Synthesis and evaluation of novel alkannin and shikonin oxime derivatives as potent antitumor agents

Unlocking the potential of 1,4-naphthoquinones: A comprehensive review of their anticancer properties

Cancer encompasses a group of pathologies with common characteristics, high incidence, and prevalence in all countries. Although there are treatments available for this disease, they are not always effective or safe, often failing to achieve the desired results. This is why it is necessary to continue the search for new therapies. One of the strategies for obtaining new antitumor drugs is the use of 1,4-naphthoquinone as a scaffold in synthetic or natural products with antitumor activity. This review focuses on compiling studies related to the antitumor activity of 1,4-naphthoquinone and its natural and synthetic derivatives over the last 10 years. The work describes the main natural naphthoquinones with antitumor activity and classifies the synthetic naphthoquinones based on the structural modifications made to the scaffold. Additionally, the formation of metal complexes using naphthoquinones as a ligand is considered. After a thorough review, 197 synthetic compounds with potent biological activity against cancer have been classified according to their chemical structures and their mechanisms of action have been described.

The Fundamental Role of Oxime and Oxime Ether Moieties in Improving the Physicochemical and Anticancer Properties of Structurally Diverse Scaffolds

The present review explores the critical role of oxime and oxime ether moieties in enhancing the physicochemical and anticancer properties of structurally diverse molecular frameworks. Specific examples are carefully selected to illustrate the distinct contributions of these functional groups to general strategies for molecular design, modulation of biological activities, computational modeling, and structure-activity relationship studies. An extensive literature search was conducted across three databases, including PubMed, Google Scholar, and Scifinder, enabling us to create one of the most comprehensive overviews of how oximes and oxime ethers impact antitumor activities within a wide range of structural frameworks. This search focused on various combinations of keywords or their synonyms, related to the anticancer activity of oximes and oxime ethers, structure-activity relationships, mechanism of action, as well as molecular dynamics and docking studies. Each article was evaluated based on its scientific merit and the depth of the study, resulting in 268 cited references and more than 336 illustrative chemical structures carefully selected to support this analysis. As many previous reviews focus on one subclass of this extensive family of compounds, this report represents one of the rare and fully comprehensive assessments of the anticancer potential of this group of molecules across diverse molecular scaffolds.

Anti-tumor effects of novel alkannin derivatives with potent selectivity on comprehensive analysis

BACKGROUND

Therapeutic approaches based on glycolysis and energy metabolism of tumor cells are new promising strategies for the treatment of cancer. Currently, researches on the inhibition of pyruvate kinase M2, a key rate limiting enzyme in glycolysis, have been corroborated as an effective cancer therapy. Alkannin is a potent pyruvate kinase M2 inhibitor. However, its non-selective cytotoxicity has affected its subsequent clinical application. Thus, it needs to be structurally modified to develop novel derivatives with high selectivity.

PURPOSE

Our study aimed to ameliorate the toxicity of alkannin through structural modification and elucidate the mechanism of the superior derivative 23 in lung cancer therapy.

METHODS

On the basis of the principle of collocation, different amino acids and oxygen-containing heterocycles were introduced into the hydroxyl group of the alkannin side chain. We examined the cell viability of all derivatives on three tumor cells (HepG2, A549 and HCT116) and two normal cells (L02 and MDCK) by MTT assay. Besides, the effect of derivative 23 on the morphology of A549 cells as observed by Giemsa and DAPI staining, respectively. Flow cytometry was performed to assess the effects of derivative 23 on apoptosis and cell cycle arrest. To further assess the effect of derivative 23 on the Pyruvate kinase M2 in glycolysis, an enzyme activity assay and western blot assay were performed. Finally, in vivo the antitumor activity and safety of the derivative 23 were evaluated by using Lewis mouse lung cancer xenograft model.

RESULTS

Twenty-three novel alkannin derivatives were designed and synthesized to improve the cytotoxicity selectivity. Among these derivatives, derivative 23 showed the highest cytotoxicity selectivity between cancer and normal cells. The anti-proliferative activity of derivative 23 on A549 cells (IC₅₀ = 1.67 ± 0.34 μM) was 10-fold higher than L02 cells (IC₅₀ = 16.77 ± 1.44 μM) and 5-fold higher than MDCK cells (IC₅₀ = 9.23 ± 0.29 μM) respectively. Subsequently, fluorescent staining and flow cytometric analysis showed that derivative 23 was able to induce apoptosis of A549 cells and arrest the cell cycle in the G0/G1 phase. In addition, the mechanistic studies suggested derivative 23 was an inhibitor of pyruvate kinase; it could regulate glycolysis by inhibiting the activation of the phosphorylation of PKM2/STAT3 signaling pathway. Furthermore, studies in vivo demonstrated derivative 23 significantly inhibited the growth of xenograft tumor.

CONCLUSION

In this study, alkannin selectivity is reported to be significantly improved following structural modification, and derivative 23 is first shown to be able to inhibit lung cancer growth via the PKM2/STAT3 phosphorylation signaling pathway in vitro, indicating the potential value of derivative 23 in treating lung cancer.

Research Progress on Structure and Anti-Gynecological Malignant Tumor of Shikonin

Gynecological malignancy seriously threatens the physical and mental health of women. Shikonin is a naphthoquinone compound with a variety of biological activities. Studies have shown that shikonin can inhibit cell proliferation, promote cell apoptosis and induce cell necrosis. And in recent years, shikonin are also being increasingly used for the study of gynecological malignant diseases. Therefore, we reviewed the mechanism of action and structure optimization of shikonin in gynecological malignant tumors, in order to provide some reference for further research and development of related drug.

Insight into the Progress on Natural Dyes: Sources, Structural Features, Health Effects, Challenges, and Potential

(1) Background: Dyes play an important role in food, medicine, textile, and other industries, which make human life more colorful. With the increasing demand for food safety, the development of natural dyes becomes more and more attractive. (2) Methods: The literature was searched using the electronic databases PubMed, Web of Science, and SciFinder and this scoping review was carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). (3) Results: 248 articles were included in this review. This review summarizes the research progress on natural dyes in the last ten years. According to structural features, natural dyes mainly include carotenoids, polyphenols, porphyrins, and alkaloids, and some of the newest dyes are summarized. Some pharmacological activities of carotenoids, anthocyanin, curcumin, and betalains in the last 10 years are summarized, and the biological effects of dyes regarding illumination conditions. The disadvantages of natural dyes, including sources, cost, stability, and poor bioavailability, limit their application. Here, some feasible strategies (potential resources, biotechnology, new extraction and separation strategies, strategies for improving stability) are described, which will contribute to the development and utilization of natural dyes. (4) Conclusion: Natural dyes show health benefits and potential in food additives. However, it is necessary for natural dyes to pass toxicity tests and quality tests and receive many regulatory approvals before their final entry into the market as food colorants or as drugs.

Anti-cancer Research on Arnebiae Radix-derived Naphthoquinone in Recent Five Years

BACKGROUND

In recent years, many naphthoquinone compounds with anticancer activity have been identified in Arnebiae Radix, and some of them have the potential to be developed into anticancer drugs.

OBJECTIVE

This article aimed to provide a comprehensive overview of the anticancer effects of naphthoquinone compounds through a detailed review of literature and Chinese patents, and discuss their potential to be developed as anticancer drugs for clinical application.

METHODS

Research papers were collected through the databases of PubMed, Cnki and SciDirect using keyword searches "naphthoquinone compounds" and "anticancer". The keywords of "shikonin" and "shikonin derivatives" were also used in PubMed, Cnki and SciDirect databases to collect research articles. The Chinese patents were collected using the Cnki patent database.

RESULTS

Naphthoquinone compounds have been found to possess anti-cancer activity, and their modes of action are associated with inducing apoptosis, inhibiting cancer cell proliferation, promoting autophagy in cancer cells, anti-cancer angiogenesis and inhibition of cell adhesion, invasion and metastasis, inhibiting glycolysis and inhibiting DNA topoisomerase activity.

CONCLUSION

Most of the naphthoquinone compounds show effective anti-cancer activity in vitro. The structure modification of naphthoquinone aims to develop anti-cancer drugs with high efficacy and low toxicity.

Selective Antitumor Effect of Shikonin Derived DMAKO-20 on Melanoma through CYP1B1

BACKGROUND

CYP1B1 is recognized as a valuable target for chemotherapy. It catalyzes the bioactivation of naphthoquinone oximes within certain cancer cell lines. However, the expression level of CYP1B1 in melanoma and the functional role regulating the activity of DMAKO-20 as a representative naphthoquinone oxime against skin carcinoma is still unknown.

OBJECTIVE

We sought to examine the expression level of CYP1B1 in melanoma and explore the molecular mechanism behind the anticancer effects of DMAKO-20 in melanoma.

METHODS

CYP1B1 expression levels in paraffin specimens taken from melanoma patients, and its expression levels in B16/F10 cancer cells were investigated using immunohistochemical staining. The molecular mechanisms behind DMAKO20 activity against melanoma was investigated by using cytotoxicity, cell scratching, apoptotic, and immunoblotting assays.

RESULTS

CYP1B1, the P450 isoform was expressed at high levels in melanoma tissues and cultured B16/F10 cells, but was undetectable in normal tissues or fibroblasts. In cell proliferation assays, the shikonin oxime DMAKO-20 exhibited potent and selective antiproliferative effects against B16/F10 melanoma cells and inhibited migration. Several mechanisms for the anticancer effects of DMAKO-20 have been identified in B16/F10 melanoma cells, including apoptosis, upregulation of mitochondrial apoptotic Bax proteins and downregulation of anti-apoptotic Bcl-2. The results from these mechanistic investigations indicated that DMAKO-20 underwent CYP1B1-mediated metabolic activation to activate anticancer metabolites within melanoma cells.

CONCLUSION

DMAKO-20 exhibited a selective cytotoxic effect on melanoma cells through CYP1B1-mediated activation. Using DMAKO-20 as a lead compound, further structural optimization may provide new drug entities for the treatments of malignant skin carcinomas.

Unsubstituted Oximes as Potential Therapeutic Agents

Oximes, which are highly bioactive molecules, have versatile uses in the medical sector and have been indicated to possess biological activity. Certain oximes exist in nature in plants and animals, but they are also obtained by chemical synthesis. Oximes are known for their anti-inflammatory, antimicrobial, antioxidant and anticancer activities. Moreover, they are therapeutic agents against organophosphate (OP) poisoning. Two oximes are already commonly used in therapy. Due to these abilities, new oxime compounds have been synthesized, and their biological activity has been verified. Often, modification of carbonyl compounds into oximes leads to increased activity. Nevertheless, in some cases, oxime activity is connected to the activity of the substrate. Recent works have revealed that new oxime compounds can demonstrate such functions and thus are considered to be potential drugs for pathogenic diseases, as adjuvant therapy in various types of cancer and inflammation and as potential next-generation drugs against OP poisoning.

Alkannin inhibits proliferation, migration and invasion of hepatocellular carcinoma cells via regulation of miR-92a

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. In our study, we aimed to investigate the effects of alkannin on HCC cells growth, migration and invasion.

METHODS

Huh7 and Hep3B2.1-7 cells were treated with alkannin. Expression of miR-92a in cell was altered by transfection with miR-92a-mimic (miR-92a-M) or miR-92a-inhibitor (miR-92a-I). Cell viability, proliferation, apoptosis, migration and invasion were detected by Cell Counting Kit-8, BrdU assay, flow cytometry, and transwell assay, respectively. The expression of miR-92a was determined by quantitative real-time PCR. The expression of proteins associated with proliferation, apoptosis and metastasis was measured by Western blot.

RESULTS

Alkannin decreased cell viability and proliferation, executed cell apoptosis, and inhibited the migration and invasion of Huh7 and Hep3B2.1-7 cells. Alkannin negatively regulated the expression of miR-92a, and transfection with miR-92a-M impeded alkannin's anti-tumor functions. PTEN and TP53INP1 were found to be target genes of miR-92a. Alkannin inhibited PTEN-dependent PI3K/AKT pathway. Furthermore, the biological effects of miR-92a-I in alkannin treated cells were eliminated by PTEN silencing.

CONCLUSION

Alkannin exerted anti-tumor activities by downregulation of miR-92a. This process might be executed by inactivating PTEN/PI3K/AKT signal pathways through the binding effects of miR-92a on PTEN.

Antiproliferative and Proapoptotic Effects of a Protein Component Purified from Aspongopus chinensis Dallas on Cancer Cells In Vitro and In Vivo

Aspongopus chinensis Dallas is used as a traditional Chinese medicine. In China, clinical evidence suggests that it has anticancer activity. However, the anticancer active components are not fully elucidated. In the present study, we purified an anticancer active component (named CHP) from A. chinensis. To gain a comprehensive insight into the protein components, shotgun proteomic analysis was conducted. The anticancer active protein band was cut from the sodium dodecyl sulphate-polyacrylamide gel electrophoresis gel and digested with trypsin to generate peptide mixture. The peptide fragments were then analysed by liquid chromatography tandem mass spectrometry; 18 proteins were identified. In addition, we evaluated the effects of CHP on the proliferation and apoptosis of two human gastric cancer cell lines (SGC-7901 and BGC-823). The cultured cells were treated with CHP at concentrations of 20, 30, and 40 μg/mL. Inhibition of cell growth was determined by the MTT assay. Hoechst 33258 staining was adopted to detect apoptosis morphologically. Apoptotic cells were quantified by Annexin V-FITC/propidium iodide staining and flow cytometry. Tumour growth was assessed by subcutaneous inoculation of 4T1 cells into BALB/c mice. There was a concentration- and time-dependent decrease in the proliferation of both cell lines at CHP concentrations of 20–40 μg/mL. Apoptotic characteristics, such as karyopyknotic pyknic hyperfluorescence bolus and nuclear fragmentation, were observed in both the cell lines by Hoechst 33258 staining. Flow cytometry showed that CHP induced significant (P < 0.01) concentration-dependent apoptosis of SGC-7901 cells. In vivo assay showed that CHP can partially inhibit tumour growth derived from 4T1 cells in vivo. The present study is the first to report that CHP in A. chinensis inhibits the proliferation of cancer cell lines via the suppression of cancer cell proliferation and acceleration of apoptosis.

Cytotoxicity of Synthesized 1,4-Naphthoquinone Oxime Derivatives on Selected Human Cancer Cell Lines

In an effort to develop potent and selective antitumor agents, a series of 1,4-naphthoquinone oxime derivatives were designed and synthesized. The cytotoxicity of these compounds were evaluated against five human cancer cell lines (colorectal cancer cell: HCT-15, breast cancer cell: MDA-MB-231, liver cancer cell: BEL-7402, colorectal cancer cell: HCT-116 and ovarian cancer cell: A2780) in vitro. Among them, compound 14 was found to be the most potent cytotoxic compound against three cell lines (MDA-MB-231, BEL-7402 and A2780) with IC₅₀ values of 0.66±0.05, 5.11±0.12 and 8.26±0.22 µM, respectively. Additionally, the length of the side chains and the position of the substituent may also affect the cytotoxic activity of the naphthoquinone oxime derivatives. In general, compound 14 effectively inhibited breast cancer cell proliferation and may become a promising anticancer agent.

Synthesis and biological evaluation of sulfur-containing shikonin oxime derivatives as potential antineoplastic agents

As a continuation of our research on developing potent and potentially safe antineoplastic agents, a set of forty five sulfur-containing shikonin oxime derivatives were synthesized and evaluated for their in vitro cytotoxic activity against human colon cancer (HCT-15), gastric carcinoma (MGC-803), liver (Bel7402), breast (MCF-7) cancer cells and human skin fibroblast (HSF) cells. All the synthesized compounds exhibited potent cytotoxic activity selectively towards HCT-15 cells and did not display apparent toxicity to the normal HSF cells, some of which were more or comparatively effective to the parent compound against HCT-15, MGC-803 and Bel7402 cells. The most active agent 9m displayed high potency against human cancer cells with IC₅₀ ranging from 0.27 ± 0.02 to 9.23 ± 0.12 μM. The structure-activity relationships (SARs) studies suggested that the nature of substituent group in the side chain is important for antitumor potency in vitro. Additionally, nitric oxide release studies revealed that the amount of nitric oxide generated from these oxime derivatives was relatively low. Furthermore, cellular mechanism investigations indicated that compound 9m could arrest cell cycle at G1 phase and induce a strong apoptotic response in HCT-15 cells. Moreover, western blot studies revealed that compound 9m induced apoptosis through the down-regulation of Bcl-2 and up-regulation of Bax, caspase 3 and 9. For all these reasons, compound 9m hold promising potential as antineoplastic agent.

One-pot synthesis of 1,4-dihydroxy-2-((E)-1-hydroxy-4-phenylbut-3-enyl)anthracene-9,10-diones as novel shikonin analogs and evaluation of their antiproliferative activities

A series of shikonin analogs have been synthesized in a one-pot reaction of quinizarin with β,γ-unsaturated aldehydes in MeOH under mild conditions and investigated for their cytotoxicity against four cancer cell lines and one normal cell line. The synthesized compounds were found to be cytotoxic against HeLa cells with no apparent toxicity against normal cell line. Further modification led to the discovery of a novel tetracyclic anthraquinone (4b/4b') with potent cytotoxic activities against cervical, breast and pancreatic cancer cell lines with no significant effect on the growth of the control mammary epithelial cell line MCF-10. The good cytotoxicity and selectivity of compound 4b/4b' suggest that it could be a promising lead for further optimization.

Synthesis, Characterization, and Anticancer Activity of New Metal Complexes Derived from 2-Hydroxy-3-(hydroxyimino)-4-oxopentan-2-ylidene)benzohydrazide

Novel metal(II) complexes derived from 2-hydroxy-N'-((Z)-3-(hydroxyimino)-4-oxopentan-2-ylidene)benzohydrazide ligand (H2L) were synthesized and characterized by elemental and thermal analyses (DTA and TGA), IR, UV-VIS, (1)H-NMR, ESR and mass spectroscopy, magnetic susceptibilities, and conductivities measurements. The complexes adopt distorted octahedral geometry. The ESR spectra of the solid copper(II) complexes are characteristic to d(9) configuration and have an axial symmetry type of a d(x (2)-y (2)) ground state. The g values confirmed the tetragonal octahedral geometry with a considerably ionic or covalent environment. The cytotoxic activity of the ligand and its metal complexes showed potent cytotoxicity effect against growth of human liver cancer HepG2 cell lines compared to the clinically used Sorafenib (Nexavar).