Synthesis and biological activities of some new (Nα-dinicotinoyl)-bis-L-leucyl linear and macrocyclic peptides

Synthesis and Oxidative Degradation of Leucine-Based Poly(diacylhydrazine)

Diacylhydrazine is thermally and chemically stable, and it remains inert to oxygen even at high temperatures. However, it is rapidly oxidized by sodium hypochlorite, leading to its decomposition into carboxylic acid and nitrogen gas. In the synthesis of a novel poly(diacylhydrazine) as an oxidatively degradable polymer, L-leucine methyl ester is acylated by terephthaloyl chloride. Subsequent hydrazination yields a bishydrazide monomer. The oxidative coupling polymerization of this monomer produces poly(diacylhydrazine). The molecular structures of the products are confirmed by an 1H NMR analysis. A polymodal molecular weight distribution and a large polydispersity index are observed by GPC in all cases. A 10% weight loss temperature is noted at 286 °C in air by TGA. The obtained polymer is not oxidized by oxygen. No glass transition is observed below the decomposition temperature. Upon the treatment of the poly(diacylhydrazine) with sodium hypochlorite solution, decomposition occurs rapidly, resulting in monomeric carboxylic acid and nitrogen gas. The L-leucine-based poly(diacylhydrazine) serves as a novel on-demand degradable polymer with high levels of thermal and chemical stability during usage.

Synthesis and Characterization of Macrocyclic Chiral Tröger's Base Phenhomazine Candidates as Anticancer Agent

1,4,7,10-Tetraoxa[10](2,8)trögerophane 5 was synthesized from its corresponding precursors. Heating of 2 with p-nitrophenoxide afforded bis(p-nitrophenyl)ether 3, which was treated with hydrazine hydrate to give bis(p-aminophenyl)ether 4. Treatment of 4 with paraformaldehyde and triflouroacetic anhydride gave trögerophane 5. Reaction of 5 with trifluroacetic anhydride afforded phenhomazine derivative 6, which was treated with potassium carbonate to afford tetrahydrophenhomazine 7. Finally, reaction of 7 with phenacylchloride, bromoacetic acid, or ethyl bromoacetate in the presence of triethyl amine under reflux, afforded the corresponding macrocyclic compounds 8, 9 and 10, respectively. The synthesized trögerophane,precursors and its newly synthesized phenhomazines derivatives were screened for anticancer activity. Results revealed that 1,4,7,10-tetraoxa[10](2,8)trögerophane had a promising selectivity towards colon cancer cell line with an IC₅₀ of 92.7 µg/ml.

Anticancer Activities of Newly Synthesized Chiral Macrocyclic Heptapeptide Candidates

As important cancer therapeutic agents, macrocyclic peptides have recently drawn great attention, mainly because they are synthetically accessible and have lower toxicity towards normal cells. In the present work, we synthesized newly macrocyclic pyridoheptapeptide derivatives. The synthesized derivatives were characterized using standard chemical and spectroscopic analytical techniques, and their anticancer activities against human breast and hepatocellular cancer cells were investigated. Results showed that compounds 1a and 1b were the most effective against hepatocellular (HepG2) and breast (MCF-7) cancer cell lines, respectively.

Chiral Pyridine-3,5-bis- (L-phenylalaninyl-L-leucinyl) Schiff Base Peptides as Potential Anticancer Agents: Design, Synthesis, and Molecular Docking Studies Targeting Lactate Dehydrogenase-A

A series of branched tetrapeptide Schiff bases 3–6 were designed and synthesized from corresponding tetrapeptide hydrazide 2 as a starting material.In vitroevaluation of the synthesized compounds 4–6 against breast MCF-7 carcinoma cells identified their excellent anticancer potency, with IC₅₀ ranging from 8.12 ± 0.14 to 17.55 ± 0.27 μM in comparison with the references, cisplatin and milaplatin (IC₅₀= 13.34 ± 0.11and 18.43 ± 0.13 μM, respectively). Furthermore, all derivatives demonstrated promising activity upon evaluation of theirin vitroandin vivosuppression of p53 ubiquitination and inhibition assessment for LDHA kinase. Finally, molecular docking studies were performed to predict the possible binding features of the potent derivatives within the ATP pocket of LDHA in an attempt to get a lead for developing a more potent LDHA inhibitor with anti-proliferative potency.

Heteroaryl Rings in Peptide Macrocycles

This Review is devoted to the chemistry of macrocyclic peptides having heterocyclic fragments in their structure. These motifs are present in many natural products and synthetic macrocycles designed against a particular biochemical target. Thiazole and oxazole are particularly common constituents of naturally occurring macrocyclic peptide molecules. This frequency of occurrence is because the thiazole and oxazole rings originate from cysteine, serine, and threonine residues. Whereas other heteroaryl groups are found less frequently, they offer many insightful lessons that range from conformational control to receptor/ligand interactions. Many options to develop new and improved technologies to prepare natural products have appeared in recent years, and the synthetic community has been pursuing synthetic macrocycles that have no precedent in nature. This Review attempts to summarize progress in this area.

Design, Synthesis and Docking Studies of Novel Macrocyclic Pentapeptides as Anticancer Multi-Targeted Kinase Inhibitors

A series of macrocyclic pyrido-pentapeptide candidates 2–6 were synthesized by using N,N-bis-[1-carboxy-2-(benzyl)]-2,6-(diaminocarbonyl)pyridine 1a,b as starting material. Structures of the newly synthesized compounds were established by IR, ¹H and ¹³C-NMR, and MS spectral data and elemental analysis. The in-vitro cytotoxicity activity was investigated for all compounds against MCF-7 and HepG-2 cell lines and the majority of the compounds showed potent anticancer activity against the tested cell lines in comparison with the reference drugs. Out of the macrocyclic pyrido-pentapeptide based compounds, 5c showed encouraging inhibitory activity on MCF-7 and HepG-2 cell lines with IC₅₀ values 9.41 ± 1.25 and 7.53 ± 1.33 μM, respectively. Interestingly, 5c also demonstrated multitarget profile and excellent inhibitory activity towards VEGFR-2, CDK-2 and PDGFRβ kinases. Furthermore, molecular modeling studies of the compound 5c revealed its possible binding modes into the active sites of those kinases.