New cytotoxic natural products from the marine sponge-derived fungus Pestalotiopsis sp. by epigenetic modification

Isolation and biological activity of six new polyketide and terpenoid derivatives from Neopestalotiopsis Clavispora AL01

A fungus strain, Neopestalotiopsis clavispora AL01, was isolated from the leaf spot of the plant Phoenix dactylifera. Further chemical investigation of the fermentation extract of this strain afforded six new secondary metabolites (1-6), along with 11 known compounds (7-17) which included a new natural compound (7). Their structures were determined by extensive spectroscopic analysis including one-and two-dimensional (1D and 2D) NMR spectroscopy, high-resolution electrospray ionization mass spectrometry (HRESIMS), and ECD and NMR calculations. All compounds were evaluated for their phytotoxic activities. Among them, compounds 10, 12 and 13 exhibited phytotoxic activities against Nicotiana tabacum. Compound 3 exhibited weak antibacterial activity against methicillin-resistant Staphylococcus aureus, Micrococcus luteus and Vibrio harveyi. Taken collectively, these findings establish a solid research foundation for future investigations on bioactive natural products derived from phytopathogenic fungi.

Recent advances on Pestalotiopsis genus: chemistry, biological activities, structure-activity relationship, and biosynthesis

Strains of the fungal genus Pestalotiopsis are reported as large promising sources of structurally varied biologically active metabolites. Many bioactive secondary metabolites with diverse structural features have been derived from Pestalotiopsis. Moreover, some of these compounds can potentially be developed into lead compounds. Herein, we have systematically reviewed the chemical constituents and bioactivities of the fungal genus Pestalotiopsis, covering a period ranging from January 2016 to December 2022. As many as 307 compounds, including terpenoids, coumarins, lactones, polyketides, and alkaloids, were isolated during this period. Furthermore, for the benefit of readers, the biosynthesis and potential medicinal value of these new compounds are also discussed in this review. Finally, the perspectives and directions for future research and the potential applications of the new compounds are summarized in various tables.

Recent Advances in Search of Bioactive Secondary Metabolites from Fungi Triggered by Chemical Epigenetic Modifiers

Genomic analysis has demonstrated that many fungi possess essential gene clusters for the production of previously unobserved secondary metabolites; however, these genes are normally reduced or silenced under most conditions. These cryptic biosynthetic gene clusters have become treasures of new bioactive secondary metabolites. The induction of these biosynthetic gene clusters under stress or special conditions can improve the titers of known compounds or the production of novel compounds. Among the inducing strategies, chemical-epigenetic regulation is considered a powerful approach, and it uses small-molecule epigenetic modifiers, which mainly act as the inhibitors of DNA methyltransferase, histone deacetylase, and histone acetyltransferase, to promote changes in the structure of DNA, histones, and proteasomes and to further activate cryptic biosynthetic gene clusters for the production of a wide variety of bioactive secondary metabolites. These epigenetic modifiers mainly include 5-azacytidine, suberoylanilide hydroxamic acid, suberoyl bishydroxamic acid, sodium butyrate, and nicotinamide. This review gives an overview on the method of chemical epigenetic modifiers to trigger silent or low-expressed biosynthetic pathways to yield bioactive natural products through external cues of fungi, mainly based on the research progress in the period from 2007 to 2022. The production of about 540 fungal secondary metabolites was found to be induced or enhanced by chemical epigenetic modifiers. Some of them exhibited significant biological activities such as cytotoxic, antimicrobial, anti-inflammatory, and antioxidant activity.

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.

Cryptic Metabolites from Marine-Derived Microorganisms Using OSMAC and Epigenetic Approaches

Marine microorganisms have proven to be a source of new natural products with a wide spectrum of biological activities relevant in different industrial sectors. The ever-increasing number of sequenced microbial genomes has highlighted a discrepancy between the number of gene clusters potentially encoding the production of natural products and the actual number of chemically characterized metabolites for a given microorganism. Homologous and heterologous expression of these biosynthetic genes, which are often silent under experimental laboratory culture conditions, may lead to the discovery of new cryptic natural products of medical and biotechnological interest. Several new genetic and cultivation-based strategies have been developed to meet this challenge. The OSMAC approach (one strain-many compounds), based on modification of growth conditions, has proven to be a powerful strategy for the discovery of new cryptic natural products. As a direct extension of this approach, the addition of chemical elicitors or epigenetic modifiers have also been used to activate silent genes. This review looks at the structures and biological activities of new cryptic metabolites from marine-derived microorganisms obtained using the OSMAC approach, the addition of chemical elicitors, and enzymatic inhibitors and epigenetic modifiers. It covers works published up to June 2021.