capped. SEM-EDAX and HR-TEM analyses demonstrated the spherical shape of Phy-AgNPs, and the 3 keV EDAX analysis confirmed the existence of silver atoms. XRD analyses showed the Phy-AgNPs crystalline structure. The size and the stability of synthesized Phy-AgNPs (65.81 nm) were measured by DLS and Zeta potential studies. While the ethyl acetate extract was analyzed with GC-MS and FTIR for secondary metabolites. The synthesized Phy-AgNPs showed effective antibacterial activity against Pseudomonas aeruginosa (15.1 ± 0.17 mm, 10 mg/mL), while the antifungal activity of Phy-AgNPs inhibited the growth of Candida albicans extremely efficiently (12.16 ± 0.28 mm, 10 mg/mL). Phy-AgNPs were evaluated for a variety of biomedical properties in which they showed significant activity. In a cell viability assay using the MTT assay, Phy-AgNPs exhibited a cytotoxic impact of up to 30.67% and 34.53% when 200 µg/mL were detected. In both in vitro and in vivo anti-inflammatory examinations, nanoparticles (NPs) exhibited a significant anti-inflammatory effect. These findings support the pharmaceutical and biomedical properties of the synthesized Phy-AgNPs.

Metabolite profiling, in vitro and in silico assessment of antibacterial and anticancer activities of Alternaria alternata endophytic in Jatropha heynei

Fungal endophytes produce a range of structurally diverse metabolites with bioactive principles. In this study, an endophytic fungus Alternaria alternata was isolated from Jatropha heynei and cultured in potato dextrose liquid broth. Culture filtrate of A. alternata was extracted in ethyl acetate and metabolites were characterized by QTOF-HRLCMS. Among compounds detected, spectral compounds such as kigelinone, and levofuraltadone were reported with antibacterial property, while 2-hydroxychrasophanol, isoathyriol, glycophymoline, columbianetin and kaempferol 3-O-β-D- galactoside were reported with cytotoxic properties. Partially purified metabolites of A. alternata showed significant antibacterial activity against tested clinical bacterial strains by agar well diffusion method. High zone of inhibition was recorded against Enterococcus faecalis, Pseudomonas syringae and Klebsiella pneumoniae. In vitro anticancer activity of fungal extract by MTT assay displayed high cytotoxic effect on human lung carcinoma cancer cell line (A549) with IC₅₀ value of 393.52 µg ml^-1, and without any significant cytotoxic effect on human breast cancer cell line (MCF-7). Further, antibacterial and anticancer spectral compounds of A. alternata were subjected to molecular docking analysis with antibacterial target proteins such as tellurite resistance protein (2JXU), indole-3-acetaldehyde dehydrogenase (5IUU) and alkyl hydroperoxide reductase (5Y63), and anticancer target human apoptotic regulator protein (1G5M). The results of the study indicated that kigelinone, levofuraltadone, 2-hydroxychrasophanol and isoathyriol in the fungal extract have significant binding modes, with best binding energy scores with their respective antibacterial and anticancer target proteins. Alternaria alternata resident in J. heynei offers a promising source of broad-spectrum antibacterial and anticancer compounds.