Discover 4β-NH-(6-aminoindole)-4-desoxy-podophyllotoxin with nanomolar-potency antitumor activity by improving the tubulin binding affinity on the basis of a potential binding site nearby colchicine domain

Comprehensive Biotechnological Strategies for Podophyllotoxin Production from Plant and Microbial Sources

Podophyllotoxin is derived from plant sources and exhibits strong anticancer activity. However, limited natural availability and environmental impacts from traditional extraction methods drive the search for alternative production approaches. This review explores diverse strategies for sustainable podophyllotoxin synthesis, including biosynthesis, semi-synthesis, and biotransformation. Biosynthetic methods involve metabolic pathway engineering in plant or microbial cells, enabling increased yields by manipulating precursor availability and gene expression. Semi-synthetic approaches modify podophyllotoxin precursors or intermediates to enhance therapeutic effects, with derivatives like etoposide and teniposide showing clinical efficacy. Biotransformation, utilising organisms such as endophytic fungi or human hepatic enzymes, enables the transformation of substrates like deoxypodophyllotoxin into podophyllotoxin or its derivatives, yielding compounds with reduced environmental impact and improved purity. The anticancer efficacy of podophyllotoxin and its derivatives stems from multiple mechanisms. These compounds disrupt cell mitosis by inhibiting microtubule assembly, impairing nucleoside transport, and blocking topoisomerase II activity, leading to DNA cleavage and cancer cell apoptosis. Podophyllotoxin and its derivatives also exhibit anti-angiogenesis and anti-metastatic effects through signalling pathway modulation. Notably, derivatives like deoxypodophyllotoxin utilise advanced delivery systems, enhancing targeted efficacy and reducing side effects. Given the varied mechanisms and growing therapeutic applications, optimising biotransformation and delivery techniques remains essential for advancing podophyllotoxin-based therapies. This comprehensive review underscores the compound's potential as a robust anticancer agent and the need for continued research to maximise its production and clinical effectiveness.

From Plant to Patient: A Historical Perspective and Review of Selected Medicinal Plants in Dermatology

Skin conditions are a common health concern faced by patients of all ages. For thousands of years, plants have been used to treat various skin conditions, including acne, vitiligo, and psoriasis, to name a few. Today, with increasing patient preference for natural therapies, modern medicine is now more than ever incorporating age-old knowledge of herbal remedies useful in treating skin conditions into modern-day treatments. This review covers various plant-derived therapeutics (polyphenon E [sincatechins], psoralen, salicylic acid, anthralin, podophyllotoxin, and Filsuvez [birch triterpenes, oleogel-S10]) that have demonstrated scientific evidence of clinical efficacy for dermatologic disorders. The discovery, composition, history of use, and current uses in dermatology are summarized for each botanical ingredient.

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

The colchicine site of β-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, 4β-quinoline-podophyllotoxin with the weakest affinity did not interact with α-tubulin. The molecular dynamics simulation and protein thermal shift results showed that 4β-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/β-tubulin dual-binding sites inhibitors design strategy.

Indole Compounds in Oncology: Therapeutic Potential and Mechanistic Insights

Cancer remains a formidable global health challenge, with current treatment modalities such as chemotherapy, radiotherapy, surgery, and targeted therapy often hindered by low efficacy and adverse side effects. The indole scaffold, a prominent heterocyclic structure, has emerged as a promising candidate in the fight against cancer. This review consolidates recent advancements in developing natural and synthetic indolyl analogs, highlighting their antiproliferative activities against various cancer types over the past five years. These analogs are categorized based on their efficacy against common cancer types, supported by biochemical assays demonstrating their antiproliferative properties. In this review, emphasis is placed on elucidating the mechanisms of action of these compounds. Given the limitations of conventional cancer therapies, developing targeted therapeutics with enhanced selectivity and reduced side effects remains a critical focus in oncological research.

An update on the development on tubulin inhibitors for the treatment of solid tumors

INTRODUCTION

Microtubules play a vital role in cancer therapeutics. They are implicated in tumorigenesis, thus inhibiting tubulin polymerization in cancer cells, and have now become a significant target for anticancer drug development. A plethora of drug molecules has been crafted to influence microtubule dynamics and presently, numerous tubulin inhibitors are being investigated. This review discusses the recently developed inhibitors including natural products, and also examines the preclinical and clinical data of some potential molecules.

AREA COVERED

The current review article summarizes the development of tubulin inhibitors while detailing their specific binding sites. It also discusses the newly designed inhibitors that may be useful in the treatment of solid tumors.

EXPERT OPINION

Microtubules play a crucial role in cellular processes, especially in cancer therapy where inhibiting tubulin polymerization holds promise. Ongoing trials signify a commitment to revolutionizing cancer treatment and exploring targeted therapies. Challenges in microtubule modulation, like resistance and off-target effects, demand focused efforts, emphasizing combination therapies and personalized treatments. Beyond microtubules, promising avenues in cancer research include immunotherapy, genomic medicine, CRISPR gene editing, liquid biopsies, AI diagnostics, and stem cell therapy, showcasing a holistic approach for future advancements.

Chemistry and Biology of Podophyllotoxins: An Update

Podophyllotoxin is an aryltetralin lignan lactone derived from different plants of Podophyllum. It consists of five rings with four chiral centers, one trans-lactone and one aryl tetrahydronaphthalene skeleton with multiple modification sites. Moreover, podophyllotoxin and its derivatives showed lots of bioactivities, including anticancer, anti-inflammatory, antiviral, and insecticidal properties. The demand for podophyllotoxin and its derivatives is rising as a result of their high efficacy. As a continuation of our previous review (Chem. Eur. J., 2017, 23, 4467-4526), herein, total synthesis, biotransformation, structural modifications, bioactivities, and structure-activity relationships of podophyllotoxin and its derivatives from 2017 to 2022 are summarized. Meanwhile, a piece of update information on the origin of new podophyllotoxin analogues from plants from 2014 to 2022 was compiled. We hope that this review will provide a reference for future high value-added applications of podophyllotoxin and its analogues in the pharmaceutical and agricultural fields.

Research status of indole-modified natural products

Indole is a heterocyclic compound formed by the fusion of a benzene ring and pyrrole ring, which has rich biological activity. Many indole-containing compounds have been sold on the market due to their excellent pharmacological activity. For example, vincristine and reserpine have been widely used in clinical practice. The diverse structures and biological activities of natural products provide abundant resources for the development of new drugs. Therefore, this review classifies natural products by structure, and summarizes the research progress of indole-containing natural product derivatives, their biological activities, structure-activity relationship and research mechanism which has been studied in the past 13 years, so as to provide a basis for the development of new drug development.

Podophyllotoxin: Recent Advances in the Development of Hybridization Strategies to Enhance Its Antitumoral Profile

Podophyllotoxin is a naturally occurring cyclolignan isolated from rhizomes of Podophyllum sp. In the clinic, it is used mainly as an antiviral; however, its antitumor activity is even more interesting. While podophyllotoxin possesses severe side effects that limit its development as an anticancer agent, nevertheless, it has become a good lead compound for the synthesis of derivatives with fewer side effects and better selectivity. Several examples, such as etoposide, highlight the potential of this natural product for chemomodulation in the search for new antitumor agents. This review focuses on the recent chemical modifications (2017-mid-2023) of the podophyllotoxin skeleton performed mainly at the C-ring (but also at the lactone D-ring and at the trimethoxyphenyl E-ring) together with their biological properties. Special emphasis is placed on hybrids or conjugates with other natural products (either primary or secondary metabolites) and other molecules (heterocycles, benzoheterocycles, synthetic drugs, and other moieties) that contribute to improved podophyllotoxin bioactivity. In fact, hybridization has been a good strategy to design podophyllotoxin derivatives with enhanced bioactivity. The way in which the two components are joined (directly or through spacers) was also considered for the organization of this review. This comprehensive perspective is presented with the aim of guiding the medicinal chemistry community in the design of new podophyllotoxin-based drugs with improved anticancer properties.

Application of Quinoline Ring in Structural Modification of Natural Products

Natural compounds are rich in pharmacological properties that are a hot topic in pharmaceutical research. The quinoline ring plays important roles in many biological processes in heterocycles. Many pharmacological compounds, including saquinavir and chloroquine, have been marketed as quinoline molecules with good anti-viral and anti-parasitic properties. Therefore, in this review, we summarize the medicinal chemistry of quinoline-modified natural product quinoline derivatives that were developed by several research teams in the past 10 years and find that these compounds have inhibitory effects on bacteria, viruses, parasites, inflammation, cancer, Alzheimer's disease, and others.

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

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

A recent antitumor story of podophyllotoxin derivatives targeting tubulin: an update (2017-2022)

So far, numerous tubulin-targeted podophyllotoxin congeners were designed and synthesized to overcome the poor water-solubility and improve the pharmaceutical characteristics. However, few studies are dedicated to exploring the interaction of tubulin with the downstream signal transduction pathways, which is important for gaining insight into the role of tubulin in the anticancer action of podophyllotoxin-based conjugates. In this review, we described a detailed account of all the advances on tubulin targeting-podophyllotoxin derivatives from 2017 and 2022 with in depth knowledge about their antitumor action and potential molecular signaling pathways directly involved in tubulin depolymerization, aiming to help researchers design and develop better anticancer drugs derived from podophyllotoxin. Moreover, we also discussed the associated challenges and future opportunities in this field. Short teaser Recent reviews summarized podophyllotoxin-based analogues, with interaction between tubulin and signal pathways being rarely involved. This review comprehensively sum up how podophyllotoxin derivatives targeting tubulin exert their antitumor action via potential molecular signaling pathways.

An update on the recent advances and discovery of novel tubulin colchicine binding inhibitors

Microtubules, formed by α- and β-tubulin heterodimer, are considered as a major target to prevent the proliferation of tumor cells. Microtubule-targeted agents have become increasingly effective anticancer drugs. However, due to the relatively sophisticated chemical structure of taxane and vinblastine, their application has faced numerous obstacles. Conversely, the structure of colchicine binding site inhibitors (CBSIs) is much easier to be modified. Moreover, CBSIs have strong antiproliferative effect on multidrug-resistant tumor cells and have become the mainstream research orientation of microtubule-targeted agents. This review focuses mainly on the recent advances of CBSIs during 2017-2022, attempts to depict their biological activities to analyze the structure-activity relationships and offers new perspectives for designing next generation of novel CBSIs.

Natural compounds targeting glycolysis as promising therapeutics for gastric cancer: A review

Gastric cancer, a common malignant disease, seriously endangers human health and life. The high mortality rate due to gastric cancer can be attributed to a lack of effective therapeutic drugs. Cancer cells utilize the glycolytic pathway to produce energy even under aerobic conditions, commonly referred to as the Warburg effect, which is a characteristic of gastric cancer. The identification of new targets based on the glycolytic pathway for the treatment of gastric cancer is a viable option, and accumulating evidence has shown that phytochemicals have extensive anti-glycolytic properties. We reviewed the effects and mechanisms of action of phytochemicals on aerobic glycolysis in gastric cancer cells. Phytochemicals can effectively inhibit aerobic glycolysis in gastric cancer cells, suppress cell proliferation and migration, and promote apoptosis, via the PI3K/Akt, c-Myc, p53, and other signaling pathways. These pathways affect the expressions of HIF-1α, HK2, LDH, and other glycolysis-related proteins. This review further assesses the potential of using plant-derived compounds for the treatment of gastric cancer and sheds insight into the development of new drugs.

Self-Assembly of Podophyllotoxin-Loaded Lipid Bilayer Nanoparticles for Highly Effective Chemotherapy and Immunotherapy via Downregulation of Programmed Cell Death Ligand 1 Production

Low drug delivery efficiency elevates the cost of medication, lowers the therapeutic efficacy, and appears as a leading reason for unmet needs in anticancer therapies. Herein, we report the development of self-assembled podophyllotoxin-loaded lipid bilayer nanoparticles that inhibit the production of programmed cell death ligand 1 in lung cancer cells and promote tumor-specific immune responses, thus offering a strategy for regulating the immunosuppressive microenvironment of tumors. In addition, encapsulation of podophyllotoxin in the nanoparticles reduced its systemic toxicity, enhanced its penetration into tumors, and increased its antitumor efficacy. Systemic injection of the nanoparticles into tumor-bearing mice not only prevented tumor immune escape but also significantly inhibited tumor growth and extended survival. In general, the podophyllotoxin-loaded nanoparticles exhibited both immunological effects and antitumor effects in addition to having better targeting activity and fewer side effects than free podophyllotoxin. We expect our findings to facilitate the development of therapies for lung cancer.

Indole derivatives as tubulin polymerization inhibitors for the development of promising anticancer agents

The α- and β-tubulins are the major polypeptide components of microtubules (MTs), which are attractive targets for anticancer drug development. Indole derivatives display a variety of biological activities including antitumor activity. In recent years, a great number of indole derivatives as tubulin polymerization inhibitors have sprung up, which encourages medicinal chemists to pursue promising inhibitors with improved antitumor activities, excellent physicochemical, pharmacokinetic and pharmacodynamic properties. In this review, the recent progress from 2010 to present in the development of indole derivatives as tubulin polymerization inhibitors was summarized and reviewed, which would provide useful clues and inspirations for further design of outstanding tubulin polymerization inhibitors.

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.

Podofilox suppresses gastric cancer cell proliferation by regulating cell cycle arrest and the c-Myc/ATG10 axis

Gastric cancer (GC) is a malignancy for which effective therapeutic drugs are limited. Podofilox exhibits antitumor effects in various types of cancer; however, whether it may inhibit GC growth remains unknown. The aim of the present study was to investigate the role of podofilox in GC. Cell Counting Kit-8, colony formation and cell cycle assays were used to detect the role of podofilox on cellular proliferation and the cell cycle, respectively. A microarray was used to detect the transcriptional changes induced by podofilox in GC cells. The results of the present study demonstrated that podofilox inhibited GC cell proliferation and colony formation. The half maximal inhibitory concentration of podofilox in AGS and HGC-27 cells was 2.327 and 1.981 nM, respectively. In addition, treatment with podofilox induced G₀/G₁ cell cycle arrest. Molecular analysis based on microarray data demonstrated that podofilox altered the expression levels of genes involved in the cell cycle, c-Myc and p53 signaling. Autophagy-related 10 (ATG10), which was highly expressed in GC tissues, was also downregulated by podofilox, as demonstrated by the results of the microarray analysis and immunoblotting. To determine the involvement of ATG10 in GC, ATG10 was knocked down in GC cells by small interfering RNA, which suppressed the proliferation and colony formation of GC cells compared with those observed in the control-transfected cells. Taken together, the results of the present study suggested that podofilox may inhibit GC cell proliferation by preventing the cell cycle progression and regulating the c-Myc/ATG10 signaling pathway.

Insight Into the Molecular Mechanism of Podophyllotoxin Derivatives as Anticancer Drugs

Podophyllotoxin (PTOX) is a biologically active compound derived from the podophyllum plant, and both it and its derivatives possess excellent antitumor activity. The PTOX derivatives etoposide (VP-16) and teniposide (VM-26) have been approved by the U.S. Food and Drug Administration (FDA) for cancer treatment, but are far from perfect. Hence, numerous PTOX derivatives have been developed to address the major limitations of PTOX, such as systemic toxicity, drug resistance, and low bioavailability. Regarding their anticancer mechanism, extensive studies have revealed that PTOX derivatives can induce cell cycle G2/M arrest and DNA/RNA breaks by targeting tubulin and topoisomerase II, respectively. However, few studies are dedicated to exploring the interactions between PTOX derivatives and downstream cancer-related signaling pathways, which is reasonably important for gaining insight into the role of PTOX. This review provides a comprehensive analysis of the role of PTOX derivatives in the biological behavior of tumors and potential molecular signaling pathways, aiming to help researchers design and develop better PTOX derivatives.

Indole Alkaloids, Synthetic Dimers and Hybrids with Potential In Vivo Anticancer Activity

Indole, a heterocyclic organic compound, is one of the most promising heterocycles found in natural and synthetic sources since its derivatives possess fascinating structural diversity and various therapeutic properties. Indole alkaloids, synthetic dimers and hybrids could act on diverse targets in cancer cells, and consequently, possess potential antiproliferative effects on various cancers both in vitro and in vivo. Vinblastine, midostaurin, and anlotinib as the representative of indole alkaloids, synthetic dimers and hybrids respectively, have already been clinically applied to treat many types of cancers, demonstrating indole alkaloids, synthetic dimers and hybrids are useful scaffolds for the development of novel anticancer agents. Covering articles published between 2010 and 2020, this review emphasizes the recent development of indole alkaloids, synthetic dimers and hybrids with potential in vivo therapeutic application for cancers.

The Anticancer Activity of Indazole Compounds: A Mini Review

The incidence and mortality of cancer continue to grow since the current medical treatments often fail to produce a complete and durable tumor response and ultimately give rise to therapy resistance and tumor relapse. Heterocycles with potential therapeutic values are of great pharmacological importance, and among them, indazole moiety is a privileged structure in medicinal chemistry. Indazole compounds possess potential anticancer activity, and indazole-based agents such as, axitinib, lonidamine and pazopanib have already been employed for cancer therapy, demonstrating indazole compounds as useful templates for the development of novel anticancer agents. The aim of this review is to present the main aspects of exploring anticancer properties, such as the structural modifications, the structure-activity relationship and mechanisms of action, making an effort to highlight the importance and therapeutic potential of the indazole compounds in the present anticancer agents.

Novel podophyllotoxin and benzothiazole derivative induces transitional morphological and functional changes in HaCaT cells

Podophyllotoxin (PPT) is an antimitotic drug used topically in the treatment of anogenital warts. Due to its toxicity it cannot be administered systemically as an anticancer agent. However, modified PPT derivatives such as etoposide and teniposide are used clinically as systemic agents. Thus, we invented novel PPT derivative KL3 that was synthesized by photocyclization. Earlier we have shown that KL3 has an anticancer effect in various cell lines. Here we compared the toxicity of KL3 vs PPT on non-cancerous normal human keratinocytes (HaCaT) and peripheral blood mononuclear cells (PBMC) showing that KL3 is less toxic than PPT to non-cancerous cells. At concentrations that neither induced cell death, nor affected cell cycle, KL3 in HaCaT cells evoked transient ultrastructural features of ER stress, swelling of mitochondria and elongation of cytoplasmic processes. Those changes partially reversed with prolonged incubation while features of autophagy were induced. PPT in equivalent concentrations induced HaCaT cell death by cell cycle arrest, intrinsic apoptosis and finally disintegration of cell membranes followed by secondary necrosis. In conclusion, we show that the KL3 derivative of PPT in contrast to PPT allows repair of normal keratinocytes and triggers mechanisms that restore non-tumor cell homeostasis.

Recent advances of podophyllotoxin/epipodophyllotoxin hybrids in anticancer activity, mode of action, and structure-activity relationship: An update (2010-2020)

Podophyllotoxins and epipodophyllotoxins, possess excellent activity against both drug-sensitive and drug-resistant even multidrug-resistant cancer cells via inhibition of tubulin polymerization. Several podophyllotoxin/epipodophyllotoxin derivatives such as etoposide and teniposide have already been applied for cancer therapy, revealing their potential as putative anticancer drugs. Hybridization of podophyllotoxin/epipodophyllotoxin moiety with other anticancer pharmacophores is a promising strategy to develop novel drug candidates so as to overcome drug resistance and improve the specificity, and numerous of podophyllotoxin/epipodophyllotoxin hybrids exhibit excellent in vitro antiproliferative and in vivo anticancer potency. This review emphasizes the recent development of podophyllotoxin/epipodophyllotoxin hybrids with potential application for cancer therapy covering articles published between 2010 and 2020. The mechanisms of action, the critical aspects of design as well as structure-activity relationships were also summarized.

Challenges and potential for improving the druggability of podophyllotoxin-derived drugs in cancer chemotherapy

Covering: up to 2020As a main bioactive component of the Chinese, Indian, and American Podophyllum species, the herbal medicine, podophyllotoxin (PTOX) exhibits broad spectrum pharmacological activity, such as superior antitumor activity and against multiple viruses. PTOX derivatives (PTOXs) could arrest the cell cycle, block the transitorily generated DNA/RNA breaks, and blunt the growth-stimulation by targeting topoisomerase II, tubulin, or insulin-like growth factor 1 receptor. Since 1983, etoposide (VP-16) is being used in frontline cancer therapy against various cancer types, such as small cell lung cancer and testicular cancer. Surprisingly, VP-16 (ClinicalTrials NTC04356690) was also redeveloped to treat the cytokine storm in coronavirus disease 2019 (COVID-19) in phase II in April 2020. The treatment aims at dampening the cytokine storm and is based on etoposide in the case of central nervous system. However, the initial version of PTOX was far from perfect. Almost all podophyllotoxin derivatives, including the FDA-approved drugs VP-16 and teniposide, were seriously limited in clinical therapy due to systemic toxicity, drug resistance, and low bioavailability. To meet this challenge, scientists have devoted continuous efforts to discover new candidate drugs and have developed drug strategies. This review focuses on the current clinical treatment of PTOXs and the prospective analysis for improving druggability in the rational design of new generation PTOX-derived drugs.