Pentapeptides for the treatment of small cell lung cancer: Optimisation by Nind-alkyl modification of the tryptophan side chain

Thermo-Responsive Niosomal In Situ Gels for Topical Delivery of Prednisolone

Prednisolone (PRD) is known for its anti-inflammatory effect on the skin. The study aimed to encapsulate PRD into niosomes and then load them into thermo-responsive in situ gels for skin inflammation to enhance drug stability, skin permeability, and patient compliance while minimizing systemic exposure. PRD was encapsulated into non-PEGylated and PEGylated niosomes and then loaded into thermo-responsive in situ gels. The non-PEGylated PRD niosomes exhibited a particle size (PS) of 354.3 ± 1.9 nm, a polydispersity index (PDI) of 0.3 ± 0.0, and a ζ-potential of - 19.4 ± 1.0 mV. While the PEGylated attained PS, PDI, and ζ-potential of 314.9 ± 4.2 nm, 0.1 ± 0.0, and - 34.6 ± 2.2 mV, respectively. In addition, PEGylated niosomes exhibited higher entrapment efficiency and drug loading than non-PEGylated niosomes. The loading of the non-PEGylated and PEGylated PRD niosomes into thermo-responsive in situ gel showed a phase transition (Tsol→gel) at 34.1 ± 0.4 and 33.2 ± 0.9°C, respectively. The in situ gels showed a pseudoplastic flow with viscoelastic properties. The PRD niosomes and their corresponding in situ gels were biocompatible against human gingival fibroblasts. A decrease in rat paw inflammation was observed after applying the PRD niosomal gels. Stability studies for 3 months at 4°C showed that the PEGylated PRD niosomes and their corresponding in situ gel were more stable than the non-PEGylated PRD niosomes and their corresponding in situ gel. In conclusion, PEGylated PRD niosomal in situ gel demonstrated superior stability and sustained release, making it a promising candidate for topical corticosteroid therapy.

Development of Mitoxantrone-Loaded Quercetin Nanoparticles for Breast Cancer Therapy with Potential for Synergism with Bioactive Natural Products

Nanoparticle (NP)-based drug delivery systems have caused a paradigm shift in cancer treatment by enabling drug targeting, sustaining drug release, and reducing systemic toxicity of chemotherapy. Here we developed a novel NP formulation for the anticancer drug mitoxantrone (MTZ) by loading it into an emerging nanomaterial derived from the plant polyphenol quercetin (QCT). QCT was partially oxidized to produce amphiphilic oxQCT which was co-assembled with poly(ethylene glycol) (PEG) and MTZ by nanoprecipitation to form MTZ NPs. The optimal NPs exhibited an average diameter of 128 nm, a polydispersity index of 0.22, and a drug loading efficiency of 76%. While only a small fraction of the loaded drug was released at physiologic pH, a significantly higher fraction was released at acidic pH. The anticancer activity of MTZ NPs was assessed in MCF-7 and MDA-MB-231 breast cancer cell lines, alone and in combination with the bioactive natural products curcumin (CUR) and thymoquinone (TQ). In cell viability assays, MTZ NPs were slightly less potent than free MTZ, most likely due to their sustained release properties, but their cytotoxicity was greatly enhanced in the presence of TQ (in MCF-7 cells) as well as CUR (in MDA-MB-231 cells). The results were corroborated by apoptosis assays such as mitochondrial membrane potential measurement, acridine orange/ethidium bromide staining, in addition to caspase activity assays. The assays revealed that the NPs' proapoptotic effect was enhanced in the presence of CUR or TQ, depending on the cell line. Our work presents a promising nanocarrier platform for MTZ with the potential to enhance its bioactivity against breast cancer when combined with bioactive natural products.

Biological evaluation of levofloxacin and its thionated derivatives: antioxidant activity, aldehyde dehydrogenase enzyme inhibition, and cytotoxicity on A549 cell line

Levofloxacin (LVX) is among the fluoroquinolones antibiotics that has also been studied in vitro and in vivo for its anticancer effects. In this study, we used LVX and novel LVX thionated derivatives; compounds 2 and 3, to evaluate their antioxidant activity, aldehyde dehydrogenase (ALDH) enzymes activity inhibition, and anticancer activity. Combination treatments with doxorubicin (DOX) were investigated as well. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the antioxidant activity. The NADH fluorescence spectrophotometric activity assay was used to determine the ALDH inhibitory effects. Resazurin dye method was applied for cell viability assays. Molecular Operating Environment software was used for the molecular docking experiments. Compared to ascorbic acid, DPPH assay showed that compound 3 had the highest antioxidant activity among the tested compounds with approximately 35% scavenging activity. On ALDH enzymes, compound 3 showed a significant ALDH activity inhibition compared to compound 2 at 200 µM. The IC50 values for the tested compounds were approximately 100 µM on A549 cell line, a non-small cell lung cancer (NSCLC) cell line. However, significant enhancement of cytotoxicity and reduction of IC50 values were observed by combining DOX and synergism was achieved with LVX with a combination index value of 0.4. The molecular docking test showed a minimum binding energy with a good affinity for compound 3 towards ALDH enzymes. Thionated LVX derivatives, may be repurposed for NSCLC therapy in combination with DOX, taking into account the antioxidant activity, ALDH activity inhibition, and the molecular docking results of compound 3.

Exploring bat-inspired cyclic tryptophan diketopiperazines as ABCB1 Inhibitors

Chemotherapy-induced drug resistance remains a major cause of cancer recurrence and patient mortality. ATP binding cassette subfamily B member 1 (ABCB1) transporter overexpression in tumors contributes to resistance, yet current ABCB1 inhibitors have been unsuccessful in clinical trials. To address this challenge, we propose a new strategy using tryptophan as a lead molecule for developing ABCB1 inhibitors. Our idea stems from our studies on bat cells, as bats have low cancer incidences and high ABCB1 expression. We hypothesized that potential ABCB1 substrates in bats could act as competitive inhibitors in humans. By molecular simulations of ABCB1-substrate interactions, we generated a benzylated Cyclo-tryptophan (C3N-Dbn-Trp2) that inhibits ABCB1 activity with efficacy comparable to or better than the classical inhibitor, verapamil. C3N-Dbn-Trp2 restored chemotherapy sensitivity in drug-resistant human cancer cells with no adverse effect on cell proliferation. Our unique approach presents a promising lead toward developing effective ABCB1 inhibitors to treat drug-resistant cancers.

Tryptophan N 1-Alkylation: Quick and Simple Access to Diversely Substituted Tryptophans

The diversification of amino acid sidechains is a major challenge in the synthesis and derivatization of peptides for pharmaceutical applications. We herein present a new protocol to alkylate the indole-nitrogen (N1) of N α-protected tryptophans. This method provides quick and epimerization-free access to tryptophan derivatives, which can directly be incorporated into peptides. Depending on the functionalities introduced in the side chain, different options for the late-stage modification of peptides are possible.

The importance of indole and azaindole scaffold in the development of antitumor agents

With some indoles and azaindoles being successfully developed as anticancer drugs, the design and synthesis of indole and azaindole derivatives with remarkable antitumor activity has received increasing attention and significant progress has been made. This paper reviews the recent progress in the study of tumorigenesis, mechanism of actions and structure activity relationships about anticancer indole and azindole derivatives. Combining structure activity relationships and molecular targets-related knowledge, this review will help researchers design more effective, safe and cost-effective anticancer indoles and azindoles agents.