Bio-inspired Step-Economical, Redox-Economical and Protecting-Group-Free Enantioselective Total Syntheses of (−)-Chaetominine and Analogues

Investigation of iso-propylchaetominine anticancer activity on apoptosis, cell cycle and Wnt signaling pathway in different cancer models

Dysregulation of the Wnt signaling pathway contributes to the development of many cancer types. Natural compounds produced with biotechnological systems have been the focus of research for being a new drug candidate both with unlimited resources and cost-effective production. In this study, it was aimed to reveal the effects of isopropylchaetominine on cytotoxic, cytostatic, apoptotic and Wnt signaling pathways in brain, pancreatic and prostate cancer. The IC50 values of isopropylchaetominine in U-87 MG, PANC1, PC3 and LNCaP cells were calculated as 91.94 μM, 41.68 μM, 54.54 μM and 7.86 μM in 72nd h, respectively. The metabolite arrests the cell cycle in G0/G1 phase in each cancer cells. Iso-propylchaetominine induced a 4.3-fold and 1.9-fold increase in apoptosis in PC3 and PANC1 cells, respectively. The toxicity of isopropylchaetominine in healthy fibroblast cells was assessed using the annexin V method, and no significant apoptotic activity was observed between the groups treated with the active substance and untreated. In U-87 MG, PANC1, PC3, and LNCaP cells under treatment with isopropylchaetominin, the expression levels of DKK3, TLE1, AES, DKK1, FRZB, DAB2, AXIN1/2, PPARD, SFRP4, APC and SOX17 tumor suppressor genes increased significantly. Decreases in expression of Wnt1, Wnt2, Wnt3, Wnt4, Wnt5, Wnt6, Wnt10, Wnt11, FRZ2, FRZ3, FRZ7, TCF7L1, BCL9, PYGO, CCND2, c-MYC, WISP1 and CTNNB1 oncogenic genes were detected. All these result shows that isopropylchaetominine can present promising new treatment strategy in different cancer types.

NBS-induced intramolecular annulation reactions for the divergent synthesis of fused- and spirocyclic indolines

An NBS-induced intramolecular annulation of 3-(1H-indol-3-yl)-N-alkoxypropanamide is described. The reactions proceed well and quickly under mild conditions with the help of a base. It was found that C2-substituents on the indole ring in 3-(1H-indol-3-yl)-N-alkoxypropanamide have a great influence upon the reaction. By using C2-methyl- and C2-phenyl-3-(1H-indol-3-yl)-N-alkoxypropanamide as templates, practical protocols for the divergent synthesis of fused- and spirocyclic indoline compounds were studied and established.

Anti-inflammatory alkaloids from the cold-seep-derived fungus Talaromyces helicus SCSIO41311

One new natural alkaloid, chaetominine B (1), together with twenty known compounds was isolated from the South China Sea cold-seep-derived fungus Talaromyces helicus SCSIO41311. Their structures were elucidated on the basis of nuclear magnetic resonance spectrum (NMR), mass spectrometry (MS) and ECD calculation, as well as comparing with previous literatures. Among them, twelve compounds showed potent NO inhibitory activities and two of them, azaspirofurans A (13) and fumiquinones B (21), exhibited NO inhibitory effects more than the positive control eicosapentaenoic acid (EPA) with IC₅₀ values of 9.65 and 15.54 μM, respectively. Moreover, compound 13 attenuated LPS-induced imbalance of cytokines release such as TNF-α, IL-1β, IL-4, and IL-10. Additionally, the NMR data and absolute configuration of compound 20 were first reported.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03237-9.

Biomimetic Enantioselective Total Synthesis of (-)-Robustanoids A and B and Analogues

We report a step-economical, enantioselective total synthesis of (-)-robustanoid B and (-)-robustanoid A and four novel natural product-like compounds. Our strategy relied on our biosynthetic hypothesis and on a novel complexity generation methodology, namely, the one-pot hydroxylative double cyclization reaction. The latter consists of a modified 3,3-dimethyldioxirane-triggered epoxidation-epoxide-ring-opening cyclization reaction cascade and Trost's regioselectivity umpolung methodology ("anti-Michael addition").

Rapid Generation of Molecular Complexity by Chemical Synthesis: Highly Efficient Total Synthesis of Hexacyclic Alkaloid (-)-Chaetominine and Its Biosynthetic Implications

The efficiency becomes a key issue in today's natural product total synthesis. While biomimetic synthesis is one of the most elegant strategies to achieve synthetic efficiency and thus to approach the ideal synthesis, most biogenetic pathways are unknown or unconfirmed. In this account, we demonstrate, through the shortest and also the most efficient asymmetric total syntheses of the hexacyclic alkaloid (-)-chaetominine to date, that on the basis of biogenetic thinking, one can develop quite efficient bio-inspired total synthesis, which in turn serves to suggest and chemically validate plausible biosynthetic routes for the natural product. The synthetic strategy thus developed is also inspiring for the development of other synthetic methods and efficient total synthesis of other natural products.

Asymmetric Total Synthesis and Absolute Configuration Determination of (-)-Verrupyrroloindoline

The first asymmetric total synthesis of (-)-verrupyrroloindoline (20% overall yield in 6 steps) is described. The short approach was enabled by Buchwald's Cu(II)-catalyzed asymmetric conjugate reduction, DMDO-triggered one-pot four-step tandem reaction, and the first amide-selective Ir-catalyzed direct reduction of β-carboethoxy tertiary lactam. Along with the total synthesis, the absolute configuration of natural verrupyrroloindoline was determined as 7 R,10 R,11 R.

Assessment of the Cytotoxic and Apoptotic Eἀects of Chaetominine in a Human Leukemia Cell Line

Chaetominine is a quinazoline alkaloid originating from the endophytic fungus Aspergillus fumigatus CY018. In this study, we showed evidence that chaetominine has cytotoxic and apoptotic effects on human leukemia K562 cells and investigated the pathway involved in chaetominine-induced apoptosis in detail. Chaetominine inhibited K562 cell growth, with an IC50 value of 35 nM, but showed little inhibitory effect on the growth of human peripheral blood mononuclear cells. The high apoptosis rates, morphological apoptotic features, and DNA fragmentation caused by chaetominine indicated that the cytotoxicity was partially caused by its pro-apoptotic effect. Under chaetominine treatment, the Bax/Bcl-2 ratio was upregulated (from 0.3 to 8), which was followed by a decrease in mitochondrial membrane potential, release of cytochrome c from mitochondria into the cytosol, and stimulation of Apaf-1. Furthermore, activation of caspase-9 and caspase-3, which are the main executers of the apoptotic process, was observed. These results demonstrated that chaetominine induced cell apoptosis via the mitochondrial pathway. Chaetominine inhibited K562 cell growth and induced apoptotic cell death through the intrinsic pathway, which suggests that chaetominine might be a promising therapeutic for leukemia.

Stereodivergent and enantioselective total syntheses of isochaetominines A–C and four pairs of isochaetominine C enantiomers: a six-step approach

We report the first total syntheses of (−)-isochaetominines A–C and eight 2,3-cis-stereoisomers of isochaetominine C, and structural revisions of (−)-pseudofischerine and (−)-aniquinazoline D.

The asymmetric total synthesis of (+)-N-acetyl norloline

The asymmetric total synthesis of (+)-N-acetyl norloline, the putative biogenic precursor of all known loline alkaloids, has been achieved in 12 steps from a commercially available compound.

Aza-Knoevenagel-type condensation of secondary amides: direct access to N-monosubstituted β,β-difunctionalized enamines

An efficient approach toN-monosubstituted β,β-difunctionalized enamines, a class of versatile building blocks for the synthesis of bioactive compounds, is reported.

Recent developments in the chemistry of quinazolinone alkaloids

This review focuses on the recent advances in the chemistry of quinazolinone alkaloids which covers the newly isolated quinazolinone alkaloids with their biological activities and the recently reported total syntheses of quinazolinone alkaloids from 2006 to 2015.