Bioassay-Guided Fractionation and Biological Activity of Cardenolides from Streptocaulon juventas.

The discovery that Na/K-ATPase acts as a signal transducer led us to investigate the structural diversity of cardiotonic steroids and study their ligand effects. By applying Na/K-ATPase activity assay-guided fractionation, we isolated a total of 20 cardiotonic steroids from Streptocaulon juventas, including an undescribed juventasoside B (10: ) and 19 known cardiotonic steroids. Their structures have been elucidated. Using our platform of purified Na/K-ATPase and an LLC-PK1 cell model, we found that 10: , at a concentration that induces less than 10% Na/K-ATPase inhibition, can stimulate the Na/K-ATPase/Src receptor complex and selectively activate downstream pathways, ultimately altering prostate cancer cell growth. By assessing the ligand effect of the isolated cardiotonic steroids, we found that the regulation of cell viability by the isolated cardiotonic steroids was not associated with their inhibitory potencies against Na/K-ATPase activity but reflected their ligand-binding affinity to the Na/K-ATPase receptor. Based on this discovery, we identified a unique active cardiotonic steroid, digitoxigenin (1: ), and verified that it can protect LLC-PK1 cells from hypoxic injury, implicating its potential use in ischemia/reperfusion injury and inducing collagen synthesis in primary human dermal fibroblast cells, and implicating that compound 2: is the molecular basis of the wound healing activity of S. juventas.

Quantification of plant cardenolides by HPLC, measurement of Na+/K+-ATPase inhibition activity, and characterization of target enzymes.

The biosynthesis of cardiac glycosides, broadly classified as cardenolides and bufadienolides, has evolved repeatedly among flowering plants. Individual species can produce dozens or even hundreds of structurally distinct cardiac glycosides. Although all cardiac glycosides exhibit biological activity by inhibiting the function of the essential Na+/K+-ATPase in animal cells, they differ in their level of inhibitory activity. For within- and between-species comparisons of cardiac glycosides to address ecological and evolutionary questions, it is necessary to not only quantify their relative abundance, but also their effectiveness in inhibiting the activity of different animal Na+/K+-ATPases. Here we describe protocols for characterizing the amount and toxicity of cardenolides from plant samples and the degree of insect Na+/K+-ATPase tolerance to inhibition: (1) an HPLC-based assay to quantify the abundance of individual cardenolides in plant extracts, (2) an assay to quantify inhibition of Na+/K+-ATPase activity by plant extracts, and (3) extraction of insect Na+/K+-ATPases for inhibition assays.

Effects of Lipophilicity and Structural Features on the Antiherpes Activity of Digitalis Cardenolides and Derivatives.

There is growing interest in exploring Digitalis cardenolides as potential antiviral agents. Hence, we herein investigated the influence of structural features and lipophilicity on the antiherpes activity of 65 natural and semisynthetic cardenolides assayed in vitro against HSV-1. The presence of an α,ß-unsaturated lactone ring at C-17, a ß-hydroxy group at C-14 and C-3ß-OR substituents were considered essential requirements for this biological activity. Glycosides were more active than their genins, especially monoglycosides containing a rhamnose residue. The activity enhanced in derivatives bearing an aldehyde group at C-19 instead of a methyl group, whereas inserting a C-5ß-OH improved the antiherpes effect significantly. The cardenolides lipophilicity was accessed by measuring experimentally their log P values (n-octanol-water partition coefficient) and disclosed a range of lipophilicity (log P 0.75±0.25) associated with the optimal antiherpes activity. In silico studies were carried out and resulted in the establishment of two predictive models potentially useful to identify and/or optimize novel antiherpes cardenolides. The effectiveness of the models was confirmed by retrospective analysis of the studied compounds. This is the first SAR study addressing the antiherpes activity of cardenolides. The developed computational models were able to predict the active cardenolides and their log P values.

Efficacy of oleandrin and PBI-05204 against bovine viruses of importance to commercial cattle health.

BACKGROUND: Bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV). and bovine coronavirus (BCV) threaten the productivity of cattle worldwide. Development of therapeutics that can control the spread of these viruses is an unmet need. The present research was designed to explore the in vitro antiviral activity of the Nerium oleander derived cardiac glycoside oleandrin and a defined N. oleander plant extract (PBI-05204) containing oleandrin. METHODS: Madin Darby Bovine Kidney (MDBK) cells, Bovine Turbinate (BT) cells, and Human Rectal Tumor-18 (HRT-18) cells were used as in vitro culture systems for BVDV, BRSV and BCV, respectively. Cytotoxicity was established using serial dilutions of oleandrin or PBI-05204. Noncytotoxic concentrations of each drug were used either prior to or at 12 h and 24 h following virus exposure to corresponding viruses. Infectious virus titers were determined following each treatment. RESULTS: Both oleandrin as well as PBI-05204 demonstrated strong antiviral activity against BVDV, BRSV, and BCV, in a dose-dependent manner, when added prior to or following infection of host cells. Determination of viral loads by PCR demonstrated a concentration dependent decline in virus replication. Importantly, the relative ability of virus produced from treated cultures to infect new host cells was reduced by as much as 10,000-fold at noncytotoxic concentrations of oleandrin or PBI-05204. CONCLUSIONS: The research demonstrates the potency of oleandrin and PBI-05204 to inhibit infectivity of three important enveloped bovine viruses in vitro. These data showing non-toxic concentrations of oleandrin inhibiting infectivity of three bovine viruses support further investigation of in vivo antiviral efficacy.

Two cardenolide glycosides from the seed fairs of Asclepias curassavica and their cytotoxic activities.

Two cardenolide glycosides, corotoxigenin 3-O-[ß-D-glucopyranosyl-(1→4)-6-deoxy-ß-D-glucopyranoside] (1) and coroglaucigenin 3-O-[ß-D-glucopyranosyl-(1→4)-6-deoxy-ß-D-glucopyranoside] (2), were isolated from the seed fairs of Asclepias curassavica. The structures of 1-2 were determined based on the combination of the analysis of their MS, NMR spectroscopic data and acid hydrolysis. The inhibitory effects of compounds 1 and 2 on human colorectal carcinoma cells (HCT116), non-small cell lung carcinoma cells (A549) and hepatic cancer cells (SMMC-7721) were evaluated. The results showed that both compounds 1 and 2 significantly inhibited the viability, proliferation, and migration of A549, HCT116 and SMMC-7721 cells, suggesting that compounds 1 and 2 can be applied in the treatment of lung, colon and liver cancers in clinical practice. This study may not only provide a scientific basis for clarifying the active ingredients in A. curassavica, but also help to understand its antitumor activity, which can promote the application of A. curassavica in clinical treatment of various cancers.

Antiproliferative activity of standardized herbal phytopreparation from Asclepias subulata.

Background: Several studies have shown that active compounds of Asclepias subulata (cardenolides) have antiproliferative effect on human cancer cells. Cardenolides isolated from A. subulata can be used as active chemical markers to elaborate phytopharmaceutical preparations. To evaluate the antiproliferative effect of a standardized extract of the aerial parts, based on Asclepias subulata cardenolides. Methods: Four standardized extracts were prepared by HPLC-DAD depending on the concentration of calotropin and the antiproliferative activity was measured for the MTT assay, on the A549, MCF-7, HeLa, PC3 and ARPE cell lines. The concentrations of calotropin used for the standardization of the extracts were 10, 7.6, 5 and 1 mg/dL. Results: Standardization of the A. subulata extract based on calotropin at 7.6 mg/g dry weight was achieved and the antiproliferative activity was evaluated over A549, HeLa and MCF-7 cell lines, obtaining proliferation percentages of 3.8 to 13.4% . Conclusions: The standardized extracts of A. subulata at different concentrations of calotropin showed antiproliferative activity against all the cell lines evaluated. The greatest effect was observed against the HeLa cell line.

Antitumour effect of odoroside A and its derivative on human leukaemia cells through the ROS/JNK pathway.

Oleandrigenin-3-O-ß-D-diginoside (a derivative of odoroside A), isolated and purified by our group, has seldom been explored for its pharmacological activity. This study aimed at clarifying the mechanisms towards the leukaemia-suppressive role of odoroside A (compound #1) and its derivative, oleandrigenin-3-O-ß-D-diginoside (compound #2) isolated from Nerium oleander. Viability and nuclear morphology change were assessed by CCK-8 assay and fluorescence microscope, respectively. Then, the cell apoptosis and autophagy induced by the compounds were detected by flow cytometry and Western blot. Xenograft model of nude mice was also applied to measure the leukaemia-suppressive effects of compound #2 in vivo. The result displayed that compound #1 and compound #2 inhibited the proliferation of HL60 and K562 cells and stronger effects were found in HL60 than K562 cells. Both of the compounds induced a dose-dependent apoptosis and autophagy in HL60 cells, where compound #2 was more potent than compound #1. Compound #2 also demonstrated a time-dependent apoptosis and autophagy in HL60 cells. Furthermore, ROS generation and JNK phosphorylation occurred in a dose-dependent manner in the cells treated with compound #2. Mitochondria also played critical role, proved by the decrease of Bcl-2, the release of cyto c to cytosol and the activation of caspase-3 and caspase-9. Moreover, the antitumour effects of compound #2 were validated in the nude mouse xenograft model in vivo. Odoroside A and its derivative inhibited the growth of leukaemia by inducing apoptosis and autophagy through the activation of ROS/JNK pathway. These results suggest that the compounds can serve as potential antitumour agents against leukaemia, especially acute myeloid leukaemia (AML).

Antiviral activity of oleandrin and a defined extract of Nerium oleander against SARS-CoV-2.

With continued expansion of the coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome 2 (SARS-CoV-2), both antiviral drugs as well as effective vaccines are desperately needed to treat patients at high risk of life-threatening disease. Here, we present in vitro evidence for significant inhibition of SARS-CoV-2 by oleandrin and a defined extract of N. oleander (designated as PBI-06150). Using Vero cells, we found that prophylactic (pre-infection) oleandrin (as either the pure compound or as the active principal ingredient in PBI-06150) administration at concentrations as low as 0.05 µg/ml exhibited potent antiviral activity against SARS-CoV-2, with an 800-fold reduction in virus production, and a 0.1 µg/ml concentration resulted in a greater than 3000-fold reduction in infectious virus production. The half maximal effective concentration (EC50) values were 11.98 ng/ml when virus output was measured at 24 h post-infection, and 7.07 ng/ml measured at 48 h post-infection. Therapeutic (post-infection) treatment up to 24 h after SARS-CoV-2 infection of Vero cells also reduced viral titers, with 0.1 µg/ml and 0.05 µg/ml concentrations causing greater than 100-fold reduction as measured at 48 h, and the 0.05 µg/ml concentration resulting in a 78-fold reduction. Concentrations of oleandrin up to 10 µg/ml were well tolerated in Vero cells. We also present in vivo evidence of the safety and efficacy of defined N. oleander extract (PBI-06150), which was administered to golden Syrian hamsters in a preparation containing as high as 130 µg/ml of oleandrin. In comparison to administration of control vehicle, PBI-06150 provided a statistically significant reduction of the viral titer in the nasal turbinates (nasal conchae). The potent prophylactic and therapeutic antiviral activities demonstrated here, together with initial evidence of its safety and efficacy in a relevant hamster model of COVID-19, support the further development of oleandrin and/or defined extracts containing this molecule for the treatment of SARS-CoV-2 and associated COVID-19 disease and potentially also for reduction of virus spread by persons diagnosed early after infection.

Anticancer Cardenolides from the aerial parts of Calortopis procera.

Column chromatography (CC) analysis of methanol and butanol extracts of the aerial parts of Calortopis procera as well as the methanol extract of its latex, led to the isolation of 8 cardenolides, of which the structures were elucidated by NMR and HRESIMS spectroscopy. They also revealed several triterpenes and flavonoid glycoside. Based on the antiproliferative activity reported for cardenolides, the activity of calotropin and calotoxin was tested against two common cancer cell lines, human triple-negative breast cancer cell line (MDA-MB-231) and human lung adenocarcinoma cell line (A549). The high toxicity of the latex also encouraged performing the same test on the same cancer cell lines. The anti-proliferative activity of calotropin and calotoxin was compared to the methanol extract and the wax of the latex. The results showed that calotropin and calotoxin have significant cytotoxicity against MDA-MB-231 and A549 cell lines ranging from 0.046 to 0.072 µM compared to the methanol extract and the wax of its latex ranging from 0.47 to 58.41 µM. Moreover, the results showed lower toxicity of all treatments to the human skin fibroblasts compared to the toxicity to both MDA-MB-231 and A549 cancer cells lines except the higher toxicity of Methanolic extracts of C. procera latex to the MDA-MB-231 cells. In conclusion, C. procera is a medicinal plant with a wide spectrum of cardinolides including calotropin and calotoxin, which are promising agents for targeted cancer phytotherapy.

Non-classical cardenolides from Calotropis gigantea exhibit anticancer effect as HIF-1 inhibitors.

Six new non-classical cardenolides (1-6), and seventeen known ones (7-23) were isolated from Calotropis gigantea. All cardenolides showed inhibitory effect on hypoxia inducible factor-1 (HIF-1) transcriptional activity with IC50 of 8.85 nM-16.69 µM except 5 and 7. The novel 19-dihydrocalotoxin (1) exhibited a comparable HIF-1 inhibitory activity (IC50 of 139.57 nM) to digoxin (IC50 of 145.77 nM), a well-studied HIF-1 inhibitor, and 11, 12, 14, 16 and 19 presented 1.4-15.4 folds stronger HIF-1 inhibition than digoxin. 1 and 11 showed a dose-dependent inhibition on HIF-1α protein, which led to their HIF-1 suppressing effects. Compared with LO2 and H9c2 normal cell lines, both 1 and 11 showed selective cytotoxicity against various cancer cell lines including HCT116, HeLa, HepG2, A549, MCF-7, A2780 and MDA-MB-231. Moreover, a comprehensive structure-activity relationship was concluded for these non-classical cardenolides as HIF-1 inhibitors, which may shed some light on the rational design and development of cardenolide-based anticancer drugs.

Screening of Promising Chemotherapeutic Candidates from Plants against Human Adult T-Cell Leukemia/Lymphoma (VI): Cardenolides from Asclepias curassavica.

In the course of our screening program for novel chemotherapeutic candidates from plants against adult T-cell leukemia/lymphoma, the extracts of Asclepias curassavica L. showed potent activity against MT-1 and MT-2 cells. Therefore, we attempted to isolate their active components. We identified a new cardenolide, 19-dihydrocalactinic acid methyl ester (1), along with 16 known cardenolides (2-17). Their structures were determined on the basis of spectroscopic data. Almost all of the isolated cardenolides inhibited the growth of both tumor cell lines. All the doubly linked cardenolides (11-17) except for 14 showed more potent activity than the other cardenolides. A comparison of the activities of 11, 14 and 16 revealed that the presence of hydroxy or acetoxy functional groups at C-16 led to a decrease in the activity. The 50% effective concentration (EC50) value of calotropin (11) against MT-2 cells was comparable to the potency of the clinical antineoplastic drug doxorubicin. The cytotoxic effect of 11 toward normal mononuclear cells obtained from the peripheral blood (PB-MNCs) was observed at a concentration 6 to 12 times higher than that used to induce growth inhibition against MT-1 and MT-2 cells. The proportions of annexin V-positive cells after 72 h of treatment with 11 were increased, indicating that it significantly induced apoptosis in MT-1 and MT-2 cells in a concentration-dependent manner. Cell cycle experiments demonstrated that 11 arrested MT-1 and MT-2 cells at the G2/M phase. Therefore, compound 11 may be a promising candidate for the treatment of adult T-cell leukemia/lymphoma.

Elucidation of the mechanism of anti-herpes action of two novel semisynthetic cardenolide derivatives.

Human herpesviruses are among the most prevalent pathogens worldwide and have become an important public health issue. Recurrent infections and the emergence of resistant viral strains reinforce the need of searching new drugs to treat herpes virus infections. Cardiac glycosides are used clinically to treat cardiovascular disturbances, such as congestive heart failure and atrial arrhythmias. In recent years, they have sparked new interest in their potential anti-herpes action. It has been previously reported by our research group that two new semisynthetic cardenolides, namely C10 (3ß-[(N-(2-hydroxyethyl)aminoacetyl]amino-3-deoxydigitoxigenin) and C11 (3ß-(hydroxyacetyl)amino-3-deoxydigitoxigenin), exhibited potential anti-HSV-1 and anti-HSV-2 with selectivity index values > 1,000, comparable with those of acyclovir. This work reports the mechanism investigation of anti-herpes action of these derivatives. The results demonstrated that C10 and C11 interfere with the intermediate and final steps of HSV replication, but not with the early stages, since they completely abolished the expression of the UL42 (ß) and gD (γ) proteins and partially reduced that of ICP27 (α). Additionally, they were not virucidal and had no prophylactic effects. Both compounds inhibited HSV replication at nanomolar concentrations, but cardenolide C10 was more active than C11 and can be considered as an anti-herpes drug candidate including against acyclovir-resistant HSV-1 strains.

Ascleposide, a natural cardenolide, induces anticancer signaling in human castration-resistant prostatic cancer through Na+ /K+ -ATPase internalization and tubulin acetylation.

BACKGROUND: Cardiac glycosides, which inhibit Na+ /K+ -ATPase, display inotropic effects for the treatment of congestive heart failure and cardiac arrhythmia. Recent studies have suggested signaling downstream of Na+ /K+ -ATPase action in the regulation of cell proliferation and apoptosis and have revealed the anticancer activity of cardiac glycosides. The study aims to characterize the anticancer potential of ascleposide, a natural cardenolide, and to uncover its primary target and underlying mechanism against human castration-resistant prostate cancer (CRPC). METHODS: Cell proliferation was examined in CRPC PC-3 and DU-145 cells using sulforhodamine B assay, carboxyfluorescein succinimidyl ester staining assay and clonogenic examination. Flow cytometric analysis was used to detect the distribution of cell cycle phase, mitochondrial membrane potential, intracellular Na+ and Ca2+ levels, and reactive oxygen species production. Protein expression was examined using Western blot analysis. Endocytosis of Na+ /K+ -ATPase was determined using confocal immunofluorescence microscopic examination. RESULTS: Ascleposide induced an increase of intracellular Na+ and a potent antiproliferative effect. It also induced a decrease of G1 phase distribution while an increase in both G2/M and apoptotic sub-G1 phases, and downregulated several cell cycle regulator proteins, including cyclins, Cdk, p21, and p27 Cip/Kip proteins, Rb and c-Myc. Ascleposide decreased the expression of antiapoptotic Bcl-2 members (eg, Bcl-2 and Mcl-1) but upregulated proapoptotic member (eg, Bak), leading to a significant loss of mitochondrial membrane potential and activation of both caspase-9 and caspase-3. Ascleposide also dramatically induced tubulin acetylation, leading to inhibition of the catalytic activity of Na+ /K+ -ATPase. Notably, extracellular high K+ (16 mM) significantly blunted ascleposide-mediated effects. Furthermore, ascleposide induced a p38 MAPK-dependent endocytosis of Na+ /K+ -ATPase and downregulated the protein expression of Na+ /K+ -ATPase α1 subunit. CONCLUSION: Ascleposide displays antiproliferative and apoptotic activities dependent on the inhibition of Na+ /K+ -ATPase pumping activity through p38 MAPK-mediated endocytosis of Na+ /K+ -ATPase and downregulation of α1 subunit, which in turn cause tubulin acetylation and cell cycle arrest. Cell apoptosis is ultimately triggered by the activation of caspase cascade attributed to mitochondrial damage through the downregulation of Bcl-2 and Mcl-1 protein expressions while upregulation of Bak protein levels. The data also suggest the potential of ascleposide in anti-CRPC development.

Synthesis and evaluation of cytotoxic and Na+/K+-ATP-ase inhibitory activity of selected 5α-oleandrigenin derivatives.

Oleandrin, the major biologically active constituent of shrub Nerium oleander preparations of which have been used in traditional Mediterranean and Asian medicine, attracts a great deal of attention due to its pronounced anticancer activity. The synthesis of oleandrigenin model, 16ß-hydroxy-3ß-methoxy-5α-card-20(22)-enolide 16-acetate, from androstenolone acetate through 17ß-(3-furyl)-intermediates has been developed. Several related 17ß-(butenolidyl)- and 17ß-(furyl)-androstane derivatives were synthesized and tested for in vitro cytotoxic and Na+/K+-ATP-ase inhibitory activities. Comparison of Na+/K+-ATP-ase inhibitory and cytotoxic activity underlines complex nature of the relationship.

Cytotoxic Cardenolides from the Leaves of Acokanthera oblongifolia.

Three previously undescribed cardenolides, acovenosigenin A 3-O-α-L-acofriopyranoside (1: ), 14-anhydroacovenosigenin A 3-O-[ß-D-glucopyranosyl-(1″→4')-O-α-L-acofriopyranoside] (2: ), and 14-anhydroacovenosigenin A 3-O-[ß-D-glucopyranosyl-(1″→4')-O-α-L-acovenopyranoside] (3: ), together with the two already known ones, 14-anhydrodigitoxigenin 3-O-ß-D-glucopyranoside (4: ) and acospectoside A (5: ), were isolated from the leaves of Acokanthera oblongifolia. The influence of cardenolides 1:  - 3: and acovenoside A (found in the Acokanthera genus) on three cancer cell lines (HT29, HCT116, and AGS) was also investigated. The most promising results, in comparison with oxaliplatin, were obtained for compound 1: , which was found to be highly cytotoxic for all tested cell lines, HT29 (IC50 = 63.49 nM), HCT116 (IC50 = 67.35 nM), and AGS (IC50 = 80.92 nM). Unfortunately, 1: also showed similar toxicity towards normal lymphocytes (IC50 = 98.03 nM).

Oleandrin sensitizes human osteosarcoma cells to cisplatin by preventing degradation of the copper transporter 1.

A major problem in osteosarcoma treatment is cisplatin resistance. We have reported the anti-osteosarcoma effect of oleandrin; however, whether oleandrin sensitizes osteosarcoma to cisplatin is unknown. We investigated the chemosensitization of oleandrin and potential mechanisms in osteosarcoma cells U-2OS, SaOS-2, and MG-63. The median-effect analysis demonstrated that cisplatin + oleandrin exerted synergistic (U-2OS and MG-63) or additive effects (SaOS-2), which were consistent with the changes of the intracellular accumulation of platinum (Pt) and Pt-DNA adducts. Immunohistochemistry staining showed that the expression level of the mature form CTR1, the major influx transporter of cisplatin, was low in osteosarcoma tissue. However, oleandrin with or without cisplatin significantly increased the expression and membrane localization of the mature CTR1. Furthermore, CTR1 knockdown reversed the synergistic effect and decreased cisplatin uptake. The mRNA microarray analysis suggested that oleandrin downregulated the expression of proteasome-related genes, which was verified by the proteasome activity assay. Besides, the proteasome inhibitor MG132 upregulated the expression of the mature CTR1 in U-2OS and MG-63 cells. Overall, we conclude that oleandrin sensitizes osteosarcoma cells to cisplatin in synergistic or additive manners. The synergy results from the enhanced cisplatin uptake via oleandrin-mediated inhibition of proteasome activity and subsequent blockage of the mature CTR1 degradation.

Medicinal Uses, Phytochemistry and Pharmacological Properties of Elaeodendron transvaalense.

Elaeodendron transvaalense is a plant species, which is in high demand as a herbal medicine in southern Africa. This study critically reviewed the medicinal applications, phytochemistry and pharmacological activities of E. transvaalense. The literature on medicinal applications, phytochemical, and pharmacological activities of E. transvaalense, was collected from multiple internet sources including Elsevier, Google Scholar, SciFinder, Web of Science, Pubmed, BMC, Science Direct, and Scopus. Complementary information was gathered from pre-electronic sources, such as books, book chapters, theses, scientific reports, and journal articles obtained from the University library. This study revealed that the species is used as herbal medicine in 62.5% of the countries where E. transvaalense is native in southern Africa. It is mainly used as herbal medicine for diarrhoea, menorrhagia, stomach aches, skin infections, inflammations, and rashes. Phytochemical compounds identified from the species, include flavonoids, peltogynoid, phenols, proanthocyanidins, tannin, and triterpenes. Ethnopharmacological research revealed that extracts and phytochemical constituents isolated from E. transvaalense have antibacterial, antifungal, anti-HIV, anti-inflammatory, antioxidant, antiplasmodial, anti-protozoan, anti-pyretic, hypoglycaemic, larvicidal, cytotoxicity, and mutagenic activities. Elaeodendron transvalense should to be subjected to detailed phytochemical, pharmacological, and toxicological evaluations aimed at correlating the medicinal uses of the species with the ethnopharmacological properties of the species.

Molluscicidal activity of cardiac glycosides isolated from Adenium obesum.

BACKGROUND: Terrestrial mollusks are one of most important agricultural pests worldwide. Natural phytochemicals have an extended history as a source of pesticides. This study was planned to isolate molluscicidal active compounds from the stems of Adenium obesum. RESULTS: The benzene-soluble fraction of the hydroethanolic extract displayed the most potent molluscicidal activity against Monacha obstructa among different solvent fractions with a median lethal dose (LD50 ) of 4.91 µg g-1 body weight (bw). The bioactivity-guided chemical exploration of the benzene-soluble fraction led to the isolation of two known cardiac glycosides, cerberin and neriifolin which showed significant molluscicidal activity with LD50 values of 5.39 and 4.3 µg g-1 bw, respectively. CONCLUSION: Isolation of the cardiac glycoside neriifolin from A. obesum and the molluscicidal activity of cerberin and neriifolin against terrestrial snails are reported for the first time. © 2019 Society of Chemical Industry.

New knowledge about old drugs; a cardenolide type glycoside with cytotoxic effect and unusual secondary metabolites from Digitalis grandiflora Miller.

Phytochemical investigation of the aerial parts of Digitalis grandiflora Miller (Plantaginaceae) led to the isolation of an undescribed cardenolide type glycoside digigrandifloroside (1) along with five known compounds, rengyoside A (2), rengyoside B (3), cleroindicin A (4), salidroside (5), and cornoside (6), from its aqueous fraction of methanolic extract. Structures of the isolated compounds were determined by means of spectroscopic techniques. 1-6 were isolated for the first time from D. grandiflora. 2 and 3 are being reported for the first time from Digitalis genus and Plantaginaceae family with this study. This is the second report for occurrence of 4 from a Digitalis species. Cytotoxic activity of the aqueous fraction was also tested against HEp-2 (Human larynx epidermoid carcinoma) and HepG2 (Human hepatocellular carcinoma) cancer cell lines and L929 (Mouse fibroblast cell) non-cancerous cell line. Aqueous fraction showed stronger cytotoxicity on HEp-2 cells than HepG2. Therefore, the cytotoxic activity of 1, 2, 4, and 6 were tested against HEp-2 and L929 cell lines. 3 and 5 couldn't be tested due to their insufficient amount. 1 showed the highest cytotoxicity against HEp-2 cells with IC50 value 10.1 µM when compared with the positive control, etoposide and 2-6 (IC50 of etoposide; 39.5 µM).

Cardenolides: Insights from chemical structure and pharmacological utility.

Cardiac glycosides (CGs) are a class of naturally occurring steroid-like compounds, and members of this class have been in clinical use for more than 1500 years. They have been used in folk medicine as arrow poisons, abortifacients, heart tonics, emetics, and diuretics as well as in other applications. The major use of CGs today is based on their ability to inhibit the membrane-bound Na+/K+-ATPase enzyme, and they are regarded as an effective treatment for congestive heart failure (CHF), cardiac arrhythmia and atrial fibrillation. Furthermore, increasing evidence has indicated the potential cytotoxic effects of CGs against various types of cancer. In this review, we highlight some of the structural features of this class of natural products that are crucial for their efficacy, some methods of isolating these compounds from natural resources, and the structural elucidation tools that have been used. We also describe their physicochemical properties and several modern biotechnological approaches for preparing CGs that do not require plant sources.