Caryophyllene-type sesquiterpenoids and α-furanones from the plant endophytic fungus Pestalotiopsis theae

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.

Pestalotiopsis Diversity: Species, Dispositions, Secondary Metabolites, and Bioactivities

Pestalotiopsis species have gained attention thanks to their structurally complex and biologically active secondary metabolites. In past decades, several new secondary metabolites were isolated and identified. Their bioactivities were tested, including anticancer, antifungal, antibacterial, and nematicidal activity. Since the previous review published in 2014, new secondary metabolites were isolated and identified from Pestalotiopsis species and unidentified strains. This review gathered published articles from 2014 to 2021 and focused on 239 new secondary metabolites and their bioactivities. To date, 384 Pestalotiopsis species have been discovered in diverse ecological habitats, with the majority of them unstudied. Some may contain secondary metabolites with unique bioactivities that might benefit pharmacology.

Two New Cytotoxic Decalin Derivatives from Marine-Derived Fungus Talaromyces sp

Two new decalin derivatives named fusarielins O (1) and P (2), together with seven known compounds (3-9) were isolated from the crude extract of the marine-derived fungus Talaromyces sp. The planar structures of the new compounds were elucidated by comprehensive spectroscopic analyses of NMR and HR-ESI-MS. The absolute configuration of 1 was assigned by Snatzke's method and comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1-9 were evaluated for their cytotoxic activities against three tumor cell lines and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities.

Alternariasin A, new pentacyclic cytochalasin from the fungus Alternaria alternate

Alternariasin A (1), one new cytochalasin possessing the benzo[4,5]indeno[2,1-d]isoindole-1,3,13(2H,3aH)-trione skeleton, and five known compounds 2-6 were isolated from the solid cultures of the Midui Glacier-derived fungus Alternaria alternata. Their structures were elucidated by NMR and MS spectroscopic analyses and by a comparison with data from the literature. The absolute configuration of 1 was assigned by combination of experimental and calculated electronic circular dichroism (ECD) spectra. Compound 1 displayed antibacterial activity against the S. aureus, B. subtilis and E. coli with MIC values of 16.7, 16.7 and 33.3 μΜ, respectively. While compound 3 showed potent cytotoxicity against a small panel of human tumour cell lines.

Endophytic fungi: A treasure trove of novel anticancer compounds

Cancer is a multifactorial disease with a convoluted genesis and progression. The emergence of multidrug resistance to presently be offered drug and relapse is by far, the most critical concern to tackle this deteriorating disease. Henceforth, there is undeniably an inflated necessity for safe, promising, and less harmful new anticancer drugs. Natural compounds from various sources like plants, animals, and microorganisms have occupied a center stage in drug discovery due to their tremendous chemical diversity and potential as therapeutic agents. Endophytic microbes are symbiotically associated with plants and have been proven to produce novel or analogues of host bioactive metabolites exhibiting a variety of biological activities including anticancer activity. This review emphasizes on structurally diverse unprecedented anticancer natural compounds that have been reported exclusively from endophytic fungi from 2016 to 2020. It covers chemical nature of metabolites, its fungal source associated with terrestrial, as well as marine plants and anticancer activity based on their cytotoxicity profile against various cancer cell lines. Many of these fungal metabolites with promising anticancer activity can be used as lead molecules for in silico experiments and deserve special attention from scientists for further in vitro and clinical research.

New Diterpenoids and Isocoumarin Derivatives from the Mangrove-Derived Fungus Hypoxylon sp

Two new diterpenoids, hypoxyterpoids A (1) and B (2), and four new isocoumarin derivatives, hypoxymarins A–D (4–7), together, with seven known metabolites (3 and 8–13) were obtained from the crude extract of the mangrove-derived fungus Hypoxylon sp. The structures of the new compounds were elucidated on the basis of 1- and 2-dimensional (1D/2D) nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric analysis. The absolute configurations of compounds 1, 2, 4, 5, and 7 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra, and the absolute configurations of C-4′ in 6 and C-9 in 7 were determined by [Rh₂(OCOCF₃)₄]-induced ECD spectra. Compound 1 showed moderate α-glucosidase inhibitory activities with IC₅₀ values of 741.5 ± 2.83 μM. Compounds 6 and 11 exhibited DPPH scavenging activities with IC₅₀ values of 15.36 ± 0.24 and 3.69 ± 0.07 μM, respectively.

New Bioactive Sesquiterpeniods From the Plant Endophytic Fungus Pestalotiopsis theae

Three new secondary metabolites pestalothenins A-C (1-3), including two new humulane-derived sesquiterpeniods (1 and 2) and one new caryophyllene-derived sesquiterpeniod (3), together with five known compounds (4-8) were isolated from the crude extract of the plant endophytic fungus Pestalotiopsis theae (N635). Their structures were elucidated by the extensive analyses of HRESIMS and NMR spectroscopic data. The absolute configurations of 1-3 were determined by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. The cytotoxic effects of these compounds were evaluated in vitro. Compound 6 showed moderate cytotoxicity against T24 and MCF7 cell lines. In addition, compounds 1-8 were also evaluated for antibacterial activity.

Alterchromanone A, one new chromanone derivative from the mangrove endophytic fungus Alternaria longipes

One new chromanone derivative, alterchromanone A (1), and four known curvularin-type macrolides (2-5) were isolated from the crude extract of the mangrove-derived endophytic fungus Alternaria longipes. Their structures were elucidated by MS and NMR spectroscopic analyses and by a comparison with data from the literature. The absolute configuration of 1 was assigned by combination of experimental and calculated electronic circular dichroism (ECD) spectra. Compound 1 exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity with an IC₅₀ value of 56.3 μg ml^-1. According to the structural features of these compounds, the plausible biosynthetic pathways of 1-5 were also proposed.