Recent progress on C-4-modified podophyllotoxin analogs as potent antitumor agents

Chemotherapeutic-Induced Cardiovascular Dysfunction: Physiological Effects, Early Detection-The Role of Telomerase to Counteract Mitochondrial Defects and Oxidative Stress

Although chemotherapeutics can be highly effective at targeting malignancies, their ability to trigger cardiovascular morbidity is clinically significant. Chemotherapy can adversely affect cardiovascular physiology, resulting in the development of cardiomyopathy, heart failure and microvascular defects. Specifically, anthracyclines are known to cause an excessive buildup of free radical species and mitochondrial DNA damage (_mtDNA) that can lead to oxidative stress-induced cardiovascular apoptosis. Therefore, oncologists and cardiologists maintain a network of communication when dealing with patients during treatment in order to treat and prevent chemotherapy-induced cardiovascular damage; however, there is a need to discover more accurate biomarkers and therapeutics to combat and predict the onset of cardiovascular side effects. Telomerase, originally discovered to promote cellular proliferation, has recently emerged as a potential mechanism to counteract mitochondrial defects and restore healthy mitochondrial vascular phenotypes. This review details mechanisms currently used to assess cardiovascular damage, such as C-reactive protein (CRP) and troponin levels, while also unearthing recently researched biomarkers, including circulating _mtDNA, telomere length and telomerase activity. Further, we explore a potential role of telomerase in the mitigation of mitochondrial reactive oxygen species and maintenance of _mtDNA integrity. Telomerase activity presents a promising indicator for the early detection and treatment of chemotherapy-derived cardiac damage.

Design, synthesis and biological evaluation of novel nitric oxide-donating podophyllotoxin derivatives as potential antiproliferative agents against multi-drug resistant leukemia cells

Multidrug resistance remains a major obstacle for the effective treatment of carcinoma. To find new drugs for the chemotherapy of drug-resistant leukemia, in this study, two novel nitric oxide-donating podophyllotoxin derivatives were synthesized and preliminarily evaluated in vitro. Biological evaluation indicated that the more active molecule, S1, enhanced the intracellular NO level and significantly inhibited the proliferation of drug-resistant K562/VCR and K562/ADR cells with IC₅₀ values of 0.008 ± 0.001 and 0.007 ± 0.001 μM, respectively, which were similar to that of sensitive K562 cells. Furthermore, it was observed that S1 blocked the G2 phase of the K562/ADR cell cycle by disruption of the microtubule organization and inhibition of CDK1 and CDK2 expression. Meanwhile, S1 induced apoptosis of K562/ADR cells via mitochondrial depolarization and activation of caspase-3. In addition, S1 suppressed the P-gp expression, induced autophagy by regulation of Beclin1 and LC3-II, and inhibited the mTOR and STAT3 signaling in K562/ADR cells. Overall, S1 may be a promising candidate against drug-resistant leukemia.

Conjugate S1 exhibited potential antiproliferative activity against multi-drug resistant leukemia cells.

Colchicine prodrugs and codrugs: Chemistry and bioactivities

Antimitotic colchicine possesses low therapeutic index due to high toxicity effects in non-target cell. However, diverse colchicine analogs have been derivatized as intentions for toxicity reduction and structure-activity relationship (SAR) studying. Hybrid system of colchicine structure with nontoxic biofunctional compounds modified further affords a new entity in chemical structure with enhanced activity and selectivity. Moreover, nanocarrier formulation strategies have been used for colchicine delivery. This review paper focuses on colchicine nanoformulation, chemical synthesis of colchicine prodrugs and codrugs with different linkers, highlights linker chemical nature and biological activity of synthesized compounds. Additionally, classification of colchicine prodrugs based on type of conjugates is discussed, as biopolymers prodrugs, fluorescent prodrug, metal complexes prodrug, metal-labile prodrug and bioconjugate prodrug. Finally, we briefly summarized the biological importance of colchicine nanoformulation, colchicine prodrugs and codrugs.

Podophyllotoxin derivatives as an excellent anticancer aspirant for future chemotherapy: A key current imminent needs

Cancer is one of the leading groups of threatened caused by abnormal state cell growth and second leading diseases involved in the major global death. To treat this, research looking for promising anticancer drugs from natural resource, or synthesized novel molecules by diverse group of scientists worldwide. Currently, drugs get into clinical practices and showing side effects with target actions which in turn leading to multidrug resistance unknowingly. Podophyllotoxin, a naturally occurring lignan and with hybrids have become one of the most attractive subjects due to their broad spectrum of pharmacological activities. Podophyllotoxin derivatives have been the centre of attention of extensive chemical amendment and pharmacological investigation in modern decades. Mainly, the innovation of the semi-synthetic anticancer drugs etoposide and teniposide has stimulated prolonged research interest in this structural phenotype. The present review focuses mainly onnew anticancer drugs from podophyllotoxin analogs, mechanism of action and their structure-activity relationships (SAR) as potential anticancer candidates for future discovery of suitable drug candidates.

Tubulin inhibitors targeting the colchicine binding site: a perspective of privileged structures

The vital roles of microtubule in mitosis and cell division make it an attractive target for antitumor therapy. Colchicine binding site of tubulin is one of the most important pockets that have been focused on to design tubulin-destabilizing agents. Over the past few years, a large number of colchicine binding site inhibitors (CBSIs) have been developed inspired by natural products or synthetic origins, and many moieties frequently used in these CBSIs are structurally in common. In this review, we will classify the CBSIs into classical CBSIs and nonclassical CBSIs according to their spatial conformations and binding modes with tubulin, and highlight the privileged structures from these CBSIs in the development of tubulin inhibitors targeting the colchicine binding site.

XWL-1-48 exerts antitumor activity via targeting topoisomerase II and enhancing degradation of Mdm2 in human hepatocellular carcinoma

A novel podophyllotoxin derivative, XWL-1-48, was synthesized as an oral topoisomerase II inhibitor. kDNA decatenation assay indicated that XWL-1-48 significantly inhibited topoisomerase II activity in a concentration-dependent manner. Moreover, the cytotoxicity of XWL-1-48 is more potent than its congener GL331 and the IC₅₀ values are from 0.34 ± 0.21 to 3.54 ± 0.54 µM in 10 cancer cell lines including KBV200 cells with P-gp overexpression. Noticeably, XWL-1-48 exerted potent antitumor activity in in vitro and in vivo human hepatocellular carcinoma (HCC) model. Further studies demonstrated that treatment of XWL-1-48 induced γ-H2AX and p-ATM expression, and further triggered DNA damage response through activation of ATM-p53-p21 and ATM-Chk2-Cdc25A pathways. Targeted inhibition of ATM by siRNA attenuated the ability of XWL-1-48 on inducing DNA damage. XWL-1-48 significantly suppressed Cyclin A and p-Cdk2 (Thr160) expression, increased p-Cdk2 (Thr14), led to inactivation of Cyclin A/Cdk2 complex, arrested cell cycle at S phase. Finally, XWL-1-48 elevated the ratio of Bax/Bcl2 and induced Fas and FasL, initiated mitochondria- and death receptor-mediated apoptosis pathway. Meanwhile, XWL-1-48 evidently enhanced degradation of Mdm2, blocked PI3K/Akt/Mdm2 pathway and suppressed HCC cell survival. Thus, XWL-1-48 may be a promising orally topoisomerase II inhibitor for treatment of HCC.

Podophyllotoxin: a novel potential natural anticancer agent

OBJECTIVE

The aim of the present review is to give an overview about the role, biosynthesis, and characteristics of Podophyllotoxin (PTOX) as a potential antitumor agent with particular emphasis on key biosynthesis processes, function of related enzymes and characterization of genes encoding the enzymes.

MATERIALS AND METHODS

Google scholar, PubMed and Scopus were searched for literatures which have studied identification, characterization, fermentation and therapeutic effects of PTOX and published in English language until end of 2016.

RESULTS

PTOX is an important plant-derived natural product, has derivatives such as etoposide and teniposide, which have been used as therapies for cancers and venereal wart. PTOX structure is closely related to the aryltetralin lactone lignans that have antineoplastic and antiviral activities. Podophyllum emodi Wall. (syn. P. hexandrum) and Podophyllum peltatum L. (Berberidaceae) are the major sources of PTOX. It has been shown that ferulic acid and methylenedioxy substituted cinnamic acid are the enzymes involved in PTOX synthesis. PTOX prevents cell growth via polymerization of tubulin, leading to cell cycle arrest and suppression of the formation of the mitotic-spindles microtubules.

CONCLUSION

Several investigations have been performed in biosynthesis of PTOX such as cultivation of these plants, though they were unsuccessful. Thus, it is important to find alternative sources to satisfy the pharmaceutical demand for PTOX. Moreover, further preclinical studies are warranted to explore the molecular mechanisms of these agents in treatment of cancer and their possible potential to overcome chemoresistance of tumor cells.

Synthesis and Antiproliferative Activity of Novel All-Trans-Retinoic Acid-Podophyllotoxin Conjugate towards Human Gastric Cancer Cells

With the purpose of creating a multifunctional drug for gastric cancer treatment, a novel all-trans-retinoic acid (ATRA) conjugate with podophyllotoxin (PPT) was designed and synthesized, and its in vitro antiproliferative activity was evaluated against human gastric cancer cell lines using CCK-8 assay. The conjugate, P-A, exhibited significant anticancer activity against MKN-45 and BGC-823 cells with IC₅₀ values of 0.419 ± 0.032 and 0.202 ± 0.055 μM, respectively. Moreover, P-A efficiently triggered cell cycle arrest and induced apoptosis in MKN-45 and BGC-823 cells due to modulation of cell cycle arrest- (CDK1, CDK2, CyclinA and CyclinB1) and apoptosis- (cleaved caspase-3, -8 and -9) related proteins, respectively. Further mechanism studies revealed that P-A could increase the expression levels of RARα and RARβ, and decrease the level of RARγ in MKN-45 and BGC-823 cells. Finally, P-A inhibited the ERK1/2 and AKT signaling in the above two cancer cell lines. More importantly, the underlying mechanisms of P-A were similar to those of precursor PPT but different with the other precursor ATRA. Together, the conjugate P-A was a promising candidate for the potential treatment of human gastric cancer.

Podophyllotoxin–pterostilbene fused conjugates as potential multifunctional antineoplastic agents against human uveal melanoma cells

Conjugate B1 showed potential multifunctional antineoplastic activity against human uveal melanoma cells.

Synthesis and evaluation of biological properties of ferrocenyl–podophyllotoxin conjugates

Ferrocenyl–podophyllotoxin conjugates have been synthesised and their antiproliferative activity, influence on cell cycle, and interactions with tubulin were evaluated.

Novel Natural Product- and Privileged Scaffold-Based Tubulin Inhibitors Targeting the Colchicine Binding Site

Tubulin inhibitors are effective anticancer agents, however, there are many limitations to the use of available tubulin inhibitors in the clinic, such as multidrug resistance, severe side-effects, and generally poor bioavailability. Thus, there is a constant need to search for novel tubulin inhibitors that can overcome these limitations. Natural product and privileged structures targeting tubulin have promoted the discovery and optimization of tubulin inhibitors. This review will focus on novel tubulin inhibitors derived from natural products and privileged structures targeting the colchicine binding site on tubulin.

Cytotoxicity, Post-Treatment Recovery, and Selectivity Analysis of Naturally Occurring Podophyllotoxins from Bursera fagaroides var. fagaroides on Breast Cancer Cell Lines

Despite prevention and treatment options, breast cancer (BC) has become one of the most important issues in the present day. Therefore, the need for more specific and efficient compounds remains paramount. We evaluated four previously isolated aryltetralin lignans: 5'-demethoxy-β-peltatin-A-methylether (1), acetylpodophyllotoxin (2), 5'-demethoxydeoxypodophyllotoxin (3), and 7',8'-dehydroacetylpodophyllotoxin (4) for cytotoxicity, clonogenicity, and selectivity against three BC cell lines: MCF-7, MDA-MB-231, and BT-549, as well as the non-tumorigenic mammary epithelial cell line MCF-10A. Cytotoxicity was evaluated after 72 h of treatment, and clonogenicity was determined at 72 h post-treatment; experiments were performed using the sulforhodamine B staining assay. Selective-index (SI) was calculated by comparing pure compound IC50 values in MCF-10A cell line against the IC50 of the same compound in cancer cell lines. Structural similarities among lignans and controls (podophyllotoxin and etoposide) were analyzed using the Tanimoto coefficient (Tc). Lignans were cytotoxic against all tested cell lines (0.011-7.22 µM) and clonogenicity testing showed a dose-dependent cytocidality for all lignans (≥0.08 µg/mL); compounds 2 and 3 were more potent (14.1 and 7.6 respectively) than etoposide in BT-549 cell line, while compound 2 displayed selectivity (SI = 28.17) in BT-549 cell line. Tc values of lignans suggested a greater similarity with podophyllotoxin structure.

Potential anti-MDR agents based on the podophyllotoxin scaffold: synthesis and antiproliferative activity evaluation against chronic myeloid leukemia cells by activating MAPK signaling pathways

Compound 9k exhibited excellent cytotoxicity, induced apoptosis and G2/M cell cycle arrest, downregulated Pgp expression and up-regulated the expression of p-ERK1/2, p-JNK and p-p38 in K562/ADR cells.

Lead Phytochemicals for Anticancer Drug Development

Cancer is a serious concern at present. A large number of patients die each year due to cancer illnesses in spite of several interventions available. Development of an effective and side effects lacking anticancer therapy is the trending research direction in healthcare pharmacy. Chemical entities present in plants proved to be very potential in this regard. Bioactive phytochemicals are preferential as they pretend differentially on cancer cells only, without altering normal cells. Carcinogenesis is a complex process and includes multiple signaling events. Phytochemicals are pleiotropic in their function and target these events in multiple manners; hence they are most suitable candidate for anticancer drug development. Efforts are in progress to develop lead candidates from phytochemicals those can block or retard the growth of cancer without any side effect. Several phytochemicals manifest anticancer function in vitro and in vivo. This article deals with these lead phytomolecules with their action mechanisms on nuclear and cellular factors involved in carcinogenesis. Additionally, druggability parameters and clinical development of anticancer phytomolecules have also been discussed.

Synthesis and Evaluation of New Podophyllotoxin Derivatives with in Vitro Anticancer Activity

A series of novel podophyllotoxin derivatives were designed and synthesized. The cytotoxic activities of these compounds were tested against three tumor cell lines (HeLa, K562, and K562/A02). Most of the derivatives (IC50 = 1-20 μM) were found to have stronger cell growth inhibitory activity than positive control etoposide. Among them, 4β-N-[(E)-(5-((4-(4-nitrophenyl)-piperazin-1-yl)methyl)furan-2-yl)prop-2-en-1-amine]-4-desoxy-podophyllotoxin (9l) demonstrated significant inhibitory activity against HeLa, K562, and K562/A02 cell lines with IC50 values of 7.93, 6.42, 6.89 μM, respectively.

Podophyllotoxin derivatives: a patent review (2012 - 2014)

INTRODUCTION

Podophyllotoxin (PPT) is a naturally occurring antimitotic agent and an interesting lead in the development of anticancer agents. Its optimization led to the development of etoposide and teniposide used in combination chemotherapy with other anticancer drugs; unlike PPT these drugs act by inhibiting topoisomerases. Clinical success and toxicity issues at later stages of etoposide usage inclined researchers to develop structurally modified PPT derivatives. Some of the compounds obtained are under clinical investigations and are anticipated to reach the market.

AREAS COVERED

The present review summarizes the attempts made by researchers across the globe to find out newer anticancer agents based on the PPT structure. It brings out the outline of the inventions filed in the form of patents during the years 2012 - 2014.

EXPERT OPINION

After the successful development of etoposide and teniposide there has been considerable interest in the PPT skeleton to develop newer chemotherapeutic agents. In this regard, several PPT derivatives such as TOP53, GL331, NK611, F11782, and so on, have been developed and are undergoing clinical trials. However, its low natural abundance is a major problem in carrying out research on PPT skeleton. This issue is expected to be addressed with the development of newer synthetic strategies to access structurally modified PPTs.

Synthesis and biological evaluation of 4β-benzoxazolepodophyllotoxin hybrids as DNA topoisomerase-II targeting anticancer agents

A series of new 4β-benzoxazolepodophyllotoxin compounds (9a–j) were prepared and screened for molecular modelling and cytotoxicity against various human tumour cell lines. Cell apoptosis evaluation was performed using Hoechst staining.

The effect of molecular structure on the anticancer drug release rate from prodrug nanoparticles

The controlled release of an anticancer agent from drug nanoparticles could be successfully achieved by optimizing the chemical structure of dimeric compounds as prodrug.

A novel strategy for screening new natural products by a combination of reversed-phase liquid chromatography fractionation and 13C NMR pattern recognition: the discovery of new anti-cancer flavone dimers from Dysosma versipellis (Hance)

A new screening strategy for the discovery of new natural products by a combination of reversed-phase liquid chromatography (RPLC) and ¹³C NMR pattern recognition.

Synthesis of novel aryl dithian valeryl podophyllotoxin ester derivatives as potential antitubulin agents

L4 can cause A549 cell cycle arrest in the G2/M phase potently by disrupting tubulin polymerization.

Novel isatin derivatives of podophyllotoxin: synthesis and cytotoxic evaluation against human leukaemia cancer cells as potent anti-MDR agents

Compound8cexhibited cytotoxicity at nanomolar range; induced G2/M cell cycle arrest accompanied by apoptosis and down-regulated the levels of Pgp, MRP-1 and GST-π.

Synthesis and biological evaluation of novel fluorinated anticancer agents incorporating the indolin-2-one moiety

A series of novel fluorinated anticancer agents containing the indolin-2-one moiety were designed, synthesized and evaluated for their anticancer activities in vitro.