Design, synthesis and biological mechanisms research on 1,2,3-triazole derivatives of Jiyuan Oridonin A

Discovery of novel oridonin sulfamide derivatives as potent NLRP3 inhibitors by a visible-light photocatalysis-enabled peripheral editing

The progress of organicsyntheticmethod can promote late-stage lead compound modification and novel active compound discovery. Molecular editing technology in the field of organic synthesis, including peripheral and skeletal editing, facilitates rapid access to molecular diversity of a lead compound. Peripheral editing of CH bond activation is gradually used in lead optimization to afford novel active scaffolds and chemical space exploitation. To develop oridonin derivatives with high anti-inflammatory potency, novel oridonin sulfamides had been designed and synthesized by a scaffoldhopping strategy based on a visible-light photocatalysis peripheral editing. All novel compounds revealed measurable inhibition of IL-1β and low cytotoxicity in THP-1 cells. The docking study indicated that the best active compound ZM640 was accommodated in thebinding site of NLRP3 with two hydrogen bond interaction. These preliminary results confirm that α, β-unsaturated carbonyl of oridonin is not essential for NLRP3 inhibitory effect. This new oridonin scaffold has its potential to be further developed as a promising class of NLRP3 inhibitors.

Natural-product-based fluorescent probes: recent advances and applications

Fluorescent probes are attractive tools for biology, drug discovery, disease diagnosis, and environmental analysis. In bioimaging, these easy-to-operate and inexpensive probes can be used to detect biological substances, obtain detailed cell images, track in vivo biochemical reactions, and monitor disease biomarkers without damaging biological samples. Over the last few decades, natural products have attracted extensive research interest owing to their great potential as recognition units for state-of-the-art fluorescent probes. This review describes representative natural-product-based fluorescent probes and recent discoveries, with a particular focus on fluorescent bioimaging and biochemical studies.

Hybrids of thiazolidinone with 1,2,3-triazole derivatives: design, synthesis, biological evaluation, in silico studies, molecular docking, molecular dynamics simulations, and ADMET profiling

A new series of thiazolidinone linked 1,2,3-triazole hybrids 5a-h was designed and synthesized using the copper-catalyzed Huisgen azide-alkyne cycloaddition (CuAAC) between thiazolidinone linked alkyne and aromatic azides. The structures of the newly synthesized compounds were established by NMR (1H and 13C) and HRMS. The targeted thiazolidinone-1,2,3-triazole hybrids were evaluated for their cytotoxic activity against four human cancer cell lines, including fibrosarcoma (HT-1080), lung carcinoma (A-549), and breast carcinoma (MCF-7 and MDA-MB-231) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliun bromide (MTT). The obtained data showed that most of these compounds have moderate anti-proliferative activity with IC50 values between 10.26 ± 0.71 and 53.93 ± 1.20 μM. The compound 5a exhibited higher activity with an IC50 value of 10.26 ± 0.71 µM, compared to 5d with an IC50 value of 11.56 ± 1.98 µM for the HT-1080 and MCF-7 cancer cells line, respectively. Moreover, Annexin-V apoptosis was assessed by flow cytometry for hybrid compounds 5a and 5d against HT-1080 and MCF-7 competitor cell lines, as they increase the level of active caspase 3/7. The experimental results were further confirmed by docking studies followed by molecular dynamic simulations. Both the potent derivatives i.e. 5a and 5d have comparable docking scores and MD simulations results showed that the docked complex of 5a is somewhat more stable than 5d primarily for protein p53. The ADMET profile of both derivatives established their safety zone and drug-like potential.Communicated by Ramaswamy H. Sarma.

Potential Focal Adhesion Kinase Inhibitors in Management of Cancer: Therapeutic Opportunities from Herbal Medicine

Focal adhesion kinase (FAK) is a multifunctional protein involved in cellular communication, integrating and transducing extracellular signals from cell-surface membrane receptors. It plays a central role intracellularly and extracellularly within the tumor microenvironment. Perturbations in FAK signaling promote tumor occurrence and development, and studies have revealed its biological behavior in tumor cell proliferation, migration, and adhesion. Herein we provide an overview of the complex biology of the FAK family members and their context-dependent nature. Next, with a focus on cancer, we highlight the activities of FAK signaling in different types of cancer and how knowledge of them is being used for screening natural compounds used in herbal medicine to fight tumor development.

Synthesis, biological evaluation and cellular localization study of fluorescent derivatives of Jiyuan Oridonin A

Jiyuan Oridonin A (JOA) is a naturally occurring ent-kaurane diterpenoid that exhibits significant potential in the field of anti-tumor drug development. However, its detailed anti-cancer mechanism of action has not been fully understood. In order to investigate its anticancer mode of action, two series of novel fluorescent derivatives of JOA conjugated with naphthalimide dyes were synthesized, and their antitumor activity against five selected cancer cell lines (MGC-803, SW1990, PC-3, TE-1 and HGC-27) was evaluated. Compared with JOA, the anti-tumor activity of the vast majority of compounds were improved. Among them, B12 exhibited promising anti-proliferative activity against HGC-27 cells with IC₅₀ value of 0.39 ± 0.09 μM. Fluorescence imaging studies demonstrated that probe B12 could enter HGC-27 cells in a dose-dependent and time-dependent manner and was mainly accumulated in mitochondria. Preliminary biological mechanism studies indicated that B12 was able to inhibit cell cloning and migration. Further studies suggested that B12-induced apoptosis was related to the mitochondrial pathway. Overall, our results provide new approaches to explore the molecular mechanism of the natural product JOA, which would contribute to its further development as an antitumor agent.

Click Chemistry in Natural Product Modification

Click chemistry is perhaps the most powerful synthetic toolbox that can efficiently access the molecular diversity and unique functions of complex natural products up to now. It enables the ready synthesis of diverse sets of natural product derivatives either for the optimization of their drawbacks or for the construction of natural product-like drug screening libraries. This paper showcases the state-of-the-art development of click chemistry in natural product modification and summarizes the pharmacological activities of the active derivatives as well as the mechanism of action. The aim of this paper is to gain a deep understanding of the fruitful achievements and to provide perspectives, trends, and directions regarding further research in natural product medicinal chemistry.

Design, Hemiysnthesis, crystal structure and anticancer activity of 1, 2, 3-triazoles derivatives of totarol

A new series of diverse triazoles linked to the hydroxyl group of totarol were synthesized using click chemistry approach. The structures of these compounds were elucidated by HRMS, IR and NMR spectroscopy. The structure of compound 3 g was also confirmed by x-ray single crystal diffraction. The cytotoxicity of these compounds was evaluated by the MTT method against four cancer cell lines, including fibrosarcoma HT-1080, lung carcinoma A-549 and breast adenocarcinoma (MDA-MB-231 and MCF-7), and the results indicated that all compounds showed weak to moderate activities against all cancer cell lines with IC₅₀ values ranging from 14.44 to 46.25 μM. On the basis of our research the structure-activity relationships (SAR) of these compounds were discussed. This work provides some important hints for further structural modification of totarol towards developing novel and highly effective anticancer drugs respectively. It is interesting to note that compound 3 g indicated a very significant cytotoxicity against HT-1080 and A-549 cell lines. The molecular docking showed that compound 3 g activated the caspase-3 and inhibited tubulin by forming stable protein-ligand complexes.

Jiyuan Oridonin A Overcomes Differentiation Blockade in Acute Myeloid Leukemia Cells With MLL Rearrangements via Multiple Signaling Pathways

Differentiation therapy with all-trans-retinoic acid (ATRA) in acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia (AML), has been extremely successful in inducing clinical remission in APL patients. However, the differentiation therapy of ATRA-based treatment has not been effective in other subtypes of AML. In this study, we evaluated a small molecule of ent-kaurene diterpenoid, Jiyuan oridonin A (JOA), on the differentiation blockade in AML cells with the mixed lineage leukemia (MLL) gene rearrangements (MLLr) in MV4-11, MOLM-13 and THP-1 cells. We found that JOA could significantly inhibit the proliferation of MOLM-13, MV4-11 and THP-1 cells. Moreover, JOA promoted cell differentiation coupled with cell-cycle exit at G0/G1 and inhibited the colony- forming capacity of these cells. We showed that the anti-proliferative effect of JOA attributed to cell differentiation is most likely through the martens tretinoin response up pathway in the MOLM-13 cell line, and the hematopoietic cell lineage pathway by the inhibition of c-KIT expression and cell adhesion pathway in the THP-1 cell line. Our findings suggest that JOA could be a novel therapeutic agent against human MLLr acute myeloid leukemia.

Synthesis and in vitro and in vivo biological evaluation of novel derivatives of flexicaulin A as antiproliferative agents

As our research focuses on anticancer drugs, a series of novel derivatives of flexicaulin A (FA), an ent-kaurene diterpene, condensed with an aromatic ring were synthesized, and their antiproliferative activities against four human cancer cell lines (TE-1, EC109, MCF-7, and MGC-803) were evaluated. The activities of most of the new compounds were better than those of FA. Compound 2y exhibited the best activity with an IC50 value reaching 0.13 μM against oesophageal cancer cells (EC109 cells). The IC50 values for 2y in normal cells (GES-1 cells and HUVECs) were 0.52 μM and 0.49 μM, respectively. Subsequent mechanistic investigations found that compound 2y can inhibit the proliferation of cancer cells and cell cloning. In addition, 2y could reduce the mitochondrial membrane potential, increase the apoptosis rate, and increase the ROS level in EC109 cells. Moreover, 2y can upregulate the expression of ROS/JNK pathway-related proteins (p-ASK1, p-MKK4, p-JNK, and p-Cjun (ser63)) and pro-apoptotic proteins (Bax, Bad, and Bim). In vivo experiments showed that 2y can inhibit tumour growth in nude mice. The mechanism involves an increase in protein expression in the ROS pathway, leading to changes in apoptosis-related proteins. In addition, compound 2y shows low toxicity. These results indicate that compound 2y holds promising potential as an antiproliferative agent.

Gramine-based structure optimization to enhance anti-gastric cancer activity

Gramine is a natural indole alkaloid with a wide range of biological activities, but its anti-gastric cancer activity is poor. Herein, a pharmacophore fusion strategy was adopted to design and synthesize a new series of indole-azole hybrids on the structural basis of gramine. Based on our previous studies, different nitrogen-containing five-membered heterocyclic rings and terminal alkyne group were introduced into the indole-based scaffold to investigate their effect on improving the anti-gastric cancer activity of gramine derivatives. Structure-activity relationship (SAR) studies highlighted the role played by terminal alkyne in enhancing the inhibitory effect, and compound 16h displayed the best antiproliferative activity against gastric cancer MGC803 cells with IC₅₀ value of 3.74 μM. Further investigations displayed compound 16h could induce mitochondria-mediated apoptosis, and caused cell cycle arrest at G2/M phase. Besides, compound 16h could inhibit the metastasis ability of MGC803 cells. Our studies may provide a new strategy for structural optimization of gramine to enhance anti-gastric cancer activity, and provide a potential candidate for the treatment of gastric cancer.

A novel synthetic acanthoic acid analogues and their cytotoxic activity in cholangiocarcinoma cells

A novel series of acanthoic acid analogues containing triazole moiety were synthesized through esterification and CuAAC reaction. Evaluation of their biological activities against four cell lines of cholangiocarcinoma cells showed that 3d exhibited the strongest activity with an IC₅₀ value of 18 µM against KKU-213 cell line, which was 8 fold more potent than acanthoic acid. Interestingly, the triazole ring and nitro group on benzyl ring play very significant role in cytotoxic activity. The computational studies revealed that 3d occupies the binding energy of -12.7 and -10.8 kcal/mol with CDK-2 and EGFR protein kinases, respectively. This result might provide a beginning for the development of acanthoic acid analogues as an anticancer agent.

Identification of a Potent Oridonin Analogue for Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is one of the most highly invasive and metastatic breast cancers without safe and effective therapeutic drugs. The natural product oridonin is reported to be a potential anti-TNBC agent. However, its moderate activity and complex structure hampered its clinical application. In this study, the novel oridonin analogues were first identified by removal of multiple hydroxyl groups and structural simplification of oridonin. The representative analogue 20 exhibited potent anticancer effects. Further structural modification on 20 generated the most potent derivative 56, which possessed 120-fold more potent antiproliferative activity than oridonin in the TNBC cell line HCC1806. Importantly, compound 56 exhibited more potent anticancer activity than paclitaxel in TNBC xenograft nude mice. Moreover, 56 could attenuate the expression of MMP-2, MMP-9, p-FAK, and integrin β1 to inhibit TNBC cell metastasis. All results suggest that compound 56 may warrant further investigation as a promising candidate agent for the treatment of TNBC.

A Small Molecule Inhibitor, OGP46, Is Effective against Imatinib-Resistant BCR-ABL Mutations via the BCR-ABL/JAK-STAT Pathway

Chronic myeloid leukemia (CML) is caused by the Philadelphia (Ph⁺) chromosome carrying the BCR-ABL oncogene, a constitutively active tyrosine kinase. The discovery of imatinib represents a major success story in the treatment against CML. However, mutations in the BCR-ABL kinase domain are a major cause of resistance to imatinib, demonstrating that BCR-ABL remains a critical drug target. Here, we investigate a novel small molecule inhibitor, OGP46, for its inhibitory activity against K562, a panel of murine BaF3 cell lines stably expressing either wild-type BCR-ABL or its mutant forms, including T315I. OGP46 exhibits potent activity against imatinib-resistant BCR-ABL mutations, including T315I. OGP46 induced cell differentiation accompanied by G0/G1 cell-cycle arrest and suppressed the colony formation capacity of cells. Treatment with OGP46 significantly decreased the mRNA and protein expression of BCR-ABL in K562 and BaF3-p210-T315I cells. Mechanistically, the anti-cancer activity of OGP46 induced by cell differentiation is likely through the BCR-ABL/JAK-STAT pathway in native BCR-ABL and mutant BCR-ABL, including T315I, of CML cells. Our findings highlight that OGP46 is active against not only native BCR-ABL but also 11 clinically relevant BCR-ABL mutations, including T315I mutation, which are resistant to imatinib. Thus, OGP46 may be a novel strategy for overcoming imatinib-resistance BCR-ABL mutations, including T315I.

1,2,3-Triazole-containing hybrids as potential anticancer agents: Current developments, action mechanisms and structure-activity relationships

Anticancer agents are critical for the cancer treatment, but side effects and the drug resistance associated with the currently used anticancer agents create an urgent need to explore novel drugs with low side effects and high efficacy. 1,2,3-Triazole is privileged building block in the discovery of new anticancer agents, and some of its derivatives have already been applied in clinics or under clinical trials for fighting against cancers. Hybrid molecules occupy an important position in cancer control, and hybridization of 1,2,3-triazole framework with other anticancer pharmacophores may provide valuable therapeutic intervention for the treatment of cancer, especially drug-resistant cancer. This review emphasizes the recent advances in 1,2,3-triazole-containing hybrids with anticancer potential, covering articles published between 2015 and 2019, and the structure-activity relationships, together with mechanisms of action are also discussed.

1,2,3-Triazole-containing hybrids as leads in medicinal chemistry: A recent overview

The 1,2,3-triazole ring is a major pharmacophore system among nitrogen-containing heterocycles. These five-membered heterocyclic motifs with three nitrogen heteroatoms can be prepared easily using 'click' chemistry with copper- or ruthenium-catalysed azide-alkyne cycloaddition reactions. Recently, the 'linker' property of 1,2,3-triazoles was demonstrated, and a novel class of 1,2,3-triazole-containing hybrids and conjugates was synthesised and evaluated as lead compounds for diverse biological targets. These lead compounds have been demonstrated as anticancer, antimicrobial, anti-tubercular, antiviral, antidiabetic, antimalarial, anti-leishmanial, and neuroprotective agents. The present review summarises advances in lead compounds of 1,2,3-triazole-containing hybrids, conjugates, and their related heterocycles in medicinal chemistry published in 2018. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Synthesis of Oridonin Derivatives via Mizoroki-Heck Reaction and Click Chemistry for Cytotoxic Activity

BACKGROUND

Natural products (NPs) are evolutionarily chosen "privileged structures" that have a profound impact upon the anticancer drug discovery and development progress. However, the search for new drugs based on structure modification of NPs has often been hindered due to the tedious and complicated synthetic pathways. Fortunately, Mizoroki-Heck reaction and copper-catalyzed alkyne-azide cycloaddition (CuAAC) could provide perfect strategies for selective modification on NPs even in the presence of liable functionalities.

OBJECTIVE

Here, we used oridonin, an ent-kaurane diterpenoid that showed a wide range of biological activities, as a parent molecule for the generation of analogues with anticancer activity.

METHODS

Derivatives of oridonin were generated based on the structure-activity relationship study of oridonin and synthesized via Mizoroki-Heck reaction and CuAAC. The cytotoxicity of new oridonin derivatives were evaluated on both cancer cells and normal cells. Furthermore, the apoptotic effect and cell cycle arrest effect of the selected potent analogue were evaluated by flow cytometry and western blotting analysis.

RESULTS

Two series of novel C-14 and C-17 modified derivatives of oridonin were obtained via Heck reaction and copper-catalyzed alkyne-azide cycloaddition (CuAAC), respectively. In vitro antiproliferative activities showed that the introduction of C-14 (2-triazole)acetoxyl- moiety could retain or enhance cytotoxicity, whereas the introduction of C-17 phenyl ring might exert negative effect. Further studies demonstrated that derivative 23 exhibited broad-spectrum antiproliferative activity, effectively overcame drug-resistance and showed weak cytotoxicity on non-cancer cells. Preliminary mechanistic studies indicated that 23 might cause G2/M phase arrest and induce apoptosis in PC-3 cells.

CONCLUSION

Mizoroki-Heck reaction and CuAAC are perfect strategies for structure modification of complex natural products. The introduction of C-14 (2-triazole)acetoxyl- moiety could retain or enhance the cytotoxicity of oridonin, the introduction of C-17 phenyl group might exert negative effect on its cytotoxicity.