The cardiac glycoside convallatoxin inhibits the growth of colorectal cancer cells in a p53-independent manner

Glycosides as Potential Medicinal Components for Ulcerative Colitis: A Review

Ulcerative colitis (UC) is a chronic, non-specific disease of unknown etiology. The disease develops mainly in the rectum or colon, and the main clinical symptoms include abdominal pain, diarrhea, and purulent bloody stools, with a wide variation in severity. The specific causative factors and pathogenesis of the disease are not yet clear, but most scholars believe that the disease is caused by the interaction of genetic, environmental, infectious, immune, and intestinal flora factors. As for the treatment of UC, medications are commonly used in clinical practice, mainly including aminosalicylates, glucocorticoids, and immunosuppressive drugs. However, due to the many complications associated with conventional drug therapy and the tendency for UC to recur, there is an urgent need to discover new, safer, and more effective drugs. Natural compounds with biodiversity and chemical structure diversity from medicinal plants are the most reliable source for the development of new drug precursors. Evidence suggests that glycosides may reduce the development and progression of UC by modulating anti-inflammatory responses, inhibiting oxidative stress, suppressing abnormal immune responses, and regulating signal transduction. In this manuscript, we provide a review of the epidemiology of UC and the available drugs for disease prevention and treatment. In addition, we demonstrate the protective or therapeutic role of glycosides in UC and describe the possible mechanisms of action to provide a theoretical basis for preclinical studies in drug development.

Anticancer Activity of the Bioactive Extract of the Morel Mushroom (Morchella elata, Ascomycetes) from Kashmir Himalaya (India) and Identification of Major Bioactive Compounds

Morel mushrooms, Morchella species are highly nutritional, excellently edible and medicinal. Anticancer activity of M. elata, growing in forests of Kashmir Himalaya was studied. Ethyl acetate extract of fruiting bodies of M. elata (MEAE) was evaluated for cytotoxicity by MTT assay using Daltons lymphoma ascites (DLA), human colon cancer (HCT-116) and normal cell lines. Anti-carcinogenic and antiangiogenic activities of MEAE were tested using mouse models. Proapoptotic activity was detected by double staining of acridine orange-ethidium bromide assay. MEAE was partially purified by column chromatography and the bioactive compounds were identified by LC-MS analysis. The bioactive extract of M. elata showed significant cytotoxicic activity against DLA (P < 0.05), HCT-116 cell lines (P < 0.05) and did not possess appreciable adverse effect on the viability of normal cells. At a concentration of 100 µg/mL, 60% cell death was observed in HCT-116 cell line while 80% cell death was found in DLA cell line. The extract also possessed profound anticarcinogenic, antiangiogenic and proapoptotic activities. LC-MS analysis showed celastrol (RT 9.504, C29H38O4, MW 450.27), convallatoxin (RT 9.60, C29H42O10, MW 550.27), cucurbitacin A (RT 11.97, C32H46O9, MW 574.71) and madecassic acid (RT 14.35, C30H48O6, MW 504.70) as the major bioactive components. Current experimental studies indicated that bioactive extract of M. elata possessed significant anticancer activity. Being an excellently edible mushroom, the potential therapeutic use of M. elata and its bioactive extract in complementary therapy of cancer is envisaged.

Chemistry and anticancer activity of cardiac glycosides: A review

The objective of this review is an attempt to emphasize the development in the chemistry and to display review of diverse therapeutic actions of cardiac glycosides. Anticancer activity of cardiac glycosides is the main activity as discussed in this review. The aim of the review is to gather the recent researches on cardiac glycosides. The present manuscript gives the platform for the researcher to have complete literature on the topic.

Convallatoxin suppresses osteosarcoma cell proliferation, migration, invasion, and enhances osteogenic differentiation by downregulating parathyroid hormone receptor 1 (PTHR1) expression and inactivating Wnt/β-catenin pathway

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents. Convallatoxin, a natural cardiac glycoside, exhibits potent anti-tumor activities. Literature has confirmed that PTHR1 is highly expressed in OS tissues and cells and downregulation of PTHR1 could decrease the invasion and growth of OS cells and increase tumor differentiation. In addition, PTHR1 could activate Wnt signaling pathway to promote the malignant functions of OS. In the present study, MG63 and U2OS cells were treated with 0, 12.5, 25, and 50 nM convallatoxin in order to elucidate the precise function of convallatox on the malignant behaviors of OS cells. Moreover, MG63 and U2OS cells treated with convallatoxin were transfected with Ov-PTHR1 or sh-DKK1, aiming to explore whether convallatoxin impeded the malignant progression of OS by modulating PTHR1 and Wnt/β-catenin pathway. CCK-8, wound healing and transwell assays were employed to assess the proliferation, migration, and invasion of OS cells. Differentiation markers (collagen 1, osteopontin, RANKL, Runx2, osteocalcin) were measured to evaluate OS cell differentiation. Results illuminated that convallatoxin suppressed proliferation, migration, and invasion as well as promoted osteogenic differentiation of OS cells. Besides, convallatoxin inhibited PTHR1 expression and inactivated Wnt/β-catenin pathway and PTHR1 overexpression activated Wnt/β-catenin pathway. Furthermore, PTHR1 overexpression or DKK1 knockdown reversed the suppressing effects of convallatoxin on OS cell proliferation, migration, and invasion, as well as the enhancing effect of convallatoxin on OS cell osteogenic differentiation. Collectively, convallatoxin may repress the malignant progression of OS by blocking PTHR1 and Wnt/β-catenin pathway.

Cardiac glycosides from Digitalis lanata and their cytotoxic activities

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities. In this study, fifteen CGs including three new ones (1–3) were isolated from Digitalis lanata Ehrh. Their structures were elucidated by HRESIMS, NMR spectroscopic methods, including homonuclear and heteronuclear coupling constant analysis, and acid-catalyzed hydrolysis and derivatization analysis of the sugar chain. The cytotoxic activities of these CGs were evaluated against three human cancer cell lines (A549, HeLa and MCF-7 cell lines), and all of them showed strong activities at nanomolar scale. The flow cytometric analysis indicated that compound 1 induced cell cycle arrest in the G2/M phase. Transcriptome analysis revealed a panel of possible targets for compound 1. RT-PCR and western blot experiments showed that 1 significantly inhibited the expression of vasohibin-2 (VASH2). Moreover, compound 1 restrained angiogenesis in a concentration-dependent manner in the chick embryo chorioallantoic membrane (CAM) model.

Cardiac glycosides (CGs) are good candidates as drug leads in the treatment of cancer because of their structural diversities and potent biological activities.

Convallatoxin, the primary cardiac glycoside in lily of the valley (Convallaria majalis), induces tissue factor expression in endothelial cells

BACKGROUND

Convallotoxin (CNT), present in lily of the valley (Convallaria majalis), is a toxin that causes food poisoning among humans and companion animals. Although various symptoms of CNT poisoning have been well described, hypercoagulability owing to CNT is only empirically known among some veterinarians, and the underlying mechanism remains to be elucidated. CNT exerts cytotoxic effects on endothelial cells.

OBJECTIVES

This study aimed to determine whether CNT induces the expression of tissue factor (TF), a potent initiator of the extrinsic coagulation cascade, in endothelial cells and leads to a hypercoagulable state.

METHODS

Human umbilical vein endothelial cells (HUVECs) were used for in vitro experiments. HUVECs were treated with or without CNT (50 and 100 nM) for 4 h. Phosphate-buffered saline was used as a control. Cell viability was determined using the WST-8 assay. Quantitative real-time polymerase chain reaction was performed to determine TF mRNA expression. TF protein expression was observed using a laser scanning confocal microscope.

RESULTS

The viability of HUVECs significantly reduced after CNT treatment compared with that of non-treated cells (p < 0.05). Moreover, a significant increase in TF mRNA and protein expression was observed after 4 h of CNT treatment. CNT elicited these effects in a dose-dependent manner.

CONCLUSIONS

TF expression induced by CNT in endothelial cells can contribute to the development of a hypercoagulable state. The present study partially revealed the mechanisms underlying the CNT-induced hypercoagulable state. The findings can contribute to the development of a novel therapy for lily of the valley poisoning.

Emergence of Cardiac Glycosides as Potential Drugs: Current and Future Scope for Cancer Therapeutics

Cardiac glycosides are natural sterols and constitute a group of secondary metabolites isolated from plants and animals. These cardiotonic agents are well recognized and accepted in the treatment of various cardiac diseases as they can increase the rate of cardiac contractions by acting on the cellular sodium potassium ATPase pump. However, a growing number of recent efforts were focused on exploring the antitumor and antiviral potential of these compounds. Several reports suggest their antitumor properties and hence, today cardiac glycosides (CG) represent the most diversified naturally derived compounds strongly recommended for the treatment of various cancers. Mutated or dysregulated transcription factors have also gained prominence as potential therapeutic targets that can be selectively targeted. Thus, we have explored the recent advances in CGs mediated cancer scope and have considered various signaling pathways, molecular aberration, transcription factors (TFs), and oncogenic genes to highlight potential therapeutic targets in cancer management.

Anticancer and Antiviral Properties of Cardiac Glycosides: A Review to Explore the Mechanism of Actions

Cardiac glycosides (CGs) have a long history of treating cardiac diseases. However, recent reports have suggested that CGs also possess anticancer and antiviral activities. The primary mechanism of action of these anticancer agents is by suppressing the Na+/k+-ATPase by decreasing the intracellular K+ and increasing the Na+ and Ca2+. Additionally, CGs were known to act as inhibitors of IL8 production, DNA topoisomerase I and II, anoikis prevention and suppression of several target genes responsible for the inhibition of cancer cell proliferation. Moreover, CGs were reported to be effective against several DNA and RNA viral species such as influenza, human cytomegalovirus, herpes simplex virus, coronavirus, tick-borne encephalitis (TBE) virus and Ebola virus. CGs were reported to suppress the HIV-1 gene expression, viral protein translation and alters viral pre-mRNA splicing to inhibit the viral replication. To date, four CGs (Anvirzel, UNBS1450, PBI05204 and digoxin) were in clinical trials for their anticancer activity. This review encapsulates the current knowledge about CGs as anticancer and antiviral drugs in isolation and in combination with some other drugs to enhance their efficiency. Further studies of this class of biomolecules are necessary to determine their possible inhibitory role in cancer and viral diseases.

Implications for glycosylated compounds and their anti-cancer effects

Glycosylated compounds are major secondary metabolites of plants, which have various therapeutic effects on human diseases, by acting as anti-cancer, antioxidant, and anti-inflammatory agents. Glycosylation increases stability, bioactivity, and solubility of compounds and improves their pharmacological properties. Two well-known examples of glycosylated compounds include cardiac and flavonoid, the anti-tumor activities of which have been emphasized by several studies. However, little is known about their role in the treatment or prevention of cancer. In this review, recent studies on anti-tumor properties of cardiac and flavonoid glycosides, and their mechanisms of action, have been investigated. More specifically, this review is aimed at focusing on the multifactorial properties of cardiac and flavonoid compounds as well as their correlation with signaling pathways in the treatment of cancer.

Convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer

BACKGROUND

Aberrant activation of STAT3 is frequently encountered and promotes survival, cellular proliferation, migration, invasion and angiogenesis in tumor cell. Convallatoxin, triterpenoid ingredient, exhibits anticancer pharmacological properties.

PURPOSE

In this work, we investigated the anticancer potential of convallatoxin and explored whether convallatoxin mediates its effect through interference with the STAT3 activation in colorectal cancer cells.

METHODS

In vitro, the underlying mechanisms of convallatoxin at inhibiting STAT3 activation were investigated by homology modeling and molecular docking, luciferase reporter assay, MTT assay, RT-PCR, Western blotting and immunofluorescence assays. Changes in cellular proliferation, apoptosis, migration, invasion and angiogenesis were analyzed by EdU labeling assay, colony formation assay, flow cytometry assay, wound-healing assay, matrigel transwell invasion assay and tube formation assays. And in vivo, antitumor activity of convallatoxin was assessed in a murine xenograft model of HCT116 cells.

RESULTS

Convallatoxin decreased the viability of colorectal cancer lines. Moreover, convallatoxin reduced the P-STAT3 (T705) via the JAK1, JAK2, and Src pathways and inhibited serine-727 phosphorylation of STAT3 via the PI3K-AKT-mTOR-STAT3 pathways in colorectal cancer cells. Interestingly, we discovered the crosstalk between mTOR and JAK2 in mTOR/STAT3 and JAK/STAT3 pathways, which collaboratively regulated STAT3 activation and convallatoxin play a role in it. Convallatoxin also downregulated the expression of target genes involved cell survival (e.g., Survivin, Bcl-xl, Bcl-2), proliferation (e.g., Cyclin D1), metastasis (e.g., MMP-9), and angiogenesis (e.g., VEGF). Indeed, we found that convallatoxin inhibited tube formation, migration, and invasion of endothelial cells, and inhibited the proliferation. Finally, in vivo observations were confirmed by showing antitumor activity of convallatoxin in a murine xenograft model.

CONCLUSION

The result of the current study show that convallatoxin promotes apoptosis and inhibits proliferation and angiogenesis through crosstalk between JAK2/STAT3 (T705) and mTOR/STAT3 (S727) signaling pathways in colorectal cancer cells and indicate that convallatoxin could be a valuable candidate for the development of colorectal cancer therapeutic.

Proton NMR and HR-LC/MS based phytochemical analysis of methanolic fraction of Alectra parasitica A. Rich. rhizomes

INTRODUCTION

Alectra parasitica (Scrophulariaceae/Orobanchaceae) is a rarely occurring parasitic plant grows on roots of Vitex negundo L. (Verbenaceae). As per Indian system of medicine, Ayurveda, it can be used in treatment of various diseases. So far, this plant has not been explored phyto-chemically in detail. Non-small cell lung cancer (NSCLC) is mostly occurring type of lung cancer, which so far can be treated by chemotherapy approach including cisplatin.

AIM

Present research work was aimed towards preparation of methanolic fraction of A. parasitica rhizomes; its phytochemical analysis by 1H-NMR and HR-LC/MS; evaluation of its anti-cancer property against NSCLC-A549 cell line.

METHODS

For preparation of methanolic fraction (MF), A. parasitica rhizome powder was defatted; extracted with combination of water and alcohol (1:1); added with lead acetate and then sulphuric acid; fractionation of ethyl acetate fraction with methanol. After phytochemical analysis of MF by preliminary chemical testing, TLC, 1H-NMR and HR-LC/MS techniques, MF was screened for its anti - cancer property against NSCLC-A549 cell line by MTT assay.

RESULTS

Detail phytochemical analysis reflected successful preparation of tannin-less MF of A. parasitica rhizomes. Different types of analytical techniques first time proved the proved the presence of various types of phytochemicals in this plant. On MTT assay, it was found that MF has anti-cancer property against NSCLC-A549 cell line with IC50 value, 306.51 μg/ml.

CONCLUSION

MF contains different phytochemicals like iridoids, flavonoids, steroid glycosides and also strigalactones; which cumulatively exert anti-cancer effect on A549. Appearance of all these compounds is significant in chemotaxonomic surveillance of this rare plant and specially, strigalactones can be proved important in establishing their parasitism with host plant.

Hetero-Tricyclic Lead Scaffold as Novel PDE5A Inhibitor for Antihypertensive Activity: In Silico Docking Studies

Objective:

To screen the phytochemicals for phosphodiesterase 5A (PDE5A) inhibitory potential and identify lead scaffolds of antihypertensive phytochemicals using in silico docking studies.

Methods:

In this perspective, reported 269 antihypertensive phytochemicals were selected. Sildenafil, a PDE5A inhibitor was used as the standard. In silico docking study was carried out to screen and identify the inhibiting potential of the selected phytochemicals against PDE5A enzyme using vLife MDS 4.4 software.

Results:

Based on docking score, π-stacking, H-bond and ionic interactions, 237 out of 269 molecules were selected which have shown one or more interactions. Protein residue Gln817A was involved in H-boding whereas Val782A, Phe820A and Leu804A were involved in π-stacking interaction with ligand. The selected 237 phytochemicals were structurally diverse, therefore 82 out of 237 molecules with one or more tricycles were filtered out for further analysis. Amongst tricyclic molecules, 14 molecules containing nitrogen heteroatom were selected for lead scaffold identification which finally resulted in three different basic chemical backbones like pyridoindole, tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline as lead scaffolds.

Conclusion:

In silico docking studies revealed that nitrogen-containing tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline tricyclic lead scaffolds have emerged as novel PDE5A inhibitors for antihypertensive activity. The identified lead scaffolds may provide antihypertensive lead molecules after its optimization.

Enoxacin and Epigallocatechin Gallate (EGCG) Act Synergistically to Inhibit the Growth of Cervical Cancer Cells in Culture

Cervical cancer is a major cause of death in females worldwide. While survival rates have historically improved, there remains a continuous need to identify novel molecules that are effective against this disease. Here, we show that enoxacin, a drug most commonly used to treat a broad array of bacterial infections, is able to inhibit growth of the cervical cancer cells. Furthermore, our data show that epigallocatechin gallate (EGCG), a plant bioactive compound abundant in green tea, and known for its antioxidant effects, similarly functions as an antiproliferative agent. Most importantly, we provide evidence that EGCG functions synergistically against cancer cell proliferation in combined treatment with enoxacin. These data collectively suggest that enoxacin and EGCG may be useful treatment options for cases of cervical cancer.

Anticancer and Immunogenic Properties of Cardiac Glycosides

Cardiac glycosides (CGs) are natural compounds widely used in the treatment of several cardiac conditions and more recently have been recognized as potential antitumor compounds. They are known to be ligands for Na/K-ATPase, which is a promising drug target in cancer. More recently, in addition to their antitumor effects, it has been suggested that CGs activate tumor-specific immune responses. This review summarizes the anticancer aspects of CGs as new strategies for immunotherapy and drug repositioning (new horizons for old players), and the possible new targets for CGs in cancer cells.