Staprexanthones, Xanthone-Type Stimulators of Pancreatic β-Cell Proliferation from a Mangrove Endophytic Fungus

Design, synthesis and biological evaluation of sulfur-containing tetrahydroxanthones as potential anti-tumor agents

Given the rising incidence and mortality rates of cancer, the development of highly effective, low-toxicity therapeutics is critical. Xanthones, a class of natural secondary metabolites, are notable for their distinct structure and exhibit promising antitumor activity, underscoring their potential as scaffolds for drug design. Sulfur heterocycles are also valuable in the development of bioactive small molecules. Therefore, we explored the introduction of sulfur in the core structure of xanthones, leading to the synthesis of a series of sulfur-containing tetrahydroxanthones. The in vitro cytotoxicity of these compounds was evaluated using the CCK8 assay, revealing that several derivatives exhibit anti-proliferative effects against HepG2 cells. Among them, compound 4k displayed potent inhibitory activity with an IC50 value of 6.08 μM and showed favorable selectivity, exhibiting low toxicity toward normal cells. Further studies demonstrated that 4k inhibited colony formation and migration of HepG2 cells, and induced apoptosis.

Plant Pathogenic Fungi: A Treasure Trove of Bioactive γ-Pyrones

Plant pathogenic fungi are among the primary causes of plant diseases, which reduce worldwide crop yield. Regardless of their pathogenicity, they substantially contribute to medicine, agriculture, and other fields through their ability to generate bioactive natural substances. Particularly, they can produce γ-pyrones, the main scaffold in various biologically active metabolites. Numerous pharmacologists and natural product chemists are intrigued by natural compounds with γ-pyrone scaffolds due to their potential use as antibacterial, antifungal, anticancer, antiinflammatory, antidiabetes, antioxidant, and antiviral agents. Despite the extensive applications and increasing reports of γ-pyrones, their systematic chemistry, manufacturing, and therapeutic significance, especially in plant pathogenic fungi, remain inadequately understood. This review, covering up to December 2024, addresses this gap by compiling 316 γ-pyrones from plant-pathogenic fungi. The γ-pyrones are categorized into chromones (35%), xanthones (28%), naphtho-γ-pyrones (25%), hybrid pyrones (6%), monocyclic pyrones (4%), flavonoids/isoflavonoids (1%), and others (1%). This review elucidates the natural origins of γ-pyrones, their biosynthesis, pharmacological properties, activity mechanisms, structure-activity relationships, and biological activity. It also discusses the present evolutionary status, problems, future directions, and potential of γ-pyrones to assist scientists in their discovery. Furthermore, it seeks to underscore the significance of γ-pyrones as promising natural products for agriculture and pharmaceutical development.

Complete genome sequence of the marine mangrove fungus Sarcopodium sp.QM3-1 confirmed its high potential for antimicrobial activity

Mangroves, owing to their unique living environment, serve as an important source of natural bioactive compounds. Sarcopodium sp. QM3-1, a marine fungus isolated from mangrove sediments of Quanzhou Bay, exhibited antifungal activity against the plant pathogen Agrobacterium tumefaciens and Magnaporthe oryzae. Whole-genome sequencing of this fungal strain revealed a genome size of 58,356,150 bp with 17,960 protein-coding genes, 539 tRNA genes, and 170 rRNA genes. Functional annotation identified a series of genes involved in the biosynthesis of secondary metabolites, including several gene clusters associated with antimicrobial activity. Notably, twenty of these gene clusters were associated with the synthesis of known bioactive compounds, including terpene, polyketides (PKS), nonribosomal peptides (NRPS), β-lactones, and phosphonates. Our findings suggest that Sarcopodium sp. QM3-1 could be a promising candidate as a biocontrol agent for combating plant pathogens in agricultural fields.

Design, synthesis, and antiproliferative activity evaluation of novel α-mangostin derivatives by ROS/MAPK signaling pathway

Novel hydroxamic acid and 3,6-amide modified α-mangostin derivatives were synthesized and evaluated their antiproliferative activities against KYSE 30 (esophageal cancer), HCT 116 (colon cancer), and HGC 27 (gastric cancer) cell lines. Most of the new derivatives displayed stronger anti-proliferative activities compared to α-mangostin. Among all the derivatives, compound 4a exhibited the most potent activity, with IC50 values of 0.57 ± 0.29 μM, 3.27 ± 0.16 μM, and 2.28 ± 1.02 μM against KYSE 30, HCT 116, and HGC 27 cells, respectively. Subsequent mechanism studies revealed that compound 4a inhibited cancer cells proliferation and colonies formation in a concentration-dependent manner. Additionally, compound 4a caused cell cycle arrest in a p53 dependent manner and induced apoptosis in p53 independent way. Meanwhile, 4a suppressed cell cycle related proteins (Cyclin D1 and cyclin B1) expression, increased pro-apoptotic proteins (cleaved PARP, cleaved caspase-7, and cleaved caspase-9) and decreased anti-apoptotic proteins (Bcl-2) expression. Moreover, 4a increased reactive oxygen species (ROS) levels in KYSE 30 cells and upregulated the expression of proteins related to the ROS related MAPK signaling pathway (p-ERK, p-p38, and p-JNK). These findings suggest that compound 4a holds promising potential as an antiproliferative agent by targeting MAPK signaling pathway to inhibit cell cycle progress, induce apoptosis and produce ROS in cancers.

Stachybotrys chartarum-A Hidden Treasure: Secondary Metabolites, Bioactivities, and Biotechnological Relevance

Fungi are renowned as a fountainhead of bio-metabolites that could be employed for producing novel therapeutic agents, as well as enzymes with wide biotechnological and industrial applications. Stachybotrys chartarum (black mold) (Stachybotriaceae) is a toxigenic fungus that is commonly found in damp environments. This fungus has the capacity to produce various classes of bio-metabolites with unrivaled structural features, including cyclosporins, cochlioquinones, atranones, trichothecenes, dolabellanes, phenylspirodrimanes, xanthones, and isoindoline and chromene derivatives. Moreover, it is a source of various enzymes that could have variable biotechnological and industrial relevance. The current review highlights the formerly published data on S. chartarum, including its metabolites and their bioactivities, as well as industrial and biotechnological relevance dated from 1973 to the beginning of 2022. In this work, 215 metabolites have been listed and 138 references have been cited.

Linear polyketides produced by co-culture of Penicillium crustosum and Penicillium fellutanum

Two new polyketides, penifellutins A (1) and B (2), possessing a 22 carbon linear skeleton, were isolated from a co-culture of the deep-sea-derived fungi Penicillium crustosum PRB-2 and Penicillium fellutanum HDN14-323. Meanwhile, two esterification products of 1, penifellutins C (3) and D (4), were obtained because compound 1 could be esterified spontaneously when stored in methanol. Their configurations were difficult to determine because of chiral central crowdedness, structural flexibility and instability. As such, we solved this issue by comprehensively using Mo₂(OAc)₄-based CD experiments, density functional theory calculation of ¹³C NMR, DP4 + probability analysis and many chemical reactions, including making acetonide derivative, Mosher's method, PGME method, etc. Compounds 1 and 2 show obvious inhibitory activity on the liver hyperplasia of zebrafish larvae at a concentration of 10 μmol/L, while 3 and 4 show no activity, indicating that two carboxyls in the structure are important active sites.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00125-8.

Marine natural products

Covering: 2020This review covers the literature published in 2020 for marine natural products (MNPs), with 757 citations (747 for the period January to December 2020) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1407 in 420 papers for 2020), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. A meta analysis of bioactivity data relating to new MNPs reported over the last five years is also presented.

Bioactive Marine Xanthones: A Review

The marine environment is an important source of specialized metabolites with valuable biological activities. Xanthones are a relevant chemical class of specialized metabolites found in this environment due to their structural variety and their biological activities. In this work, a comprehensive literature review of marine xanthones reported up to now was performed. A large number of bioactive xanthone derivatives (169) were identified, and their structures, biological activities, and natural sources were described. To characterize the chemical space occupied by marine-derived xanthones, molecular descriptors were calculated. For the analysis of the molecular descriptors, the xanthone derivatives were grouped into five structural categories (simple, prenylated, O-heterocyclic, complex, and hydroxanthones) and six biological activities (antitumor, antibacterial, antidiabetic, antifungal, antiviral, and miscellaneous). Moreover, the natural product-likeness and the drug-likeness of marine xanthones were also assessed. Marine xanthone derivatives are rewarding bioactive compounds and constitute a promising starting point for the design of other novel bioactive molecules.

Secondary metabolites from mangrove-associated fungi: source, chemistry and bioactivities

Covering 1989 to 2020The mangrove forests are a complex ecosystem occurring at tropical and subtropical intertidal estuarine zones and nourish a diverse group of microorganisms including fungi, actinomycetes, bacteria, cyanobacteria, algae, and protozoa. Among the mangrove microbial community, mangrove associated fungi, as the second-largest ecological group of the marine fungi, not only play an essential role in creating and maintaining this biosphere but also represent a rich source of structurally unique and diverse bioactive secondary metabolites, attracting significant attention of organic chemists and pharmacologists. This review summarizes the discovery relating to the source and characteristics of metabolic products isolated from mangrove-associated fungi over the past thirty years (1989-2020). Its emphasis included 1387 new metabolites from 451 papers, focusing on bioactivity and the unique chemical diversity of these natural products.

Penipyrols C-G and methyl-penipyrol A, α-pyrone polyketides from the mangrove derived fungus Penicillium sp. HDN-11-131

Six new α-pyrone polyketides, penipyrols C-G (1-5) and methyl-penipyrol A (6), together with one biogenetically related known compound, penipyrol A (7), were isolated from the extract of fungus Penicillium sp. HDN-11-131. Their structures including the absolute configurations were established by extensive spectroscopic analysis, Mosher's method, and ECD calculations as well as biogenic considerations. Compounds 1-4 possess a rare skeleton featuring γ-butyrolactone linked to α-pyrone ring through double bond. Compound 1 can induce pancreatic β-cell regeneration in zebrafish at 10 μM, which demonstrated promising anti-diabetes potential.