The ester derivatives obtained by C-ring modification of podophyllotoxin induce apoptosis and inhibited proliferation in PC-3M cells via down-regulation of PI3K/Akt signaling pathway.

Podophyllotoxin (PPT) has been reported to have many pharmacological activities, especially its anti-tumor effects. To improve the cytotoxicity and selective effect of PPT, in this study, we have designed and synthesized 20 ester derivatives by introducing Boc-amino acids or organic acids at the C-4 position of PPT. The cytotoxicity of these compounds was evaluated with PC-3M, HemECs, A549, MCF-7 and HepG2 cells. We observed that the proliferation of PC-3M cells was inhibited by all 20 ester derivatives in the largest degree, comparing to the other cell lines. Comparing to PPT (IC50 = 234.90 ± 20.7 nM), eight derivatives had better performance in inhabiting proliferation of PC-3M cells, six of them belong to Boc-amino acid ester derivatives, and the derivative named V-05 (IC50 = 1.28 ± 0.1 nM) had the strongest inhibitation effect. Changes in cell proliferation and apoptotic signaling pathways were studied by DAPI staining, colony formation assay, migration assay, flow cytometry and western blot analysis. We found that V-05 were able to inhibit PC-3M cells proliferation and migration, and induced apoptosis by downregualting p-PI3K, p-Akt and Bcl-2, and upregulating Cleaved caspase-3 and Bax. Our research provides the first insight for the application of PPT derivatives in PC-3M cells, which may offer information to the effective medicine development for human prostate cancer treatment.

Synthesis of novel potent cytotoxicy podophyllotoxin-naphthoquinone compounds via microwave-assited multicomponent domino reactions.

A series of novel podophyllotoxin-naphthoquinone compounds 5a-p were synthesized in good yields using microwave-assisted four-component reactions of 2-hydroxy-1,4-naphthoquinone, aromatic benzaldehydes, tetronic acid and ammonium acetate. All the synthesized compounds were fully characterized by spectral data and evaluated for their cytotoxicity activities against KB, HepG2, Lu1, MCF7, and non-cancerous Hek-293 cell lines. Among 16 new compounds screened, compounds 5a, 5d, 5h, and 5k displayed high potent inhibitory activities with IC50 < 40 nM against HepG2 and SK-Lu-1 cell lines, and showed lower toxicity for non-cancerous Hek-293 cell line, demonstrating the potential importance of these compounds in the development of potential anticancer agents.

Design and Synthesis of Novel Podophyllotoxins Hybrids and the Effects of Different Functional Groups on Cytotoxicity.

Development of novel anticancer therapeutic candidates is one of the key challenges in medicinal chemistry. Podophyllotoxin and its derivatives, as a potent cytotoxic agent, have been at the center of extensive chemical amendment and pharmacological investigation. Herein, a new series of podophyllotoxin-N-sulfonyl amidine hybrids (4a-4v, 5a-5f) were synthesized by a CuAAC/ring-opening procedure. All the synthesized podophyllotoxins derivatives were evaluated for in vitro cytotoxic activity against a panel of human lung (A-549) cancer cell lines. Different substituents', or functional groups' antiproliferative activities were discussed. The -CF3 group performed best (IC50: 1.65 µM) and exhibited more potent activity than etoposide. Furthermore, molecular docking and dynamics studies were also conducted for active compounds and the results were in good agreement with the observed IC50 values.

Derivatives of Deoxypodophyllotoxin Induce Apoptosis through Bcl-2/Bax Proteins Expression.

BACKGROUND: Deoxypodophyllotoxin, isolated from the Traditional Chinese Medicine Anthriscus sylvestris, is well-known because of its significant anti-tumor activity with strong toxicity in vitro and in vivo. OBJECTIVE: In this article, a series of deoxypodophyllotoxin derivatives were synthesized and their anti-tumor effectiveness was evaluated. METHODS: The anti-tumor activity of deoxypodophyllotoxin derivatives was investigated by the MTT assay method. Apoptosis percentage was measured by flow cytometer analysis using Annexin-V-FITC. RESULTS: The derivatives revealed obvious cytotoxicity in the MTT assay by decreasing the number of late cancer cells. The decrease of Bcl-2/Bax could be observed in MCF-7, HepG2, HT-29, and MG-63 using Annexin V-FITC. The ratio of Bcl-2/Bax in the administration group was decreased, which was determined by the ELISA kit. CONCLUSION: The derivatives of deoxypodophyllotoxin could induce apoptosis in tumor cell lines by influencing Bcl-2/Bax.

Synthesis and evaluation of etoposide and podophyllotoxin analogs against topoisomerase IIα and HCT-116 cells.

Etoposide is a widely-used anticancer agent that targets human type II topoisomerases. Evidence suggests that metabolism of etoposide in myeloid progenitor cells is associated with translocations involved in leukemia development. Previous studies suggest halogenation at the C-2' position of etoposide reduces metabolism. Halogens were introduced into the C-2' position by electrophilic aromatic halogenation onto etoposide (ETOP, 1), podophyllotoxin (PPT, 2), and 4-dimethylepipodophyllotoxin (DMEP, 3), and to bridge the gap of knowledge regarding the activity of these metabolically stable analogs. Five halogenated analogs (6-10) were synthesized. Analogs 8-10 displayed variable ability to inhibit DNA relaxation. Analog 9 was the only analog to show concentration-dependent enhancement of Top2-mediated DNA cleavage. Dose response assay results indicated that 8 and 10 were most effective at decreasing the viability of HCT-116 and A549 cancer cell lines in culture. Flow cytometry with 8 and 10 in HCT-116 cells provide evidence of sub-G1 cell populations indicative of apoptosis. Taken together, these results indicate C-2' halogenation of etoposide and its precursors, although metabolically stable, decreases overall activity relative to etoposide.

Synthetic dimeric-drug phospholipid: a versatile liposomal platform for cancer therapy.

An amphiphilic dimeric-podophyllotoxin (PODO) phospholipid was synthesized to assemble into liposomes as a combination of prodrug and nanocarrier. The results have demonstrated that the cell membrane-like delivery system possessed an improved cellular uptake and favorable antitumor efficacy with reduced side-effects. This strategy provides a new effective platform in drug delivery for cancer chemotherapy.

Recent advances in the chemoenzymatic synthesis of bioactive natural products.

The field of organic chemistry has recently witnessed a rapid rise in the use of chemoenzymatic strategies for the synthesis of complex molecules. Under this paradigm, biocatalytic methods and contemporary synthetic methods are used synergistically in a multistep approach toward a target molecule. In light of the unparalleled regioselectivity and stereoselectivity of enzymatic transformations and the reaction diversity of contemporary organic chemistry, chemoenzymatic strategies hold enormous potential for streamlining access to important bioactive molecules. This review covers recent demonstrations of chemoenzymatic approaches in chemical synthesis, with special emphasis on the preparation of medicinally relevant natural products.

Synthesis of d-ring modified acid hydrazide derivatives of podophyllotoxin and their anticancer studies as Tubulin inhibiting agents.

A new series (except compound 3a) of d-ring modified acid hydrazides of podophyllotoxin were synthesized by cleaving of its d-ring with various hydrazines. Furthermore, the synthesized compounds were screened for their anticancer activity against human tumor cell lines i.e., MCF-7, HeLa and A-549 and among the synthesized compounds 3c and 3f have shown significant anticancer activity almost similar to that of standard drug etoposide. Molecular modelling studies were also conducted for active compounds and found that the free energies obtained were in good agreement with the observed IC50 values.

Design and synthesis of 4ß-Acetamidobenzofuranone-podophyllotoxin hybrids and their anti-cancer evaluation.

A new series of amide derivatives of 4ß-Acetamidobenzofuranone-podophyllotoxin hybrids (14a-g) were synthesized and their chemical structures were confirmed by 1H, 13C NMR and mass spectral data. Further, all the synthesized Acetamidobenzofuranone-podophyllotoxin hybrids were evaluated for in vitro cytotoxic activity against a panel of four human cancer cell lines i.e., human breast (MCF-7, MDA MB-231), lung (A549), and prostrate (DU-145). Among benzofuranone-podophyllotoxin hybrid compounds, 14b and 14e were exhibited more potent activity than standard drug and 14c and 14f were showed anticancer activity equivalent to etoposide.

[Synthesis and antitumor activity of novel indole podophyllotoxin derivatives].

According to drug design flattening principle,a series of novel indole podophyllotoxin derivatives which were introduced different indole substituents in C-4 position on the basis of podophyllotoxin nucleus were synthesized with the starting material podophyllotoxin and 1 H-indole-5-carboxylic acid. Its anti-tumor activity in vitro was tested in order to screen for high-efficiency and low-toxic compounds. Six target compounds were synthesized,and were confirmed by~1 H-NMR,~(13)C-NMR,HR-ESI-MS and melting point determination analysis. All these target compounds were not reported by previous literature. Using etoposide as positive control drug,all the target compounds were screened for cytotoxicity against He La cells,K562 cells and K562/A02 cell in vitro by MTT method. The antitumor activity screening results showed that compounds 4 b,4 e,4 f exhibited higher inhibitory rate against He La cells and K562 cells than those of control drug VP-16. This route has the advantages on simple operation and reasonable design,provides some practical reference value for the further development on the structure modification of podophyllotoxin and study on anti-tumor activity.

Novel hybrids of podophyllotoxin and formononetin inhibit the growth, migration and invasion of lung cancer cells.

In this study, three hybrids of podophyllotoxin and formononetin were synthesized and evaluated for anticancer efficacy. Some of the derivatives exhibited potent cytotoxicity against a panel of human and mouse cancer cell lines, with IC50 values in the low micromolar to submicromolar range. Evaluation against A549 lung tumor cell line identified that the IC50 value of compound 10a was 0.753 µM, indicating that 10a was 2.568-fold more efficacious than parent podophyllotoxin. Mechanistic studies revealed that 10a induced A549 cell apoptosis mainly via caspase pathway, as well as disrupted the microtubule organization by occupying the colchicine binding site of the tubulin. Moreover, wound healing assay and transwell invasion assay indicated that 10a displayed potent inhibitory effects on invasion and migration in A549 cancer cells. In additiona, a decrease in vimentin immunostaining was also observed in A549 cells after treatment with 10a. Overall, hybrid 10a might be a promising candidate for the potential treatment of human lung carcinoma.

Stereoselective synthesis of 4ß-acyloxypodophyllotoxin derivatives as insecticidal agents.

As our ongoing work on research of natural-product-based insecticidal agents, some 4α/ß-acyloxypodophyllotoxin derivatives were synthesized, and were evaluated against the pre-third-instar larvae of B. mori, A. dissimilis and M. separate in vivo at the concentration of 1 mg ml-1, respectively. Among all derivatives, compounds 2 g, h and 4c, d showed more promising insecticidal activities than their precursors - podophyllotoxin and epipodophyllotoxin. Furthermore, derivatives 2 g, h and 4c, d exhibited more relative amicable activities than their precursors - podophyllotoxin and epipodophyllotoxin. This results indicated that 4ß-acyloxy moiety in the podophyllotoxin derivatives was significant for obtaining the more potent compounds.

Synthesis and anticancer activity of dimeric podophyllotoxin derivatives.

BACKGROUND: Podophyllotoxin is a potent cytotoxic agent and serves as a useful lead compound for the development of antitumor drugs. Several podophyllotoxin-derived antitumor agents, including etoposide, are currently in clinical use; however, their therapeutic efficacy is often limited due to side effects and the development of resistance by cancer cells. Previous studies have shown that 4ß-1,2,3-triazole derivatives of podophyllotoxin exhibit more potent anticancer activity and better binding to topoisomerase-II than etoposide. The effect of dimerization of such derivatives on the anticancer activity has not been studied. METHODS: Two moieties of podophyllotoxin were linked at the C-4 position via 1,2,3-triazole rings to give a series of novel dimeric podophyllotoxin derivatives. 4ß-Azido-substituted podophyllotoxin derivatives (23 and 24) were coupled with various dipropargyl functionalized linkers by utilizing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to provide dimeric products in very good yield. The in vitro anticancer activity of the synthesized compounds was evaluated by MTT assay against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, and SW480). The normal BEAS-2B (lung) cell line was also included for study in order to evaluate the cancer selectivity of the most active compound as compared with normal cells. RESULTS: A group of 16 dimeric podophyllotoxin derivatives with different linkers were synthesized and structurally characterized. Most compounds do not show significant cytotoxicity (IC50 > 40 mM) against all five cancer cell lines. However, one compound (29) which bears a perbutyrylated glucose residue on the glycerol linker is highly potent against all five cancer cell lines tested, with IC50 values ranging from 0.43 to 3.50 µM. This compound (29) also shows good selectivity towards cancer cell lines as compared with the normal BEAS-2B (lung) cell line, showing selectivity indexes from 4.4 to 35.7. CONCLUSION: The anticancer activity of dimeric podophyllotoxin derivatives is generally speaking not improved as compared to their monomeric counterparts, and the potency of these dimeric derivatives can be largely affected by the nature of the linker between the two moieties. Among the synthesized derivatives, compound 29 is significantly more cytotoxic and selective towards cancer cells than etoposide and cisplatin, which are currently in clinical use. Compound 29 is a promising anticancer drug and needs further studies.

Novel Podophyllotoxin Derivatives as Potential Tubulin Inhibitors: Design, Synthesis, and Antiproliferative Activity Evaluation.

A number of podophyllotoxin derivatives (3A-3J) had been designed and synthesized, and their biological activities were evaluated in this study. Moreover, the antiproliferation activities of these compounds against four human cancer cell lines (HepG2, HeLa, A549, and MCF-7) were also tested. The results indicated that the most promising compound 3D displayed potent inhibitory activity over the four human cancer cell lines and was further demonstrated to have potent tubulin polymerization inhibitory effects without damaging the non-cancer cells. Additionally, 3D was verified to effectively interfere with tubulin and could prevent the mitosis of cancer cells, leading to cell cycle arrest and eventually inducing apoptosis in a dose- and time-dependent manner. Moreover, the Western blotting and siRNA results showed that Bcl-2 was downregulated in HepG2 cells treated with 3D. Finally, the molecular docking simulation results revealed that 3D could fit well in the colchicine-binding pocket. Taken together, this study has provided certain novel antitubulin agents for possible cancer chemotherapy.

Synthesis and biological evaluation of benzo[b]furo[3,4-e][1,4]diazepin-1-one derivatives as anti-cancer agents.

A new series of novel Podophyllotoxin-like benzo[b]furo[3,4-e][1,4]diazepin-1-ones possessing structural elements of 4-aza-2,3-didehydropodophyllotoxins with central diazepine ring was designed and synthesized as anti-cancer agents. In initial assessment, the cytotoxic activity of the synthesized compounds was evaluated against three cancer cell lines including MCF-7, PC3 and B16-F10 employing the MTT assay. Some of compounds (12h, 13a, 13c and 14b) showed significant cytotoxic activity. So, we investigated the cytotoxicity of compounds 12h, 13a, 13c and 14b, along with podophyllotoxin as the reference drug in different cancer cell lines including A549, A2780, DU145, HeLa, and normal Huvec cell line. Among these four compounds, 13c showed promising antiproliferative activity against all cancer cells stronger than the other compounds and comparable to reference drug podophyllotoxin in some cancer cells. All these four compounds did not show significant cytotoxicity on normal Huvec cell line. The flow cytometry analysis of the MCF-7, PC3 and A2780 human cancer cell lines treated with 13c showed that 13c, induced apoptosis in the MCF-7, PC3 and A2780 human cancer cell lines, which is in good agreement to its cytotoxic activity as well. Compound 13c did not show significant influence on tubulin assembly and exert its cytotoxic effects via induction of apoptosis and has potent and selective cytotoxic effects in cancer cells.

Synthesis and biological evaluation of podophyllotoxin derivatives as selective antitumor agents.

To improve podophyllotoxin's cytotoxicity and selective effect, twenty-two podophyllotoxin derivatives had been designed and synthesized. The cytotoxicity of these compounds was evaluated on A549, MCF-7, HepG2 and L-02 cell lines. As a result, most of the compounds were more potent than the positive drugs Etoposide (VP-16) and Doxorubicin which were widely used in clinical for antitumor. There were no magnitude differences about these de-protected (without Boc group) podophyllotoxin amino acid derivatives' cytotoxicity between three tumor cell lines and normal hepatic L-02 cells. Interestingly, some protected (with Boc group) amino acid derivatives and some ligustrazine derivatives showed high selectivity, especially the compound 2 (sarcosine derivative with Boc group). It exhibited highly selectivity both on the cancer cells and the normal cells. The IC50 of compound 2 was 9.5 ±â€¯0.03 nM, 132.6 ±â€¯24.1 nM, 96.4 ±â€¯1.3 nM and 160.2 ±â€¯4.7 nM against A549, MCF-7, HepG2 and L-02 cells, respectively. The SI (IC50L-02/IC50A549) value of compound 2, Doxorubicin and Etoposide was 16.9, 0.2 and 0.5, respectively. Meanwhile, SI (IC50MCF-7/IC50A549) value and SI (IC50HepG2/IC50A549) value of compound 2 were 14.0 and 10.1, respectively. In summary, compound 2 showed high selectivity especially on A549 cells. Further research on cell apoptosis indicated that compound 2 could induce apoptosis of A549 cells through nuclei fragmentation and had lower toxicity to normal hepatic L-02 cells. The detection of apoptosis and cell cycle analysis indicated that compound 2 induced A549 cells apoptosis and prevented A549 cells transition from S to G2 phase while there were no obvious changes on L-02 cells. Moreover, the structure-activity relationships of these derivatives were briefly discussed.

Synthesis of novel isoxazoline-containing podophyllotoxin/2'(2',6')-(di)halogenopodophyllotoxin derivatives and their insecticidal/acaricidal activities.

In continuation of our program aimed at the development of natural product-based pesticidal agents, a series of isoxazoline-containing podophyllotoxin/2'(2',6')-(di)halogenopodophyllotoxin derivatives were prepared, and their structures were well characterized by 1H NMR, IR, optical rotation, HRMS and mp. Especially the structure of compound Ia was further confirmed by 1H-1H COSY and NOESY spectrum. Among them, two compounds showed good insecticidal and acaricidal activities against Mythimna separata and Tetranychus cinnabarinus. Their structure-activity relationships were also observed.

Synthesis and Computational Studies Demonstrate the Utility of an Intramolecular Styryl Diels-Alder Reaction and Di-t-butylhydroxytoluene Assisted [1,3]-Shift to Construct Anticancer dl-Deoxypodophyllotoxin.

Deoxypodophyllotoxin is a secondary metabolite lignan possessing potent anticancer activity with potential as a precursor for known anticancer drugs, but its use is limited by scarcity from natural sources. We here report the total synthesis of racemic deoxypodophyllotoxin in seven steps using an intramolecular styryl Diels-Alder reaction strategy uniquely suited to assemble the deoxypodophyllotoxin core. Density functional theory was used to analyze concerted, polar, and singlet-open-shell diradical reaction pathways, which identified a low-energy concerted [4 + 2] Diels-Alder pathway followed by a faster di-t-butylhydroxytoluene assisted [1,3]-formal hydrogen shift.

Design and synthesis of piperazine acetate podophyllotoxin ester derivatives targeting tubulin depolymerization as new anticancer agents.

In this paper, a series of podophyllotoxin piperazine acetate ester derivatives were synthesized and investigated due to their antiproliferation activity on different human cancer cell lines. Among the congeners, C5 manifested prominent cytotoxicity towards the cancer cells, without causing damage on the non-cancer cells through inhibiting tubulin assembly and having high selectively causing damage on the human breast (MCF-7) cell line (IC50=2.78±0.15µM). Treatments of MCF-7 cells with C5 resulted in cell cycle arrest in G2/M phase and microtubule network disruption. Moreover, regarding the expression of cell cycle relative proteins CDK1, a protein required for mitotic initiation was up-regulated. Besides, Cyclin A, Cyclin B1 and Cyclin D1 proteins were down-regulated. Meanwhile, it seems that the effect of C5 on MCF-7 cells apoptosis inducing was observed to be not obvious enough. In addition, docking analysis demonstrated that the congeners occupy the colchicine binding pocket of tubulin.

Synthesis and evaluation of biological properties of ferrocenyl-podophyllotoxin conjugates.

Three types, esters, amides and 1,2,3-triazoles, of ferrocenyl-podophyllotoxin conjugates were synthesised, and their anticancer activity was evaluated. We observed that the most potent ferrocenyl derivatives were esters. Esters 15, 16 and 17 acted in a similar way to podophyllotoxin, i.e. reduced the number of G1 phase cells and induced G2/M blockage, while esters 14 and 18 and amide 19 blocked cells in S phase in a similar manner to etoposide.