Cytotoxic effect of carbohydrate derivatives of digitoxigenin involves modulation of plasma membrane Ca2+ -ATPase.

Cardiac glycosides, such as digoxin and digitoxin, are compounds that interact with Na+ /K+ -ATPase to induce anti-neoplastic effects; however, these cardiac glycosides have narrow therapeutic index. Thus, semi-synthetic analogs of digitoxin with modifications in the sugar moiety has been shown to be an interesting approach to obtain more selective and more effective analogs than the parent natural product. Therefore, the aim of this study was to assess the cytotoxic potential of novel digitoxigenin derivatives, digitoxigenin-α-L-rhamno-pyranoside (1) and digitoxigenin-α-L-amiceto-pyranoside (2), in cervical carcinoma cells (HeLa) and human diploid lung fibroblasts (Wi-26-VA4). In addition, we studied the anticancer mechanisms of action of these compounds by comparing its cytotoxic effects with the potential to modulate the activity of three P-type ATPases; Na+ /K+ -ATPase, sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA), and plasma membrane Ca2+ -ATPase (PMCA). Briefly, the results showed that compounds 1 and 2 were more cytotoxic and selectivity for HeLa tumor cells than the nontumor cells Wi-26-VA4. While the anticancer cytotoxicity in HeLa cells involves the modulation of Na+ /K+ -ATPase, PMCA and SERCA, the modulation of these P-type ATPases was completely absent in Wi-26-VA4 cells, which suggest the importance of their role in the cytotoxic effect of compounds 1 and 2 in HeLa cells. Furthermore, the compound 2 inhibited directly erythrocyte ghosts PMCA and both compounds were more cytotoxic than digitoxin in HeLa cells. These results provide a better understanding of the mode of action of the synthetic cardiac glycosides and highlights 1 and 2 as potential anticancer agents.

Periplogenin suppresses the growth of esophageal squamous cell carcinoma in vitro and in vivo by targeting STAT3.

The mortality rate of esophageal squamous cell carcinoma (ESCC) is higher than that of other cancers worldwide owing to a lack of therapeutic targets and related drugs. This study aimed to find new drugs by targeting an efficacious therapeutic target in ESCC patients. Signal transducer and activator of transcription 3 (STAT3) is hyperactive in ESCC. Herein, we identified a novel STAT3 inhibitor, periplogenin, which strongly inhibited phosphorylation of STAT3 at Tyr705. Docking models and pull-down assays revealed that periplogenin bound directly and specifically to STAT3, leading to significant suppression of subsequent dimerization, nuclear import, and transcription activities. In addition, STAT3 knockdown cell lines were insensitive to periplogenin, whereas in contrast, STAT3-overexpressing cells were more sensitive to periplogenin, indicating that STAT3 was a target of periplogenin. Intraperitoneally administered periplogenin exhibited efficacious therapeutic effects in ESCC patient-derived xenograft models and dramatically impaired the phosphorylation of STAT3 and expression levels of STAT3-mediated downstream genes. Thus, our study demonstrated that periplogenin acted as a new STAT3 inhibitor, suppressing the growth of ESCC in vitro and in vivo, providing a basis for its potential application in ESCC treatment and prevention.

Biased Effect of Cardiotonic Steroids on Na/K-ATPase-Mediated Signal Transduction.

Recent studies have revealed that Na/K-ATPase (NKA) can transmit signals through ion-pumping-independent activation of pathways relayed by distinct intracellular protein/lipid kinases, and endocytosis challenges the traditional definition that cardiotonic steroids (CTS) are NKA inhibitors. Although additional effects of CTS have long been suspected, revealing its agonist impact through the NKA receptor could be a novel mechanism in understanding the basic biology of NKA. In this study, we tested whether different structural CTS could trigger different sets of NKA/effector interactions, resulting in biased signaling responses without compromising ion-pumping capacity. Using purified NKA, we found that ouabain, digitoxigenin, and somalin cause comparable levels of NKA inhibition. However, although endogenous ouabain stimulates both protein kinases and NKA endocytosis, digitoxigenin and somalin bias to protein kinases and endocytosis, respectively, in LLC-PK1 cells. The positive inotropic effects of CTS are traditionally regarded as NKA inhibitors. However, CTS-induced signaling occurs at concentrations at least one order of magnitude lower than that of inotropy, which eliminates their well known toxic actions on the heart. The current study adds a novel mechanism that CTS could exert its biased signaling properties through the NKA signal transducer. SIGNIFICANCE STATEMENT: Although it is now well accepted that NKA has an ion-pumping-independent signaling function, it is still debated whether direct and conformation-dependent NKA/effector interaction is a key to this function. Therefore, this investigation is significant in advancing our understanding of the basic biology of NKA-mediated signal transduction and gaining molecular insight into the structural elements that are important for cardiotonic steroid's biased action.

Periplogenin Activates ROS-ER Stress Pathway to Trigger Apoptosis via BIP-eIF2α- CHOP and IRE1α-ASK1-JNK Signaling Routes.

BACKGROUND: Periplogenin (PPG), a natural compound isolated from traditional Chinese herb Cortex Periplocae, has been reported to possess anti-inflammatory and anti-cancer properties. OBJECTIVE: The present study aims to investigate the antitumor effects of PPG and the underlying mechanism in human colorectal cancer cells. METHODS: The inhibition of cell growth in vitro was assessed by MTT assay. The induction of apoptosis and the ROS production induced by PPG was investigated by flow cytometry analysis. Western blotting was applied to measure the protein expression. Small interference RNA (siRNA) and a specific pharmacological inhibitor were used to knock down or inhibit the expression of related genes. RESULTS: PPG was able to cause the production of ROS, inhibit the cancer cell growth and induce apoptosis. Nacetylcysteine was able to inhibit ROS production and apoptosis. PPG up-regulated the protein levels of BIP, peIF2α and CHOP as well as IRE1α and p-JNK, and down-regulated the protein level of p-ASK1, all of which were reversed by N-acetylcysteine. Importantly, knockdown of CHOP or JNK protein level attenuated the PPGelicited apoptosis. CONCLUSION: PPG-induced apoptosis was regulated by ROS-mediated BIP/eIF2α/CHOP and BIP/ASK1/JNK signaling pathways in colon cancer cells, suggesting that PPG is a promising therapeutic agent for the treatment of human colon cancer.

Investigation of the cytotoxic activity of two novel digitoxigenin analogues on H460 lung cancer cells.

Cardiac glycosides (CGs) are natural compounds traditionally used for the treatment of heart disorders, and recently new therapeutic possibilities were proposed. Their antitumor reports and clinical trials have notably enhanced, including those targeted for lung cancer, the most lethal type that lacks of new treatment agents, instigating the research of these molecules. The CGs studied here, named C10 {3ß-[(N-(2-hydroxyethyl)aminoacetyl]amino-3-deoxydigitoxigenin} and C18 (3ß-(aminoacetyl)amino-3-deoxydigitoxigenin), are semisynthetic derivatives prepared from digitoxigenin scaffold. Both compounds demonstrated high cytotoxicity for different cancer cell lines, especially H460 lung cancer cells, and their cytotoxic effects were deeply investigated using different methodological approaches. C10 induced cell death at lower concentrations and during shorter periods of treatment than C18, and increased the number of small and irregular nuclei, which are characteristics of apoptosis. This type of cell death was confirmed by caspase-3/7 assay. Both compounds reduced H460 cells proliferative potential by long-term action, and C10 showed the strongest potential. Moreover, these compounds induced a significant decrease of the area and viability of H460 spheroids providing preclinical favorable profiles to develop new chemotherapeutic agents.

Cytotoxic 20,22-Dihydrodigitoxigenin Glycosides and Other Constituents of Vallaris glabra Stems.

Ten cardiac glycosides (1-10) including six 20,22-dihydrodigitoxigenin and four gitoxigenin glycosides were isolated from the stems of Vallaris glabra together with six known triterpenoid cinnamates. Spectroscopic data of these previously undescribed compounds are reported. All isolates were evaluated for their growth inhibitory activities against three cancer cell lines, and compound 2 was the most active against KB cells with an IC50 value of 0.03 ± 0.001 µM. Also, compounds 1, 3, 5, and 6 and the triterpenoid cinnamates 11-13 showed inhibitory activity (IC50 < 10 µM) for one or more of the cell lines used.

The alpha-1 subunit of the Na+,K+-ATPase (ATP1A1) is required for macropinocytic entry of respiratory syncytial virus (RSV) in human respiratory epithelial cells.

Human respiratory syncytial virus (RSV) is the leading viral cause of acute pediatric lower respiratory tract infections worldwide, with no available vaccine or effective antiviral drug. To gain insight into virus-host interactions, we performed a genome-wide siRNA screen. The expression of over 20,000 cellular genes was individually knocked down in human airway epithelial A549 cells, followed by infection with RSV expressing green fluorescent protein (GFP). Knockdown of expression of the cellular ATP1A1 protein, which is the major subunit of the Na+,K+-ATPase of the plasma membrane, had one of the strongest inhibitory effects on GFP expression and viral titer. Inhibition was not observed for vesicular stomatitis virus, indicating that it was RSV-specific rather than a general effect. ATP1A1 formed clusters in the plasma membrane very early following RSV infection, which was independent of replication but dependent on the attachment glycoprotein G. RSV also triggered activation of ATP1A1, resulting in signaling by c-Src-kinase activity that transactivated epidermal growth factor receptor (EGFR) by Tyr845 phosphorylation. ATP1A1 signaling and activation of both c-Src and EGFR were found to be required for efficient RSV uptake. Signaling events downstream of EGFR culminated in the formation of macropinosomes. There was extensive uptake of RSV virions into macropinosomes at the beginning of infection, suggesting that this is a major route of RSV uptake, with fusion presumably occurring in the macropinosomes rather than at the plasma membrane. Important findings were validated in primary human small airway epithelial cells (HSAEC). In A549 cells and HSAEC, RSV uptake could be inhibited by the cardiotonic steroid ouabain and the digitoxigenin derivative PST2238 (rostafuroxin) that bind specifically to the ATP1A1 extracellular domain and block RSV-triggered EGFR Tyr845 phosphorylation. In conclusion, we identified ATP1A1 as a host protein essential for macropinocytic entry of RSV into respiratory epithelial cells, and identified PST2238 as a potential anti-RSV drug.

Anti-epileptic effect of 16-O-acetyldigitoxigenin via suppressing mTOR signaling pathway.

Epilepsy is a common chronic disease of the central nervous system that can last for years or even decades, causing serious adverse effects on the body, mind, and psychology of patients. Traditional antiepileptic drugs can effectively control seizures, but because of large individual differences, serious adverse reactions, narrow therapeutic window and other shortcomings, more effective, new treatment drugs are looked for. Streptocaulon griffithii is a plant of Asclepiadaceae. 16-O-acetyldigitoxigenin (ACE) is a strong cardiac glycoside isolated from methanol extract of Streptocaulon griffithii. The aim of this study was to investigate the antiepileptic effect of ACE on Pilocarpine (Pilo) induced epilepsy in mice, and to explore the effect of mTOR signaling pathway on its antiepileptic effect. The results showed that ACE had antiepileptic and neuroprotective effects on Pilo induced epilepsy mice. ACE attenuates Pilo induced seizures by inhibiting the activation of p-mTOR/p-70S6K pathway, and inhibits Pilocarpine induced brain damage by inhibiting mTOR signaling pathway. These results suggest that ACE has a promising future in the treatment of epilepsy and other nervous system diseases.

Potential anti-herpes and cytotoxic action of novel semisynthetic digitoxigenin-derivatives.

In recent years, new therapeutic possibilities were proposed for cardiac glycosides traditionally used to treat heart diseases, such as anticancer and antiviral activities. In this sense, this work aimed to synthesize the readily accessible 3ß-azido-3-deoxydigitoxigenin (5) from digitoxigenin (1). Two new series of compounds were obtained from derivative (5): (i) O-glycosyl trizols through click chemistry with propargyl glycosides; and (ii) compounds substituted in the alpha carbonyl position with different residues linked via an amino-group. All obtained derivatives have their chemical structures confirmed, and their anti-herpes (against HSV-types 1 and 2 replication) and cytotoxic (against PC3, A549, HCT-8 and LNCaP cell lines) activities evaluated. Compounds 10 and 11 exhibited the most promising results against HSV-1 (KOS and 29-R strains) and HSV-2 (333 strain) replication with SI values > 1000. Both compounds were also the most cytotoxic for the human cancer cell lines tested with IC50 values similar to those of paclitaxel. They also presented reduced toxicity toward non-cancerous cell lines (MRC-5 and HGF cells). Promising compounds were tested in regard to their ability to inhibit Na+/K+-ATPase. The inhibition rate correlates suitably with the bioactivity demonstrated by those both compounds against the different human cancer cells tested as well as against HSV replication. Moreover, the results showed that specific chemical features of compound 10 and 11 influenced the bioactivities tested. In summary, it was possible to obtain novel digitoxigenin-derivatives with remarkable cytotoxic and anti-herpes activities as well as low toxicity and high selectivity. In this way, they could be considered potential molecules for the development of new drugs.

Cytotoxicity of AMANTADIG - a semisynthetic digitoxigenin derivative - alone and in combination with docetaxel in human hormone-refractory prostate cancer cells and its effect on Na+/K+-ATPase inhibition.

Cardiac glycosides (CGs) are natural compounds used to treat congestive heart failure. They have garnered attention as a potential cancer treatment option, especially because they bind to Na+/K+-ATPase as a target and activate intracellular signaling pathways leading to a variety of cellular responses. In this study we evaluated AMANTADIG, a semisynthetic cardenolide derivative, for its cytotoxic activity in two human androgen-insensitive prostate carcinoma cell lines, and the potential synergistic effects with docetaxel. AMANTADIG induced cytotoxic effects in both cell lines, and a combination with docetaxel showed a moderate and strong synergism in DU145 and PC-3 cells, respectively, at concentrations considerably lower than their IC50 values. Cell cycle analyses showed that AMANTADIG and its synergistic combination induced G2/M arrest of DU145 and PC-3 cells by modulating Cyclin B1, CDK1, p21 and, mainly, survivin expression, a promising target in cancer therapy. Furthermore, AMANTADIG presented reduced toxicity toward non-cancerous cell type (PBMC), and computational docking studies disclosed high-affinity binding to the Na+/K+-ATPase α subunit, a result that was experimentally confirmed by Na+/K+-ATPase inhibition assays. Hence, AMANTADIG inhibited Na+/K+-ATPase activity in PC-3 cells, as well as in purified pig kidney at nanomolar range. Altogether, these data highlight the potent effects of AMANTADIG in combination with docetaxel and offer important insights for the development of more effective and selective therapies against prostate cancer.

Cytotoxic and cytostatic effects of digitoxigenin monodigitoxoside (DGX) in human lung cancer cells and its link to Na,K-ATPase.

Cardiac glycosides (CGs) are natural compounds widely used to treat several cardiac conditions and more recently have been recognized as potential antitumor agents. They are known as Na,K-ATPases ligands, which is a promising drug target in cancer. In this study, the short and long-lasting cytotoxic effects of the natural cardenolide digitoxigenin monodigitoxoside (DGX) were evaluated against two non-small cell lung cancer lines (A549 and H460 cells). It was found that DGX induced cytotoxic effects in both cells and the apoptotic effects were more pronounced on H460 cells. In long-term analysis, using the clonogenic and the cumulative population doubling (CPD) assays, DGX showed a reduction of cell survival, after 15days without re-treatment. To better understand DGX effects in A549 cells, several assays were conducted. In cell cycle analysis, DGX caused an arrest in S and G2/M phases. This compound also increased the number of cells in subG1 phase in a concentration- and time-dependent manner. The presence of ß-galactosidase positive cells, large nucleus and flattened cells indicated senescence. Additionally, DGX inhibited Na,K-ATPase activity in A549 cells, as well as in purified pig kidney and in human red blood cell membrane preparations, at nanomolar range. Moreover, results of molecular docking showed that DGX binds with high efficiency (-11.4Kcal/mol) to the Na,K-ATPase (PDB:4HYT). Taken together, our results highlight the potent effects of DGX both in A549 and H460 cells, and disclose its link with Na,K-ATPase inhibition.

A new semisynthetic cardenolide analog 3ß-[2-(1-amantadine)- 1-on-ethylamine]-digitoxigenin (AMANTADIG) affects G2/M cell cycle arrest and miRNA expression profiles and enhances proapoptotic survivin-2B expression in renal cell carcinoma cell lines.

Cardiac glycosides are well known in the treatment of cardiovascular diseases; however, their application as treatment option for cancer patients is under discussion. We showed that the cardiac glycoside digitoxin and its analog AMANTADIG can inhibit the growth of renal cell carcinoma (RCC) cell lines and increase G2/M cell cycle arrest. To identify the signaling pathways and molecular basis of this G2/M arrest, microRNAs were profiled using microRNA arrays. Cardiac glycoside treatment significantly deregulated two microRNAs, miR-2278 and miR-670-5p. Pathway enrichment analysis showed that all cardiac glycoside treatments affected the MAPK and the axon guidance pathway. Within these pathways, three genes, MAPK1, NRAS and RAC2, were identified as in silico targets of the deregulated miRNAs. MAPK1 and NRAS are known regulators of G2/M cell cycle arrest. AMANTADIG treatment enhanced the expression of phosphorylated MAPK1 in 786-O cells. Secondly, we studied the expression of survivin known to be affected by cardiac glycosides and to regulate the G2/M cell phase. AMANTADIG treatment upregulated the expression of the pro-apoptotic survivin-2B variant in Caki-1 and 786-O cells. Moreover, treatment with AMANTADIG resulted in significantly lower survivin protein expression compared to 786-O control cells. Summarizing, treatment with all cardiac glycosides induced G2/M cell cycle arrest and downregulated the miR-2278 and miR-670-5p in microarray analysis. All cardiac glycosides affected the MAPK-pathway and survivin expression, both associated with the G2/M phase. Because cells in the G2/M phase are radio- and chemotherapy sensitive, cardiac glycosides like AMANTADIG could potentially improve the efficacy of radio- and/or chemotherapy in RCCs.

Molecular docking of the anticancer bioactive compound proceraside with macromolecules involved in the cell cycle and DNA replication.

The bioactive compounds proceraside A, frugoside and calotropin, which were extracted from the root bark of Calotropis procera (Aiton) W.T. Aiton (family Asclepiadaceae), were recently reported to inhibit the growth of inhibition against various human cancer cell lines in vitro. However, their modes of action have not been clearly defined. Therefore, we attempted an in silico approach to gain insights into their binding modes against the following selected molecular targets: CDK-2, CDK-6, topoisomerase I, BCL-2, VEGFR-2, telomere: G-quadruplex, and topoisomerase II. These targets were selected based on their key roles in cancer progression via the regulation of the cell cycle and DNA replication. Molecular-docking analyses revealed that proceraside A was the best docked ligand against all the targets, with the exception of telomere-G: quadruplex. Furthermore, it displayed the lowest binding energies and inhibition constants, and critical hydrogen bonds and hydrophobic interactions with the targets were also revealed. The present study may aid in the identification of possible targets for proceraside A, and might provide a plausible explanation for its proven anti-tumor activities. Moreover, the result of this study may further guide structure-activity relationship studies used to generate more potent target-specific inhibitors.

Periplogenin induces necroptotic cell death through oxidative stress in HaCaT cells and ameliorates skin lesions in the TPA- and IMQ-induced psoriasis-like mouse models.

Psoriasis is a multifactorial skin disease that inconveniences many patients. Considering the side effects and drug resistance of the current therapy, it is urgent to discover more effective and safer anti-psoriatic drugs. In the present study, we screened over 250 traditional Chinese medicine compounds for their ability to inhibit the cell viability of cultured human HaCaT keratinocytes, a psoriasis-relevant in vitro model, and found that periplogenin was highly effective. Mechanistic studies revealed that apoptosis and autophagy were not induced by periplogenin in HaCaT cells. However, periplogenin caused PI to permeate into cells, increased lactate LDH release and rapidly increased the number of necrotic cells. Additionally, the typical characteristics of necrosis were observed in the periplogenin-treated HaCaT cells. Notably, the necroptosis inhibitor Nec-1 and NSA were able to rescue the cells from necrotic cell death, supporting that necroptosis was involved in periplogenin-induced cell death. Furthermore, the ROS levels were elevated in the periplogenin-treated cells, NAC (an antioxidant) and Nec-1 could inhibit the ROS levels, and NAC could attenuate necroptotic cell death, indicating that the periplogenin-induced necroptotic cell death was mediated by oxidative stress. More importantly, in the murine models of TPA-induced epidermal hyperplasia and IMQ-induced skin inflammation, topical administration of periplogenin ameliorated skin lesions and inflammation. In sum, our results indicate, for the first time, that periplogenin is a naturally occurring compound with potent anti-psoriatic effects in vitro and in vivo, making it a promising candidate for future drug research.

Inhibition of cell proliferation, invasion and migration by the cardenolides digitoxigenin monodigitoxoside and convallatoxin in human lung cancer cell line.

Cardiac glycosides consist of a large family of naturally derived compounds that are clinically used to treat congestive heart failure, and also present anticancer properties. In this study, the cytotoxic effects of two cardenolides, digitoxigenin monodigitoxoside (DGX) and convallatoxin (CON) were screened in four human tumour cell lines. Both compounds showed anti-proliferative effects in all tumour cells, at nanomolar concentrations. Since the human lung cancer cell line A549 was the most sensitive, we investigated the anti-proliferative, anti-migratory and anti-invasive effects of these cardenolides. DGX and CON reduced A549 cell migration, being able to reduce more than 90% of cell invasion. Their effects on the expression of key regulators of metastatic mechanism showed decreased levels of MMP-2, MMP-9 and p-FAK. Both compounds also presented low toxicity for healthy cells. Finally, this work provides the first insights into the effects of these cardenolides on key steps of lung cancer metastasis.

The New Semisynthetic Cardenolide Analog 3ß-[2-(1-Amantadine)-1-on-ethylamine]-digitoxigenin (AMANTADIG) Efficiently Suppresses Cell Growth in Human Leukemia and Urological Tumor Cell Lines.

BACKGROUND/AIM: The use of cardenolides in the treatment of cardiac insufficiency is well-established. However, the potential of cardenolides in tumor therapy has not been comprehensively studied. The aim of the present study was to characterize the cytotoxic effects of the new semisynthetic cardenolide analog AMANTADIG (3ß-[2-(1-amantadine)-1-on-ethylamine]-digitoxigenin), and the cardenolide digitoxin on leukemia and urological tumor cell lines. MATERIALS AND METHODS: The anti-proliferative effects of AMANTADIG and digitoxin on leukemia and urological cancer cell lines were analyzed using (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction viability assay. RESULTS: AMANTADIG and digitoxin exhibited anti-proliferative activities against the leukemia cell lines in the low nanomolar range. The prostate cancer and renal cell carcinoma cell lines were equally sensitive to AMANTADIG and digitoxin, however, the leukemia cell lines were more sensitive to both cardenolides. CONCLUSION: The new cardenolide analog AMANTADIG appears effective in cell growth inhibition of leukemia and urological tumor cell lines.

Cardenolide aglycones inhibit tumor necrosis factor α-induced expression of intercellular adhesion molecule-1 at the translation step by blocking Na⁺/K⁺-ATPase.

Cardiac glycosides, which are inhibitors of Na(+)/K(+)-ATPase, are classified into cardenolides and bufadienolides. We have recently shown that two cardenolide glycosides, ouabain and odoroside A, inhibit Na(+)/K(+)-ATPase, thereby preventing nuclear factor κB-inducible protein expression by blocking Na(+)-dependent amino acid transport. In this study, we investigated the mechanism of action of cardenolide aglycones in tumor necrosis factor α (TNF-α)-induced gene expression. Ouabagenin, digitoxigenin, and digoxigenin were found to inhibit the TNF-α-induced cell-surface expression of intercellular adhesion molecule-1 (ICAM-1) in human lung carcinoma A549 cells. Those cardenolide aglycones did not inhibit the TNF-α-induced expression of ICAM-1 mRNA, but strongly inhibited the TNF-α-induced expression of ICAM-1 as translation product. The inhibition of the TNF-α-induced ICAM-1 expression by ouabagenin, digitoxigenin, and digoxigenin was significantly reversed by the ectopic expression of ouabain-resistant rat Na(+)/K(+)-ATPase α1 isoform. Moreover, knockdown of Na(+)/K(+)-ATPase α1 isoform augmented the inhibition of the TNF-α-induced ICAM-1 expression by ouabagenin or ouabain. These results clearly indicate that cardenolide aglycones inhibit the TNF-α-induced ICAM-1 expression at the translation step by blocking Na(+)/K(+)-ATPase.

C3'/C4'-Stereochemical Effects of Digitoxigenin α-L-/α-D-Glycoside in Cancer Cytotoxicity.

Sweet'n low in stereo: A Wharton reaction was employed along with a diastereoselective palladium-catalyzed glycosylation and other post-glycosylation transformations to synthesize digitoxin analogues. Cytotoxic evaluation against a panel of cancer cell lines uncovered the stereochemical and substitutional limits of the C3'/C4'-hydroxy functionality in digitoxin monosaccharide.

A cardiac glucoside with in vitro anti-HIV activity isolated from Elaeodendron croceum.

Human immunodeficiency virus (HIV) affects more than 40 million people worldwide and more than 5 million in South Africa alone. There is no cure for the disease yet, and novel effective drugs need to be discovered to make any progress in combating the disease. Twelve extracts from indigenous South African plants were analysed, of which Elaeodendron croceum showed potent inhibition of transcription factors and a recombinant HIV strain in an MT-2 VSV-pseudotyped recombinant virus assay at 100 ng mL(-1). Bioassay guided isolation of an ethanolic extract of E. croceum yielded a well-known digitoxigenin-glucoside as the only active compound. It showed significant inhibition (90%) at 0.2 µM. The in vitro toxicity of digitoxigenin-glucoside proved to be quite low, and its therapeutic index was 250. This observation indicates that digitoxigenin-glucoside could represent a potential pharmacophore for the treatment of HIV from natural sources.

Periplogenin-3-O- -D-glucopyranosyl -(1-->6)- -D-glucopyaranosyl- -(1-->4) -D-cymaropyranoside, isolated from Aegle marmelos protects doxorubicin induced cardiovascular problems and hepatotoxicity in rats.

Doxorubicin is a common chemotherapeutic anticancer drug. Its use is associated with adverse effects including cardiotoxicity. Several therapeutics interventions have been attempted to reduce the toxicity and to improve the efficacy of the drug. However, on phytochemicals very few investigations have been made. In the present study we have evaluated the potential of a cardenolide, periplogenin, isolated from the leaves of Aegle marmelos in protecting the doxorubicin induced cardiotoxicity and lipid peroxidation (LPO) in rats. Doxorubicin induced cardiac and hepatotoxicity were characterized by marked biochemical changes including an increase in serum creatine kinase-MB (CK-MB), glutamate-pyruvate transaminase (SGPT), and tissue LPO, with a decrease in superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). It also increased the levels of different serum lipids, but decreased the amount of high-density lipoprotein (HDL). Cotherapy of the test cardenolide and doxorubicin for 4 weeks reversed all these adverse effects. However, out of three different concentrations (12.5, 25, and 50 mg/kg p.o.) of the test periplogenin, 25 mg/kg appeared to be most effective. When its efficacy was compared with that of vitamin E (alpha-tocopherol) the isolated compound exhibited a better therapeutic potential. The isolated periplogenin from the leaves of A. marmelos could potentially inhibit doxorubicin-induced cardiovascular problems in rats. However, its moderate dose was found to be most effective.