Synthesis and antitumor activity of novel per-butyrylated glycosides of podophyllotoxin and its derivatives

Recent developments on the synthesis of biologically active glycohybrids

The exploration of hybridization emerges as a potent tool in advancing drug discovery research, with a significant emphasis on carbohydrate-containing hybrid scaffolds. Evidence indicates that linking carbohydrate molecules to privileged bioactive scaffolds enhances the bioactivity of drug molecules. This synergy results in a diverse range of activities, making carbohydrate scaffolds pivotal for synthesizing compound libraries with significant functional and structural diversity. Beyond their synthesis utility, these scaffolds offer applications in screening bioactive molecules, presenting alternative avenues for drug development. This comprehensive review spanning 2015 to 2023 focuses on synthesized glycohybrid molecules, revealing their bioactivity in areas such as anti-microbial, anti-cancer, anti-diabetic, anti-inflammatory activities, enzyme inhibition and pesticides. Numerous novel glycohybrids surpass positive control drugs in biological activity. This focused study not only highlights the diverse bioactivities of glycohybrids but also underscores their promising role in innovative drug development strategies.

Natural product inspired leads in the discovery of anticancer agents: an update

Natural products have emerged as major leads for the discovery and development of new anti-cancer drugs. The plant-derived anti-cancer drugs account for approximately 60% and the quest for new anti-cancer agents is in progress. Anti-cancer leads have been isolated from plants, animals, marine organisms, and microorganisms from time immemorial. The process of semisynthetic modifications of the parent lead has led to the generation of new anti-cancer agents with improved therapeutic efficacy and minimal side effects. The various chemo-informatics tools, bioinformatics, high-throughput screening, and combinatorial synthesis are able to deliver the new natural product lead molecules. Plant-derived anticancer agents in either late preclinical development or early clinical trials include taxol, vincristine, vinblastine, topotecan, irinotecan, etoposide, paclitaxel, and docetaxel. Similarly, anti-cancer agents from microbial sources include dactinomycin, bleomycin, mitomycin C, and doxorubicin. In this review, we highlighted the importance of natural products leads in the discovery and development of novel anti-cancer agents. The semisynthetic modifications of the parent lead to the new anti-cancer agent are also presented. Further, the leads in the preclinical settings with the potential to become effective anticancer agents are also reviewed.Communicated by Ramaswamy H. Sarma.

Novel Perbutyrylated Glucose Derivatives of (-)-Epigallocatechin-3-Gallate Inhibit Cancer Cells Proliferation by Decreasing Phosphorylation of the EGFR: Synthesis, Cytotoxicity, and Molecular Docking

Lung cancer is one of the most commonly occurring cancer mortality worldwide. The epidermal growth factor receptor (EGFR) plays an important role in cellular functions and has become the new promising target. Natural products and their derivatives with various structures, unique biological activities, and specific selectivity have served as lead compounds for EGFR. D-glucose and EGCG were used as starting materials. A series of glucoside derivatives of EGCG (7-12) were synthesized and evaluated for their in vitro anticancer activity against five human cancer cell lines, including HL-60, SMMC-7721, A-549, MCF-7, and SW480. In addition, we investigated the structure-activity relationship and physicochemical property-activity relationship of EGCG derivatives. Compounds 11 and 12 showed better growth inhibition than others in four cancer cell lines (HL-60, SMMC-7721, A-549, and MCF), with IC50 values in the range of 22.90-37.87 μM. Compounds 11 and 12 decreased phosphorylation of EGFR and downstream signaling protein, which also have more hydrophobic interactions than EGCG by docking study. The most active compounds 11 and 12, both having perbutyrylated glucose residue, we found that perbutyrylation of the glucose residue leads to increased cytotoxic activity and suggested that their potential as anticancer agents for further development.

2, 4, 5-Trideoxyhexopyranosides Derivatives of 4'- Demethylepipodophyllotoxin: De novo Synthesis and Anticancer Activity

BACKGROUND

Podophyllotoxin is a natural lignan which possesses anticancer and antiviral activities. Etoposide and teniposide are semisynthetic glycoside derivatives of podophyllotoxin and are increasingly used in cancer medicine.

OBJECTIVE

The present work was aimed to design and synthesize a series of 2, 4, 5-trideoxyhexopyranosides derivatives of 4'-demethylepipodophyllotoxin as novel anticancer agents.

METHODS

A divergent de novo synthesis of 2, 4, 5-trideoxyhexopyranosides derivatives of 4'-demethylepipodophyllotoxin has been established via palladium-catalyzed glycosylation. The abilities of synthesized glycosides to inhibit the growth of A549, HepG2, SH-SY5Y, KB/VCR and HeLa cancer cells were investigated by MTT assay. Flow cytometric analysis of cell cycle with propidium iodide DNA staining was employed to observe the effect of compound 5b on cancer cell cycle.

RESULTS

Twelve D and L monosaccharides derivatives 5a-5l have been efficiently synthesized in three steps from various pyranone building blocks employing de novo glycosylation strategy. D-monosaccharide 5b showed highest cytotoxicity on five cancer cell lines with the IC50 values from 0.9 to 6.7 mM. It caused HepG2 cycle arrest at G2/M phase in a concentration-dependent manner.

CONCLUSION

The present work leads to the development of novel 2, 4, 5-trideoxyhexopyranosides derivatives of 4'- demethylepipodophyllotoxin. The biological results suggested that the replacement of the glucosyl moiety of etoposide with 2, 4, 5-trideoxyhexopyranosyl is favorable to their cytotoxicity. D-monosaccharide 5b caused HepG2 cycle arrest at G2/M phase in a concentration-dependent manner.

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.

Enzymatic O-Glycosylation of Etoposide Aglycone by Exploration of the Substrate Promiscuity for Glycosyltransferases

The 4-O-β-d-glucopyranoside of DMEP ((-)-4'-desmethylepipodophyllotoxin) (GDMEP), a natural product from Podophyllum hexandrum, is the direct precursor to the topoisomerase inhibitor etoposide, used in dozens of chemotherapy regimens for various malignancies. The biosynthesis pathway for DMEP has been completed, while the enzyme for biosynthesizing GDMEP is still unclear. Here, we report the enzymatic O-glycosylation of DMEP with 53% conversion by exploring the substrate promiscuity and entrances of glycosyltransferases. Notably, we found 6 essential amino acid residues surrounding the putative substrate entrances exposed to the protein surface in UGT78D2, CsUGT78D2, and CsUGT78D2-like, and these residues may determine substrate specificity and high O-glycosylation activity toward DMEP. Our results provide an effective route for one-step synthesis of GDMEP. Identification of the key residues and entrances of glycosyltransferases will promote precise identification of glycosyltransferase biocatalysts for novel substrates and provide a rational basis for glycosyltransferase engineering.

Divergent de novo synthesis of 2,4,5-trideoxyhexopyranosides derivatives of podophyllotoxin as anticancer agents

Aim: Identification of new anticancer glycosidic derivatives of podophyllotoxin. Methods: 14 podophyllotoxin D- and L-monosaccharides have been synthesized in three steps employing de novo glycosylation strategy, and their abilities to inhibit the growth of HeLa, HepG2, MCF-7, A549 and MDA-MB-231 cancer cells were investigated by MTT assay. Molecular docking study of compound 5j with tubulin was performed. Immunofluorescence was applied for detecting the inhibitory effect of 5j on tubulin polymerization. Results & conclusion: Most of synthesized compounds showed strong cytotoxicity activity against five cancer cell lines. Compound 5j possessed the highest cytotoxicity with the IC50 values from 41.6 to 95.2 nM, and could concentration-dependently inhibit polymerization of the microtubule cytoskeleton of MCF-7 cells. Molecular docking disclosed that sugar moiety-dedicated hydrogen bond endowed 5j a higher binding affinity for tubulin.

Glucoside Derivatives Of Podophyllotoxin: Synthesis, Physicochemical Properties, And Cytotoxicity

Background

Widespread concern of the side effects and the broad-spectrum anticancer property of podophyllotoxin as an antitumor agent highlight the need for the development of new podophyllotoxin derivatives. Although some per-butyrylated glucosides of podophyllotoxin and 4β-triazolyl-podophyllotoxin glycosides show good anticancer activity, the per-acetylated/free of podophyllotoxin glucosides and their per-acetylated are not well studied.

Methods

A few glucoside derivatives of PPT were synthesized and evaluated for their in vitro cytotoxic activities against five human cancer cell lines, HL-60 (leukemia), SMMC-7721 (hepatoma), A-549 (lung cancer), MCF-7 (breast cancer), and SW480 (colon cancer), as well as the normal human pulmonary epithelial cell line (BEAS-2B). In addition, we investigated the structure–activity relationship and the physicochemical property–anticancer activity relationship of these compounds.

Results

Compound 6b shows the highest cytotoxic potency against all five cancer cell lines tested, with IC₅₀ values ranging from 3.27±0.21 to 11.37±0.52 μM. We have also found that 6b displays higher selectivity than the etoposide except in the case of HL-60 cell line. The active compounds possess similar physicochemical properties: MSA > 900, %PSA < 20, ClogP > 2, MW > 700 Da, and RB > 10.

Conclusion

We synthesized several glucoside derivatives of PPT and tested their cytotoxicity. Among them, compound 6b showed the highest cytotoxicity. Further studies including selectivity of active compounds have shown that the selectivity indexes of 6b are much greater than the etoposide except in the case of HL-60 cell line. The active compounds possessed similar physicochemical properties. This study indicates that active glucoside analogs of podophyllotoxin have potential as lead compounds for developing novel anticancer agents.

Synthesis and Cytotoxicities of Novel Podophyllotoxin Xyloside Derivatives

Novel podophyllotoxin xyloside derivatives 8 to 11 were synthesized and evaluated for their cytotoxicities against a panel of 5 human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, SW480) using [3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays. These derivatives showed good to moderate activities, with compound 9 having an IC50 value of 4.42 μM against the A-549 cell line. Overall, compound 9 might be a promising candidate for further development.

Design, Synthesis, and Biological Evaluation of Novel Biotinylated Podophyllotoxin Derivatives as Potential Antitumor Agents

Podophyllotoxin has long been used as an active substance for cytotoxic activity. Fourteen novel biotinylated podophyllotoxin derivatives were designed, synthesized, and evaluated for cytotoxic activity for this study. The synthesized compounds were evaluated for cytotoxic activity in the following human cancer cell lines, SW480, MCF-7, A-549, SMMC-7721, and HL-60 by MTT assay. Most of them exhibited potent cytotoxic effects and compound 15 showed the highest cytotoxic activity among the five cancer cell lines tested, having its IC50 values in the range of 0.13 to 0.84 μM. Apoptosis analysis revealed that compound 15 caused obvious induction of cell apoptosis. Compound 15 significantly down-regulated the expression level of the marker proteins (caspase-3 and PARP) in H1299 and H1975 cells, activated the transcription of IRE1α, increased the expression of GRP78 and XBP-1s, and finally induced apoptosis of H1299 cells. In vivo studies showed that 15 at a dose of 20 mg/kg suppressed tumor growth of S180 cell xenografts in icr mice significantly. Further molecular docking studies suggested that compound 15 could bind well with the ATPase domain of Topoisomerase-II. These data suggest that compound 15 is a promising agent for cancer therapy deserving further research.

Plant-derived Glycosides with α-Glucosidase Inhibitory Activity: Current Standing and Future Prospects

Background:

The α-glucosidase (EC 3.2.1.20), a calcium-containing intestinal enzyme which is positioned in the cells which cover the intestinal microvilli brush border. The carbohydrates require metabolism by α-glucosidase before being absorbed into the small intestine, and as a result, this enzyme represents a significant drug target for the effective management of diabetes. There are few α- glucosidase inhibitors in the clinical practice that is challenged by several limitations. Thus, new effective and safe therapeutic agents in this class are required. In this regard, plant secondary metabolites are a very promising source to be investigated. Herein in this review, we have focused on the preclinical studies on various glycosides with in vitro α-glucosidase inhibitory activity.

Methods:

The literature available on various websites such as GoogleScholar, PubMed, Scopus. All the peer-reviewed articles were included without considering the impact factor.

Results:

The surveyed literature revealed marked inhibitory profile of various glycosides derived from plants, and some of them were extremely potent relatively to the standard, acarbose in preclinical trials and exhibited multiple targeted effects.

Conclusion:

Keeping in view the results, these glycosides are strong candidates for further, more detailed studies to ascertain their clinical potential and for effective contribution in effective management of diabetes, where multiple targets are required to address

A comprehensive review of topoisomerase inhibitors as anticancer agents in the past decade

The topoisomerase enzymes play an important role in DNA metabolism, and searching for enzyme inhibitors is an important target in the search for new anticancer drugs. Discovery of new anticancer chemotherapeutical capable of inhibiting topoisomerase enzymes is highlighted in anticancer research. Therefore, biologists, organic chemists and medicinal chemists all around the world have been identifying, designing, synthesizing and evaluating a variety of novel bioactive molecules targeting topoisomerase. This review summarizes types of topoisomerase inhibitors in the past decade, and divides them into nine classes by structural characteristics, including N-heterocycles compounds, quinone derivatives, flavonoids derivatives, coumarin derivatives, lignan derivatives, polyphenol derivatives, diterpenes derivatives, fatty acids derivatives, and metal complexes. Then we discussed the application prospect and development of these anticancer compounds, as well as concluded parts of their structural-activity relationships. We believe this review would be invaluable in helping to further search potential topoisomerase inhibition as antitumor agent in clinical usage.

Synthesis and anticancer activity of dimeric podophyllotoxin derivatives

Background

Podophyllotoxin is a potent cytotoxic agent and serves as a useful lead compound for the development of antitumor drugs. Several podophyllotoxin-derived antitumor agents, including etoposide, are currently in clinical use; however, their therapeutic efficacy is often limited due to side effects and the development of resistance by cancer cells. Previous studies have shown that 4β-1,2,3-triazole derivatives of podophyllotoxin exhibit more potent anticancer activity and better binding to topoisomerase-II than etoposide. The effect of dimerization of such derivatives on the anticancer activity has not been studied.

Methods

Two moieties of podophyllotoxin were linked at the C-4 position via 1,2,3-triazole rings to give a series of novel dimeric podophyllotoxin derivatives. 4β-Azido-substituted podophyllotoxin derivatives (23 and 24) were coupled with various dipropargyl functionalized linkers by utilizing the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to provide dimeric products in very good yield. The in vitro anticancer activity of the synthesized compounds was evaluated by MTT assay against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7, and SW480). The normal BEAS-2B (lung) cell line was also included for study in order to evaluate the cancer selectivity of the most active compound as compared with normal cells.

Results

A group of 16 dimeric podophyllotoxin derivatives with different linkers were synthesized and structurally characterized. Most compounds do not show significant cytotoxicity (IC₅₀ > 40 mM) against all five cancer cell lines. However, one compound (29) which bears a perbutyrylated glucose residue on the glycerol linker is highly potent against all five cancer cell lines tested, with IC₅₀ values ranging from 0.43 to 3.50 μM. This compound (29) also shows good selectivity towards cancer cell lines as compared with the normal BEAS-2B (lung) cell line, showing selectivity indexes from 4.4 to 35.7.

Conclusion

The anticancer activity of dimeric podophyllotoxin derivatives is generally speaking not improved as compared to their monomeric counterparts, and the potency of these dimeric derivatives can be largely affected by the nature of the linker between the two moieties. Among the synthesized derivatives, compound 29 is significantly more cytotoxic and selective towards cancer cells than etoposide and cisplatin, which are currently in clinical use. Compound 29 is a promising anticancer drug and needs further studies.

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

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

Assembled liposomes of dual podophyllotoxin phospholipid: preparation, characterization and in vivo anticancer activity

Aim: A novel amphiphilic prodrug dual podophyllotoxin (PPT) succinate glycerophosphorylcholine (Di-PPT-GPC) assembled liposomes was developed to improve efficiency of PPT. Materials & methods: Di-PPT-GPC liposomes were prepared by thin film technique and characterized by dynamic light scattering and cryo-electron microscopy. Results: In vitro release studies showed that Di-PPT-GPC liposomes could significantly release PPT in weakly acidic environment but had good stability under biological conditions. Methyl tetrazolium assay data revealed that the liposomes have comparable cytotoxicities to free PPT against MCF-7, HeLa and U87 cells. More importantly, in vivo antitumor evaluation indicated that Di-PPT-GPC liposomes exhibited favorable tumor growth inhibition without side effects. Conclusion: Di-PPT-GPC liposomes might have potential to promote the therapeutic effect of PPT for cancer therapy.