Novel Canthin-6-one Derivatives: Design, Synthesis, and Their Antiproliferative Activities via Inducing Apoptosis, Deoxyribonucleic Acid Damage, and Ferroptosis

A series of novel canthin-6-one (CO) derivatives (8a-l) were designed and synthesized by introducing different amide side chains at the C-2 position, and their water solubility, antiproliferative activity, and preliminary mechanism were investigated. Most compounds displayed high cytotoxicity exhibiting low-micromolar IC50 values against four human cancer cell lines, especially HT29 cells. Meanwhile, the water solubility of active CO derivatives was significantly improved. Among these compounds, compound 8h with the N-methyl piperazine group exhibiting the highest antiproliferative capability with an IC50 value of 1.0 μM against HT29 cells, which was 8.6-fold lower than that of CO. Furthermore, 8h could upregulate the levels of reactive oxygen species, leading to mitochondrial damage. In addition, 8h could promote cell apoptosis and DNA damage by regulating the expression of apoptosis-associated proteins (Bcl-2 and cleaved-caspase 3) and the DNA damage-associated protein (H2AX). Most importantly, 8h also exerted ferroptosis by reducing the GSH level and GPX4 expression as well as increasing the lipid peroxidation level. Thus, the novel CO derivative 8h with N-methylpiperazine represents a promising anticancer candidate and warrants a more intensive study.

Structures and Biological Activities of Alkaloids Produced by Mushrooms, a Fungal Subgroup

Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.

Cytotoxicity of fagaramide derivative and canthin-6-one from Zanthoxylum (Rutaceae) species against multidrug resistant leukemia cells

In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH₂Cl₂ (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH₂Cl₂ (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC₅₀ values below 50 μM against the drug sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cell lines. It is interesting to note that 3 was more active than the standard drug, doxorubicin against CEM/ADR5000 leukemia cells. Compounds 3 and 6 showed good selectivity on leukemia cells than normal cells. In future studies 3 should be tested against a panel of drug resistant human cells.

Mushroom-Derived Indole Alkaloids

Mushrooms are known to produce over 140 natural products bearing an indole heterocycle. In this review, the isolation of these mushroom-derived indole alkaloids is discussed, along with their associated biological activities.

Fruitful Decades for Canthin-6-ones from 1952 to 2015: Biosynthesis, Chemistry, and Biological Activities

In this review, more than 60 natural canthin-6-one alkaloids and their structures are considered. The biosynthesis, efficient and classic synthetic approaches, and biological activities of canthin-6-one alkaloids, from 1952 to 2015, are discussed. From an analysis of their structural properties and an investigation of the literature, possible future trends for canthin-6-one alkaloids are proposed. The information reported will be helpful in future research on canthin-6-one alkaloids.

Cytotoxic alkaloids from Fusarium incarnatum associated with the mangrove tree Aegiceras corniculatum

Several unusual alkaloids, N-2-methylpropyl-2-methylbutenamide (1), 2-acetyl-1,2,3,4-tetrahydro-β-carboline (2), fusarine (3), fusamine (4), and 3-(1-aminoethylidene)-6-methyl-2H-pyran-2,4(3H)-dione (5), were isolated from the culture broth of Fusarium incarnatum (HKI0504), an endophytic fungus of the mangrove plant Aegiceras corniculatum. Compounds 2, 4, and 5 exhibit weak antiproliferative and cytotoxic activities against HUVEC, K-562, and HeLa human cell lines, respectively.

N-containing compounds of macromycetes

This review surveys the chemical, biological, and mycological literature dealing with the isolation, structural elucidation, biological activities, and synthesis of nitrogen-containing compounds from the fruiting bodies or the culture broths of macromycetes.

Two-step total syntheses of canthin-6-one alkaloids: new one-pot sequential Pd-catalyzed Suzuki-Miyaura coupling and Cu-catalyzed amidation reaction

Canthin-6-one (1) and nine analogues including the naturally occurring 9-methoxycanthin-6-one (2) and amaroridine (3) are prepared rapidly and in high yields via a convergent "non-classical" strategy that focuses on construction of the central ring B. The strategy relies on concomitant Pd-catalyzed Suzuki-Miyaura C-C coupling followed by a Cu-catalyzed C-N coupling that can be achieved either stepwise or in a new one-pot protocol starting from the appropriate 8-bromo-1,5-naphthyridine.

Brunneins A-C, beta-carboline alkaloids from Cortinarius brunneus

Four beta-carboline alkaloids, brunneins A-C (1-3) and 3-(7-hydroxy-9H-beta-carboline-1-yl)propanoic acid (4), were isolated from fruiting bodies of the agaricoid fungus Cortinarius brunneus. The structures of 1-3 were determined by analysis of NMR and MS data, and the structure of compound 4 was determined by comparison with published data. Brunnein A (1) exhibited very low cholinesterase inhibitory effects and no cytotoxicity.

An attempt to determine the absolute configuration of two ascolactone stereoisomers with time-dependent density functional theory

Two stereoisomers of ascolactone (A, B), natural products with two asymmetric carbon atoms, are isolated from the marine-derived fungus Ascochyta salicorniae. Although these compounds show virtually opposite CD spectra and [alpha]D, 1H- and 13C-NMR data exclude the presence of enantiomers and suggest ascolactone A and B to be epimeric lactones. By comparing the experimental CD spectra with those calculated employing time-dependent density functional theory (TDDFT), we elucidate the configuration at one of the asymmetric carbon atoms.

Polyketides from the marine-derived fungus Ascochyta salicorniae and their potential to inhibit protein phosphatases

Chemical investigation of the marine fungus Ascochyta salicorniae led to the isolation of two new epimeric compounds, ascolactones A (1) and B (2), in addition to the structurally-related polyketides hyalopyrone (3), ascochitine (4), ascochital (5) and ascosalipyrone (6). The absolute configurations of the epimeric compounds 1 and 2 were assigned as (1R,9R) and (1S,9R), respectively, through simulation of the chiroptical properties using quantum-chemical CD calculations, and chiral GC-MS subsequent to oxidative cleavage (Baeyer-Villiger oxidation) of the side chain. In silico screening using the PASS software identified some of the A. salicorniae compounds (1-6) as potential inhibitors of protein phosphatases. Compound was found to inhibit the enzymatic activity of MPtpB with an IC(50) value of 11.5 microM.

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning up to the end of 2004. Newly isolated alkaloids, structure determinations, total synthesis and biological activities are included.