Dehydroabietylamine-substituted trifluorobenzene sulfonamide rhodamine B hybrids as anticancer agents overcoming drug resistance

Attachment of a conjugate assembled from a novel fluorinated carbonic anhydrase inhibitor and rhodamine B onto dehydroabietylamine (DHA) or cyclododecylamine led to first-in-class conjugates of good cytotoxicity; thereby IC50 values (from SRB assays; employed tumor cell lines A2780, A2780Cis, A549, HT29, MCF7, and non-malignant human fibroblasts CCD18Co) between 0.2 and 0.7 μM were found. Both conjugates showed similar cytotoxic activity but the dehydroabietylamine derived conjugate outperformed its cyclododecyl analog in terms of tumor cell/non-tumor cell selectivity. Both conjugates accumulate intracellular, and the DHA conjugate was able to overcome drug resistance which is effective independent of the expression status of carbonic anhydrase IX.

Discovery of Dehydroabietylamine Derivatives as Antibacterial and Antifungal Agents

A diverse array of biologically active derivatives was derived by modifying the chemically active sites of dehydroabietylamine. Herein, we describe the synthesis of a new series of C-19-arylated dehydroabietylamine derivatives using a palladium-catalyzed C(sp3)-H activation reaction. Five analogues (3b, 3d, 3h, 3n, and 4a) exhibited antibacterial activity against Escherichia coli. Compound 4a exhibited strong inhibitory activity against DNA Topo II and Topo IV. Molecular docking modeling indicated that it can bind effectively to the target through interactions with amino acid residues. The synthesized compounds were tested in vitro for their antifungal activity against six common phytopathogenic fungi. The mechanism of action of compound 4c against Rhizoctorzia solani was investigated, revealing that it disrupts the morphology of the mycelium and enhances cell membrane permeability.

Merging Photoredox/Nickel Catalysis for Cross-Electrophile Coupling of Aziridines with Pyridin-1-ium Salts via Dearomatization

Merging photoredox/nickel catalysis enabling the cross-electrophile coupling of aziridines with pyridin-1-ium salts involving dearomatization for the synthesis of β-(1,4-dihydropyridin-4-yl)-ethylamines, especially including bioactive motif-based analogues, is described. This method allows incorporation of a 1,4-dihydropyridin-4-yl group and formation a N-H amino group to construct highly valuable β-(1,4-dihydropyridin-4-yl)-ethylamine frameworks in a single step through the C2-N bond regioselective cleavage and dearomatization alkylation cascades with precise regioselectivity and excellent functional group tolerance, and represents an appealing cross-electrophile coupling strategy to accomplish transformations between two electrophiles, including aziridines and pyridin-1-ium salts, by avoiding prefunctionalization.

Novel dehydroabietylamine derivatives as potent inhibitors of acetylcholinesterase

Nowadays, the inhibition of acetylcholinesterase is one of the main pharmacological strategies for the treatment of Alzheimer's disease. Therefore, a set of thirty-four derivatives of the diterpenoid dehydroabietylamine has been synthesized and screened in colorimetric Ellman's assays to determine their ability to inhibit the enzymes acetylcholinesterase (AChE, from electric eel) and butyrylcholinesterase (BChE, from equine serum). A systematic variation of the substitution of dehydroabietylamides enabled an approach to analogs showing a remarkable inhibition potency for AChE. Particularly N-benzoyldehydroabietylamines 11, 12 and 13 were excellent inhibitors for AChE, showing inhibition rates comparable to standard galantamine hydrobromide.

Accessing Drug Metabolites via Transition-Metal Catalyzed C-H Oxidation: The Liver as Synthetic Inspiration

Can classical and modern chemical C-H oxidation reactions complement biotransformation in the synthesis of drug metabolites? We have surveyed the literature in an effort to try to answer this important question of major practical significance in the pharmaceutical industry. Drug metabolites are required throughout all phases of the drug discovery and development process; however, their synthesis is still an unsolved problem. This Review, not intended to be comprehensive or historical, highlights relevant applications of chemical C-H oxidation reactions, electrochemistry and microfluidic technologies to drug templates in order to access drug metabolites, and also highlights promising reactions to this end. Where possible or appropriate, the contrast with biotransformation is drawn. In doing so, we have tried to identify gaps where they exist in the hope to spur further activity in this very important research area.

Discovery of novel PDE9 inhibitors capable of inhibiting Aβ aggregation as potential candidates for the treatment of Alzheimer's disease

Recently, phosphodiesterase-9 (PDE9) inhibitors and biometal-chelators have received much attention as potential therapeutics for the treatment of Alzheimer’s disease (AD). Here, we designed, synthesized, and evaluated a novel series of PDE9 inhibitors with the ability to chelate metal ions. The bioassay results showed that most of these molecules strongly inhibited PDE9 activity. Compound 16 showed an IC₅₀ of 34 nM against PDE9 and more than 55-fold selectivity against other PDEs. In addition, this compound displayed remarkable metal-chelating capacity and a considerable ability to halt copper redox cycling. Notably, in comparison to the reference compound clioquinol, it inhibited metal-induced Aβ_1-42 aggregation more effectively and promoted greater disassembly of the highly structured Aβ fibrils generated through Cu²⁺-induced Aβ aggregation. These activities of 16, together with its favorable blood-brain barrier permeability, suggest that 16 may be a promising compound for treatment of AD.

Multigram synthesis and in vivo efficacy studies of a novel multitarget anti-Alzheimer's compound

We describe the multigram synthesis and in vivo efficacy studies of a donepezil‒huprine hybrid that has been found to display a promising in vitro multitarget profile of interest for the treatment of Alzheimer's disease (AD). Its synthesis features as the key step a novel multigram preparative chromatographic resolution of intermediate racemic huprine Y by chiral HPLC. Administration of this compound to transgenic CL4176 and CL2006 Caenorhabditis elegans strains expressing human Aβ42, here used as simplified animal models of AD, led to a significant protection from the toxicity induced by Aβ42. However, this protective effect was not accompanied, in CL2006 worms, by a reduction of amyloid deposits. Oral administration for 3 months to transgenic APPSL mice, a well-established animal model of AD, improved short-term memory, but did not alter brain levels of Aβ peptides nor cortical and hippocampal amyloid plaque load. Despite the clear protective and cognitive effects of AVCRI104P4, the lack of Aβ lowering effect in vivo might be related to its lower in vitro potency toward Aβ aggregation and formation as compared with its higher anticholinesterase activities. Further lead optimization in this series should thus focus on improving the anti-amyloid/anticholinesterase activity ratio.