Development of 13H-benzo[f]chromeno[4,3-b][1,7]naphthyridines and their salts as potent cytotoxic agents and topoisomerase I/IIα inhibitors

A Review on Shikonin and Its Derivatives as Potent Anticancer Agents Targeted against Topoisomerases

The topoisomerases (TOPO) play indispensable roles in DNA metabolism, by regulating the topological state of DNA. Topoisomerase I and II are the well-established drug-targets for the development of anticancer agents and antibiotics. These drugs-targeting enzymes have been used to establish the relationship between drug-stimulated DNA cleavable complex formation and cytotoxicity. Some anticancer drugs (such as camptothecin, anthracyclines, mitoxantrone) are also widely used as Topo I and Topo II inhibitors, but the poor water solubility, myeloma suppression, dose-dependent cardiotoxicity, and multidrug resistance (MDR) limited their prolong use as therapeutics. Also, most of these agents displayed selective inhibition only against Topo I or II. In recent years, researchers focus on the design and synthesis of the dual Topo I and II inhibitors, or the discovery of the dual Topo I and II inhibitors from natural products. Shikonin (a natural compound with anthraquinone skeleton, isolated from the roots of Lithospermum erythrorhizon) has drawn much attention due to its wide spectrum of anticancer activities, especially due to its dual Topo inhibitive performance, and without the adverse side effects, and different kinds of shikonin derivatives have been synthesized as TOPO inhibitors for the development of anticancer agents. In this review, the progress of the shikonin and its derivatives together with their anticancer activities, anticancer mechanism, and their structure-activity relationship (SAR) was comprehensively summarized by searching the CNKI, PubMed, Web of Science, Scopus, and Google Scholar databases.

Design, Synthesis, and Cytotoxicity and Topoisomerase I/IIα Inhibition Activity of Pyrazolo[4,3-f]quinoline Derivatives

With the several targets of cancer treatment, inhibition of DNA topoisomerase activity is one of the well-known focuses in cancer chemotherapy. Here, we describe the design and synthesis of a novel series of pyrazolo[4,3-f]quinolines with potential anticancer/topoisomerase inhibition activity. Forty newly designed pyrazolo[4,3-f]quinoline derivatives were synthesized via inverse imino Diels–Alder reaction. The antiproliferative activity of the synthesized derivatives was initially measured in the human NUGC-3 cancer cell line. Then, the selected compounds 1B, 1C, 1M, 2A, 2D, 2E, 2F, and 2R with higher activity among tested compounds were screened against six cancer cell lines, including ACHN, HCT-15, MM231, NCI-H23, NUGC-3, and PC-3. The results demonstrated that the compounds 1M, 2E, and 2P were most effective in all cancer cell lines exhibiting GI₅₀ below 8 µM. Among them, 2E showed an equivalent inhibition pattern of topoisomerase IIα activity to that of etoposide, positive control at a 100 µM dose.

Induction of Paraptotic Cell Death in Breast Cancer Cells by a Novel Pyrazolo[3,4-h]quinoline Derivative through ROS Production and Endoplasmic Reticulum Stress

Chemotherapy has been a standard intervention for a variety of cancers to impede tumor growth, mainly by inducing apoptosis. However, development of resistance to this regimen has led to a growing interest and demand for drugs targeting alternative cell death modes, such as paraptosis. Here, we designed and synthesized a novel derivative of a pyrazolo[3,4-h]quinoline scaffold (YRL1091), evaluated its cytotoxic effect, and elucidated the underlying molecular mechanisms of cell death in MDA-MB-231 and MCF-7 breast cancer (BC) cells. We found that YRL1091 induced cytotoxicity in these cells with numerous cytoplasmic vacuoles, one of the distinct characteristics of paraptosis. YRL1091-treated BC cells displayed several other distinguishing features of paraptosis, excluding autophagy or apoptosis. Briefly, YRL1091-induced cell death was associated with upregulation of microtubule-associated protein 1 light chain 3B, downregulation of multifunctional adapter protein Alix, and activation of extracellular signal-regulated kinase 1/2 and c-Jun N-terminal kinase. Furthermore, the production of reactive oxygen species (ROS) and newly synthesized proteins were also observed, subsequently causing ubiquitinated protein accumulation and endoplasmic reticulum (ER) stress. Collectively, these results indicate that YRL1091 induces paraptosis in BC cells through ROS generation and ER stress. Therefore, YRL1091 can serve as a potential candidate for the development of a novel anticancer drug triggering paraptosis, which may provide benefit for the treatment of cancers resistant to conventional chemotherapy.

Antitumor Activity and Mechanism of Robustic Acid from Dalbergia benthami Prain via Computational Target Fishing

Dalbergia benthami Prain (D.benthami) is an important legume species of the Dalbergia family, due to the use of its trunk and root heart in traditional Chinese medicine (TCM). In the present study, we reported the isolation, characterization and pharmacological activities of robustic acid (RA) from the ethyl acetate extract of D. benthami Prain. The SwissADME prediction showed that the RA satisfied the Lipinski’s rule of five (molecule weight (MW): 380.39 g/mol, lipid-water partition coefficient (log P): 3.72, hydrogen bond donors (Hdon): 1, hydrogen bond acceptors (Hacc): 6, rotatable bonds (Rbon): 3. Other chemical and pharmacological properties of this RA were also evaluated, including topological polar surface area (TPSA) = 78.13 Å and solubility (Log S) = −4.8. The probability values of the antineoplastic, anti-free radical activities and topoisomerase I (TopoI) inhibitory activity were found to be 0.784, 0.644 and 0.379, respectively. The molecular docking experiment using the Surflex-Dock showed that the Total Score and C Score of RNA binding with the human DNA-Topo I complex were 7.80 and 4. The MTS assay experiment showed that the inhibitory rates of RA on HL-60, MT4, Hela, HepG2, SK-OV-3 and MCF-7 cells were 37.37%, 97.41%, 81.22%, 34.4%, 32.68% and 51.4%, respectively. In addition, RA exhibited an inhibitory effect on the angiogenesis of zebrafish embryo, a good TopoI inhibitory activity at a 10 mM concentration and in a dose-dependent manner, excellent radical scavenging in the DPPH and ABTS assays, and the free radical scavenging rate was close to the positive control (BHT) at different concentrations (0.5–2.0 mg/mL). Furthermore, 18 potential targets were found for this RA by PharmMapper, including ANXA3, SRC, FGFR2, GSK3B, CSNK2B, YARS, LCK, EPHA2, MAPK14, RORA, CRABP2, PPP1CC, METAP2, MME, TTR, MET and KDR. The GO and KEGG pathway analysis revealed that the “protein tyrosine kinase activity”, “rap1 signaling pathway” and “PI3K-Akt signaling pathway” were significantly enriched by the RA target genes. Our results will provide new insights into the pharmaceutical use of this species. More importantly, our data will expand our understanding of the molecular mechanisms of RA functions.

Synthesis, anticancer evaluation and molecular docking studies of new benzimidazole- 1,3,4-oxadiazole derivatives as human topoisomerase types I poison

In this study, some benzimidazole-oxadiazole derivatives were synthesised and tested for their in vitro anticancer activities on five cancer cell lines, including HeLa, MCF7, A549, HepG2 and C6. Their structures were elucidated by IR, ¹H-NMR, ¹³C-NMR, 2 D-NMR and HRMS spectroscopic methods. Among all screened compounds; 5a, 5b, 5d, 5e, 5k, 5l, 5n and 5o exhibited potent selective cytotoxic activities against various tested cancer cell lines. Especially, compounds 5l and 5n exhibited the most antiproliferative activity than Hoechst 33342 and doxorubicin against HeLa cell line, with IC₅₀ of 0.224 ± 0.011 µM and 0.205 ± 0.010 µM, respectively. Furthermore, these potent lead cytotoxic agents were evaluated in terms of their inhibition potency against Topoisomerase I and it was determined that selected compounds inhibited the Topoisomerase I. Docking studies were performed and probable interactions in the DNA-Topo I enzyme complex was determined.

Design, Synthesis, and Dual Evaluation of Quinoline and Quinolinium Iodide Salt Derivatives as Potential Anticancer and Antibacterial Agents

A series of novel quinoline and quinolinium iodide derivatives were designed and synthesized to discover potential anticancer and antibacterial agents. With regard to anticancer properties, in vitro cytotoxicities against three human cancer cell lines (A-549, HeLa and SGC-7901) were evaluated. The antibacterial properties against two strains, Escherichia coli (ATCC 29213) and Staphylococcus aureus (ATCC 8739), along with minimum inhibitory concentration (MIC) values were evaluated. The target alkyliodine substituted compounds exhibited significant antitumor and antibacterial activity, of which compound 8-((4-(benzyloxy)phenyl)amino)-7-(ethoxycarbonyl)-5-propyl-[1,3]dioxolo[4,5-g]quinolin-5-ium (12) was found to be the most potent derivative with IC₅₀ values of 4.45±0.88, 4.74±0.42, 14.54±1.96, and 32.12±3.66 against A-549, HeLa, SGC-7901, and L-02 cells, respectively, stronger than the positive controls 5-FU and MTX. Furthermore, compound 12 had the most potent bacterial inhibitory activity. The MIC of this compound against both E. coli and S. aureus was 3.125 nmol ⋅ mL^-1 , which was smaller than that against the reference agents amoxicillin and ciprofloxacin.

Synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines through silver-mediated Appel reaction/C–Br bond cleavage/double selective rearrangement sequence

A reduction and sequential silver-mediated Appel reaction/C–Br cleavage/double rearrangement cascade strategy was developed for the selective synthesis of chromeno[4,3-b]quinolines and spirobenzofuran-3,3′-quinolines.