Imidazo[2,1-b]thiazole-Coupled Natural Noscapine Derivatives as Anticancer Agents

Antiproliferative Noscapinoids Bearing an Amidothiadiazole Scaffold as Apoptosis Inducers: Design, Synthesis and Molecular Docking

Noscapine an FDA-approved antitussive agent. With low cytotoxicity with higher concentrations, noscapine and its derivatives have been shown to have exceptional anticancer properties against a variety of cancer cell lines. In order to increase its potency, in this study, we synthesized a series of new amido-thiadiazol coupled noscapinoids and tested their cytotoxicity in vitro. All of the newly synthesised compounds demonstrated potent cytotoxic potential, with IC₅₀ values ranging from 2.1 to 61.2 μM than the lead molecule, noscapine (IC₅₀ value ranges from 31 to 65.5 μM) across all cell lines, without affecting normal cells (IC₅₀ value is>300 μM). Molecular docking of all these molecules with tubulin (PDB ID: 6Y6D, resolution 2.20 Å) also revealed better binding affinity (docking score range from -5.418 to -9.679 kcal/mol) compared to noscapine (docking score is -5.304 kcal/mol). One of the most promising synthetic derivatives 6aa (IC₅₀ value ranges from 2.5 to 7.3 μM) was found to bind tubulin with the highest binding affinity (ΔG_binding is -28.97 kcal/mol) and induced apoptosis in cancer cells more effectively.

Substrate-directed Synthesis of Isocoumarin and 3-Ylidenephthalide Conjugated Noscapinoids and their Antiproliferative Activities

A series of new noscapinoids designed; synthesized and assessed whether its 3-ylidenephthalide and isocoumarin conjugates improved cytotoxicity. Cu-catalysed Sonogashira coupling of N-propargyl noscapine with 2-bromobenzoic acids followed by in-situ substrate-directed 5-exo-dig or 6-endo-dig cyclization produced 3-ylidenephthalide 6 a-6 f and isocoumarin 7 a-7 h analogues in very good yields. In comparison to the lead drug, noscapine, all the newly synthesised derivatives exhibited strong cytotoxic potential in vitro with IC₅₀ ranging from 5.4 μM to 39.5 μM across the evaluated panel of cancer cell lines, without harming normal cells (IC₅₀ >300 μM).

Novel Anti-Tubulin Compounds from Trigonella foenum-graecum Seeds; Insights into In-vitro and Molecular Docking Studies

Background

Fenugreek, also known as Trigonella foenum-graecum L, is a natural plant that belongs to the Fabaceae family and has been known as a promising source of bioactive compounds. It has been widely used as traditional medicine since it has shown to lower blood glucose, manage cholesterol levels and further aid in the prevention and treatment of cancer. Herein, we aim to evaluate the anticancer activity of methanolic fenugreek seed extract against several cancer cell lines.

Methods

We sought to investigate the phytochemical classes present in multiple fenugreek seeds extracts using HPLC-DAD followed by LC/MS, predict and investigate anticancer activity using PASS online webserver, the CellTiter-Glo assay, evaluate ADME properties, and perform molecular docking for all bioactive compounds via Maestro software.

Results

Multiple extracts exhibited distinct phytochemical classes that demonstrated different biological activities. Fenugreek methanolic extract contains flavonoid chemical class, which showed the highest anticancer activity against the HCT8 cell line of colorectal cancer (IC₅₀ of 8.83 μg/mL), followed by KAIMRC1 breast cancer cell line (IC₅₀ of 35.06 μg/mL), HL60 leukemia cell line (37.80 μg/mL), MDA-MB-231 breast cancer cell line (38.51 μg/mL), and lastly, HCT116 colorectal cancer cell line with IC₅₀ of 56.03 μg/mL. In contrast, the chloroform extract was inactive. The molecular docking study for all the bioactive compounds suggested that flavonoids F6 (−9.713 and −12.132), F7 (−10.166 and −12.411), and F11 (−10.084 and −13.516) possess the highest docking scores through SP and XP scores, respectively.

Conclusion

The obtained results confirm that the bioactive compounds present in fenugreek seeds exhibit anticancer activity against several cancer cells that can mediate via tubulin polymerization inhibition. Although our study has evaluated the anticancer potential of Trigonella foenum-graecum as a promising natural source for new anticancer agents, fenugreek biological activity needs further research and investigations on their mechanism of action and toxicity profile.

Semi-Synthesis of New 1,2,3-Triazole Derivatives of 9-Bromonoscapine and their Anticancer Activities

Novel 1,2,3-triazole-tethered 9-bromonoscapine derivatives were synthesized by the propargylation of N-nornoscapine followed by Huisgen's 1,3-dipolar cycloaddition of the terminal alkynes with different azides. Cytotoxicity of the products was studied by MTT assay against the MCF-7 breast cancer cell line. Most of the compounds revealed a better cytotoxicity than N-nornoscapine and 9-bromonornoscapine as the parent compounds. Among the synthesized compounds, those with a hydroxylated aliphatic side chain (5p, 5q, and 5r) showed the highest activities (IC50s: 47.2, 37.9, and 32.3 μg/mL, respectively). Molecular docking studies showed that these compounds also had the highest docking scores and effective interactions with binding sites equal to -8.074, -7.425 and -7.820 kcal/mol, respectively.

Identification of novel anti-cancer agents by the synthesis and cellular screening of a noscapine-based library

Noscapine is a natural product first isolated from the opium poppy (Papaver somniferum L.) with anticancer properties. In this work, we report the synthesis and cellular screening of a noscapine-based library. A library of novel noscapine derivatives was synthesized with modifications in the isoquinoline and phthalide scaffolds. The so generated library, consisting of fifty-seven derivatives of the natural product noscapine, was tested against MDA-MB-231 breast cancer cells in a cellular proliferation assay (with a Z' > 0.7). The screening resulted in the identification of two novel noscapine derivatives as inhibitors of MDA cell growth with IC₅₀ values of 5 µM and 1.5 µM, respectively. Both hit molecules have a five-fold and seventeen-fold higher potency, compared with that of lead compound noscapine (IC₅₀ 26 µM). The identified active derivatives retain the tubulin-binding ability of noscapine. Further testing of both hit molecules, alongside the natural product against additional cancer cell lines (HepG2, HeLa and PC3 cells) confirmed our initial findings. Both molecules have improved anti-proliferative properties when compared to the initial natural product, noscapine.

Synthetic and Medicinal Perspective of Fused-Thiazoles as Anticancer Agents

BACKGROUND

Cancer is second leading disease after cardiovascular disease. Presently, Chemotherapy, Radiotherapy and use of chemicals are some treatments available these days. Thiazole and its hybrid compounds extensively used scaffolds in drug designing and development of novel anticancer agents due to their wide pharmacological profiles. Fused thiazole scaffold containing drugs are available in market as a promising group of anticancer agents.

METHODS

The detailed study has been done using different database that focused on potent thiazole hybrid compounds with anticancer activity. The literature included in this review is focused on novel fused thiazole derivatives exhibiting anticancer potency in last decade.

RESULTS

Literature suggested that thiazoles and its fused and linked congener serve excellent pharmacological profile as an anticancer agent. Various synthetic strategies for fused thiazole are also summarized in this article. Novel thiazole and its fused congener showed anticancer activity against various cancer cell lines.

INTERPRETATION

Thiazole is a promising scaffold reported in literature with broad range of biological activities. This article covers the thiazole compounds fused with other carbocyclic/heterocycle including benzene, imidazole, pyridine, pyrimidine, quinoline, phenothiazine, thiopyrano, steroids, pyrrole etc. with anticancer activity from last decades. Several inhibitors for breast cancer, colon cancer, melanoma cancer, ovarian cancer, tubulin cancer etc. were reported in this review. Thus, this review will definitely aid to develop a lead for the new selective anticancer agents in future.

Thiazole Ring-A Biologically Active Scaffold

BACKGROUND

Thiazole is a good pharmacophore nucleus due to its various pharmaceutical applications. Its derivatives have a wide range of biological activities such as antioxidant, analgesic, and antimicrobial including antibacterial, antifungal, antimalarial, anticancer, antiallergic, antihypertensive, anti-inflammatory, and antipsychotic. Indeed, the thiazole scaffold is contained in more than 18 FDA-approved drugs as well as in numerous experimental drugs.

OBJECTIVE

To summarize recent literature on the biological activities of thiazole ring-containing compounds Methods: A literature survey regarding the topics from the year 2015 up to now was carried out. Older publications were not included, since they were previously analyzed in available peer reviews.

RESULTS

Nearly 124 research articles were found, critically analyzed, and arranged regarding the synthesis and biological activities of thiazoles derivatives in the last 5 years.

Bioengineering of Anti-Inflammatory Natural Products

Inflammatory processes occur as a generic response of the immune system and can be triggered by various factors, such as infection with pathogenic microorganisms or damaged tissue. Due to the complexity of the inflammation process and its role in common diseases like asthma, cancer, skin disorders or Alzheimer's disease, anti-inflammatory drugs are of high pharmaceutical interest. Nature is a rich source for compounds with anti-inflammatory properties. Several studies have focused on the structural optimization of natural products to improve their pharmacological properties. As derivatization through total synthesis is often laborious with low yields and limited stereoselectivity, the use of biosynthetic, enzyme-driven reactions is an attractive alternative for synthesizing and modifying complex bioactive molecules. In this minireview, we present an outline of the biotechnological methods used to derivatize anti-inflammatory natural products, including precursor-directed biosynthesis, mutasynthesis, combinatorial biosynthesis, as well as whole-cell and in vitro biotransformation.

Induction of microtubule hyper stabilization and robust G2 /M arrest by N-4-CN in human breast carcinoma MDA-MB-231 cells

AIM

Elucidation of the antiproliferative efficacy and mechanism of action of a design-optimized noscapine analog, N-4-CN.

METHODS

Cell viability was studied using an MTT assay. The drug-tubulin interactions were investigated using spectrofluorometry. The architectural defects, hyper stabilization, and recovery competence of cellular microtubules were studied using immunofluorescence microscopy. DCF-DH and rhodamine 123 were used as probes to to examine the levels of reactive oxygen species and the loss of mitochondrial membrane potential, respectively. Flow cytometry revealed the cell cycle progression pattern of the drug-treated cells.

KEY FINDINGS

Among the cell lines tested, N-4-CN showed the strongest inhibition of the viability of the triple-negative breast cancer (TNBC) cell line MDA-MB-231(IC₅₀ , 2.7 ± 0.1 µmol/L) and weakest inhibition of the noncancerous epithelial cell line, VERO (IC₅₀ , 60.2 ± 3 µmol/L). It perturbed tertiary structure of tubulin and stabilized colchicine binding to the protein. In cells, N-4-CN hyperstabilized the microtubules, and prevented the recovery of cold-depolymerized microtubules. Its multitude of effects on tubulin and microtubules facilitated cell cycle arrest and subsequent cell death that were complemented by elevated levels of reactive oxygen species (ROS).

SIGNIFICANCE

Owing to its ability to perturb a well-defined cancer drug target, tubulin, and to promote ROS-facilitated apoptosis, N-4-CN could be investigated further as a potential therapeutic against many neoplasms, including TNBC.