Podophyllotoxin: History, Recent Advances and Future Prospects

Etoposide targets 2A protease to inhibit enterovirus 71 replication

Enterovirus 71 (EV71) is a major pathogen that causes hand, foot, and mouth disease (HFMD) in infants and children. Notably, no clinically approved drugs specifically target EV71. The EV71 2A protease (2Apro), a cysteine protease produced by the virus, is essential for the virus' replication and has a significant impact on the functioning of host cells. Thus, it presents a valuable target for the discovery of antiviral medications. In this study, based on the monomers and their derivatives in the Library of Traditional Chinese Medicine (TCM), we performed virtual screening and biological experiments. We identified a derivative of a traditional herbal monomer, Etoposide, commonly isolated from the roots and rhizomes of Podophyllum spp. Etoposide inhibited replication of EV71 A, B, C, and CVA16 viruses in a concentration-dependent manner in a variety of cell lines with minimal cytotoxicity. Furthermore, both molecular dynamics simulations and site-directed mutagenesis assays revealed that Etoposide inhibited the activity of the EV71 2A protease by mainly binding to two residues, Y89 and P107. The findings indicate that Etoposide serves as a promising inhibitor of the EV71 2Apro, demonstrating strong antiviral properties and positioning itself as a formidable candidate for clinical trials against EV71.IMPORTANCEWe first used a drug screening approach focused on monomeric compounds and their derivatives from traditional Chinese medicine to identify an EV71 2Apro inhibitor-Etoposide. We then performed biological experiments to validate that Etoposide suppresses the replication of the EV71 virus in a concentration-dependent manner with minimal cytotoxicity to various cell lines. Remarkably, it shows inhibitory activity against EV71 A, B, C, and CVA16, suggesting that Etoposide may be a potential broad-spectrum inhibitor. We revealed a novel mechanism that Etoposide inhibits EV71 proliferation by targeting 2Apro, and the interactions with Y89 and P107 are of great importance. The findings suggest that Etoposide serves as a promising inhibitor of EV71 2Apro, demonstrating significant antiviral properties. It stands out as a strong candidate for broad-spectrum applications in clinical research.

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.

4'-Demethylpodophyllotoxin functions as a mechanism-driven therapy by targeting the PI3K-AKT pathway in Colorectal cancer

The treatment of colorectal cancer (CRC) poses significant challenges in terms of drug resistance and poor prognosis, necessitating the exploration of effective therapeutic strategies. In this study, high-throughput drug screening was utilized to identify Chinese herbal medicines with notable therapeutic effects on CRC. Among the compounds identified, 4'-demethylpodophyllotoxin (DOP), a derivative of podophyllotoxin, emerged as a potent anti-cancer compound. DOP exhibited time- and dose-dependent growth inhibition on CRC cell lines and tumor organoids derived from patients. RNA-seq revealed that DOP activated the PI3K-AKT pathway, leading to tumor cell apoptosis and cell cycle arrest at the G2/M phase. Additionally, DOP induced DNA damage in CRC cells. To further validate its therapeutic efficacy in CRC, the DLD1-derived xenograft model demonstrated that DOP effectively suppressed CRC growth in vivo. In conclusion, these findings highlight the significant therapeutic potential of DOP as an anti-tumor drug for treating CRC, thereby opening new avenues for investigating Podophyllotoxin derivatives in this specific field.

Insights into podophyllotoxin lactone features: New cyclolignans as potential dual tubulin-topoisomerase II inhibitors

Chemomodulation of natural cyclolignans as podophyllotoxin has been a successful approach to obtain semisynthetic bioactive derivates. One example of this approach is the FDA-approved drug etoposide for solid and hematological tumors. It differs from the antimitotic activity of the natural product in its mechanism of action, this drug being a topoisomerase II inhibitor instead of a tubulin antimitotic. Within the molecular requirements for the activity of these compounds, the trans-γ-lactone moiety presented in the parent compound has always been a feature to be explored to chemomodulate its bioactivity. In this study, we have obtained different compounds that comply with the molecular characteristics for antitubulin and antitopoisomerase II activity combined in a single molecule. Furthermore, we explored the influence of the trans-lactone moiety on the final activity, finding that the cis-lactone was also interesting in terms of bioactivity. The best values of cytotoxicity and cell cycle inhibition were obtained for a compound lacking the lactone ring, thus mimicking the podophyllic aldehyde functionalization, a selective antimitotic podophyllotoxin derivate. The analogs with cis-lactone also presented interesting cytotoxic activity. The present study illustrates the potential of the chemomodulation of natural products such as natural cyclolignan podophyllotoxin derivates for the discovery of new antitumor agents.

Promises of natural products as clinical applications for cancer

Cancer represents a substantial threat to human health and mortality, necessitating the development of novel pharmacological agents with innovative mechanisms of action. Consequently, extensive research has been directed toward discovering new anticancer compounds derived from natural sources, including plants, microbes, and marine organisms. This review offers a comprehensive analysis of natural anticancer agents that are either currently undergoing clinical trials or have been integrated into clinical practice. A comprehensive understanding of the historical origins of natural anticancer agents, alongside traditional targets for tumor treatment and the distinct characteristics of cancer, can significantly facilitate researchers in the discovery and development of innovative anticancer drugs for clinical use. Furthermore, the exploration of microbial and marine sources is currently a prominent area of focus in the clinical application and advancement of new anticancer therapies. Detailed classification and elucidation of the functions and antitumor properties of these natural products are essential. It is imperative to comprehensively summarize and comprehend the natural anticancer drugs that have been and continue to be utilized in clinical settings.

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.

Beyond Essential Oils: Diterpenes, Lignans, and Biflavonoids from Juniperus communis L. as a Source of Multi-Target Lead Compounds

Common Juniper (Juniperus communis L.) is a gymnosperm that stands out through its fleshy, spherical female cones, often termed simply "berries". The cone berries and various vegetative parts (leaves, twigs and even roots) are used in traditional phytotherapy, based on the beneficial effects exerted by a variety of secondary metabolites. While the volatile compounds of Juniperus communis are known for their aromatic properties and have been well-researched for their antimicrobial effects, this review shifts focus to non-volatile secondary metabolites-specifically diterpenes, lignans, and biflavonoids. These compounds are of significant biomedical interest due to their notable pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, and anticancer effects. The aim of this review is to offer an up-to-date account of chemical composition of Juniperus communis and related species, with a primary emphasis on the bioactivities of diterpenes, lignans, and biflavonoids. By examining recent preclinical and clinical data, this work assesses the therapeutic potential of these metabolites and their mechanisms of action, underscoring their value in developing new therapeutic options. Additionally, this review addresses the pharmacological efficacy and possible therapeutic applications of Juniperus communis in treating various human diseases, thus supporting its potential role in evidence-based phytotherapy.

Dual-aptamer-decorated reduction-activated dimeric-prodrug nanoparticles for broad-spectrum treatment of leukemia

Leukemia remains a fatal disease for most affected patients, and a simple and effective therapeutic strategy is urgently needed. Targeted delivery chemo-drugs to leukemia cells shows promise, but the diverse subtypes of leukemia make single-ligand nanomedicine often ineffective. Herein, a dual-aptamer decorated, reduction-responsive dimeric prodrug-based nanoparticle (NP), termed SXP-NPs, was developed using the two leukemia-specific aptamers Sgc8c and XQ-2d, a reduction-responsive podophyllotoxin (POD) dimeric prodrug, and DSPE-PEG2000. Because the receptors of XQ-2d (CD71) and Sgc8c (PTK7) are overexpressed in different subtypes of leukemia cells, SXP-NPs can broadly and selectively recognize these leukemia cells after intravenous administration, subsequently releasing POD in response to the intracellular high-reduction environment to kill the leukemia cells. In vitro experiments showed that these simple SXP-NPs can specifically bind to various leukemia cancer cells and kill them. In vivo experiments revealed that SXP-NPs can remarkably reduce spleen weight, decrease white blood cell counts, and extend overall survival in a preclinical leukemia animal model. The in vitro and in vivo validation demonstrated that SXP-NPs offer several advantages, including high drug-loading potential, broad-spectrum recognition of leukemia cells, reduced systemic toxicity, and enhanced therapeutic effects of the drug. Taken together, this study provides a simple and effective strategy for broad-spectrum leukemia therapy and highlights the clinical potential of SXP-NPs.

Protective effects of a novel bicyclic γ-butyrolactone compound against H2O2 or corticosterone-induced neural cell apoptosis

Oxidative stress plays a pivotal role in various neurological disorders, encompassing both neurodegenerative diseases such as Alzheimer's and Parkinson's, and mood disorders like depression. The balance between the generation of reactive oxygen species (ROS) and the cell's antioxidant defenses, when disrupted, can lead to neuronal damage and neurologic dysfunction. In this study, we focused on the pathogenic role of oxidative stress in various neurologic disease models in vitro and investigated the neuroprotective capabilities of some novel bicyclic γ-butyrolactone compounds, with particular emphasis on the compound designated as 'bd'. Our investigation leveraged the HT22 and SH-SY5Y cells to model oxidative stress induced by H2O2 or corticosterone (CORT), common triggers of neuronal damage in neurodegenerative and mood disorders. We discovered that compound bd robustly reduced ROS production and suppressed neuronal apoptosis, suggesting its potential in treating a wider array of neurological conditions influenced by oxidative stress. In conclusion, our research underscores the importance of addressing oxidative stress in the context of diverse neurological disorders. The identification of compound bd as a neuroprotective agent with potential efficacy against ROS-induced apoptosis in neural cells opens new horizons for therapeutic development, offering hope for patients suffering from neurodegenerative diseases, depression, and other stress-related neurological conditions.

Genomic characterization and identification of candidate genes for putative podophyllotoxin biosynthesis pathway in Penicillium herquei HGN12.1C

Previous studies have reported the functional role, biochemical features and synthesis pathway of podophyllotoxin (PTOX) in plants. In this study, we employed combined morphological and molecular techniques to identify an endophytic fungus and extract PTOX derivatives. Based on the analysis of ITS sequences and the phylogenetic tree, the isolate was classified as Penicillium herquei HGN12.1C, with a sequence identity of 98.58%. Morphologically, the HGN12.1C strain exhibits white colonies, short-branched mycelia and densely packed hyphae. Using PacBio sequencing at an average read depth of 195×, we obtained a high-quality genome for the HGN12.1C strain, which is 34.9 Mb in size, containing eight chromosomes, one mitochondrial genome and a GC content of 46.5%. Genome analysis revealed 10 genes potentially involved in PTOX biosynthesis. These genes include VdtD, Pinoresinollariciresinol reductase (PLR), Secoisolariciresinol dehydrogenase (SDH), CYP719A23, CYP71BE54, O-methyltransferase 1 (OMT1), O-methyltransferase 3 (OMT3), 2-ODD, CYP71CU and CYP82D61. Notably, the VdtD gene in fungi shares functional similarities with the DIR gene found in plants. Additionally, we identified peltatin, a PTOX derivative, in the HGN12.1C extract. Docking analysis suggests a potential role for the 2-ODD enzyme in converting yatein to deoxypodophyllotoxin. These findings offer invaluable insights into the synthesis mechanism of PTOX in fungi, shedding light on the relationship between host plants and endophytes.

Reversal of the tamoxifen‑resistant breast cancer malignant phenotype by proliferation inhibition with bromosulfonamidine amino‑podophyllotoxin

One of the lignans isolated from plants within the genus Podophyllum is podophyllotoxin (PPT). PPT and its derivatives are pharmacologically active compounds with potential antiproliferative properties in several kinds of tumors. Although these compounds have been used to treat other malignancies, no PPT derivative-based chemotherapeutic agent has been used to cure tamoxifen (TAM)-resistant breast cancer in clinical trials, to the best of our knowledge. Thus, using TAM-resistant breast cancer as a disease model, the present study assessed the effects of a recently synthesized PPT derivative, bromosulfonamidine amino-PPT (BSAPPT), on TAM-resistant breast cancer. Using the tamoxifen-resistant breast cancer cell model (MCF-7/TAMR) in vitro, Cell Counting Kit-8 and colony formation assays were adopted to evaluate the effect of BSAPPT on cell proliferation. Cell apoptosis and cell cycle assays were used to assess the influence of BSAPPT on cell apoptosis and the cell cycle in MCF-7/TAMR. The targets of the potential mechanism of action were analyzed by RT-qPCR and western blotting. The present study demonstrated that BSAPPT suppressed MCF-7/TAMR cell proliferation in a dose-dependent manner. By modulating the level of expression of genes linked to both apoptosis and the cell cycle, BSAPPT triggered MCF-7/TAMR cells to undergo apoptosis and prevented them from entering the cell cycle. Consequently, BSAPPT blocked these cells from proliferating, thereby halting the malignant advancement of TAM-resistant breast cancer. Therefore, these findings indicate that new therapeutic agents involving BSAPPT may be developed to facilitate the treatment of TAM-resistant breast cancer.

A natural compound-empowered podophyllotoxin prodrug nanoassembly magnifies efficacy-toxicity benefits in cancer chemotherapy

Small-molecule prodrug nanoassembly technology with a unique advantage in off-target toxicity reduction has been widely used for antitumor drug delivery. However, prodrug activation remains a rate-limiting step for exerting therapeutic actions, which requires to quickly reach the minimum valid concentrations of free drugs. Fortunately, we find that a natural compound (BL-193) selectively improves the chemotherapy sensitivity of breast cancer cells to podophyllotoxin (PPT) at ineffective dose concentrations. Based on this, we propose to combine prodrug nanoassembly with chemotherapy sensitization to fully unleash the chemotherapeutic potential of PPT. Specifically, a redox-sensitive prodrug (PSSF) of PPT is synthesized by coupling 9-fluorenyl-methanol (Fmoc-OH) with PPT linked via disulfide bond. Intriguingly, PSSF with a π-conjugated structure readily co-assembles with BL-193 into stable nanoassembly. Significantly, BL-193 serves as an excellent chemosensitizer that creates an ultra-low-dose chemotherapeutic window for PPT. Moreover, prodrug design and precise hybrid nanoassembly well manage off-target toxicity. As expected, such a BL-193-empowered prodrug nanoassembly elicits potent antitumor responses. This study offers a novel paradigm to magnify chemotherapy efficacy-toxicity benefits.

Exploring the mechanism of enterotoxicity mediated by the microbiome-butyrate-PPAR axis in podophyllotoxin through the toxicological evidence chain (TEC) concept

Podophyllotoxin (PPT) is a lignan derived from the roots and stems of the Podophyllum plant. However, its enterotoxicity restricts its clinical application. The underlying mechanisms by which PPT exerts its action remain largely elusive. This study aimed to evaluate the molecular mechanisms underlying PPT-induced enterotoxicity utilizing the concept of toxicological evidence chain. Changes in body weight, behavior, and histopathological and biochemical markers in rats were observed. Additionally, microbiome, metabolome, and transcriptome analyses were integrated to identify potential microorganisms, metabolic markers, and major pathways using a co-occurrence network. Our findings suggested that PPT induced pathological changes in rats, including weight loss, diarrhea, and inflammation accompanied by increased levels of IFN-γ, IL-5, IL-6, GRO/KC, and IL-12p70. The decrease in butyrate levels in the PPT group may be related to the enrichment of Firmicutes. The reduction of butyrate levels may impair the expression of PPARγ, subsequently promoting Escherichia-Shigella proliferation. Additionally, the suppression of PPARs pathway may result in the increased production of inflammatory factors, contributing to enterotoxicity. This study offers a novel understanding of the molecular mechanisms underlying PPT-induced enterotoxicity, making a significant contribution to developing strategies to mitigate PPT toxicity and prevent associated diseases.

The role of the methoxy group in approved drugs

The methoxy substituent is prevalent in natural products and, consequently, is present in many natural product-derived drugs. It has also been installed in modern drug molecules with no remnant of natural product features because medicinal chemists have been taking advantage of the benefits that this small functional group can bestow on ligand-target binding, physicochemical properties, and ADME parameters. Herein, over 230 methoxy-containing small-molecule drugs, as well as several fluoromethoxy-containing drugs, are presented from the vantage point of the methoxy group. Biochemical mechanisms of action, medicinal chemistry SAR studies, and numerous X-ray cocrystal structures are analyzed to identify the precise role of the methoxy group for many of the drugs and drug classes. Although the methoxy substituent can be considered as the hybridization of a hydroxy and a methyl group, the combination of these functionalities often results in unique effects that can amount to more than the sum of the individual parts.

Exploring anticancer properties of the phytoconstituents and comparative analysis of their chemical space parameters with USFDA-approved synthetic anticancer agents

The present review article thoroughly analyses natural products and their derived phytoconstituents as a rich source of plausible anticancer drugs. The study thoroughly explores the chemical components derived from various natural sources, thus emphasizing their unique structural characteristics and therapeutic potential as an anticancer agent. The review contains the critical chemical constituents' in-depth molecular mechanisms, their source's chemical structures and the categories. The review also comprises an exhaustive and comprehensive analysis of different chemical spacing parameters of the anticancer agents derived from natural products. It compares them with USFDA-approved synthetic anticancer drugs up to 2020, thus providing a meaningful understanding of the relationship between natural and synthetic compounds portraying the anticancer assets. The review also delves more deeply into the chemical analysis of the heterocyclic moieties from the natural product arena, illustrating the anticancer mechanisms. The present article is, therefore, expected to serve as a valuable resource for natural product and medicinal chemists, encouraging and promoting an integrated approach to exploit the potential of natural products in drug discovery development and translational research, which have a prerequisite of bench to bedside approach. The work could guide researchers toward innovative approaches for the ever-evolving field of anticancer drug discovery.

Functions and mechanisms of enzymes assembling lignans and norlignans

Lignans and norlignans are distributed throughout the plant kingdom and exhibit diverse chemical structures and biological properties that offer potential for therapeutic use. Originating from the phenylpropanoid biosynthesis pathway, their characteristic carbon architectures are formed through unique enzyme catalysis, featuring regio- and stereoselective C-C bond forming processes. Despite extensive research on these plant natural products, their biosynthetic pathways, and enzyme mechanisms remain enigmatic. This review highlights recent advancements in elucidating the functions and mechanisms of the biosynthetic enzymes responsible for constructing the distinct carbon frameworks of lignans and norlignans.

Identification and characterization of camptothecin tailoring enzymes in Nothapodytes tomentosa

Camptothecin is a complex monoterpenoid indole alkaloid with remarkable antitumor activity. Given that two C-10 modified camptothecin derivatives, topotecan and irinotecan, have been approved as potent anticancer agents, there is a critical need for methods to access other aromatic ring-functionalized congeners (e.g., C-9, C-10, etc.). However, contemporary methods for chemical oxidation are generally harsh and low-yielding when applied to the camptothecin scaffold, thereby limiting the development of modified derivatives. Reported herein, we have identified four tailoring enzymes responsible for C-9 modifications of camptothecin from Nothapodytes tomentosa, via metabolomic and transcriptomic analysis. These consist of a cytochrome P450 (NtCPT9H) which catalyzes the regioselective oxidation of camptothecin to 9-hydroxycamptothecin, as well as two methyltransferases (NtOMT1/2, converting 9-hydroxycamptothecin to 9-methoxycamptothecin), and a uridine diphosphate-glycosyltransferase (NtUGT5, decorating 9-hydroxycamptothecin to 9-β-D-glucosyloxycamptothecin). Importantly, the critical residues that contribute to the specific catalytic activity of NtCPT9H have been elucidated through molecular docking and mutagenesis experiments. This work provides a genetic basis for producing camptothecin derivatives through metabolic engineering. This will hasten the discovery of novel C-9 modified camptothecin derivatives, with profound implications for pharmaceutical manufacture.

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.

In Vivo and Clinical Studies of Natural Products Targeting the Hallmarks of Cancer

Despite more than 200 approved anticancer agents, cancer remains a leading cause of death worldwide due to disease complexity, tumour heterogeneity, drug toxicity, and the emergence of drug resistance. Accordingly, the development of chemotherapeutic agents with higher efficacy, a better safety profile, and the capability of bypassing drug resistance would be a cornerstone in cancer therapy. Natural products have played a pivotal role in the field of drug discovery, especially for the pharmacotherapy of cancer, infectious, and chronic diseases. Owing to their distinctive structures and multiple mechanistic activities, natural products and their derivatives have been utilized for decades in cancer treatment protocols. In this review, we delve into the potential of natural products as anticancer agents by targeting cancer's hallmarks, including sustained proliferative signalling, evading growth suppression, resisting apoptosis and cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. We highlight the molecular mechanisms of some natural products, in vivo studies, and promising clinical trials. This review emphasizes the significance of natural products in fighting cancer and the need for further studies to uncover their fully therapeutic potential.

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.

Subtype-selective prenylated isoflavonoids disrupt regulatory drivers of MYCN-amplified cancers

Transcription factors have proven difficult to target with small molecules because they lack pockets necessary for potent binding. Disruption of protein expression can suppress targets and enable therapeutic intervention. To this end, we developed a drug discovery workflow that incorporates cell-line-selective screening and high-throughput expression profiling followed by regulatory network analysis to identify compounds that suppress regulatory drivers of disease. Applying this approach to neuroblastoma (NBL), we screened bioactive molecules in cell lines representing its MYC-dependent (MYCNA) and mesenchymal (MES) subtypes to identify selective compounds, followed by PLATESeq profiling of treated cells. This revealed compounds that disrupt a sub-network of MYCNA-specific regulatory proteins, resulting in MYCN degradation in vivo. The top hit was isopomiferin, a prenylated isoflavonoid that inhibited casein kinase 2 (CK2) in cells. Isopomiferin and its structural analogs inhibited MYC and MYCN in NBL and lung cancer cells, highlighting the general MYC-inhibiting potential of this unique scaffold.

Etiology of lung carcinoma and treatment through medicinal plants, marine plants and green synthesized nanoparticles: A comprehensive review

Lung cancer, a leading global cause of mortality, poses a significant public health challenge primarily linked to tobacco use. While tobacco contributes to over 90% of cases, factors like dietary choices and radiation exposure also play a role. Despite potential benefits from early detection, cancer patients face hurdles, including drug resistance, chemotherapy side effects, high treatment costs, and limited healthcare access. Traditional medicinal plant knowledge has recently unveiled diverse cancer chemopreventive agents from terrestrial and marine sources. These phytochemicals regulate intricate molecular processes, influencing the immune system, apoptosis, cell cycle, proliferation, carcinogen elimination, and antioxidant levels. In pursuing cutting-edge strategies to combat the diverse forms of cancer, technological advancements have spurred innovative approaches. Researchers have focused on the green synthesis of metallic nanoparticles using plant metabolites. This method offers distinct advantages over conventional physical and chemical synthesis techniques, such as cost-effectiveness, biocompatibility, and energy efficiency. Metallic nanoparticles, through various pathways such as the generation of reactive oxygen species, modulation of enzyme activity, DNA fragmentation, disruption of signaling pathways, perturbation of cell membranes, and interference with mitochondrial function resulting in DNA damage, cell cycle arrest, and apoptosis, exhibit significant potential for preventive applications. Thus, the amalgamation of phytocompounds and metallic nanoparticles holds promise as a novel approach to lung cancer therapy. However, further refinements and advancements are necessary to enhance the environmentally friendly process of metallic nanoparticle synthesis.

Intramolecular Heteroatom and Styryl Diels-Alder Reactions, Asymmetric Cycloadditions of Chiral 3-Phenylallyl Maleic Esters

Polycyclic aryl naphthalene and tetralin dihydro arylnaphthalene lactone lignans possess anticancer and antibiotic activity. Related furo[3,4-c]pyranones, typified by the sequester-terpenoid isobolivianine, show similar antiproliferative bioactivity. Efficient syntheses of compounds featuring these polycyclic cores have proven challenging due to low yields and poor stereoselectivity. We report the synthesis of chiral cinnamyl but-2-enanoates and 3,3-diphenylallyl-but-2-enoates 1 as new Diels-Alder substrates. These compounds undergo [4 + 2]-cycloadditions to give furo[3,4-c]pyranones 2 in good yield (70%) and diastereoselectivity (7:1), together with naphthyl 3 and dihydronaphthyl tetralins 4 as minor products. Molecular structures and stereochemistries of the major products were verified using X-ray diffraction. Density functional theory calculations revealed that the cycloaddition process involves a bispericyclic/ambimodal process where there is a single transition state that leads to both intramolecular styryl Diels-Alder (ISDA) 3, 4 and intramolecular hetero Diels-Alder (IHDA) cycloadducts 2. With the elevated temperature conditions after cycloaddition, the resulting ISDA cycloadduct either undergoes [3,3]-sigmatropic rearrangement to the more stable major IHDA product or aromatization leading to the phenyltetralin.

The therapeutic potential of natural metabolites in targeting endocrine-independent HER-2-negative breast cancer

Breast cancer (BC) is a heterogenous disease, with prognosis and treatment options depending on Estrogen, Progesterone receptor, and Human Epidermal Growth Factor Receptor-2 (HER-2) status. HER-2 negative, endocrine-independent BC presents a significant clinical challenge with limited treatment options. To date, promising strategies like immune checkpoint inhibitors have not yielded breakthroughs in patient prognosis. Despite being considered archaic, agents derived from natural sources, mainly plants, remain backbone of current treatment. In this context, we critically analyze novel naturally-derived drug candidates, elucidate their intricate mechanisms of action, and evaluate their pre-clinical in vitro and in vivo activity in endocrine-independent HER-2 negative BC. Since pre-clinical research success often does not directly correlate with drug approval, we focus on ongoing clinical trials to uncover current trends. Finally, we demonstrate the potential of combining cutting-edge technologies, such as antibody-drug conjugates or nanomedicine, with naturally-derived agents, offering new opportunities that utilize both traditional cytotoxic agents and new metabolites.

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.

Phytochemical Profiling and Antioxidant Activities of the Most Favored Ready-to-Use Thai Curries, Pad-Ka-Proa (Spicy Basil Leaves) and Massaman

Food is one of the factors with the highest impact on human health. Today, attention is paid not only to food properties such as energy provision and palatability but also to functional aspects including phytochemical, antioxidant properties, etc. Massaman and spicy basil leaf curries are famous Thai food dishes with a good harmony of flavor and taste, derived from multiple herbs and spices, including galangal rhizomes, chili pods, garlic bulbs, peppers, shallots, and coriander seeds, that provide an array of health benefits. The characterization of phytochemicals detected by LC-ESI-QTOF-MS/MS identified 99 components (Masaman) and 62 components (spicy basil leaf curry) such as quininic acid, hydroxycinnamic acid, luteolin, kaempferol, catechin, eugenol, betulinic acid, and gingerol. The cynaroside and luteolin-7-O-glucoside found in spicy basil leaf curry play a key role in antioxidant activities and were found at a significantly higher concentration than in Massaman curry. Phenolic and flavonoid compounds generally exhibit a bitter and astringent taste, but all the panelists scored both curries higher than 7 out of 9, confirming their acceptable flavor. Results suggest that the Massaman and spicy basil leaves contain various phytochemicals at different levels and may be further used as functional ingredients and nutraceutical products.

Tandem Hock and Friedel-Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

The Hock cleavage, which is compatible with tandem processes, was applied to the synthesis of 1-aryltetralines through a one-pot transformation from readily available benzyl(prenyl)malonate substrates. After the photooxygenation of the prenyl moiety, the resulting hydroperoxide was directly engaged in a Hock cleavage by adding a Lewis acid. The presence of an aromatic nucleophile in the reaction mixture and that of a benzyl moiety on the substrate resulted in tandem Friedel-Crafts reactions to form the 1-aryltetraline products. These compounds share a close analogy to the cyclolignan natural products. Experimental observations and a DFT study support the involvement of an aldehyde intermediate during the Friedel-Crafts reactions, rather than an oxocarbenium.

Podophyllotoxin-mediated neurotoxicity via the microbiota-gut-brain axis in SD rats based on the toxicological evidence chain (TEC) concept

Podophyllotoxin (PPT) is a naturally occurring aryltetralin lignan. However, its clinical application has been limited due to its neurotoxicity, the mechanism of which remains unclear. This study aimed to investigate the potential involvement of the microbiota-gut-brain (MGB) axis in PPT-induced neurotoxicity using the toxicological evidence chain concept. Our approach included behavioral testing in rats, evaluation of colon and hippocampal pathological changes, examination of proinflammatory factors, brain-gut peptides, and an in-depth analysis of gut microbiome and metabolic profiles. Our results demonstrated that PPT exposure compromised cognitive functions, induced damage to the colon and hippocampus, and increased intestinal permeability in rats. Furthermore, it elevated proinflammatory factors, particularly TNF-α and IL-6, while causing disruptions in the gut microbiota, favoring Escherichia-Shigella over Lactobacillus. Significant alterations in metabolic profiles in feces, serum, and hippocampus, particularly in tryptophan metabolism with a correlation to inflammatory factors and Escherichia-Shigella, were also observed. Our findings suggest that PPT promotes the enrichment of Escherichia-Shigella leading to inflammatory factor production and alterations in kynurenine metabolism in the hippocampus, potentially contributing to neurotoxicity. The study provides novel insights into the mechanistic pathways of PPT-induced neurotoxicity, emphasizing the role of the MGB axis and offering avenues for therapeutic interventions.

A Zero-Valent Sulfur Transporter Helps Podophyllotoxin Uptake into Bacterial Cells in the Presence of CTAB

Podophyllotoxin (PTOX) is naturally produced by the plant Podophyllum species. Some of its derivatives are anticancer drugs, which are produced mainly by using chemical semi-synthesis methods. Recombinant bacteria have great potential in large-scale production of the derivatives of PTOX. In addition to introducing the correct enzymes, the transportation of PTOX into the cells is an important factor, which limits its modification in the bacteria. Here, we improved the cellular uptake of PTOX into Escherichia coli with the help of the zero-valent sulfur transporter YedE1E2 in the presence of cetyltrimethylammonium bromide (CTAB). CTAB promoted the uptake of PTOX, but induced the production of reactive oxygen species. A protein complex (YedE1E2) of YedE1 and YedE2 enabled E. coli cells to resist CTAB by reducing reactive oxygen species, and YedE1E2 was a hypothetical transporter. Further investigation showed that YedE1E2 facilitated the uptake of extracellular zero-valent sulfur across the cytoplasmic membrane and the formation of glutathione persulfide (GSSH) inside the cells. The increased GSSH minimized oxidative stress. Our results indicate that YedE1E2 is a zero-valent sulfur transporter and it also facilitates CTAB-assisted uptake of PTOX by recombinant bacteria.

Target discovery of bioactive natural products with native-compound-coupled CNBr-activated Sepharose 4B beads (NCCB): Applications, mechanisms and outlooks

Natural products (NPs) represent a treasure trove for drug discovery and development due to their chemical structural diversity and a broad spectrum of biological activities. Uncovering the biological targets and understanding their molecular mechanism of actions are crucial steps in the development of clinical therapeutics. However, the structural complexity of NPs and intricate nature of biological system present formidable challenges in target identification of NPs. Although significant advances have been made in the development of new chemical tools, these methods often require high levels of synthetic skills for preparing chemical probes. This can be costly and time-consuming relaying on operationally complicated procedures and instruments. In recent efforts, we and others have successfully developed an operationally simple and practical chemical tool known as native-compound-coupled CNBr-activated Sepharose 4B beads (NCCB) for NP target identification. In this approach, a native compound readily reacts with commercial CNBr-activated Sepharose 4B beads with a process that is easily performed in any biology laboratory. Based on NCCB, our group has identified the direct targets of more than 60 NPs. In this review, we will elucidate the application scopes, including flavonoids, quinones, terpenoids and others, characteristics, chemical mechanisms, procedures, advantages, disadvantages, and future directions of NCCB in specific target discovery.

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.

Comprehensive Profiling and Therapeutic Insights into Differentially Expressed Genes in Hepatocellular Carcinoma

Background: Drug repurposing is a strategy that complements the conventional approach of developing new drugs. Hepatocellular carcinoma (HCC) is a highly prevalent type of liver cancer, necessitating an in-depth understanding of the underlying molecular alterations for improved treatment. Methods: We searched for a vast array of microarray experiments in addition to RNA-seq data. Through rigorous filtering processes, we have identified highly representative differentially expressed genes (DEGs) between tumor and non-tumor liver tissues and identified a distinct class of possible new candidate drugs. Results: Functional enrichment analysis revealed distinct biological processes associated with metal ions, including zinc, cadmium, and copper, potentially implicating chronic metal ion exposure in tumorigenesis. Conversely, up-regulated genes are associated with mitotic events and kinase activities, aligning with the relevance of kinases in HCC. To unravel the regulatory networks governing these DEGs, we employed topological analysis methods, identifying 25 hub genes and their regulatory transcription factors. In the pursuit of potential therapeutic options, we explored drug repurposing strategies based on computational approaches, analyzing their potential to reverse the expression patterns of key genes, including AURKA, CCNB1, CDK1, RRM2, and TOP2A. Potential therapeutic chemicals are alvocidib, AT-7519, kenpaullone, PHA-793887, JNJ-7706621, danusertibe, doxorubicin and analogues, mitoxantrone, podofilox, teniposide, and amonafide. Conclusion: This multi-omic study offers a comprehensive view of DEGs in HCC, shedding light on potential therapeutic targets and drug repurposing opportunities.

Dormancy release of seeds of Podophyllum hexandrum Royle accompanied by changes in phytochemicals and inorganic elements

Podophyllum hexandrum Royle is an alpine medicinal plant of considerable importance, and its seed dormancy severely inhibits population renewal. Although cold stratification can break dormancy to a certain extent, the migration and accumulation of phytochemicals and inorganic elements in the seeds during dormancy release and their functions remain unclear. Changes in phytochemicals and inorganic elements in different seed parts were analyzed during dormancy. The key differential phytochemicals and inorganic elements were screened and their association with dormancy release and their roles in dormancy release were explored. The results showed that dormancy release may have occurred following the decrease in palmitic acid and linoleic acid content in the seeds and the increase in 2,3-dihydro-3,5-dihydro-6-methyl-4 (h)-pyran-4-one content in the endosperm. Meanwhile, 6-propyltridecane and hexadecane in the seed coat may enhance the water permeability of seeds to speed up germination. Mg may migrate from the seed coat to the endosperm and seed embryos, whereas Co may migrate from the seed embryo to the seed coat. Ca, Mn, Mg, and Co are involved in various physiological metabolic processes, which may facilitate the dormancy release of P. hexandrum seeds. These findings have enhanced our understanding of the mechanisms of dormancy release in P. hexandrum seeds and can serve as a reference for the development of more effective dormancy-breaking techniques for the conservation of this endangered medicinal plant.

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.

Identification of Novel β-Tubulin Inhibitors Using a Combined In Silico/In Vitro Approach

Due to their potential as leads for various therapeutic applications, including as antimitotic and antiparasitic agents, the development of tubulin inhibitors offers promise for drug discovery. In this study, an in silico pharmacophore-based virtual screening approach targeting the colchicine binding site of β-tubulin was employed. Several structure- and ligand-based models for known tubulin inhibitors were generated. Compound databases were virtually screened against the models, and prioritized hits from the SPECS compound library were tested in an in vitro tubulin polymerization inhibition assay for their experimental validation. Out of the 41 SPECS compounds tested, 11 were active tubulin polymerization inhibitors, leading to a prospective true positive hit rate of 26.8%. Two novel inhibitors displayed IC50 values in the range of colchicine. The most potent of which was a novel acetamide-bridged benzodiazepine/benzimidazole derivative with an IC50 = 2.9 μM. The screening workflow led to the identification of diverse inhibitors active at the tubulin colchicine binding site. Thus, the pharmacophore models show promise as valuable tools for the discovery of compounds and as potential leads for the development of cancer therapeutic agents.

Exploring the mechanism of action of podophyllotoxin derivatives through molecular docking, molecular dynamics simulation and MM/PBSA studies

The chemical structure of a compound directly affects its biological activity, as different functional groups can change a compound's activity. With this in mind, the current study aims to predict the likely mechanism of action of several podophyllotoxin derivatives whose biological activities have already been documented. The interactions of the derivatives of podophyllotoxin with tubulin (PDB ID: 6NNG) and topoisomerase II (PDB ID: 3QX3), the two recognised targets of podophyllotoxin, were examined using molecular docking experiments. According to the molecular docking result, tubulin, and the investigated variants of podophyllotoxin interact more effectively than topoisomerase. The greatest docking score of the compounds was -12.200 against tubulin and -4.511 against topoisomerase, indicating that tubulin is the target of these drugs. Further to ascertain the strength of the interaction between the best-docked derivatives and the target protein, additional molecular dynamics investigations were also incorporated. With tubulin, the derivatives engage steadily, while with topoisomerase, the ligands shift from the protein's initial binding site to its DNA binding site. MMPBSA analysis was used to examine the stability of their relationship.Communicated by Ramaswamy H. Sarma.

Nephrotoxicity assessment of podophyllotoxin-induced rats by regulating PI3K/Akt/mTOR-Nrf2/HO1 pathway in view of toxicological evidence chain (TEC) concept

Adverse reactions to traditional Chinese medicine have hindered the healthy development and internationalization process of the traditional Chinese medicine industry. The critical issue that needs to be solved urgently is to evaluate the safety of traditional Chinese medicine systematically and effectively. Podophyllotoxin (PPT) is a highly active compound extracted from plants of the genus Podophyllum such as Dysosma versipellis (DV). However, its high toxicity and toxicity to multiple target organs affect the clinical application, such as the liver and kidney. Based on the concurrent effects of PPT's medicinal activity and toxicity, it would be a good example to conduct a systematic review of its safety. Therefore, this study revolves around the Toxicological Evidence Chain (TEC) concept. Based on PPT as the main toxic constituent in DV, observe the objective toxicity impairment phenotype of animals. Evaluate the serum biochemical indicators and pathological tissue sections for substantial toxic damage results. Using metabolomics, lipidomics, and network toxicology to evaluate the nephrotoxicity of PPT from multiple perspectives systematically. The results showed that PPT-induced nephrotoxicity manifested as renal tubular damage, mainly affecting metabolic pathways such as glycerophospholipid metabolism and sphingolipid metabolism. PPT inhibits the autophagy process of kidney cells through the PI3K/Akt/mTOR and Nrf2/HO1 pathways and induces the activation of oxidative stress in the body, thereby causing nephrotoxic injury. This study fully verified the feasibility of the TEC concept for the safety and toxicity evaluation of traditional Chinese medicine. Provide a research template for systematically evaluating the safety of traditional Chinese medicine.

Current status of research on endophytes of traditional Tibetan medicinal plant and their metabolites

The Qinghai-Tibet Plateau, known as the "Third Pole of the World," has a rich variety of medicinal plants that play an important role in the field of medicine due to its unique geographical environment. However, due to the limited resources of Tibetan medicinal plants and the fragility of the ecological environment of the Qinghai-Tibet Plateau, more and more Tibetan medicinal plants are on the verge of extinction. As a reservoir of biologically active metabolites, endophytes of medicinal plants produce a large number of compounds with potential applications in modern medicine (including antibacterial, immunosuppressive, antiviral, and anticancer) and are expected to be substitutes for Tibetan medicinal plants. This paper reviews 12 Tibetan medicinal plants from the Qinghai-Tibet Plateau, highlighting the diversity of their endophytes, the diversity of their metabolites and their applications. The results show that the endophytes of Tibetan medicinal plants are remarkably diverse, and the efficacy of their metabolites involves various aspects, such as antioxidant, anti-disease and anti-parasitic. In addition, conservation measures for the resources of Tibetan medicinal plants are summarised to provide a reference for an in-depth understanding of the endophytes of Tibetan medicinal plants and to stimulate the scientific community to bioprospect for the endophytes of Tibetan medicinal plants, as well as to provide ideas for their rational exploitation.

Enhanced podophyllotoxin production of endophyte Fusarium proliferatum TQN5T by host extract and phenylalanine

Fermentation technology using endophytes is considered a potential alternative approach for producing pharmaceutical compounds like podophyllotoxin (PTOX). In this study, fungus TQN5T (VCCM 44284) was selected from endophytic fungi isolated from Dysosma versipellis in Vietnam for PTOX production through TLC. The presence of PTOX in TQN5T was further confirmed by HPLC. Molecular identification indicated TQN5T as Fusarium proliferatum with 99.43% identity. This result was asserted by morphological characteristics such as white cottony, filamentous colony, layer and branched mycelium, and clear hyphae septa. Cytotoxic assay indicated both biomass extract and culture filtrate of TQN5T presented strong cytotoxicity on LU-1 and HepG2 with IC50 of 0.11, 0.20, 0.041, and 0071, respectively, implying anti-cancer compounds were accumulated in the mycelium and secreted into the medium. Further, the production of PTOX in TQN5T was investigated in the fermentation condition supplemented with 10 µg/ml of host plant extract or phenylalanine as elicitors. The results revealed a significantly higher amount of PTOX in the PDB + PE and PDB + PA at all studied time points in comparison with PDB (control). Especially, after 168 h of culture, PTOX content in the PDB with plant extract reached the peak with 314 µg/g DW which is 10% higher than the best yield of PTOX in previous studies, denoting F. proliferatum TQN5T as a promising PTOX producer. This is the first study on enhancing the PTOX production in endophytic fungi by supplementing phenylalanine-a precursor for PTOX biosynthesis in plants into fermented media, suggesting a common PTOX biosynthetic pathway between host plant and endophytes. KEY POINTS: • Fusarium proliferatum TQN5T was proven for PTOX production. • Both mycelia extract and spent broth extract of Fusarium proliferatum TQN5T presented strong cytotoxicity on cancer cell lines LU-1 and HepG2. • The supplementation of 10 µg/ml host plant extract and phenylalanine into fermentation media of F. proliferatum TQN5T improved the yield of PTOX.

Transcriptome analysis reveals differentially expressed genes involved in somatic embryogenesis and podophyllotoxin biosynthesis of Sinopodophyllum hexandrum (Royle) T. S. Ying

Sinopodophyllum hexandrum (Royle) T. S. Ying, an important source of podophyllotoxin (PTOX), has become a rare and endangered plant because of over-harvesting. Somatic embryogenesis (SE) is the main way of seedling rapid propagation and germplasm enhancement, but the regeneration of S. hexandrum has not been well established, and the PTOX biosynthesis abilities at different SE stages remain unclear. Therefore, it is extremely important to elucidate the SE mechanism of S. hexandrum and clarify the biosynthesis variation of PTOX. In this study, the transcriptomes of S. hexandrum at different SE stages were sequenced, the contents of PTOX and 4'-demethylepipodophyllotoxin were assayed, and the transcript expression patterns were validated by qRT-PCR. The results revealed that plant hormone (such as auxins, abscisic acid, zeatin, and gibberellins) related pathways were significantly enriched among different SE stages, indicating these plant hormones play important roles in SE of S. hexandrum; the expression levels of a series of PTOX biosynthesis related genes as well as PTOX and 4'-demethylepipodophyllotoxin contents were much higher in embryogenic callus stage than in the other stages, suggesting embryogenic callus stage has the best PTOX biosynthesis ability among different SE stages. This study will contribute to germplasm conservation and fast propagation of S. hexandrum, and facilitate the production of PTOX.

Curing childhood cancer the "Natural" Way: Nature as the source of chemotherapy agents

For many centuries, products of natural origin from plants, marine, microbes and soil micro-organisms have been studied by numerous researchers across the world to yield many of the chemotherapeutic agents we use in this modern era. There has been a tremendous gain in knowledge from various screening and separating techniques which led to the discovery of biologically active small molecules from natural products. Preclinical studies testing the antitumor activities of these agents against tumor cell lines and xenograft animal models were the gateway to the clinical trials in humans leading to the approval of these agents that are in clinical use today. This review summarizes how various chemotherapeutic agents were discovered from products of natural origin, their preclinical development, and their indications in both pediatric and adult oncology. Many of these natural products have contributed to the very high cure rates of both pediatric leukemias and solid tumors.

Etoposide: A rider on the cytokine storm

For more than 40 years, the epipodophyllotoxin drug etoposide is prescribed to treat cancer. This semi-synthetic compound remains extensively used to treat advanced small-cell lung cancer and in various chemotherapy regimen for autologous stem cell transplantation, and other anticancer protocols. Etoposide is a potent topoisomerase II poison, causing double-stranded DNA breaks which lead to cell death if they are not repaired. It is also a genotoxic compound, responsible for severe side effects and secondary leukemia occasionally. Beyond its well-recognized function as an inducer of cancer cell death (a "killer on the road"), etoposide is also useful to treat immune-mediated inflammatory diseases associated with a cytokine storm syndrome. The drug is essential to the treatment of hemophagocytic lymphohistiocytosis (HLH) and the macrophage activation syndrome (MAS), in combination with a corticosteroid and other drugs. The use of etoposide to treat HLH, either familial or secondary to a viral or parasitic infection, or treatment-induced HLH and MAS is reviewed here. Etoposide dampens inflammation in HLH patients via an inhibition of the production of pro-inflammatory mediators, such as IL-6, IL-10, IL-18, IFN-γ and TNF-α, and reduction of the secretion of the alarmin HMGB1. The modulation of cytokines production by etoposide contributes to deactivate T cells and to dampen the immune stimulation associated to the cytokine storm. This review discussed the clinical benefits and mechanism of action of etoposide (a "rider on the storm") in the context of immune-mediated inflammatory diseases, notably life-threatening HLH and MAS. The question arises as to whether the two faces of etoposide action can apply to other topoisomerase II inhibitors.

Pulsatilla Decoction and its bioactive component β-peltatin induce G2/M cell cycle arrest and apoptosis in pancreatic cancer

BACKGROUND

Pancreatic cancer (PAC), a malignancy that is fatal and commonly diagnosed at a late stage. Despite considerable advancements in cancer treatment, the survival rate of PAC remains largely consistent for the past 60 years. The traditional Chinese medicine formula Pulsatilla Decoction (PD) has been clinically used to treat inflammatory diseases for millennia and recently as a supplementary anti-cancer treatment in China. However, the bioactive ingredients and mechanisms underlying its anti-cancer effect remains unclear.

METHODS

The composition and quality control of PD were verified through analysis by high performance liquid chromatography. Cell viability was determined using Cell Counting Kit-8 assay. The cell cycle distribution was analyzed through PI staining and flow cytometry analysis, while apoptotic cells were measured by double staining with Annexin V-FITC and PI. We used immunoblotting to examine protein expressions. The in vivo effects of β-peltatin and podophyllotoxin were evaluated on a subcutaneously-xenografted BxPC-3 cell nude mice model.

RESULTS

The current study demonstrated that PD markedly inhibited PAC cell proliferation and triggered their apoptosis. Four herbal PD formula was then disassembled into 15 combinations of herbal ingredients and a cytotoxicity assay showed that the Pulsatillae chinensis exerted the predominant anti-PAC effect. Further investigation indicated that β-peltatin was potently cytotoxic with IC₅₀ of ~ 2 nM. β-peltatin initially arrested PAC cells at G2/M phase, followed by apoptosis induction. Animal study confirmed that β-peltatin significantly suppressed the growth of subcutaneously-implanted BxPC-3 cell xenografts. Importantly, compared to podophyllotoxin that is the parental isomer of β-peltatin but clinically obsoleted due to its severe toxicity, β-peltatin exhibited stronger anti-PAC effect and lower toxicity in mice.

CONCLUSIONS

Our results demonstrate that Pulsatillae chinensis and particularly its bioactive ingredient β-peltatin suppress PAC by triggering cell cycle arrest at G2/M phase and apoptosis.

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.

Arylnaphthalene Lignans with Anti-SARS-CoV-2 and Antiproliferative Activities from the Underground Organs of Linum austriacum and Linum perenne

Diphyllin (1) and justicidin B (2) are arylnaphthalene lignans with antiviral and antiproliferative effects. Compound 1 is also known as an effective inhibitor of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To evaluate the in vitro antiviral and cytotoxic potency of both lignans in SARS-CoV-2 -infected cells and various cancer cell lines, respectively, 1 and 2 were isolated from the underground organs of Linum austriacum and Linum perenne. Two previously undescribed arylnaphthalene lignans, denominated linadiacin A and B (3 and 4), were also isolated and identified. In acidic media, 3 was converted by a two-step reaction into 2 via the intermediate 4. Optimum acid treatment conditions were determined to isolate lignans by one-step preparative high-performance liquid chromatography (HPLC). The results of the conversion, HPLC-tandem mass spectrometry, nuclear magnetic resonance spectroscopy, and molecular modeling studies allowed complete structure analysis. Compounds 1 and 2 were the most effective against SARS-CoV-2 with a 3-log reduction in the viral copy number at a 12.5 μM concentration. Ten human cancer cell lines showed sensitivity to at least one of the isolated lignans.

Anticancer Podophyllotoxin Recovery from Juniper Leaves at Atmospheric and High Pressure Using Eco-Friendly Solvents

Podophyllotoxin (PPT) is a precursor for the synthesis of drugs against cancer and other diseases. The present sources of PPT (Sinopodophyllum hexandrum and Podophyllum peltatum) are endangered species, with PPT production highly dependent on their growing conditions. In connection with the identification of new sources of PPT, the present study aimed to recover PPT from Juniperus virginiana leaves via atmospheric or high pressure extraction methods with a focus on using eco-friendly solvents. PPT quantification was determined by UHPLC/HRMS/MS. A thorough study of conventional extraction was carried out to reveal the optimal conditions (solvent ethyl acetate at room temperature and a duration of 1 h) for maximizing the PPT recovery (about 30 mg/g of dry extract and 3 mg/g of dry initial plant material). Peleg's equation was applied for process kinetics modeling. The best PPT content in the final dry extract (42-45 mg/g of dry extract) was obtained by high pressure methods under supercritical (scCO₂ with ethanol or ethyl acetate, 30 MPa, 50 °C and 100 min) or accelerated solvent extraction conditions (solvent ethyl acetate, 10.35 MPa, 20 °C and 3 cycles for 15 min). Seasonal stability and storage stability of the raw material were also determined. The present results have potential applications in the pharmacy for the delivery of PPT from juniper leaves.

Lignans from the Roots and Rhizomes of Dysosma versipellis and Their Cytotoxic Activities

One new dibenzyltyrolactone lignan dysoslignan A (1), three new arylnaphthalide lignans dysoslignan B-C (2-4), along with fourteen known metabolites (5-18), were isolated from the roots and rhizomes of Dysosma versipellis. Their structures and stereochemistry were determined from analysis of NMR spectroscopic and circular dichroism (CD) data. Compound 2 represents the first report of naturally occurring arylnaphthalide lignan triglycoside. The cytotoxic activities of all isolated compounds were evaluated against A-549 and SMMC-7721 cell lines. Compounds 7-10 and 14-16 were more toxic than cisplatin in two tumor cell lines. This investigation clarifies the potential effective substance basis of D. versipellis in tumor treatment.

Analogues of Anticancer Natural Products: Chiral Aspects

Life is chiral, as its constituents consist, to a large degree, of optically active molecules, be they macromolecules (proteins, nucleic acids) or small biomolecules. Hence, these molecules interact disparately with different enantiomers of chiral compounds, creating a preference for a particular enantiomer. This chiral discrimination is of special importance in medicinal chemistry, since many pharmacologically active compounds are used as racemates—equimolar mixtures of two enantiomers. Each of these enantiomers may express different behaviour in terms of pharmacodynamics, pharmacokinetics, and toxicity. The application of only one enantiomer may improve the bioactivity of a drug, as well as reduce the incidence and intensity of adverse effects. This is of special significance regarding the structure of natural products since the great majority of these compounds contain one or several chiral centres. In the present survey, we discuss the impact of chirality on anticancer chemotherapy and highlight the recent developments in this area. Particular attention has been given to synthetic derivatives of drugs of natural origin, as naturally occurring compounds constitute a major pool of new pharmacological leads. Studies have been selected which report the differential activity of the enantiomers or the activities of a single enantiomer and the racemate.