Novel Steroidal 5α,8α-Endoperoxide Derivatives with Semicarbazone/Thiosemicarbazone Side-chain as Apoptotic Inducers through an Intrinsic Apoptosis Pathway: Design, Synthesis and Biological Studies

Design, synthesis, and biological evaluation of novel ciprofloxacin derivatives as potential anticancer agents targeting topoisomerase II enzyme

A series of novel ciprofloxacin (CP) derivatives substituted at the N-4 position with biologically active moieties were designed and synthesised. 14 compounds were 1.02- to 8.66-fold more potent than doxorubicin against T-24 cancer cells. Ten compounds were 1.2- to 7.1-fold more potent than doxorubicin against PC-3 cancer cells. The most potent compounds 6, 7a, 7b, 8a, 9a, and 10c showed significant Topo II inhibitory activity (83-90% at 100 μM concentration). Compounds 6, 8a, and 10c were 1.01- to 2.32-fold more potent than doxorubicin. Compounds 6 and 8a induced apoptosis in T-24 (16.8- and 20.1-fold, respectively compared to control). This evidence was supported by an increase in the level of apoptotic caspase-3 (5.23- and 7.6-fold, sequentially). Both compounds arrested the cell cycle in the S phase in T-24 cancer cells while in PC-3 cancer cells the two compounds arrested the cell cycle in the G1 phase. Molecular docking simulations of compounds 6 and 8a into the Topo II active site rationalised their remarkable Topo II inhibitory activity.

Design, synthesis, and biological evaluation of new celecoxib analogs as apoptosis inducers and cyclooxygenase-2 inhibitors

Series of new celecoxib analogs were synthesized to assess their anticancer activity against the MCF-7 cell line. Four compounds, 3a, 3c, 5b, and 5c, showed 1.4-9.2-fold more potent anticancer activity than celecoxib. The antiproliferative activity of the most potent compounds, 3c, 5b, and 5c, seems to be associated well with their ability to induce apoptosis in MCF-7 cells (18-24-fold). This evidence was supported by an increase in the expression of the tumor suppressor gene p53 (4-6-fold), the elevation in the Bax/BCL-2 ratio, and a significant increase in the level of active caspase-7 (4-7-fold). Moreover, compounds 3c and 5c showed significant cyclooxygenase-2 (COX-2) inhibitory activity. They were also docked into the crystal structure of the COX-2 enzyme (PDB ID: 3LN1) to understand their mode of binding.

Design, synthesis and biological evaluation of novel diosgenin-benzoic acid mustard hybrids with potential anti-proliferative activities in human hepatoma HepG2 cells

To discover new lead compounds with anti-tumour activities, in the present study, natural diosgenin was hybridised with the reported benzoic acid mustard pharmacophore. The in vitro cytotoxicity of the resulting newly synthesised hybrids (8–10, 14a–14f, and 15a–15f) was then evaluated in three tumour cells (HepG2, MCF-7, and HeLa) as well as normal GES-1 cells. Among them, 14f possessed the most potential anti-proliferative activity against HepG2 cells, with an IC₅₀ value of 2.26 µM, which was 14.4-fold higher than that of diosgenin (IC₅₀ = 32.63 µM). Furthermore, it showed weak cytotoxicity against GES-1 cells (IC₅₀ > 100 µM), thus exhibiting good antiproliferative selectivity between normal and tumour cells. Moreover, 14f could induce G0/G1 arrest and apoptosis of HepG2 cells. From a mechanistic perspective, 14f regulated cell cycle-related proteins (CDK2, CDK4, CDK6, cyclin D1 and cyclin E1) as well mitochondrial apoptosis pathway-related proteins (Bax, Bcl-2, caspase 9, and caspase 3). These findings suggested that hybrid 14f serves as a promising anti-hepatoma lead compound that deserves further research.

Novel diosgenin-amino acid-benzoic acid mustard trihybrids exert antitumor effects via cell cycle arrest and apoptosis

In discovering new powerful antitumor agents, two series of novel diosgenin-amino acid-benzoic acid mustard trihybrids (7a-7 g and 12a-12 g) were designed and synthesized. The antiproliferative activities were tested against five human tumor cell lines and one normal cell line using CCK-8 assays. Among the trihybrids, 12e was the most promising compound, which inhibited T24 cells with IC₅₀ value of 6.96 μM, and was stronger than its parent compound diosgenin (IC₅₀ = 32.33 μM). In addition, 12e had weak cytotoxicity on the normal GES-1 cell line (IC₅₀ = 213.74 μM). Moreover, 12e could cause G2/M cell cycle arrest, increase the percentage of apoptosis, induce mitochondrial depolarization, and promote reactive oxygen species generation in T24 cells. Further studies on antitumor mechanism demonstrated that 12e triggered the intrinsic (mitochondrial) and extrinsic (death receptor) apoptotic pathways. More importantly, 12e could inhibit T24 cell proliferation in an in vivo zebrafish xenograft model. Therefore, 12e, as a novel trihybrid with potent cytotoxicity, might be applied as a promising skeleton for antitumor agents, which deserved further optimization.

DP from Euphorbia fischeriana S. mediated apoptosis in leukemia cells via the PI3k/Akt signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia fischeriana S. (E. fischeriana) is a classic Chinese herb with toxicity that is mainly used for cancer treatment and in insect repellent, anti-inflammatory and anti-edema applications (Liu et al., 2001). 12-Deoxyphorbol13-palmitate (DP), a tetracyclic diterpene monomer compound, was extracted from the roots of E. fischeriana by our research groups.

AIM

Previous studies found that DP could inhibit the proliferation of leukemia cells in vitro. However, the underlying mechanism of DP in leukemia is unknown. Hence, DP's pharmacological effect on leukemia cells was investigated in this study.

MATERIALS AND METHODS

DP was obtained from the Natural Medicine Chemistry Laboratory of Qiqihaer Medical University. In vitro, K562 cells and HL60 cells were incubated with DP or DP combined with LY294002 at different concentrations. Cell proliferation and apoptosis were detected by the relevant experimental methods. In vivo, nude mouse xenograft models were established by injecting K562 cells. DP was intraperitoneally administered to observe the influence on the growth of transplanted tumors. Gene detection and immunoblot analysis were performed to validate the mechanisms.

RESULTS

The cell counting kit-8 (CCK-8) assay proved that DP inhibited the growth of K562 and HL60 cells in a time- or dose-dependent manner. At 12 h, DP could induce apoptosis by Annexin V-FITC/propidium iodide (PI) dual labeling, loss of mitochondrial membrane potential (MMP), intracellular reactive oxygen species (ROS), acridine orange/ethidium bromide (AO/EB) staining and transmission electron microscopy (TEM) observation in K562 or HL60 cells. Furthermore, in an assay of gene and protein expression, we found that DP could downregulate the gene and protein expression levels of Bcl-2, upregulate the gene and protein expression levels of Bax and Bim, and downregulate the protein expression levels of PI3k, p-Akt, and p-FoxO3a. Moreover, the effects of DP on proliferation and apoptosis in K562 cells were enhanced by LY294002. Then, we tested the antitumor effects of DP in vivo. Nude mouse xenograft models were established by subcutaneously injecting K562 cells. We found that tumor volume was significantly decreased in DP-treated xenograft nude mice. Morphologic changes, apoptosis degree, and related gene and protein expression levels in transplanted tumor tissue of DP-treated nude mice were assessed by different experimental methods.

CONCLUSIONS

The in vivo and in vitro experimental results indicated that DP might inhibit the proliferation and induce the apoptosis of leukemia cells, which might be a result of suppressing the PI3k/Akt signaling pathways.

Design and Synthesis of Novel Betulin Derivatives Containing Thio-/Semicarbazone Moieties as Apoptotic Inducers through Mitochindria-Related Pathways

Two new series of betulin derivatives with semicarbazone (7a-g) or thiosemicarbazone (8a-g) groups at the C-28 position were synthesized. All compounds were evaluated for their in vitro cytotoxicities in human hepatocellular carcinoma cells (HepG2), human breast carcinoma cells (MCF-7), human lung carcinoma cells (A549), human colorectal cells (HCT-116) and normal human gastric epithelial cells (GES-1). Among these compounds, 8f displayed the most potent cytotoxicity with an IC₅₀ value of 5.86 ± 0.61 μM against MCF-7 cells. Furthermore, the preliminary mechanism studies in MCF-7 cells showed that compound 8f could trigger the intracellular mitochondrial-mediated apoptosis pathway by losing MMP level, which was related with the upregulation of Bax, P53 and cytochrome c expression; the downregulation of Bcl-2 expression; activation of the expression levels of caspase-3, caspase-9, cleaved caspase-3 and cleaved caspase-9; and an increase in the amounts of intracellular reactive oxygen species. These results indicated that compound 8f may be used as a valuable skeleton structure for developing novel antitumor agents.

DG-8d, a novel diosgenin derivative, decreases the proliferation and induces the apoptosis of A549 cells by inhibiting the PI3k/Akt signaling pathway

Lung neoplasm has a relatively poor prognosis, and the clinical efficacy of targeted medicine remains unsatisfactory. Therefore, the development of novel efficient anti-lung cancer drugs is urgently needed. In our previous study, we showed that a novel diosgenin derivative 8d (DG-8d), which contained 5-(3-pyridyl)-1,3,4-thiadiazole moiety, had significant cytotoxic activity on human tumor cells, especially the A549 cells. However, the underlying mechanism of DG-8d was unknown. In this study, the pharmacological effect of DG-8d on the A549 cells was inspected.

METHOD

Cell viability and apoptosis were detected by CCK-8 assays, morphological changes and quantitative analysis of flow cytometry. Levels of gene and protein expression of apoptosis-related and PI3k/Akt pathway were evaluated by qRT-PCR, immunostaining and Western blot analysis.

RESULT

The findings proved that DG-8d could inhibit cell growth and induce apoptosis. The effect of DG-8d on the proliferation and apoptosis in the A549 cells were improved with LY294002 (PI3K inhibitor). Moreover, the effect of DG-8d on apoptosis was further confirmed by AO-EB dye, mitochondrial depolarization and accrued intracellular ROS. Gene and protein detection showed that DG-8d or DG-8d combined with LY294002 could down-regulate signaling molecules of Bcl-2, PI3k, p-Akt, p-FoxO3a and up-regulate signaling molecules of Bax snd Bim. In addition, nuclear translocation of FoxO3a was observed significantly in the cells.

CONCLUSION

DG-8d could inhibit the proliferation and induce the apoptosis of the A549 cells, which maybe mainly because of the suppression of the PI3k/Akt pathways. Finally, we believe that DG-8d can be developed as a possible agent for carcinoma therapy.

Design and synthesis of diosgenin derivatives as apoptosis inducers through mitochondria-related pathways

Diosgenin (DSG) has attracted attention recently as a potential anticancer therapeutic agent due to its profound antitumor activity. To better utilize DSG as an antitumor compound, two series of DSG-amino acid ester derivatives (3a-3g and 7a-7g) were designed and synthesized, and their cytotoxic activities against six human cancer cell lines (K562, T24, MNK45, HepG2, A549, and MCF-7) were evaluated. The results obtained showed that a majority of derivatives exhibited cytotoxic activities against these six human tumor cells. Structure-activity relationship analysis revealed that the introduction of l-tryptophan to the C-3 position of DSG and the C-26 position of derivative 5 was the preferred option for these compounds to display significant cytotoxic activities. Among them, compound 7g exhibited significant cytotoxicity against the K562 cell line (IC₅₀ = 4.41 μM) and was 6.8-fold more potent than diosgenin (IC₅₀ = 30.04 μM). Further cellular mechanism studies in K562 cells elucidated that compound 7g triggered mitochondrial-related apoptosis by increasing the generation of intracellular reactive oxygen species (ROS) and decreasing mitochondrial membrane potential (MMP), which was associated with upregulation of the gene and protein expression levels of Bax, downregulation of the gene and protein expression levels of Bcl-2 and activation of the caspase cascade. The above results suggested that compound 7g might be considered a promising scaffold for further modification of more potent anticancer agents.

Sisters in structure but different in character, some benzaldehyde and cinnamaldehyde derivatives differentially tune Aspergillus flavus secondary metabolism

Great are the expectations for a new generation of antimicrobials, and strenuous are the research efforts towards the exploration of diverse molecular scaffolds-possibly of natural origin - aimed at the synthesis of new compounds against the spread of hazardous fungi. Also high but winding are the paths leading to the definition of biological targets specifically fitting the drug's structural characteristics. The present study is addressed to inspect differential biological behaviours of cinnamaldehyde and benzaldehyde thiosemicarbazone scaffolds, exploiting the secondary metabolism of the mycotoxigenic phytopathogen Aspergillus flavus. Interestingly, owing to modifications on the parent chemical scaffold, some thiosemicarbazones displayed an increased specificity against one or more developmental processes (conidia germination, aflatoxin biosynthesis, sclerotia production) of A. flavus biology. Through the comparative analysis of results, the ligand-based screening strategy here described has allowed us to delineate which modifications are more promising for distinct purposes: from the control of mycotoxins contamination in food and feed commodities, to the environmental management of microbial pathogens, to the investigation of specific structure-activity features for new generation drug discovery.