Synthesis of a terphenyl substituted 4-aza-2,3-didehydropodophyllotoxin analogues as inhibitors of tubulin polymerization and apoptosis inducers

A potent Bioorganic azapodophyllotoxin derivative Suppresses tumor Progression in Triple negative breast Cancer: An Insight into its Inhibitory effect on tubulin polymerization and Disruptive effect on microtubule assembly

Triple negative breast cancer (TNBC) has long been a challenging disease owing to its high aggressive behaviour, poor prognosis and its limited treatment options. The growing demand of new therapeutics against TNBC enables us to examine the therapeutic efficiency of an emerging class of anticancer compounds, azapodophyllotoxin derivative (HTDQ), a nitrogen analogue of podophyllotoxin, using different biochemical, spectroscopic and computational approaches. The anticancer activities of HTDQ are studied by performing MTT assay in a dose depended manner on Triple negative breast cancer cells using MDA-MB-468 and MDA-MB-231 cell lines with IC50 value 937 nM and 1.13 µM respectively while demonstrating minimal effect on normal epithelial cells. The efficacy of HTDQ was further tested in 3D tumour spheroids formed by the human TNBC cell line MDA-MB468 and also the murine MMTV positive TNBC cell line 4 T1. The shrinkage that observed in the tumor spheroid clearly indicates that HTDQ remarkably decreases the growth of tumor spheroid thereby affirming its cytotoxicity. The 2D cell viability assay shows significant morphological alteration that possibly caused by the cytoskeleton disturbances. Hence the binding interaction of HTDQ with cytoskeleton protein tubulin, its effect on tubulin polymerisation as well as depolymerisation of preformed microtubules along with the conformational alternation in the protein itself have been investigated in detail. Moreover, the apoptotic effects of HTDQ have been examined using a range of apoptotic markers. HTDQ-treated cancer cells showed increased expression of cleaved PARP-1 and pro-caspase-3, suggesting activation of the apoptosis process. HTDQ also upregulated pro-apoptotic Bax expression while inhibiting anti-apoptotic Bcl2 expression, supporting its ability to induce apoptosis in cancer cells. Hence the consolidated biochemical and spectroscopic research described herein may provide enormous information to use azapodophyllotoxin as promising anticancer therapeutics for TNBC cells.

Synthesis, molecular docking analysis and in vitro evaluation of new heterocyclic hybrids of 4-aza-podophyllotoxin as potent cytotoxic agents

Two different synthetic approaches to novel heterocyclic hybrid compounds of 4-azapodophyllotoxin were investigated. The obtained products were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry. MTT protocol was then performed to examine the cytotoxic activity of these products against KB, HepG2, A549, MCF7, and Hek-293 cell lines. The cytotoxic assessment indicated that all products displayed moderate to high cytotoxicity against all tested cancer cell lines. The most active compound 13k containing the 2-methoxypyridin-4-yl group exhibited selective cytotoxicity against KB, A549, and HepG2 cell lines with the IC50 values ranging from 0.23 to 0.27 μM, which were between 5- to 10-fold more potent than the positive control ellipticine. Compounds 13a (HetAr = thiophen-3-yl) and 13d (HetAr = 5-bromofuran-2-yl) displayed high cytotoxic selectivity for A549 and HepG2 cancer cell lines when compared to the other cancer cell lines and low toxicity to the normal Hek-293 cell line. Molecular docking study was conducted to evaluate the interaction of new synthesized compounds with the colchicine-binding-site of tubulin. Besides that, physicochemical and pharmacokinetic properties of the most active compounds 13h,k were predicted.

Natural product inspired leads in the discovery of anticancer agents: an update

Natural products have emerged as major leads for the discovery and development of new anti-cancer drugs. The plant-derived anti-cancer drugs account for approximately 60% and the quest for new anti-cancer agents is in progress. Anti-cancer leads have been isolated from plants, animals, marine organisms, and microorganisms from time immemorial. The process of semisynthetic modifications of the parent lead has led to the generation of new anti-cancer agents with improved therapeutic efficacy and minimal side effects. The various chemo-informatics tools, bioinformatics, high-throughput screening, and combinatorial synthesis are able to deliver the new natural product lead molecules. Plant-derived anticancer agents in either late preclinical development or early clinical trials include taxol, vincristine, vinblastine, topotecan, irinotecan, etoposide, paclitaxel, and docetaxel. Similarly, anti-cancer agents from microbial sources include dactinomycin, bleomycin, mitomycin C, and doxorubicin. In this review, we highlighted the importance of natural products leads in the discovery and development of novel anti-cancer agents. The semisynthetic modifications of the parent lead to the new anti-cancer agent are also presented. Further, the leads in the preclinical settings with the potential to become effective anticancer agents are also reviewed.Communicated by Ramaswamy H. Sarma.

Synthesis, Molecular Docking, and Cytotoxic Evaluation of Fluorinated Podophyllotoxin Derivatives

Objective: The study was conducted to evaluate the in vitro and in silico anticancer activity of fluorinated podophyllotoxin derivatives. Methods: Microwave-assisted multicomponent reactions were carried out in an Anton Paar Microwave Synthetic Reactor Monowave 400 in order to synthesize fluorinated podophyllotoxin derivatives. These products were identified by spectral analysis and evaluated for their cytotoxicity against 4 types of human cancer cell lines (KB, HepG2, A549, and MCF7), as well as human embryonic kidney (Hek) 293 cells using MTT protocol. Molecular docking was conducted using 2 crystal structures of tubulin—colchicine (PDB ID: 4O2B) and topoisomerase II—etoposide (PDB ID: 3QX3) complexes. Results: Two potent cytotoxic fluorinated podophyllotoxin–naphthoquinone compounds were synthesized in good yields. They displayed high cytotoxic activity against all the tested cell lines, with IC50 values ranging from 0.58 to 3.17 µM. Notably, product 8a showed low toxicity against the Hek-293 cell line. Molecular docking results showed that products 8a and 8b participated in the same key interactions provided by etoposide with both topoisomerase and DNA chain domains. The binding energy values calculated for 8a and 8b are acceptable. Conclusion: This study revealed that products 8a and 8b exhibited promising in vitro and in silico anticancer activity and could be recognized as promising anticancer agents.

Synthesis and Cytotoxic Evaluation of Fluoro and Trifluoromethyl Substituents Containing Novel Naphthoquinone-Fused Podophyllotoxins

A series of novel naphthoquinone-fused podophyllotoxins containing fluoro and trifluoromethyl substituents were synthesized in a medium with good yields using two different synthetic approaches: microwave-assisted four-component reactions of 2-hydroxy-1,4-naphthoquinone, tetronic acid, fluorinated arylaldehydes, and ammonium acetate, and microwave-assisted three-component reactions of 2-amino-1,4-naphthoquinone, tetronic acid, and fluorinated arylaldehydes. The structures of all products were confirmed by spectral analysis. Together, cytotoxicity assessment of the products against four human cancer cell lines (human carcinoma [KB], human hepatocellular carcinoma [HepG2], lung cancer [A549], breast carcinoma [MCF7], and human embryonic kidney [Hek-293]) was performed by MTT assay. Among the obtained compounds, compound 7f turned out to be the most potent anticancer agent with significant cytotoxic activity against KB, HepG2, and MCF cancer cell lines.

Synthesis and biological activity, and molecular modelling studies of potent cytotoxic podophyllotoxin-naphthoquinone compounds

A new approach for the synthesis of podophyllotoxin-naphthoquinone compounds using microwave-assisted three-component reactions is reported in this study. Novel podophyllotoxin-naphthoquinone derivatives with modification on ring E were synthesized. All the synthetic compounds were assessed in terms of their cytotoxicity profile against four cancer cell lines (KB, HepG2, A549, and MCF7), and noncancerous Hek-293 cell lines. Notably, treatment of SK-LU-1 cells with compounds 5a and 5b resulted in G2/M phase arrest of the cell cycle, caspase-3/7 activation, and apoptosis. Additionally, molecular docking studies were performed and showed important interaction of two compounds against residues in the colchicine-binding-site of tubulin as well. Taken together, compounds 5a and 5b were identified as potent anticancer agents.

A new approach for the synthesis of podophyllotoxin-naphthoquinone compounds using microwave-assisted three-component reactions is reported in this study.

Indazole-based microtubule-targeting agents as potential candidates for anticancer drugs discovery

Tremendous research is focused on developing novel drug candidates targeting microtubules to inhibit their function in several cellular processes, including cell division. In this regard, several indazole derivatives were sought to target the colchicine binding site on the β-tubulin, a crucial protein required to form microtubules, to develop microtubule targeting agents. Even though there are several reviews on the indazole-based compounds, none of them focused on using indazole scaffold to develop microtubule targeting agents. Therefore, this review aims to present the advances in research on compounds containing indazole scaffolds as microtubule targeting agents based on the articles published in the last two decades. Among the articles reviewed, we found that compounds 6 and 7 showed the lowest IC₅₀ values of 0.6 ∼ 0.9 nM in the cell line studies, making them the strongest indazole derivatives that target microtubules. The compounds 30, 31, 37 (IC₅₀ = ∼ 1 nM) and compounds 8, 38 (IC₅₀ = ∼ 2 nM) have proved to be potent microtubule inhibitors. The compounds 18, 31, 44, 45 also showed strong anticancer activity (IC₅₀ = ∼ 8 nM). It is important to notice that except for compounds 9, 12, 13, 15, and SRF, the top activity compounds including 6, 7, 8, 10, 11, 30, 31, 37, 44, and 45 contain 3,4,5‑trimethoxyphenyl substitution similar to that of colchicine. Therefore, it appears that the 3,4,5‑trimethoxyphenyl substituent on the indazole scaffold is crucial for targeting CBS.

Insight Into the Molecular Mechanism of Podophyllotoxin Derivatives as Anticancer Drugs

Podophyllotoxin (PTOX) is a biologically active compound derived from the podophyllum plant, and both it and its derivatives possess excellent antitumor activity. The PTOX derivatives etoposide (VP-16) and teniposide (VM-26) have been approved by the U.S. Food and Drug Administration (FDA) for cancer treatment, but are far from perfect. Hence, numerous PTOX derivatives have been developed to address the major limitations of PTOX, such as systemic toxicity, drug resistance, and low bioavailability. Regarding their anticancer mechanism, extensive studies have revealed that PTOX derivatives can induce cell cycle G2/M arrest and DNA/RNA breaks by targeting tubulin and topoisomerase II, respectively. However, few studies are dedicated to exploring the interactions between PTOX derivatives and downstream cancer-related signaling pathways, which is reasonably important for gaining insight into the role of PTOX. This review provides a comprehensive analysis of the role of PTOX derivatives in the biological behavior of tumors and potential molecular signaling pathways, aiming to help researchers design and develop better PTOX derivatives.

Intercepted-Knoevenagel condensation for the synthesis of unsymmetrical fused-tricyclic 4H-pyrans

4H-Pyrans (4H-Pys) and 1,4-dihydropyridines (1,4-DHPs) are important classes of heterocyclic scaffolds in medicinal chemistry. Herein, an indium(III)-catalyzed one-pot domino reaction for the synthesis of highly functionalized 4H-Pys, and a model of 1,4-DHP is reported. This alternative approach to the challenging Hantzsch 4-component reaction enables the synthesis of fused-tricyclic heterocycles, and the mechanistic studies underline the importance of an intercepted-Knoevenagel adduct to achieve higher chemoselectivity towards these types of unsymmetrical heterocycles.

Podophyllotoxin derivatives as an excellent anticancer aspirant for future chemotherapy: A key current imminent needs

Cancer is one of the leading groups of threatened caused by abnormal state cell growth and second leading diseases involved in the major global death. To treat this, research looking for promising anticancer drugs from natural resource, or synthesized novel molecules by diverse group of scientists worldwide. Currently, drugs get into clinical practices and showing side effects with target actions which in turn leading to multidrug resistance unknowingly. Podophyllotoxin, a naturally occurring lignan and with hybrids have become one of the most attractive subjects due to their broad spectrum of pharmacological activities. Podophyllotoxin derivatives have been the centre of attention of extensive chemical amendment and pharmacological investigation in modern decades. Mainly, the innovation of the semi-synthetic anticancer drugs etoposide and teniposide has stimulated prolonged research interest in this structural phenotype. The present review focuses mainly onnew anticancer drugs from podophyllotoxin analogs, mechanism of action and their structure-activity relationships (SAR) as potential anticancer candidates for future discovery of suitable drug candidates.

Recent Advances in the Chemistry and Biology of Podophyllotoxins

Podophyllotoxin and its related aryltetralin cyclolignans belong to a family of important products that exhibit various biological properties (e.g., cytotoxic, insecticidal, antifungal, antiviral, anti-inflammatory, neurotoxic, immunosuppressive, antirheumatic, antioxidative, antispasmogenic, and hypolipidemic activities). This Review provides a survey of podophyllotoxin and its analogues isolated from plants. In particular, recent developments in the elegant total chemical synthesis, structural modifications, biosynthesis, and biotransformation of podophyllotoxin and its analogues are summarized. Moreover, a deoxypodophyllotoxin-based chemosensor for selective detection of mercury ion is described. In addition to the most active podophyllotoxin derivatives in each series against human cancer cell lines and insect pests listed in the tables, the structure-activity relationships of podophyllotoxin derivatives as cytotoxic and insecticidal agents are also outlined. Future prospects and further developments in this area are covered at the end of the Review. We believe that this Review will provide necessary information for synthetic, medicinal, and pesticidal chemistry researchers who are interested in the chemistry and biology of podophyllotoxins.

Semi-synthesis and anti-lung cancer activity evaluation of aryl dihydrothiazol acyl podophyllotoxin ester derivatives

S12, the best anticancer agent among the 17 podophyllotoxin derivatives, showed a proliferative inhibition effect via inhibiting tubulin polymerization.

Synthesis and biological evaluation of podophyllotoxin congeners as tubulin polymerization inhibitors

A series of new podophyllotoxin derivatives containing structural modifications at C-7, C-8, and C-9 were synthesized and evaluated for their cytotoxic activity against three human cancer cell lines. All the synthesized compounds showed significant growth inhibition with GI50 values in micromolar levels while some of the compounds were several times more potent against MCF-7 and HeLa cell lines than MIAPACA cell line. Three compounds (12a, 12d and 12e) emerged as potent compounds with broad spectrum of cytotoxic activity against all the tested cell lines with GI50 values in the range of 0.01-2.1 μM. These compounds induce microtubule depolymerization and arrests cells at the G2/M phase of the cell cycle. Moreover, compounds 12d and 12e disrupted microtubule network and accumulated tubulin in the soluble fraction in a similar manner to their parent podophyllotoxin scaffold. In addition, structure activity relationship studies within the series were also discussed. Molecular docking studies of these compounds into the colchicine-binding site of tubulin, revealed possible mode of inhibition by these compounds.