Three new long-chain polyenes from the mangrove-derived fungus Penicillium herquei JX4

Genomic characterization and identification of candidate genes for putative podophyllotoxin biosynthesis pathway in Penicillium herquei HGN12.1C

Previous studies have reported the functional role, biochemical features and synthesis pathway of podophyllotoxin (PTOX) in plants. In this study, we employed combined morphological and molecular techniques to identify an endophytic fungus and extract PTOX derivatives. Based on the analysis of ITS sequences and the phylogenetic tree, the isolate was classified as Penicillium herquei HGN12.1C, with a sequence identity of 98.58%. Morphologically, the HGN12.1C strain exhibits white colonies, short-branched mycelia and densely packed hyphae. Using PacBio sequencing at an average read depth of 195×, we obtained a high-quality genome for the HGN12.1C strain, which is 34.9 Mb in size, containing eight chromosomes, one mitochondrial genome and a GC content of 46.5%. Genome analysis revealed 10 genes potentially involved in PTOX biosynthesis. These genes include VdtD, Pinoresinollariciresinol reductase (PLR), Secoisolariciresinol dehydrogenase (SDH), CYP719A23, CYP71BE54, O-methyltransferase 1 (OMT1), O-methyltransferase 3 (OMT3), 2-ODD, CYP71CU and CYP82D61. Notably, the VdtD gene in fungi shares functional similarities with the DIR gene found in plants. Additionally, we identified peltatin, a PTOX derivative, in the HGN12.1C extract. Docking analysis suggests a potential role for the 2-ODD enzyme in converting yatein to deoxypodophyllotoxin. These findings offer invaluable insights into the synthesis mechanism of PTOX in fungi, shedding light on the relationship between host plants and endophytes.

New Secondary Metabolites of Mangrove-Associated Strains

Positioned at the dynamic interface between terrestrial and marine realms, mangroves embody a vibrant tapestry of biodiversity, encompassing an array of plants, animals, and microorganisms. These microbial inhabitants of mangrove habitats have emerged as a pivotal resource for antimicrobials and a plethora of pharmaceutically valuable compounds, spanning enzymes, antineoplastic agents, pesticides, immunosuppressants, and immunomodulators. This review delves into the recent landscape (January 2021 to May 2024, according to the time of publication) of novel secondary metabolites isolated from mangrove-associated microorganisms, analyzing 41 microbial strains that collectively yielded 165 distinct compounds. Our objective is to assess the productivity and potential of natural products derived from microbial populations within mangrove ecosystems in recent times. Notably, fungi stand out as the preeminent contributors to the emergence of these novel natural products, underscoring their pivotal role in the bioprospecting endeavors within these unique environments.

Penicimides A and B, two novel diels-alder [4 + 2] cycloaddition ergosteroids from Penicillium herquei

Two novel naturally occurring [4 + 2] Diels-Alder cycloaddition ergosteroids (1 and 2), three undescribed oxidized ergosteroids (3-5), and eleven known analogs (6-16) were isolated from Penicillium herquei. Compounds 1 and 2 represent the first reported cycloadducts of a steroid with 1,4,6-trimethyl-1,6-dihydropyridine-2,5-dione or 4,6-dimethyl-1,6-dihydropyridine-2,5-dione to date. Compound 3 is the C-15 epimer of (22E,24R)-9α,11β-dihydroxyergosta-4,6,8(14),22-tetraen-3-one (14). The chemical structures of these compounds were elucidated through widespread spectroscopic analyses, mainly including HRESIMS and 1D and 2D NMR data, calculated 13C NMR-DP4+ analysis, and electronic circular dichroism (ECD) data analyses. Biological evaluations of Compounds 1-16 revealed that 3, 9-11, and 15 inhibited the production of NO in LPS-induced RAW264.7 cells with an IC50 value from 7.37 ± 0.69 to 38.9 ± 2.25 μM (the positive control dexamethasone IC50: 9.54 ± 0.71 μM). In addition, Compound 3 exhibited a potent inhibitory effect on the secretion of the proinflammatory cytokines TNF-α and IL-6, the transcription level of the proinflammatory macrophage markers TNF-α, and the expression of the iNOS protein.