The metabolites of mangrove endophytic fungus Zh6-B1 from the South China Sea

Dactylfungins and Tetralones: Bioactive Metabolites from a Nematode-Associated Laburnicola nematophila

A chemical investigation of Laburnicola nematophila, isolated from cysts of the plant parasitic nematode Heterodera filipjevi, affored three dactylfungin derivatives (1-3) and three tetralone congeners (4-6). Dactylfungin C (1), laburnicolin (4), and laburnicolenone (5) are previously undescribed natural products. Chemical structures of the isolated compounds were determined based on 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry and comparison with data reported in the literature. The relative configurations of compounds 1, 2, and 4-6 were determined based on their ROESY data and analysis of their coupling constants (J values). The absolute configurations of 4-6 were determined through the comparison of their measured and calculated TDDFT-ECD spectra. Compounds 1-3 were active against azole-resistant Aspergillus fumigatus.

Cytotoxic Compounds from Marine Fungi: Sources, Structures, and Bioactivity

Marine fungi, such as species from the Penicillium and Aspergillus genera, are prolific producers of a diversity of natural products with cytotoxic properties. These fungi have been successfully isolated and identified from various marine sources, including sponges, coral, algae, mangroves, sediment, and seawater. The cytotoxic compounds derived from marine fungi can be categorized into five distinct classes: polyketides, peptides, terpenoids and sterols, hybrids, and other miscellaneous compounds. Notably, the pre-eminent group among these compounds comprises polyketides, accounting for 307 out of 642 identified compounds. Particularly, within this collection, 23 out of the 642 compounds exhibit remarkable cytotoxic potency, with IC50 values measured at the nanomolar (nM) or nanogram per milliliter (ng/mL) levels. This review elucidates the originating fungal strains, the sources of isolation, chemical structures, and the noteworthy antitumor activity of the 642 novel natural products isolated from marine fungi. The scope of this review encompasses the period from 1991 to 2023.

Mangrove-associated endomycota: diversity and functional significance as a source of novel drug leads

Endophytic fungi are known for their unprecedented ability to produce novel lead compounds of clinical and pharmaceutical importance. This review focuses on the unexplored fungal diversity associated with mangroves, emphasizing their biodiversity, distribution, and methodological approaches targeting isolation, and identification. Also highlights the bioactive compounds reported from the mangrove fungal endophytes. The compounds are categorized according to their reported biological activities including antimicrobial, antioxidant and cytotoxic property. In addition, protein kinase, α-glucosidase, acetylcholinesterase, tyrosinase inhibition, antiangiogenic, DNA-binding affinity, and calcium/potassium channel blocking activity are also reported. Exploration of these endophytes as a source of pharmacologically important compounds will be highly promising in the wake of emerging antibiotic resistance among pathogens. Thus, the aim of this review is to present a detailed report of mangrove derived endophytic fungi and to open an avenue for researchers to discover the possibilities of exploring these hidden mycota in developing novel drug leads.

Applications of Photoredox Catalysis for the Radical-Induced Cleavage of C–C Bonds

Selective cleavage of C–C bonds forms one of the greatest challenges in current organic chemistry, due to the relative strength of these bonds. However, such transformations are an invaluable instrument to break down and construct new carbon–carbon bonds. To achieve this, photochemistry can be used as a tool to generate radicals and induce the cleavage of these bonds due to their high reactivity. This review examines some of the most influential contributions in this field since 2010.

1 Introduction

2 C–C Bond Cleavage

2.1 Homogeneous Catalyst

2.1.1 N-Centered Radical

2.2.2 O-Centered Radical

2.2 Heterogeneous Catalyst

3 C=C Bond Cleavage

3.1 Homogeneous Catalyst

3.2 Heterogeneous Catalyst

4 C≡C Bond Cleavage

4.1 Homogeneous Catalyst

4.2 Heterogeneous Catalyst

5 Conclusion

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.

Synthesis of (+)-xestodecalactone A

The total synthesis of Benzannulated macrolide, (+)-Xestodecalactone A was accomplished starting from commercially available enantiomerically pure propylene oxide and 3,5-dihydroxyphenylacetic acid using Grignard reaction, alkylation of 1,3-dithiane and Yamaguchi macrolactonisation as key steps.

Photocatalytic Aerobic Oxidative Ring Expansion of Cyclic Ketones to Macrolactones by Cerium and Cyanoanthracene Catalysis

We describe a cerium-catalyzed aerobic oxidative ring expansion for the expedient construction of synthetically challenging macrolactones under visible-light conditions. Cyanoanthracene has been employed as co-catalyst to accelerate the turnover of the cerium cycle leading to a fast conversion within 20 min of irradiation. Taking advantage of the high efficiency and operationally simple conditions, a collection of over 100 macrolactones equipped with ring systems ranging from 9- to 19-membered macrocycles have been prepared from simple building blocks. Moreover, the enabling potential of this strategy to simplify the generation of molecular complexity has been demonstrated through the concise synthesis of sonnerlactone.

Total Synthesis and Structural Revision of Greensporone F and Dechlorogreensporone F

The first asymmetric total syntheses of the real isolation product (2S,5R,8R)-greensporone F and (2S,5R,8R)-dechlorogreensporone F, 14-membered resorcylic acid lactones with a cis-2,5-disubstituted tetrahydrofuran ring system, was accomplished. The synthesis features a late-stage Lewis acid-catalyzed stereoselective intramolecular oxa-Michael reaction, E-selective ring-closing metathesis, De Brabander's esterification, and Jacobsen's hydrolytic kinetic resolution as the key steps. Synthesis of both real isolation and erroneously proposed structure necessitated the revision of the absolute configuration of greensporone F and dechlorogreensporone F. The erroneous representation of (2S,5S,8S)-configuration in greensporone F and dechlorogreensporone F was assigned to be (2S,5R,8R) by comparison with the NMR data and specific rotation of the synthetic compounds with that of the reported data.

Stereochemical determination of four 10-membered ring resorcylic acid lactones from the desert plant endophytic fungus Chaetosphaeronema hispidulum

Four 10-membered ring resorcylic acid lactones (RALs) including a new compound hispidulactone F (1) and three known analogs hispidulactone B (2), 2 R, 4R-sonnerlactone (3), and 2 R, 4S-sonnerlactone (4) were isolated from the special bioenvironmental desert plant endophytic fungus Chaetosphaeronema hispidulum. The structure of the new compound hispidulactone F (1) was determined by extensive spectra analysis including HR-ESI-MS, NMR (¹H, ¹³C, ¹H-¹H COSY, HSQC, and HMBC). Hispidulactone F (1) and hispidulactone B (2) were a pair of stereoisomers at C-3, whereas 2 R, 4R-sonnerlactone (3) and 2 R, 4S-sonnerlactone (4) were another pair of stereoisomers at C-4. The stereochemistries of the hydroxyl groups at C-3 in 1 and 2, and at C-4 in 3 and 4 were first determined by modified Mosher's reactions. Thus, the absolute configuration C-3 in hispidulactone B (2) was not right in our previous report, and was rectified to be R. Compounds 1 and 4 were evaluated for their cytotoxic effects on the proliferation of HepG2. The possible biosynthetic pathway of compounds 1-4 was also presented.

Total synthesis and stereochemical revision of relgro and 10′-oxorelgro

The first total synthesis and correct stereochemical assignments of relgro (6′S,10′S)-configuration and 10′-oxorelgro with (6′S)-configuration are described.

Bioactive Resorcylic Acid Lactones with Different Ring Systems from Desert Plant Chaetosphaeronema hispidulum. [corrected]

Five new resorcylic acid lactones (RALs) hispidulactones A-E (1, 4, 5, 8, and 9), a new natural product (2), and four known ones (3, 6, 7, and 10) with different ring systems were isolated from the desert plant Chaetosphaeronema hispidulum. [corrected]. The new compounds were characterized by NMR data, CD spectra, and X-ray experiment. The new natural product (2) displayed strongly biological effects on the seedlings growth of Arabidopsis thaliana, Digitaria sanguinalis, and Echinochloa crusgalli with a dose-dependent relationship. Compounds 1, 2, and 6 were also tested cytotoxic activities against three cancer cell lines HCT116, Hela, and MCF7 and only did the new natural product (2) display biological activities with IC₅₀ values at 54.86 ± 1.52, 4. 90 ± 0.02, and 20.04 ± 4.00 μM, respectively, whereas the IC₅₀ values of the positive control cis-platinum were 11.36 ± 0.42, 3.54 ± 0.12, and 14.32 ± 1.01 μM, respectively.

Endophytic Fungi-Alternative Sources of Cytotoxic Compounds: A Review

Cancer is a major cause of death worldwide, with an increasing number of cases being reported annually. The elevated rate of mortality necessitates a global challenge to explore newer sources of anticancer drugs. Recent advancements in cancer treatment involve the discovery and development of new and improved chemotherapeutics derived from natural or synthetic sources. Natural sources offer the potential of finding new structural classes with unique bioactivities for cancer therapy. Endophytic fungi represent a rich source of bioactive metabolites that can be manipulated to produce desirable novel analogs for chemotherapy. This review offers a current and integrative account of clinically used anticancer drugs such as taxol, podophyllotoxin, camptothecin, and vinca alkaloids in terms of their mechanism of action, isolation from endophytic fungi and their characterization, yield obtained, and fungal strain improvement strategies. It also covers recent literature on endophytic fungal metabolites from terrestrial, mangrove, and marine sources as potential anticancer agents and emphasizes the findings for cytotoxic bioactive compounds tested against specific cancer cell lines.

Stereoselective Total Syntheses of (3R,5R)-Sonnerlactone and (3R,5S)-Sonnerlactone

A highly convergent and concise total syntheses of (3 R,5 R)-Sonnerlactone and (3 R,5 S) Sonnerlactone from a readily available L-malic acid is described. The following series of reactions such as Barbier allylation, photochemical esterification and Ring Closing Metathesis (RCM) are utilized as key steps to accomplish their syntheses.

Asymmetric total synthesis of (+)-O-methylasparvenone, a rare nitrogen-free serotonin 2C receptor antagonist

The first enantioselective synthesis of the fungal metabolite (+)-O-methylasparvenone is reported.

Bioactive terpenes from marine-derived fungi

Marine-derived fungi continue to be a prolific source of secondary metabolites showing diverse bioactivities. Terpenoids from marine-derived fungi exhibit wide structural diversity including numerous compounds with pronounced biological activities. In this review, we survey the last five years’ reports on terpenoidal metabolites from marine-derived fungi with particular attention on those showing marked biological activities.

Bioactive natural products derived from mangrove-associated microbes

This review summarizes new findings concerning the sources and characteristics of various natural products that can be extracted from mangrove-associated microbes over the past three years (January 2011–December 2013).

Pulvinulin A, Graminin C, and cis-Gregatin B – New Natural Furanones from Pulvinula sp. 11120, a Fungal Endophyte of Cupressus arizonica

Three new natural furanones, pulvinulin A (1), graminin C (2), and cis-gregatin B (3), together with the known fungal metabolites, graminin B (4) and 10-norparvulenone (5), were isolated from Pulvinula sp. 11120, an endophytic fungal strain occurring in healthy foliage of Cupressus arizonica (Arizona cypress). The structures of 1 and 2 were elucidated by the analysis of their spectroscopic data and chemical interconversions, and that of 3 was determined by comparison with data for synthetic cis-gregatin B. Comparison of spectroscopic data of 4 and 5 with those reported identified them as graminin B and 10-norparvulenone, respectively. Metabolites 1–4 exhibited antibacterial activity against E. coli.

Recent progress regarding the bioactivities, biosynthesis and synthesis of naturally occurring resorcinolic macrolides

Macrolides, which comprise a family of lactones with different ring sizes, belong to the polyketide class of natural products. Resorcinolic macrolides, an important subgroup, possess interesting structures and exhibit a wide variety of bioactivities, such as anti-tumor, anti-bacteria, and anti-malaria activities, etc. This review summarizes progress in isolation, bioactivity studies, biosynthesis, and representative chemical syntheses of this group of macrolides in recent decades, encompassing 63 naturally occurring macrolides published in 120 articles.

Natural products chemistry research 2010's progress in China

This article reviews the progresses made by Chinese scientists in the field of natural products chemistry in 2010. Selected compounds with unique structural features and/or promising bioactivities were described herein on the basis of structural types.

Marine natural products

Covering: 2010. Previous review: Nat. Prod. Rep., 2011, 28, 196. This review covers the literature published in 2010 for marine natural products, with 895 citations (590 for the period January to December 2010) 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 (1003 for 2010), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.