Computational Study Into the Oxidative Ring-Closure Mechanism During the Biosynthesis of Deoxypodophyllotoxin.

The nonheme iron dioxygenase deoxypodophyllotoxin synthase performs an oxidative ring-closure reaction as part of natural product synthesis in plants. How the enzyme enables the oxidative ring-closure reaction of (-)-yatein and avoids substrate hydroxylation remains unknown. To gain insight into the reaction mechanism and understand the details of the pathways leading to products and by-products we performed a comprehensive computational study. The work shows that substrate is bound tightly into the substrate binding pocket with the C7'-H bond closest to the iron(IV)-oxo species. The reaction proceeds through a radical mechanism starting with hydrogen atom abstraction from the C7'-H position followed by ring-closure and a final hydrogen transfer to form iron(II)-water and deoxypodophyllotoxin. Alternative mechanisms including substrate hydroxylation and an electron transfer pathway were explored but found to be higher in energy. The mechanism is guided by electrostatic perturbations of charged residues in the second-coordination sphere that prevent alternative pathways.

Deoxypodophyllotoxin Induces ROS-Mediated Apoptosis by Modulating the PI3K/AKT and p38 MAPK-Dependent Signaling in Oral Squamous Cell Carcinoma.

Deoxypodophyllotoxin (DPT), a naturally occurring flavonolignan, possesses several pharmacological properties, including anticancer property. However, the mechanisms underlying DPT mode of action in oral squamous cell carcinoma (OSCC) remain unknown. This study aimed to investigate the anticancer effects of DPT on OSCC and the underlying mechanisms. Results of the MTT assay revealed that DPT significantly reduced the cell viability in a time- and dose-dependent manner. Flow cytometry analysis revealed that DPT induces apoptosis in OSCC cells in a dose-dependent manner. Moreover, DPT enhanced the production of mitochondrial reactive oxygen species (ROS) in OSCC cells. Mechanistically, DPT induced apoptosis in OSCC cells by suppressing the PI3K/AKT signaling pathway while activating the p38 MAPK signaling to regulate the expression of apoptotic proteins. Treatment with SC79, an AKT activator, reversed the effects of DPT on AKT signaling in OSCC cells. Taken together, these results provide the basis for the use of DPT in combination with conventional chemotherapy for the treatment of oral cancer.

A comprehensive insight into the antineoplastic activities and molecular mechanisms of deoxypodophyllotoxin: Recent trends, challenges, and future outlook.

Lignans constitute an important group of polyphenols, which have been demonstrated to potently suppress cancer cell proliferation. Numerous in vitro and in vivo studies indicate that deoxypodophyllotoxin as a natural lignan possesses potent anticancer activities against various types of human cancer. The purpose of current review is to provide the reader with the latest findings in understanding the anticancer effects and molecular mechanisms of deoxypodophyllotoxin. This review comprehensively describes the influence of deoxypodophyllotoxin on signaling cascades and molecular targets implicated in cancer cell proliferation and invasion. A number of various signaling molecules and pathways, including apoptosis, necroptosis, cell cycle, angiogenesis, vascular disruption, ROS, MMPs, glycolysis, and microtubules as well as NF-κB, PI3K/Akt/mTOR, and MAPK cascades have been reported to be responsible for the anticancer activities of deoxypodophyllotoxin. The results of present review suggest that the cyclolignan deoxypodophyllotoxin can be developed as a novel and potent anticancer agent, especially as an alternative option for treatment of resistant tumors to chemotherapy.

Mechanistic analysis of carbon-carbon bond formation by deoxypodophyllotoxin synthase.

Deoxypodophyllotoxin contains a core of four fused rings (A to D) with three consecutive chiral centers, the last being created by the attachment of a peripheral trimethoxyphenyl ring (E) to ring C. Previous studies have suggested that the iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, deoxypodophyllotoxin synthase (DPS), catalyzes the oxidative coupling of ring B and ring E to form ring C and complete the tetracyclic core. Despite recent efforts to deploy DPS in the preparation of deoxypodophyllotoxin analogs, the mechanism underlying the regio- and stereoselectivity of this cyclization event has not been elucidated. Herein, we report 1) two structures of DPS in complex with 2OG and (±)-yatein, 2) in vitro analysis of enzymatic reactivity with substrate analogs, and 3) model reactions addressing DPS's catalytic mechanism. The results disfavor a prior proposal of on-pathway benzylic hydroxylation. Rather, the DPS-catalyzed cyclization likely proceeds by hydrogen atom abstraction from C7', oxidation of the benzylic radical to a carbocation, Friedel-Crafts-like ring closure, and rearomatization of ring B by C6 deprotonation. This mechanism adds to the known pathways for transformation of the carbon-centered radical in Fe/2OG enzymes and suggests what types of substrate modification are likely tolerable in DPS-catalyzed production of deoxypodophyllotoxin analogs.

Gamma-Aminobutyric Acid (GABA) Promotes Growth in Zebrafish Larvae by Inducing IGF-1 Expression via GABAA and GABAB Receptors.

Insulin-like growth factor-1 (IGF-1) primarily increases the release of gamma-aminobutyric acid (GABA) in neurons; moreover, it is responsible for the promotion of longitudinal growth in children and adolescents. Therefore, in this study, we investigated whether exogenous GABA supplementation activates IGF-mediated growth performance. Zebrafish larvae treated with GABA at three days post fertilization (dpf) showed a significant increase in the total body length from 6 to 12 dpf through upregulation of growth-stimulating genes, including IGF-1, growth hormone-1 (GH-1), growth hormone receptor-1 (GHR-1), and cholecystokinin A (CCKA). In particular, at 9 dpf, GABA increased total body length from 3.60 ± 0.02 to 3.79 ± 0.03, 3.89 ± 0.02, and 3.92 ± 0.04 mm at concentrations of 6.25, 12.5, and 25 mM, and the effect of GABA at 25 mM was comparable to 4 mM ß-glycerophosphate (GP)-treated larvae (3.98 ± 0.02 mm). Additionally, the highest concentration of GABA (50 mM) -induced death in 50% zebrafish larvae at 12 dpf. GABA also enhanced IGF-1 expression and secretion in preosteoblast MC3T3-E1 cells, concomitant with high levels of the IGF-1 receptor gene (IGF-1R). In zebrafish larvae, the GABA-induced growth rate was remarkably decreased in the presence of an IGF-1R inhibitor, picropodophyllin (PPP), which indicates that GABA-induced IGF-1 enhances growth rate via IGF-1R. Furthermore, we investigated the effect of GABA receptors on growth performance along with IGF-1 activation. Inhibitors of GABAA and GABAB receptors, namely bicuculline and CGP 46381, respectively, considerably inhibited GABA-induced growth rate in zebrafish larvae accompanied by a marked decrease in the expression of growth-stimulating genes, including IGF-1, GH-1, GHR-1, and CCKA, but not with an inhibitor of GABAC receptor, TPMPA. Additionally, IGF-1 and IGF-1R expression was impaired in bicuculline and CGP 46381-treated MC3T3-E1 cells, but not in the cells treated with TPMPA. Furthermore, treatment with bicuculline and CGP 46381 significantly downregulated GABA-induced IGF-1 release in MC3T3-E1 cells. These data indicate that GABA stimulates IGF-1 release via GABAA and GABAB receptors and leads to growth promotion performance via IGF-1R.

Synthesis of (-)-deoxypodophyllotoxin and (-)-epipodophyllotoxin via a multi-enzyme cascade in E. coli.

BACKGROUND: The aryltetralin lignan (-)-podophyllotoxin is a potent antiviral and anti-neoplastic compound that is mainly found in Podophyllum plant species. Over the years, the commercial demand for this compound rose notably because of the high clinical importance of its semi-synthetic chemotherapeutic derivatives etoposide and teniposide. To satisfy this demand, (-)-podophyllotoxin is conventionally isolated from the roots and rhizomes of Sinopodophyllum hexandrum, which can only grow in few regions and is now endangered by overexploitation and environmental damage. For these reasons, targeting the biosynthesis of (-)-podophyllotoxin precursors or analogues is fundamental for the development of novel, more sustainable supply routes. RESULTS: We recently established a four-step multi-enzyme cascade to convert (+)-pinoresinol into (-)-matairesinol in E. coli. Herein, a five-step multi-enzyme biotransformation of (-)-matairesinol to (-)-deoxypodophyllotoxin was proven effective with 98 % yield at a concentration of 78 mg/L. Furthermore, the extension of this cascade to a sixth step leading to (-)-epipodophyllotoxin was evaluated. To this end, seven enzymes were combined in the reconstituted pathway involving inter alia three plant cytochrome P450 monooxygenases, with two of them being functionally expressed in E. coli for the first time. CONCLUSIONS: Both, (-)-deoxypodophyllotoxin and (-)-epipodophyllotoxin, are direct precursors to etoposide and teniposide. Thus, the reconstitution of biosynthetic reactions of Sinopodophyllum hexandrum as an effective multi-enzyme cascade in E. coli represents a solid step forward towards a more sustainable production of these essential pharmaceuticals.

Activation of IGF-1 pathway and suppression of atrophy related genes are involved in Epimedium extract (icariin) promoted C2C12 myotube hypertrophy.

The regenerative effect of Epimedium and its major bioactive flavonoid icariin (ICA) have been documented in traditional medicine, but their effect on sarcopenia has not been evaluated. The aim of this study was to investigate the effects of Epimedium extract (EE) on skeletal muscle as represented by differentiated C2C12 cells. Here we demonstrated that EE and ICA stimulated C2C12 myotube hypertrophy by activating several, including IGF-1 signal pathways. C2C12 myotube hypertrophy was demonstrated by enlarged myotube and increased myosin heavy chains (MyHCs). In similar to IGF-1, EE/ICA activated key components of the IGF-1 signal pathway, including IGF-1 receptor. Pre-treatment with IGF-1 signal pathway specific inhibitors such as picropodophyllin, LY294002, and rapamycin attenuated EE induced myotube hypertrophy and MyHC isoform overexpression. In a different way, EE induced MHyC-S overexpression can be blocked by AMPK, but not by mTOR inhibitor. On the level of transcription, EE suppressed myostatin and MRF4 expression, but did not suppress atrogenes MAFbx and MuRF1 like IGF-1 did. Differential regulation of MyHC isoform and atrogenes is probably due to inequivalent AKT and AMPK phosphorylation induced by EE and IGF-1. These findings suggest that EE/ICA stimulates pathways partially overlapping with IGF-1 signaling pathway to promote myotube hypertrophy.

Deoxypodophyllotoxin Inhibits Cell Growth and Induces Apoptosis by Blocking EGFR and MET in Gefitinib-Resistant Non-Small Cell Lung Cancer.

As one of the major types of lung cancer, non-small cell lung cancer (NSCLC) accounts for the majority of cancer-related deaths worldwide. Treatments for NSCLC includes surgery, chemotherapy, and targeted therapy. Among the targeted therapies, resistance to inhibitors of the epidermal growth factor receptor (EGFR) is common and remains a problem to be solved. MET (hepatocyte growth factor receptor) amplification is one of the major causes of EGFR-tyrosine kinase inhibitor (TKI) resistance. Therefore, there exists a need to find new and more efficacious therapies. Deoxypodophyllotoxin (DPT) extracted from Anthriscus sylvestris roots exhibits various pharmacological activities including anti-inflammation and anti-cancer effects. In this study we sought to determine the anti-cancer effects of DPT on HCC827GR cells, which are resistant to gefitinib (EGFR-TKI) due to regulation of EGFR and MET and their related signaling pathways. To identify the direct binding of DPT to EGFR and MET, we performed pull-down, ATP-binding, and kinase assays. DPT exhibited competitive binding with ATP against the network kinases EGFR and MET and reduced their activities. Also, DPT suppressed the expression of p-EGFR and p-MET as well as their downstreat proteins p-ErbB3, p-AKT, and p-ERK. The treatment of HCC827GR cells with DPT induced high ROS generation that led to endoplasmic-reticulum stress. Accordingly, loss of mitochondrial membrane potential and apoptosis by multi-caspase activation were observed. In conclusion, these results demonstrate the apoptotic effects of DPT on HCC827GR cells and signify the potential of DPT to serve as an adjuvant anti-cancer drug by simultaneously inhibiting EGFR and MET.

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.

Deoxypodophyllotoxin, a Lignan from Anthriscus sylvestris, Induces Apoptosis and Cell Cycle Arrest by Inhibiting the EGFR Signaling Pathways in Esophageal Squamous Cell Carcinoma Cells.

Deoxypodophyllotoxin (DPT) derived from Anthriscus sylvestris (L.) Hoffm has attracted considerable interest in recent years because of its anti-inflammatory, antitumor, and antiviral activity. However, the mechanisms underlying DPT mediated antitumor activity have yet to be fully elucidated in esophageal squamous cell carcinoma (ESCC). We show here that DPT inhibited the kinase activity of epidermal growth factor receptor (EGFR) directly, as well as phosphorylation of its downstream signaling kinases, AKT, GSK-3ß, and ERK. We confirmed a direct interaction between DPT and EGFR by pull-down assay using DPT-beads. DPT treatment suppressed ESCC cell viability and colony formation in a time- and dose-dependent manner, as shown by MTT analysis and soft agar assay. DPT also down-regulated cyclin B1 and cdc2 expression to induce G2/M phase arrest of the cell cycle and upregulated p21 and p27 expression. DPT treatment of ESCC cells triggered the release of cytochrome c via loss of mitochondrial membrane potential, thereby inducing apoptosis by upregulation of related proteins. In addition, treatment of KYSE 30 and KYSE 450 cells with DPT increased endoplasmic reticulum stress, reactive oxygen species generation, and multi-caspase activation. Consequently, our results suggest that DPT has the potential to become a new anticancer therapeutic by inhibiting EGFR mediated AKT/ERK signaling pathway in ESCC.

Highly loaded deoxypodophyllotoxin nano-formulation delivered by methoxy polyethylene glycol-block-poly (D,L-lactide) micelles for efficient cancer therapy.

Cancer is a kind of malignant diseases that threatens human health and the research application of anti-tumor drug therapeutics is growingly always been focused on. Many new compounds with great anticancer activity were synthesized but cannot be hard to be developed into clinical use due to its poor water solubility. Deoxypodophyllotoxin (DPT) is just an example. We develop lyophilized Deoxypodophyllotoxin (DPT) loaded polymeric micelles using methoxy polyethylene glycol-block-Poly (D, L-lactide) (mPEG-PLA). DPT-PM freeze-dried powder was successfully prepared using optimized formulation. mPEG-PLA was added to hydration media before hydrating as cryoprotectants. The freeze-dried powder exhibited white pie-solid without collapsing, and the particle size of DPT-PM reconstituted with water was about 20-35 nm. The entrapment efficiency of the reconstituted solution was 98%, which shows no differences with the micelles before lyophilization. In-vitro cytotoxicity and cellular uptake studies showed that DPT-PM has a higher degree of cytotoxicity comparing with DPT and mPEG-PLA micelles and uptake of mPEG-PLA was concentration and time-dependent. In vivo characterization of DPT-PM was done for pharmacokinetics behaviors, antitumor activity and safety. The obtained results showed significant improvement in plasma clearance bioavailability (p <0.05) and prolonged blood circulation time comparing with DPT-HP-ß-CD. Moreover, mPEG-PLA micelles had a better degree of anti-tumor efficacy, this was due to better accumulation of mPEG-PLA in tumor cell via enhanced permeability and retention (EPR) effect. Therefore, DPT-PM has great clinical value, and can be expected to be a novel antitumor preparation.

Potential anti-neuroblastoma agents from Juniperus oblonga.

Neuroblastoma (NB) is a neuroendocrine tumor derived from neural crest cells. Approximately 90% of cases occur in children less than 5 years old. The amplification of MYCN correlates with high-risk neuroblastoma and patients with MYCN amplified showed poorer prognosis than those without MYCN amplification. In this study, three compounds isolated from Juniperus oblonga showed anti-proliferative activity against NB cell lines with and without tetracycline inducible MYCN over-expression which were identified as (-)-deoxypodophyllotoxin (1), (-)-matairesinol (2) and (+)-isocupressic acid (3). The effects of compounds 2 and 3 in NB cells included a decrease in NB cell viability and induction of apoptosis. Compound 1 was more effective in NB cells over-expressing MycN. Compound 1 also showed almost 2-fold induction of intracellular free calcium levels in M2(+) cells, which may indicate a different mechanism of action for this compound. Cytotoxicity studies against the human embryonic kidney cell (HEK-293) showed compounds 1, 2 and 3 were ineffective in the non-cancer cells at concentrations approximating their IC50 against the NB cell lines. These results may lead to safer and more effective treatment options for NB patients especially for those with high-risk NB.

Deoxypodophyllotoxin Exerts Anti-Cancer Effects on Colorectal Cancer Cells Through Induction of Apoptosis and Suppression of Tumorigenesis.

Deoxypodophyllotoxin (DPT) is a cyclolignan compound that exerts anti-cancer effects against various types of cancers. DPT induces apoptosis and inhibits the growth of breast, brain, prostate, gastric, lung, and cervical tumors. In this study, we sought to determine the effect of DPT on cell proliferation, apoptosis, motility, and tumorigenesis of three colorectal cancer (CRC) cell lines: HT29, DLD1, and Caco2. DPT inhibited the proliferation of these cells. Specifically, the compound-induced mitotic arrest in CRC cells by destabilizing microtubules and activating the mitochondrial apoptotic pathway via regulation of B-cell lymphoma 2 (Bcl-2) family proteins (increasing Bcl-2 associated X (BAX) and decreasing B-cell lymphoma-extra-large (Bcl-xL)) ultimately led to caspase-mediated apoptosis. In addition, DPT inhibited tumorigenesis in vitro, and in vivo skin xenograft experiments revealed that DPT significantly decreased tumor size and tumor weight. Taken together, our results suggest DPT to be a potent compound that is suitable for further exploration as a novel chemotherapeutic for human CRC.

Deoxypodophyllotoxin inhibits cell viability and invasion by blocking the PI3K/Akt signaling pathway in human glioblastoma cells.

Deoxypodophyllotoxin (DPT) is a natural chemical that has been demonstrated to inhibit cellular viability and motility in various cancer cell types. Although previous studies have indicated that programmed cell death and cell cycle arrest are involved in the suppression of glioma development by DPT, the underlying mechanism has not been fully explored. Different methods were used to the elucidate the mechanisms of DPT that inhibit the malignant behavior of glioma cells. Cellular viability was assessed by MTT assay. Relative protein and mRNA expression levels were detected by western blot analysis and reverse transcription­quantitative polymerase chain reaction analyses, respectively. Cell cycle distribution and the apoptosis rate were detected by flow cytometry. Hochest 33258 staining was also performed to detect apoptosis. Transwell assays without and with Matrigel were used to assess migration and invasion abilities, respectively. It was determined that DPT suppressed cellular viability by inducing cell cycle arrest at the G1/S phase by targeting the phosphatidylinositol 4,5­bisphosphate 3­kinase (PI3K)/RAC­α serine/threonine­protein kinase (Akt)­cyclin­dependent kinase inhibitor 1­cyclin­dependent kinase 2/cyclin E signaling cascades. Additionally, DPT significantly enhanced apoptosis by attenuating the PI3K/Akt­mediated suppression of Bcl­2­associated agonist of cell death expression, which was accompanied by an increased apoptosis regulator BAX/apoptosis regulator Bcl­2 ratio. Furthermore, DPT downregulated the invasiveness of glioma cells by hindering PI3K/Akt­matrix metalloproteinase (MMP)9/MMP2 signaling pathways. In conclusion, DPT effectively inhibited the expression of PI3K and downregulated PI3K/Akt­mediated signaling pathways to prevent glioblastoma progression.

Deoxypodophyllotoxin in Anthriscus sylvestris alleviates fat accumulation in the liver via AMP-activated protein kinase, impeding SREBP-1c signal.

Deoxypodophyllotoxin (DPT) is a naturally occurring flavolignan in Anthriscus sylvestris known as cow parsley or wild chervil, and has been reported to have inhibitory effects against several pathological processes including cancer, inflammation and infection. Here, we report the effects of DPT in the fatty liver induced by high fat diet in vivo as well as its regulatory mechanism related with the transcription factor for lipogenic genes such as sterol regulatory element binding protein-1c (SREBP-1c) in vitro. C57BL/6 mice were fed high fat diet for 10 weeks and also orally administrated with DPT for additional 4 weeks. 5 and 10 mg/kg of DPT decreased lipid accumulation in the liver induced by high fat diet, as indicated by histological parameters such as Oil Red O staining and hematoxylin & eosin as well as the contents of hepatic triglyceride and cholesterol. In hepatocytes, DPT inhibited the liver X receptor α-mediated SREBP-1c induction and expression of the lipogenic genes, including fatty acid synthase, acetyl-CoA carboxylase and stearoyl-CoA desaturase-1. Moreover, DPT induced AMP-activated protein kinase (AMPK) activation, which has been known to inhibit the expression of SREBP-1c in hepatocyte. Also this compound restored the dysregulation of AMPK and SREBP-1c induced by high fat diet in mice. In conclusion, we demonstrated that DPT significantly inhibited fatty liver by adjusting lipid metabolism coordinated with AMPK activation and SREBP-1c inhibition.

Optimization and characterization of deoxypodophyllotoxin loaded mPEG-PDLLA micelles by central composite design with response surface methodology.

The therapeutic application of deoxypodophyllotoxin (DPT) is limited due to its poor water solubility and stability. In the present study, the micelles assembled by the amphiphilic block copolymers (mPEG-PDLLA) were constructed to improve the solubility and safety of DPT for their in vitro and in vivo application. The central composite design was utilized to develop the optimal formulation composed of 1221.41 mg mPEG-PDLLA, the weight ratio of 1 : 4 (mPEG-PDLLA : DPT), 30 mL hydration volume and the hydration temperature at 40 °C. The results showed that the micelles exhibited uniformly spherical shape with the diameter of 20 nm. The drug-loading and entrapment efficiency of deoxypodophyllotoxin-polymeric micelles (DPT-PM) were about (20 ± 2.84)% and (98 ± 0.79)%, respectively, indicating that the mathematical models predicted well for the results. Compared to the free DPT, the cytotoxicity showed that blank micelles possessed great safety for Hela cells. In addition, the DPT loaded micelle formulation achieved stronger cytotoxicity at the concentration of 1 × 10-7 mol·L-1, which showed significant difference from free DPT (P < 0.05). In conclusion, the micelles were highly promising nano-carriers for the anti-tumor therapy with DPT.

Effect of in vitro morphogenesis on the production of podophyllotoxin derivatives in callus cultures of Linum album.

The anticancer compound podophyllotoxin and other related lignans can be produced in Linum album in vitro cultures, although their biosynthesis varies according to the degree of differentiation of the plant material. In general, L. album cell cultures do not form the same lignans as roots or other culture systems. Our aim was to explore how the lignan-producing capacity of organogenic cell masses is affected by the conditions that promote their formation and growth. Thus, L. album biomass obtained from plantlets was cultured in darkness or light, with or without the addition of plant growth regulators, and the levels of podophyllotoxin, methoxypodophyllotoxin and other related lignans were determined in each of these conditions. The organogenic capacity of the cell biomass grown in the different conditions was studied directly and also with light and scanning electronic microscopy, leading to the observation of.several somatic embryos and well-formed shoots. The main lignan produced was methoxypodophyllotoxin, whose production was clearly linked to the organogenic capacity of the cell biomass, which to a lesser extent was also the case for podophyllotoxin.

Predicting Antitumor Effect of Deoxypodophyllotoxin in NCI-H460 Tumor-Bearing Mice on the Basis of In Vitro Pharmacodynamics and a Physiologically Based Pharmacokinetic-Pharmacodynamic Model.

Antitumor evaluation in tumor-bearing mouse is time- and energy-consuming. We aimed to investigate whether in vivo antitumor efficacy could be predicted on the basis of in vitro pharmacodynamics using deoxypodophyllotoxin (DPT), an antitumor candidate in development, as a model compound. Proliferation kinetics of monolayer-cultivated NCI-H460 cells under various DPT concentrations were quantitatively investigated and expressed as calibration curves. Koch two-phase natural growth model combined with sigmoid Emax model, i.e., dM/dt = 2λ0λ1M/(λ1 + 2λ0M) - Emax C γ /(EC50γ + C γ )·M, was introduced to describe cell proliferation (M) against time under DPT treatment (C). Estimated in vitro pharmacodynamic parameters were: EC50, 8.97 nM; Emax , 0.820 day-1, and γ, 7.13. A physiologically based pharmacokinetic model including tumor compartment was introduced to predict DPT disposition in plasma, tumor tissue, and main normal tissues of NCI-H460 tumor-bearing mice following a single dose. The in vivo pharmacodynamic model and parameters were assumed the same as the in vitro ones, and linked with simulated tumor pharmacokinetic profiles by a physiologically based pharmacokinetic (PBPK) model to build a PBPK-pharmacodynamic (PBPK-PD) model. After natural growth parameters (λ0 and λ1) were estimated, the objective in this study was to predict with the PBPK-PD model the tumor growth in NCI-H460 tumor-bearing mice during multidose DPT treatment, a use of the model similar to what others have reported. In our work, the model was successfully applied to predict tumor growth in SGC-7901 tumor-bearing mice. The resulting data indicated that in vivo antitumor efficacy might be predicted on the basis of in vitro cytotoxic assays via a PBPK-PD model approach. We demonstrated that the approach is reasonable and applicable and may facilitate and accelerate anticancer candidate screening and dose regimen design in the drug discovery process.

A Promising Microtubule Inhibitor Deoxypodophyllotoxin Exhibits Better Efficacy to Multidrug-Resistant Breast Cancer than Paclitaxel via Avoiding Efflux Transport.

Multidrug resistance (MDR) is a common limitation for the clinical use of microtubule-targeting chemotherapeutic agents, and it is the main factor for poor prognoses in cancer therapy. Here, we report on deoxypodophyllotoxin (DPT), a promising microtubule inhibitor in phase 1, as a promising candidate to circumvent this obstacle. DPT remarkably suppressed tumor growth in xenograft mice bearing either paclitaxel (PTX)-sensitive MCF-7/S or acquired resistance MCF-7/Adr (MCF-7/A) cells. Also, DPT exhibited similar accumulation in both tumors, whereas PTX displayed much a lower accumulation in the resistant tumors. In vitro, DPT exhibited a much lower resistance index (0.552) than those of PTX (754.5) or etoposide (38.94) in both MCF-7/S and MCF-7/A cells. Flow cytometry analysis revealed that DPT (5 and 10 nM) caused arrest of the G2/M phase in the two cell lines, whereas PTX (up to 10 nM) had no effect on cell-cycle progression of the MCF-7/A cells. Microtubule dynamics assays revealed that DPT destabilized microtubule assembly in a different mode. Cellular pharmacokinetic assays indicated comparable intracellular and subcellular accumulations of DPT in the two cell lines but a much lower retention of PTX in the MCF-7/A cells. Additionally, transport assays revealed that DPT was not the substrate of P-glycoprotein, breast cancer resistance protein, or MDR-associated protein 2, indicating a lower occurrence rate of MDR. DPT might be a promising microtubule inhibitor for breast cancer therapy, especially for treatment of drug-resistant tumors.

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.