Beauvericin production by the Lepidoptera pathogenic fungus Isaria tenuipes: Analysis of natural specimens, synnemata from cultivation, and mycelia from liquid-media fermentation

Low beauvericin concentrations promote PC-12 cell survival under oxidative stress by regulating lipid metabolism and PI3K/AKT/mTOR signaling

Beauvericin (BEA), a naturally occurring cyclic peptide with good pharmacological activity, has been widely explored in anticancer research. Although BEA is toxic, studies have demonstrated its antioxidant activity. However, to date, the antioxidant mechanisms of BEA remain unclear. Herein, we conducted a comprehensive and detailed study of the antioxidant mechanism of BEA using an untargeted metabolomics approach, subsequently validating the results. BEA concentrations of 0.5 and 1 μM significantly inhibited H2O2-induced oxidative stress (OS), decreased reactive oxygen species levels in PC-12 cells, and restored the mitochondrial membrane potential. Untargeted metabolomics indicated that BEA was primarily involved in lipid-related metabolism, suggesting its role in resisting OS in PC-12 cells by participating in lipid metabolism. BEA combated OS damage by increasing phosphatidylcholine, phosphatidylethanolamine, and sphingolipid levels. In the current study, BEA upregulated proteins related to the PI3K/AKT/mTOR pathway, thereby promoting cell survival. These findings support the antioxidant activity of BEA at low concentrations, warranting further research into its pharmacological effects.

Bifusicoumarins A-D: Cytotoxic 3S-dihydroisocoumarins from the entomopathogenic fungus Cordyceps bifusispora (NBRC 108997)

Cordyceps is a genus of ascomycete fungi with some of them being edible and/or having a long tradition in Chinese medicine. The chemical characterization of a solvent extract of the entomopathogenic fungus Cordyceps bifusispora afforded four undescribed coumarins, bifusicoumarin A-D (1-4), along with previously reported metabolites (5-8). Structural elucidation was performed via NMR, UV and HRMS analyses, X-ray single crystal diffraction and experimental ECD. The high throughput resazurin reduction assay, that measures cell viability, indicated that 5 has a IC₅₀ between 1 and 15 μM for several assayed tumor lines. Moreover, a protein-interaction network indicated that C. bifusispora is a promising source of additional antitumor metabolites based on SwissTargetPrediction software predictions.

Integration of Untargeted Metabolomics with Transcriptomics Provides Insights into Beauvericin Biosynthesis in Cordyceps chanhua under H2O2-Induced Oxidative Stress

Cordyceps chanhua is an important cordycipitoid mushroom widely used in Asia and beyond. Beauvericin (BEA), one of the bioactive compounds of C. chanhua, has attracted much attention because of its medicinal value and food safety risk. In order to clear up the relationship between oxidative stress and BEA synthesis, we investigated the impact of H2O2-induced oxidative stress on the secondary metabolism of C. chanhua using untargeted metabolomics and a transcript profiling approach. Metabolic profiling of C. chanhua mycelia found that in total, 73 differential metabolites were identified, including organic acids, phospholipids, and non-ribosomal peptides (NRPs), especially the content of BEA, increasing 13-fold under oxidative stress treatment. Combining transcriptomic and metabolomic analyses, we found that the genes and metabolites associated with the NRP metabolism, especially the BEA biosynthesis, were highly significantly enriched under H2O2-induced stress, which indicated that the BEA metabolism might be positive in the resistance of C. chanhua to oxidative stress. These results not only aid in better understanding of the resistance mechanisms of C. chanhua against oxidative stress but also might be helpful for molecular breeding of C. chanhua with low BEA content.

Characterization and Toxicity of Crude Toxins Produced by Cordyceps fumosorosea against Bemisia tabaci (Gennadius) and Aphis craccivora (Koch)

Cordyceps fumosorosea, an insect pathogenic fungus, produces different toxins/secondary metabolites which can act as pest control agents. This study reports the extraction and characterization of crude mycelial extracts of C. fumosorosea isolate SP502 along with their bio-efficacy against Bemisia tabaci and Aphis craccivora. Fourier transform infrared spectroscopy, liquid chromatography, mass spectrometery and nuclear magnetic resonance analysis of C. fumosorosea isolate SP502 extracts showed the presence of five major compounds—Trichodermin, 5-Methylmellein, Brevianamide F, Enniatin and Beauvericin—which all may potentially be involved in insecticidal activity. The HPLC analysis of C. fumosorosea mycelial extracts and Beauvericin standard showed similar chromatographic peaks, with the content of Beauvericin in the crude toxin being calculated as 0.66 mg/ml. The median lethal concentrations of C. fumosorosea mycelial extracts towards first, second, third and fourth instar nymphs of A. craccivora were 46.35, 54.55, 68.94, and 81.92 µg/mL, respectively. The median lethal concentrations of C. fumosorosea mycelial extracts towards first, second, third and fourth instar nymphs of B. tabaci were 62.67, 72.84, 77.40, and 94.40 µg/mL, respectively. Our results demonstrate that bioactive compounds produced by C. fumosorosea isolate SP502 have insecticidal properties and could, therefore, be developed into biopesticides for the management of B. tabaci and A. craccivora.

Isaria tenuipes Peck, an entomopathogenic fungus from Darjeeling Himalaya: Evaluation of in-vitro antiproliferative and antioxidant potential of its mycelium extract

BACKGROUND

Isaria tenuipes is one of the potent species in the members of the genus Isaria, which is well reported to possess multiple bioactive substances of therapeutic importance. Therefore, an in vitro experimental study was carried to evaluate the bioactivities of the crude methanolic extract from the mycelium of this fungus.

METHODS

The fungus was authenticated through morphological characters and the species discrepancy was resolved using the nuclear rDNA ITS sequence. The methanolic extract was fingerprinted by FTIR. The antioxidant components in terms of total phenols and flavonoids were determined as gallic acid and quercetin equivalents respectively. Antioxidant activities of the methanolic extract was assessed using 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2, 2/-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) radical cation (ABTS0+), Fe2+chelating activity, and hydroxyl radical scavenging assays. Cytotoxicity of the extract was determined by [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] (MTT) assay on three cancer cell lines: HeLa, HepG2, and PC3. Apoptosis was further studied by propidium iodide (PI) and Annexin-V/PI staining flow cytometric analysis. Anti-proliferation capacity was studied by colony-forming assay.

RESULTS

In the present study total phenol content of the dried methanol extract was 148.09 ± 3.51μg gallic acid equivalent/mg and flavonoid was 9.02±0.95 μg quercetin/mg. The antioxidant activities of methanol-water extract (8:2 v/v) from cultured mycelia of I. tenuipes investigated and evaluated with 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay revealed IC50 value of 5.04mg/ml with an inhibition rate of 74.77% at 10mg/ml and with an iron-chelating assay the chelating ability was recorded to be 86.76% where the IC50 value was 4.43 mg/ml. In comparison among the antioxidant assays, 2,2/-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) radical cation (ABTS0+) and hydroxyl assay exhibited radical scavenging rate of 44.42% and 49.82% respectively at a concentration of 10 mg/ml. The IC50 value of the extract in MTT assay was 43.45μg/ml with HeLa cells, 119.33μg/ml with PC3 cells, and 125.55μg/ml with HepG2 cells.

CONCLUSION

In this study, it can be concluded that the crude methanolic extract exhibited potent antioxidant and antiproliferative activities suggesting natural antioxidative and antiproliferative agents.