Chemical Constituents from Endophytic Fungus Annulohypoxylon cf. stygium in Leaves of Anoectochilus roxburghii

The Mutually Inspiring Biological and Chemical Synthesis of Fungal Bicyclo[2.2.2]diazaoctane Indole Alkaloids

Fungal indole alkaloids bearing a bicyclo[2.2.2]diazaoctane (BCDO) core structure are a fascinating family of natural products that exhibit a wide spectrum of biological activities. These compounds also display remarkable structural diversity, with many different diastereomers and enantiomers produced by specific fungal strains. The biogenesis of the unique BCDO moiety has long been proposed to involve an intramolecular [4+2] hetero-Diels-Alder (IMDA) reaction, but the exact mechanisms for this hypothetical transformation have remained elusive until recently. This review aims to summarize the whole history of synthetic and biosynthetic studies of fungal BCDO indole alkaloids, by covering the discovery, biomimetic syntheses, total syntheses, biosynthetic pathway elucidation, and biological activities of representative compounds. We highlight the mutual inspiration and corroboration between biological and synthetic chemists in exploring the intriguing biosynthetic mysteries of this family of natural products. We also provide perspectives and clues for the remaining biosynthetic problems.

Integrated analysis of miRNA-mRNA regulatory networks in Anoectochilus roxburghii in response to blue laser light

Anoectochilus roxburghii (Wall.) Lind. has significant medicinal and economic value, and the social demand for this species is increasing annually. Laser light sources have different luminescent mechanisms compared with ordinary light sources and are also important factors regulating the synthesis of functional metabolites in A. roxburghii. However, the regulatory mechanism through which A. roxburghii responds to blue laser light has not been investigated. Previous studies have shown that blue-laser treatment results in more red leaves than blue- or white-light treatment. Here, the differences in the effects of laser treatment on A. roxburghii were analyzed by transcriptome sequencing. Gene Ontology analysis revealed that the membranes, calcium ion binding, brassinosteroid-mediated signaling pathway and response to salicylic acid play important roles in the response of A. roxburghii to blue laser light. Kyoto Encyclopedia of Genes and Genomes analysis revealed the involvement of multiple pathways in the response to blue-laser treatment, and among these, beta biosynthesis, flavone and flavonol biosynthesis, thiamine metabolism, limonene and pinene biosynthesis, and peroxisomes play core roles. Cytoscape interaction analysis of the differentially expressed miRNA targets indicated that novel_miR_66, novel_miR_78 and novel_miR_212 were most likely involved in the effect of blue laser light on A. roxburghii. Metabolic content measurements showed that blue laser light increased the beet red pigment, thiamine, total flavonoid and limonene contents, and qPCR analysis confirmed that novel_miR_21, novel_miR_66, novel_miR_188 and novel_miR_194 might participate in the blue-laser signaling network through their target genes and thereby regulate the functional metabolite accumulation in A. roxburghii. This study provides a scientific basis for high-yield A. roxburghii production.

The Biosynthesis, Structure Diversity and Bioactivity of Sterigmatocystins and Aflatoxins: A Review

Sterigmatocystins and aflatoxins are a group of mycotoxins mainly isolated from fungi of the genera Aspergillus. Since the discovery of sterigmatocystins in 1954 and aflatoxins in 1961, many scholars have conducted a series of studies on their structural identification, synthesis and biological activities. Studies have shown that sterigmatocystins and aflatoxins have a wide range of biological activities such as antitumour, antibacterial, anti-inflammatory, antiplasmodial, etc. The sterigmatocystins and aflatoxins had been shown to be hepatotoxic and nephrotoxic in animals. This review attempts to give a comprehensive summary of progress on the chemical structural features, synthesis, and bioactivity of sterigmatocystins and aflatoxins reported from 1954 to April 2024. A total of 72 sterigmatocystins and 20 aflatoxins are presented in this review. This paper reviews the chemical diversity and potential activity and toxicity of sterigmatocystins and aflatoxins, enhances the understanding of sterigmatocystins and aflatoxins that adversely affect humans and animals, and provides ideas for their prevention, research and development.

Secondary Metabolites and Their Cytotoxic Activity of Artemisia nitrosa Weber. and Artemisia marschalliana Spreng

As a promising source of biologically active substances, the Artemisia species from Kazakhstan have not been investigated efficiently. Considering the rich history, medicinal values, and availability of the Artemisia plants, systematic investigations of two Artemisia species growing in the East Kazakhstan region were conducted. In this study, one new germacrane-type sesquiterpene lactone (11), together with 10 known sesquiterpenes and its dimer, were characterized from A. nitrosa Weber. Additionally, one new chromene derivative (1') with another 12 known compounds, including coumarins, sesquiterpene diketones, phenyl propanoids, polyacetylenics, dihydroxycinnamic acid derivatives, fatty acids, naphthalene derivatives, flavones, and caffeic acid derivatives were isolated from A. marschalliana Spreng. All compounds were isolated and identified for the first time from these two Artemisia species. The structures of new compounds (11, 1') were established by using UV, TOFMS, LC-MS, 1D and 2D NMR spectroscopic analyses. The cytotoxicity of all isolated compounds was evaluated. As a result, all compounds did not show significant inhibition against HL-60 and A-549 cell lines. The sesquiterpenoids isolated from A. nitrosa were tested for their inhibitory activity against the LPS-induced NO release from the RAW624.7 cells, and neither of them exhibited significant activity.

Deep-Sea Natural Products from Extreme Environments: Cold Seeps and Hydrothermal Vents

The deep sea has been proven to be a great treasure for structurally unique and biologically active natural products in the last two decades. Cold seeps and hydrothermal vents, as typical representatives of deep-sea extreme environments, have attracted more and more attention. This review mainly summarizes the natural products of marine animals, marine fungi, and marine bacteria derived from deep-sea cold seeps and hydrothermal vents as well as their biological activities. In general, there were 182 compounds reported, citing 132 references and covering the literature from the first report in 1984 up to March 2022. The sources of the compounds are represented by the genera Aspergillus sp., Penicillium sp., Streptomyces sp., and so on. It is worth mentioning that 90 of the 182 compounds are new and that almost 60% of the reported structures exhibited diverse bioactivities, which became attractive targets for relevant organic synthetic and biosynthetic studies.