Podophyllotoxin derivatives-tubulin complex reveals a potential binding site of tubulin polymerization inhibitors in α-tubulin adjacent to colchicine site.

The colchicine site of ß-tubulin has been proven to be essential binding sites of microtubule polymerization inhibitors. Recent studies implied that GTP pocket of α-tubulin adjacent to colchicine sites is a potential binding site for developing tubulin polymerization inhibitors. However, the structural basis for which type of structural fragments was more beneficial for enhancing the affinity of α-tubulin is still unclear. Here, podophyllotoxin derivatives-tubulin complex crystals indicated that heterocyclic with the highly electronegative and small steric hindrance was conducive to change configuration and enhance the affinity of the residues in GTP pocket of α-tubulin. Triazole with lone-pairs electrons and small steric hindrance exhibited the strongest affinity for enhancing affinity of podophyllotoxin derivatives by forming two hydrogen bonds with αT5 Ser178. Pyrimidine with the secondary strong affinity could bind Asn101 to make the αH7 configuration deflection, which reduces the stability of tubulin result in its depolymerization. Conversely, 4ß-quinoline-podophyllotoxin with the weakest affinity did not interact with α-tubulin. The molecular dynamics simulation and protein thermal shift results showed that 4ß-triazole-podophyllotoxin-tubulin was the most stable mainly due to two hydrogen bonds and the higher van der Waals force. This work provided a structural basis of the potential binding sites for extending the α/ß-tubulin dual-binding sites inhibitors design strategy.

Podophyllotoxin via SIRT1/PPAR /NF-κB axis induced cardiac injury in rats based on the toxicological evidence chain (TEC) concept.

BACKGROUND: The study of cardiotoxicity of drugs has become an important part of clinical safety evaluation of drugs. It is commonly known that podophyllotoxin (PPT) and its many derivatives and congeners are broad-spectrum pharmacologically active substances. Clinical cardiotoxicity of PPT and its derivatives has been raised, basic research on the mechanism of cardiotoxicity remains insufficient. PURPOSE: In present study, our group's innovative concept of toxicological evidence chain (TEC) was applied to reveal the cardiac toxicity mechanism of PPT by targeted metabolomics, TMT-based quantitative proteomics and western blot. METHODS: The injury phenotype evidence (IPE) acquired from the toxicity manifestations, such as weight and behavior observation of Sprague-Dawley rat. The damage to rat hearts were assessed through histopathological examination and myocardial enzymes levels, which were defined as Adverse Outcomes Evidence (AOE). The damage to rat hearts was assessed through histopathological examination and myocardial enzyme levels, which were defined as evidence of adverse outcomes.Overall measurements of targeted metabolomics based on energy metabolism and TMT-based quantitative proteomics were obtained after exposure to PPT to acquire the Toxic Event Evidence (TEE). The mechanism of cardiac toxicity was speculated based on the integrated analysis of targeted metabolomics and TMT-based quantitative proteomics, which was verified by western blot. RESULTS: The results indicated that exposure to PPT could result in significant elevation of myocardial enzymes and pathological alterations in rat hearts. In addition, we found that PPT caused disorders in cardiac energy metabolism, characterized by a decrease in energy metabolism fuels. TMT-based quantitative proteomics revealed that the PPAR (Peroxisome proliferators-activated receptor) signaling pathway needs further study. It is worth noting that PPT may suppress the expression of SIRT1, subsequently inhibiting AMPK, decreasing the expression of PGC-1α, PPARα and PPARγ. This results in disorders of glucose oxidation, glycolysis and ketone body metabolism. Additionally, the increase in the expression of p-IKK and p-IκBα, leads to the nuclear translocation of NF-κB p65 from the cytosol, thus triggering inflammation. CONCLUSION: This study comprehensively evaluated cardiac toxicity of PPT and initially revealed the mechanism of cardiotoxicity,suggesting that PPT induced disorders of energy metabolism and inflammation via SIRT1/PPAR/NF-κB axis, potentially contributing to cardiac injury.

Cellular Distribution and Ultrastructural Changes in HaCaT Cells, Induced by Podophyllotoxin and Its Novel Fluorescent Derivative, Supported by the Molecular Docking Studies.

Podophyllotoxin (PPT) is an active pharmaceutical ingredient (API) with established antitumor potential. However, due to its systemic toxicity, its use is restricted to topical treatment of anogenital warts. Less toxic PPT derivatives (e.g., etoposide and teniposide) are used intravenously as anticancer agents. PPT has been exploited as a scaffold of new potential therapeutic agents; however, fewer studies have been conducted on the parent molecule than on its derivatives. We have undertaken a study of ultrastructural changes induced by PPT on HaCaT keratinocytes. We have also tracked the intracellular localization of PPT using its fluorescent derivative (PPT-FL). Moreover, we performed molecular docking of both PPT and PPT-FL to compare their affinity to various binding sites of tubulin. Using the Presto blue viability assay, we established working concentrations of PPT in HaCaT cells. Subsequently, we have used selected concentrations to determine PPT effects at the ultrastructural level. Dynamics of PPT distribution by confocal microscopy was performed using PPT-FL. Molecular docking calculations were conducted using Glide. PPT induces a time-dependent cytotoxic effect on HaCaT cells. Within 24 h, we observed the elongation of cytoplasmic processes, formation of cytoplasmic vacuoles, progressive ER stress, and shortening of the mitochondrial long axis. After 48 h, we noticed disintegration of the cell membrane, progressive vacuolization, apoptotic/necrotic vesicles, and a change in the cell nucleus's appearance. PPT-FL was detected within HaCaT cells after ~10 min of incubation and remained within cells in the following measurements. Molecular docking confirmed the formation of a stable complex between tubulin and both PPT and PPT-FL. However, it was formed at different binding sites. PPT is highly toxic to normal human keratinocytes, even at low concentrations. It promptly enters the cells, probably via endocytosis. At lower concentrations, PPT causes disruptions in both ER and mitochondria, while at higher concentrations, it leads to massive vacuolization with subsequent cell death. The novel derivative of PPT, PPT-FL, forms a stable complex with tubulin, and therefore, it is a useful tracker of intracellular PPT binding and trafficking.

Podophyllic Aldehyde, a Podophyllotoxin Derivate, Elicits Different Cell Cycle Profiles Depending on the Tumor Cell Line: A Systematic Proteomic Analysis.

When new antitumor therapy drugs are discovered, it is essential to address new target molecules from the point of view of chemical structure and to carry out efficient and systematic evaluation. In the case of natural products and derived compounds, it is of special importance to investigate chemomodulation to further explore antitumoral pharmacological activities. In this work, the compound podophyllic aldehyde, a cyclolignan derived from the chemomodulation of the natural product podophyllotoxin, has been evaluated for its viability, influence on the cell cycle, and effects on intracellular signaling. We used functional proteomics characterization for the evaluation. Compared with the FDA-approved drug etoposide (another podophyllotoxin derivative), we found interesting results regarding the cytotoxicity of podophyllic aldehyde. In addition, we were able to observe the effect of mitotic arrest in the treated cells. The use of podophyllic aldehyde resulted in increased cytotoxicity in solid tumor cell lines, compared to etoposide, and blocked the cycle more successfully than etoposide. High-throughput analysis of the deregulated proteins revealed a selective antimitotic mechanism of action of podophyllic aldehyde in the HT-29 cell line, in contrast with other solid and hematological tumor lines. Also, the apoptotic profile of podophyllic aldehyde was deciphered. The cell death mechanism is activated independently of the cell cycle profile. The results of these targeted analyses have also shown a significant response to the signaling of kinases, key proteins involved in signaling cascades for cell proliferation or metastasis. Thanks to this comprehensive analysis of podophyllic aldehyde, remarkable cytotoxic, antimitotic, and other antitumoral features have been discovered that will repurpose this compound for further chemical transformations and antitumoral analysis.

Synthesis of Novel 4-Acyloxy-2'-Bromo-6'-Chloropodophyllotoxin Derivatives Displaying Significant Insecticidal Activity Against Mythimna Separata.

In order to explore novel natural product-based insecticidal agent, two important intermediates (2 and 3) and 4-acyloxy-2'-bromo-6'-chloropodophyllotoxin derivatives (4 a-f and 5 a-f) were designed and prepared, and their structures were confirmed by 1H-NMR, 13C NMR, HRMS, ESI-MS, optical rotation and melting point (mp). The stereochemical configuration of compound 4 b was unambiguously confirmed by single-crystal X-ray diffraction. Moreover, we evaluated the insecticidal activity of target compounds 4 a-f and 5 a-f against a serious agricultural pest of Mythimna separata by using the leaf-dipping method. Among all tested compounds, compounds 4 d, 5 d and 5 f exhibited stronger insecticidal activity with a final mortality rate exceeding 60 %. Especially compound 5 d exhibited the best insecticidal activity, with a final mortality rate of 74.1 %. It has been proven that introducing bromine or chlorine atoms at the C-2', C-2' and C-6' positions of the E ring of podophyllotoxin can produce more potent compounds. In addition, the configuration of the C-4 position is important for insecticidal activity, and 4ß-configuration is optimal. This will pave the way for further design, structural modification, and development of derivatives of podophyllotoxin as insecticidal agents.

Cytotoxic Cyclolignans Obtained by the Enlargement of the Cyclolignan Skeleton of Podophyllic Aldehyde, a Selective Podophyllotoxin-Derived Cyclolignan.

Podophyllotoxin, a cyclolignan natural product, has been the object of extensive chemomodulation to obtain better chemotherapeutic agents. Among the obtained podophyllotoxin derivatives, podophyllic aldehyde showed very interesting potency and selectivity against several tumoral cell lines, so it became our lead compound for further modifications, as described in this work, oriented toward the enlargement of the cyclolignan skeleton. Thus, modifications performed at the aldehyde function included nucleophilic addition reactions and the incorporation of the aldehyde carbon into several five-membered rings, such as thiazolidinones and benzo-fused azoles. The synthesized derivatives were evaluated against several types of cancer cells, and although some compounds were cytotoxic at the nanomolar range, most of them were less potent and less selective than the parent compound podophyllic aldehyde, with the most potent being those having the lactone ring of podophyllotoxin. In silico ADME evaluation predicted good druggability for most of them. The results indicate that the γ-lactone ring is important for potency, while the α,ß-unsaturated aldehyde is necessary to induce selectivity in these cyclolignans.

PROTAC EZH2 degrader-1 overcomes the resistance of podophyllotoxin derivatives in refractory small cell lung cancer with leptomeningeal metastasis.

BACKGROUND: Leptomeningeal metastasis (LM) of small cell lung cancer (SCLC) is a highly detrimental occurrence associated with severe neurological disorders, lacking effective treatment currently. Proteolysis-targeting chimeric molecules (PROTACs) may provide new therapeutic avenues for treatment of podophyllotoxin derivatives-resistant SCLC with LM, warranting further exploration. METHODS: The SCLC cell line H128 expressing luciferase were mutated by MNNG to generate H128-Mut cell line. After subcutaneous inoculation of H128-Mut into nude mice, H128-LM and H128-BPM (brain parenchymal metastasis) cell lines were primarily cultured from LM and BPM tissues individually, and employed to in vitro drug testing. The SCLC-LM mouse model was established by inoculating H128-LM into nude mice via carotid artery and subjected to in vivo drug testing. RNA-seq and immunoblotting were conducted to uncover the molecular targets for LM. RESULTS: The SCLC-LM mouse model was successfully established, confirmed by in vivo live imaging and histological examination. The upregulated genes included EZH2, SLC44A4, VEGFA, etc. in both BPM and LM cells, while SLC44A4 was particularly upregulated in LM cells. When combined with PROTAC EZH2 degrader-1, the drug sensitivity of cisplatin, etoposide (VP16), and teniposide (VM26) for H128-LM was significantly increased in vitro. The in vivo drug trials with SCLC-LM mouse model demonstrated that PROTAC EZH2 degrader-1 plus VM26 or cisplatin/ VP16 inhibited H128-LM tumour significantly compared to VM26 or cisplatin/ VP16 alone (P < 0.01). CONCLUSION: The SCLC-LM model effectively simulates the pathophysiological process of SCLC metastasis to the leptomeninges. PROTAC EZH2 degrader-1 overcomes chemoresistance in SCLC, suggesting its potential therapeutic value for SCLC LM.

Mitocytosis Mediated by an Enzyme-Activable Mitochondrion-Disturbing Polymer-Drug Conjugate Enhances Active Penetration in Glioblastoma Therapy.

The application of nanomedicines for glioblastoma (GBM) therapy is hampered by the blood-brain barrier (BBB) and the dense glioblastoma tissue. To achieve efficient BBB crossing and deep GBM penetration, this work demonstrates a strategy of active transcellular transport of a mitochondrion-disturbing nanomedicine, pGBEMA22-b-pSSPPT9 (GBEPPT), in the GBM tissue through mitocytosis. GBEPPT is computer-aided designed and prepared by self-assembling a conjugate of an amphiphilic block polymer and a drug podophyllotoxin (PPT). When GBEPPT is delivered to the tumor site, overexpressed γ-glutamyl transpeptidase (GGT) on the brain-blood endothelial cell, or the GBM cell triggered enzymatic hydrolysis of γ-glutamylamide on GBEPPT to reverse its negative charge to positive. Positively charged GBEPPT rapidly enter into the cell and target the mitochondria. These GBEPPT disturb the homeostasis of mitochondria, inducing mitocytosis-mediated extracellular transport of GBEPPT to the neighboring cells via mitosomes. This intracellular-to-intercellular delivery cycle allows GBEPPT to penetrate deeply into the GBM parenchyma, and exert sustainable action of PPT released from GBEPPT on the tumor cells along its penetration path at the tumor site, thus improving the anti-GBM effect. The process of mitocytosis mediated by the mitochondrion-disturbing nanomedicine may offer great potential in enhancing drug penetration through malignant tissues, especially poorly permeable solid tumors.

Design, synthesis and biological evaluation of novel podophyllotoxin derivatives as tubulin-targeting anticancer agents.

CONTEXT: Podophyllotoxin (PPT) derivatives, used in cancer therapy, require development toward enhanced efficacy and reduced toxicity. OBJECTIVE: This study synthesizes PPT derivatives to assess their anticancer activities. MATERIALS AND METHODS: Compounds E1-E16 antiproliferative activity was tested against four human cancer cell lines (H446, MCF-7, HeLa, A549) and two normal cell lines (L02, BEAS-2B) using the CCK-8 assay. The effects of compound E5 on A549 cell growth were evaluated through molecular docking, in vitro assays (flow cytometry, wound healing, Transwell, colony formation, Western blot), and in vivo tests in female BALB/c nude mice treated with E5 (2 and 4 mg/kg). E5 (4 mg/kg) significantly reduced xenograft tumor growth compared to the DMSO control group. RESULTS: Among the 16 PPT derivatives tested for cytotoxicity, E5 exhibited potent effects against A549 cells (IC50: 0.35 ± 0.13 µM) and exceeded the reference drugs PPT and etoposide to inhibit the growth of xenograft tumours. E5-induced cell cycle arrest in the S and G2/M phases accelerated tubulin depolymerization and triggered apoptosis and mitochondrial depolarization while regulating the expression of apoptosis-related proteins and effectively inhibited cell migration and invasion, suggesting a potential to limit metastasis. Molecular docking showed binding of E5 to tubulin at the colchicine site and to Akt, with a consequent down-regulation of PI3K/Akt pathway proteins. DISCUSSION AND CONCLUSIONS: This research lays the groundwork for advancing cancer treatment through developing and using PPT derivatives. The encouraging results associated with E5 call for extended research and clinical validation, leading to novel and more effective cancer therapies.

Podophyllotoxin-loaded PEGylated E-selectin peptide conjugate targeted cancer site to enhance tumor inhibition and reduce side effect.

E-selectin, which is highly expressed in vascular endothelial cells near tumor and get involved in the all tumor growth steps: occurrence, proliferation and metastasis, is considered as a promise targeted protein for antitumor drug discovery. Herein, we would like to report the design, preparation and the anticancer evaluation of the peptide-PEG-podophyllotoxin conjugate(PEG-Pep-PODO), in which the short peptide (CIELLQAR) was used as the E-selectin ligand for the targeting purpose and the PEG portion the molecule got the conjugate self-assembled to form a water soluble nanoparticle. In vitro release study showed that the conjugated and entrapped PODO could be released simultaneously in the presence of GSH (highly expressed in tumor environmental conditions) and the GSH would catalyze the break of the disufur bond which linked of the PODO and the peptide-PEG portion of the conjugate. Cell adhesion test of the PEG-Pep-PODO indicated that E-selectin ligand peptide CIELLQAR could get specifically and efficiently binding to the E-selectin expressing human umbilical vein endothelial cells (HUVEC). In vitro cytotoxicity assay further revealed that PEG-Pep-PODO significantly improved the selectivity of PEG-Pep-PODO for killing the tumor cells and normal cells compared with PODO solution formulation. More importantly, the in vivo experiment demonstrated that the conjugate would accumulate of the PODO payload in tumor through targeting endothelial cells in the tumor microenvironment, which resulted in the much improved in vivo inhibition of tumor growth, intratumoral microvessel density, and decreased systemic toxicity of this nanoparticle over the free PODO. Furthermore, this water soluble conjugate greatly improved the pharmacokinetic properties of the mother molecule.

Podophyllotoxin reduces the aggressiveness of human oral squamous cell carcinoma through myeloid cell leukemia­1.

Podophyllotoxin (PPT), which is derived from the podophyllum plant, exhibits marked cytotoxic effects against cancer cells; however, the precise molecular mechanism underlying its activity against human oral squamous cell carcinoma (OSCC) has not been elucidated. In the present study, the mechanism by which PPT induced cytotoxicity in two OSCC cell lines, HSC3 and HSC4, was determined. The effects of PPT on cytotoxicity in HSC3 and HSC4 cells were analyzed using Annexin V/PI double staining, Sub­G1 analysis, soft agar assays, western blotting, and quantitative PCR. The changes in the mitochondrial membrane potential were assessed using a JC­1 assay and cytosolic and mitochondrial fractionation. A myeloid cell leukemia­1 (Mcl­1) overexpression cell lines were also established to study the role of Mcl­1 on apoptosis. The results showed that PPT inhibited the growth of the two human OSCC cell lines and induced apoptosis, which was accompanied by mitochondrial membrane depolarization. Compared with the control, PPT reduced the expression of Mcl­1 in both cell lines through a proteasome­dependent protein degradation process. Overall, these results suggested that targeting of Mcl­1 protein by PPT induced apoptosis, providing a foundation for further pre­clinical and clinical study of its value in the management of OSCC.

L-Cysteine-Modified Transfersomes for Enhanced Epidermal Delivery of Podophyllotoxin.

The purpose of this study was to evaluate L-cysteine-modified transfersomes as the topical carrier for enhanced epidermal delivery of podophyllotoxin (POD). L-cysteine-deoxycholic acid (LC-DCA) conjugate was synthesized via an amidation reaction. POD-loaded L-cysteine-modified transfersomes (POD-LCTs) were prepared via a thin membrane dispersion method and characterized for their particle size, zeta potential, morphology, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and in vitro release. Subsequently, in vitro skin permeation and retention, fluorescence distribution in the skin, hematoxylin-eosin staining and in vivo skin irritation were studied. The POD-LCTs formed spherical shapes with a particle size of 172.5 ± 67.2 nm and a zeta potential of -31.3 ± 6.7 mV. Compared with the POD-Ts, the POD-LCTs provided significantly lower drug penetration through the porcine ear skin and significantly increased the skin retention (p < 0.05). Meaningfully, unlike the extensive distribution of the POD-loaded transfersomes (POD-Ts) throughout the skin tissue, the POD-LCTs were mainly located in the epidermis. Moreover, the POD-LCTs did not induce skin irritation. Therefore, the POD-LCTs provided an enhanced epidermal delivery and might be a promising carrier for the topical delivery of POD.

Modified Podophyllotoxin Phenoxyacetamide Phenylacetate Derivatives: Tubulin/AKT1 Dual-Targeting and Potential Anticancer Agents for Human NSCLC.

Cancer is a major disease threatening human health worldwide, among which non-small-cell lung cancer (NSCLC) is the most deadly. Clinically, almost all anticancer drugs eventually fail to consistently benefit patients due to serious drug resistance. AKT is a key effector of the PI3K/AKT/mTOR pathway, which is closely related to the occurrence, development, and drug resistance of tumors. Herein, we first designed and synthesized 20 kinds of novel hybrid molecules targeting both tubulin and AKT based on a podophyllotoxin (PPT) skeleton through computer-aided drug design. By CCK8 assay, we screened the compound D1-1 (IC50 = 0.10 µM) with the strongest inhibitory activity against H1975 cells, and its activity was 100 times higher than PPT (IC50 = 12.56 µM) and 300 times higher than gefitinib (IC50 = 32.15 µM). Affinity analysis results showed that D1-1 not only retained the tubulin targeting of PPT but also showed strong AKT targeting. Subsequent pharmacological experiments showed that D1-1 significantly inhibited the proliferation and metastasis of H1975 cells and slightly induced their apoptosis by inhibiting both tubulin polymerization and the AKT pathway activation. Collectively, these data demonstrate that the novel hybrid molecule D1-1 may be an excellent lead compound for the treatment of human NSCLC as a dual inhibitor of tubulin and AKT.

Podophyllotoxin derivatives targeting tubulin: An update (2017-2022).

Numerous tubulin-targeted podophyllotoxin congeners have been designed and synthesized to overcome the poor water solubility of podophyllotoxin and improve its pharmaceutical characteristics. Understanding the interaction of tubulin with its downstream signal transduction pathways is important for insights into the role of tubulin in the anticancer action of podophyllotoxin-based conjugates. In this review, we provide a detailed account of recent advances in tubulin targeting-podophyllotoxin derivatives with a focus on their antitumor action and potential molecular signaling pathways directly involved in tubulin depolymerization. Such information will be of benefit to researchers designing and developing anticancer drugs derived from podophyllotoxin. Moreover, we also discuss the associated challenges and future opportunities in this field.

Conjugating 4ß-NH-(5-Aminoindazole)-podophyllotoxin and Galectin-1-Targeted Aptamer for Synergistic Chemo-Immunotherapy of Hepatocellular Carcinoma.

By conjugating a chemotherapeutic candidate drug 4ß-NH-(5-aminoindazole)-podophyllotoxin (ßIZP) and an immunosuppressive protein galectin-1 targeted aptamer AP74, a chemo-immunotherapy molecule (AP74-ßIZP) is developed against liver cancer. AP74-ßIZP can target galectin-1 and enrich the tumor microenvironment to improve the tumor inhibition ratio by 6.3%, higher than that of ßIZP in a HepG2 xenograft model. In safety evaluation, ßIZP cannot be released from AP74-ßIZP in normal tissues with low glutathione level. Therefore, the degrees of organs injury and myelosuppression after the treatment with AP74-ßIZP are lower than those with ßIZP. After 21 d treatment at a drug dose of 5 mg kg-1 , AP74-ßIZP does not cause weight loss in mice, while the weight is significantly reduced by 24% and 14% from oxaliplatin and ßIZP, respectively. In immune synergy, AP74-IZP enhances CD4/CD8 cell infiltration to promote the expression of cell factor (i.e., IL-2, TNF-α, and IFN-γ), which further improves the antitumor activity. The tumor inhibition ratio of AP74-ßIZP is 70.2%, which is higher than that of AP74 (35.2%) and ßIZP (48.8%). Because of the dual effects of chemotherapy and immunotherapy, AP74-ßIZP exhibits superior activity and lower toxicity. The approach developed in this work could be applicable to other chemotherapy drugs.

Discovery of Podofilox as a Potent cGAMP-STING Signaling Enhancer with Antitumor Activity.

Cyclic GMP-AMP (cGAMP) is a second messenger that activates the stimulator of interferon genes (STING) innate immune pathway to induce the expression of type I IFNs and other cytokines. Pharmacologic activation of STING is considered a potent therapeutic strategy in cancer. In this study, we used a cell-based phenotypic screen and identified podophyllotoxin (podofilox), a microtubule destabilizer, as a robust enhancer of the cGAMP-STING signaling pathway. We found that podofilox enhanced the cGAMP-mediated immune response by increasing STING-containing membrane puncta and the extent of STING oligomerization. Furthermore, podofilox changed the trafficking pattern of STING and delayed trafficking-mediated STING degradation. Importantly, the combination of cGAMP and podofilox had profound antitumor effects on mice by activating the immune response through host STING signaling. Together, these data provide insights into the regulation of cGAMP-STING pathway activation and demonstrate what we believe to be a novel approach for modulating this pathway and thereby promoting antitumor immunity.

Aryltetralin lignans from Hyptis brachiata inhibiting T lymphocyte proliferation.

Increased activation and proliferation of T lymphocytes plays an essential role in the development of chronic inflammation and autoimmune diseases. Currently used immunosuppressive drugs often do not provide long-lasting relief of symptoms and show a gradual loss of efficacy over time, and are accompanied by various side effects. Therefore, novel immunosuppressive lead substances are needed. For this purpose, an in-house library consisting of 600 extracts of plants from Panama was screened for inhibition of human T lymphocyte proliferation. As one of the hits, an ethyl acetate extract from the aerial parts of Hyptis brachiata (Lamiaceae) exhibited strong inhibitory effects. Subsequent investigation resulted in the isolation of seven aryltetralin lignans, five arylnaphthalene lignans, two flavonoids, three triterpenes, and cinnamyl cinnamate. Aryltetralin lignans inhibited T lymphocyte proliferation in a concentration-dependent manner without induction of apoptosis. No relevant inhibition was observed for the arylnaphthalene lignans, flavonoids, and triterpenes. Additional cell cycle arrest investigations revealed that isolated aryltetralin lignans potently inhibited cell division in G2/M phase similarly to podophyllotoxin. Multifluorescence panel analyses of the extract also showed weak suppressive effects on the production of IL-2 and TNF-α. Therefore, preparations made out of H. brachiata could be further explored as an interesting herbal alternative in the treatment of autoimmune diseases.

In Vitro and In Silico Biological Studies of 4-Phenyl-2-quinolone (4-PQ) Derivatives as Anticancer Agents.

Our previous study found that 2-phenyl-4-quinolone (2-PQ) derivatives are antimitotic agents, and we adopted the drug design concept of scaffold hopping to replace the 2-aromatic ring of 2-PQs with a 4-aromatic ring, representing 4-phenyl-2-quinolones (4-PQs). The 4-PQ compounds, whose structural backbones also mimic analogs of podophyllotoxin (PPT), maybe a new class of anticancer drugs with simplified PPT structures. In addition, 4-PQs are a new generation of anticancer lead compounds as apoptosis stimulators. On the other hand, previous studies showed that 4-arylcoumarin derivatives with 5-, 6-, and 7-methoxy substitutions displayed remarkable anticancer activities. Therefore, we further synthesized a series of 5-, 6-, and 7-methoxy-substituted 4-PQ derivatives (19-32) by Knorr quinoline cyclization, and examined their anticancer effectiveness. Among these 4-PQs, compound 22 demonstrated excellent antiproliferative activities against the COLO205 cell line (50% inhibitory concentration (IC50) = 0.32 µM) and H460 cell line (IC50 = 0.89 µM). Furthermore, we utilized molecular docking studies to explain the possible anticancer mechanisms of these 4-PQs by the docking mode in the colchicine-binding pocket of the tubulin receptor. Consequently, we selected the candidate compounds 19, 20, 21, 22, 25, 27, and 28 to predict their absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles. Pharmacokinetics (PKs) indicated that these 4-PQs displayed good drug-likeness and bioavailability, and had no cardiotoxic side effects or carcinogenicity, but we detected risks of drug-drug interactions and AMES toxicity (mutagenic). However, structural modifications of these 4-PQs could improve their PK properties and reduce their side effects, and their promising anticancer activities attracted our attention for further studies.

Podophyllotoxin and its derivatives: Potential anticancer agents of natural origin in cancer chemotherapy.

The use of plant secondary metabolites has gained considerable attention among clinicians in the prevention and treatment of cancer. A secondary metabolite isolated mainly from the roots and rhizomes of Podophyllum species (Berberidaceae) is aryltetralin lignan - podophyllotoxin (PTOX). The purpose of this review is to discuss the therapeutic properties of PTOX as an important anticancer compound of natural origin. The relevant information regarding the antitumor mechanisms of podophyllotoxin and its derivatives were collected and analyzed from scientific databases. The results of the analysis showed PTOX exhibits potent cytotoxic activity; however, it cannot be used in its pure form due to its toxicity and generation of many side effects. Therefore, it practically remains clinically unusable. Currently, high effort is focused on attempts to synthesize analogs of PTOX that have better properties for therapeutic use e.g. etoposide (VP-16), teniposide, etopophos. PTOX derivatives are used as anticancer drugs which are showing additional immunosuppressive, antiviral, antioxidant, hypolipemic, and anti-inflammatory effects. In this review, attention is paid to the high potential of the usefulness of in vitro cultures of P. peltatum which can be a valuable source of lignans, including PTOX. In conclusion, the preclinical pharmacological studies in vitro and in vivo confirm the anticancer and chemotherapeutic potential of PTOX and its derivatives. In the future, clinical studies on human subjects are needed to certify the antitumor effects and the anticancer mechanisms to be certified and analyzed in more detail and to validate the experimental pharmacological preclinical studies.

JNC-1043, a Novel Podophyllotoxin Derivative, Exerts Anticancer Drug and Radiosensitizer Effects in Colorectal Cancer Cells.

The objective of this study was to determine whether (5S)-5-(4-benzyloxy-3,5-dimethoxy-phenyl)-5,9-dihydro-8H-furo [3',4':6,7] naphtho [2,3-d] [1,3]dioxol-6-one (JNC-1043), which is a novel chemical derivative of ß-apopicropodophyllin, acts as a novel potential anticancer reagent and radiosensitizer in colorectal cancer (CRC) cells. Firstly, we used MTT assays to assess whether JNC-1043 could inhibit the cell proliferation of HCT116 and DLD-1 cells. The IC50 values of these cell lines were calculated as 114.5 and 157 nM, respectively, at 72 h of treatment. Using doses approximating the IC50 values, we tested whether JNC-1043 had a radiosensitizing effect in the CRC cell lines. Clonogenic assays revealed that the dose-enhancement ratios (DER) of HCT116 and DLD-1 cells were 1.53 and 1.25, respectively. Cell-counting assays showed that the combination of JNC-1043 and γ-ionizing radiation (IR) enhanced cell death. Treatment with JNC-1043 or IR alone induced cell death by 50~60%, whereas the combination of JNC-1043 and IR increased this cell death by more than 20~30%. Annexin V-propidium iodide assays showed that the combination of JNC-1043 and IR increased apoptosis by more 30~40% compared to that induced by JNC-1043 or IR alone. DCFDA- and MitoSOX-based assays revealed that mitochondrial ROS production was enhanced by the combination of JNC-1043 and IR. Finally, we found that suppression of ROS by N-acetylcysteine (NAC) blocked the apoptotic cell death induced by the combination of JNC-1043 and IR. The xenograft model also indicated that the combination of JNC-1043 and IR increased apoptotic cell death in tumor mass. These results collectively suggest that JNC-1043 acts as a radiosensitizer and exerts anticancer effects against CRC cells by promoting apoptosis mediated by mitochondrial ROS.