Bio-active cardenolides from the leaves of Nerium oleander

A toxic shrub turned therapeutic: The dichotomy of Nerium oleander bioactivities

Nerium oleander L. is a medicinal plant, used for the treatment of cancers and hyperglycemia across the world, especially in Indian sub-continent, Turkey, Morocco, and China. Although clinical studies supporting its pharmacological effects remain critically underexplored, accidental and intentional consumption of any part of the plant causes fatal toxicity in animals and humans. While the polyphenolic fraction of oleander leaves has been attributed to its pre-clinical pharmacological activities, the presence of diverse cardiac glycosides (especially oleandrin) causes apoptosis to cancer cells in vitro and results in clinical signs of oleander poisoning. Thus, the dual pharmacological and toxicological role of oleander is a perplexing dichotomy in phytotherapy. The current investigative review, therefore, intended to analyze the intrinsic and extrinsic factors that likely contribute to this conundrum. Especially by focusing on gut microbial diversity, abundance, and metabolic functions, oleander-associated pharmacological and toxicological studies have been critically analyzed to define the dual effects of oleander. Electronic databases were extensively screened for relevant research articles (including pre-clinical and clinical) related to oleander bioactivities and toxicity. Taxonomic preference was given to the plant N. oleander L. and synonymous plants as per 'The World Flora Online' database (WCSP record #135196). Discussion on yellow oleander (Cascabela thevetia (L.) Lippold) has intentionally been avoided since it is a different plant. The review indicates that the gut microbiota likely plays a key role in differentially modulating the pharmacological and toxicological effects of oleander. Other factors identified influencing the oleander bioactivities include dose and mode of treatment, cardiac glycoside pharmacokinetics, host-endogenous glycosides, plant material processing and phytochemical extraction methods, plant genotypic variations, environmental effects on the phytochemical quality and quantity, gene expression variations, host dietary patterns and co-morbidity, etc. The arguments proposed are also relevant to other medicinal plants containing toxic cardiac glycosides.

Interaction of Odoroside A, A Known Natural Cardiac Glycoside, with Na+/K+-ATPase

The nature of odoroside A, a cardiac glycoside (CG) extracted from Nerium oleander, as well as its chemical structure is quite similar to a well-known CG, ouabain possessing a steroid skeleton, a five-membered unsaturated lactone ring, and a sugar moiety as a common structure. Like ouabain, odoroside A inhibits the activity of Na⁺/K⁺-ATPase (NKA) and shows significant anticancer activity, however its inhibitory mechanism remains unknown. CGs show various physiological activities, including cardiotonic and anticancer activities, through the inhibition of NKA by direct interaction. Additionally, X-ray crystallographic analysis revealed the inhibitory mechanism of ouabain and digoxin in relation to NKA. By using different molecular modeling techniques, docking simulation of odoroside A and NKA was conducted based on the results of these X-ray crystallographic analyses. Furthermore, a comparison of the results with the binding characteristics of three known CGs (ouabain, digoxin, and digitoxin) was also conducted. Odoroside A fitted into the CG binding pocket on the α-subunit of NKA revealed by X-ray crystallography. It had key interactions with Thr797 and Phe783. Also, three known CGs showed similar interactions with Thr797 and Phe783. Interaction modes of odoroside A were quite similar to those of ouabain, digoxin, and digitoxin. Docking simulations indicated that the sugar moiety enhanced the interaction between NKA and CGs, but did not show enhanced NKA inhibitory activity because the sugar moiety was placed outside the entrance of active site. Thus, these results suggest that the inhibitory mechanism of odoroside A to NKA is the same as the known CGs.

Molecular Modes of Action of an Aqueous Nerium oleander Extract in Cancer Cells In Vitro and In Vivo

Cancer drug resistance remains a major obstacle in clinical oncology. As most anticancer drugs are of natural origin, we investigated the anticancer potential of a standardized cold-water leaf extract from Nerium oleander L., termed Breastin. The phytochemical characterization by nuclear magnetic resonance spectroscopy (NMR) and low- and high-resolution mass spectrometry revealed several monoglycosidic cardenolides as major constituents (adynerin, neritaloside, odoroside A, odoroside H, oleandrin, and vanderoside). Breastin inhibited the growth of 14 cell lines from hematopoietic tumors and 5 of 6 carcinomas. Remarkably, the cellular responsiveness of odoroside H and neritaloside was not correlated with all other classical drug resistance mechanisms, i.e., ATP-binding cassette transporters (ABCB1, ABCB5, ABCC1, ABCG2), oncogenes (EGFR, RAS), tumor suppressors (TP53, WT1), and others (GSTP1, HSP90, proliferation rate), in 59 tumor cell lines of the National Cancer Institute (NCI, USA), indicating that Breastin may indeed bypass drug resistance. COMPARE analyses with 153 anticancer agents in 74 tumor cell lines of the Oncotest panel revealed frequent correlations of Breastin with mitosis-inhibiting drugs. Using tubulin-GFP-transfected U2OS cells and confocal microscopy, it was found that the microtubule-disturbing effect of Breastin was comparable to that of the tubulin-depolymerizing drug paclitaxel. This result was verified by a tubulin polymerization assay in vitro and molecular docking in silico. Proteome profiling of 3171 proteins in the NCI panel revealed protein subsets whose expression significantly correlated with cellular responsiveness to odoroside H and neritaloside, indicating that protein expression profiles can be identified to predict the sensitivity or resistance of tumor cells to Breastin constituents. Breastin moderately inhibited breast cancer xenograft tumors in vivo. Remarkably, in contrast to what was observed with paclitaxel monotherapy, the combination of paclitaxel and Breastin prevented tumor relapse, indicating Breastin's potential for drug combination regimens.

Medicinal Plants Used for Dermatological Disorders among the People of the Kingdom of Saudi Arabia: A Narrative Review

Historically, skin disorders have received less attention in health management than other life-threatening diseases that occur on a global scale. However, numerous skin problems are reported to primary health care systems worldwide, particularly in tropical locations. While modern physicians often address most skin conditions, it is estimated that over 70% of individuals with skin illnesses do not seek treatment. Traditional medicine dates all the way back to human civilization's inception. Numerous materials are utilized in traditional medicinal remedies, but the use of plants is particularly critical. Saudi Arabia is one of the world's most botanically varied countries, having an extensive folk medicine heritage. While several reviews on the use of plants to cure skin disorders has been published worldwide, very few have been undertaken in Saudi Arabia, much alone a comprehensive one. Thus, the present review identified the most significant and medicinally relevant herbs used in the treatment of various dermatological conditions in Saudi Arabia. A total of 43 plants were identified and described in this study. This investigation omitted publications that lacked detailed data and had only fragmented information regarding the herb's traditional use in topical applications.

Oleandrin, a cardiac glycoside, induces immunogenic cell death via the PERK/elF2α/ATF4/CHOP pathway in breast cancer

Chemotherapeutic agents have been linked to immunogenic cell death (ICD) induction that is capable of augmenting anti-tumor immune surveillance. The cardiac glycoside oleandrin, which inhibits Na⁺/K⁺-ATPase pump (NKP), has been shown to suppress breast cancer growth via inducing apoptosis. In the present study, we showed that oleandrin treatment triggered breast cancer cell ICD by inducing calreticulin (CRT) exposure on cell surface and the release of high-mobility group protein B1 (HMGB1), heat shock protein 70/90 (HSP70/90), and adenosine triphosphate (ATP). The maturation and activation of dendritic cells (DCs) were increased by co-culturing with the oleandrin-treated cancer cells, which subsequently enhanced CD8⁺ T cell cytotoxicity. Murine breast cancer cell line EMT6 was engrafted into BALB/c mice, and tumor-bearing mice were administered with oleandrin intraperitoneally every day. Oleandrin inhibited tumor growth and increased tumor infiltrating lymphocytes including DCs and T cells. Furthermore, the differential mRNA expression incurred by oleandrin was investigated by mRNA sequencing and subsequently confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. Mechanistically, oleandrin induced endoplasmic reticulum (ER) stress-associated, caspase-independent ICD mainly through PERK/elF2α/ATF4/CHOP pathway. Pharmacological and genetic inhibition of protein kinase R-like ER kinase (PERK) suppressed oleandrin-triggered ICD. Taken together, our findings showed that oleandrin triggered ER stress and induced ICD-mediated immune destruction of breast cancer cells. Oleandrin combined with immune checkpoint inhibitors might improve the efficacy of immunotherapy.

Phenolic compounds from Nerium oleander leaves: microwave assisted extraction, characterization, antiproliferative and cytotoxic activities

A microwave-assisted extraction (MAE) method was used for the extraction of phenolic compounds from Nerium oleander leaves. The influence of variables such as ethanol concentration, microwave power, irradiation time and liquid/solid ratio on polyphenol extraction was modelled using a second-order regression equation based on response surface methodology (RSM). The optimal conditions for MAE were: extraction solvent 35% ethanol concentration, 500 W microwave power, 60 s irradiation time and a solvent/material ratio of 20 mL g^-1. Under optimal MAE conditions, the recovery of TPC was 25.752 mg GAE per g dw. 19 compounds have been identified by HPLC-ESI-MS/MS analysis; the main compounds identified were chlorogenic acid, rutin and quinic acid esters, such as caffeoylquinic acids and dicaffeoylquinic acids. Additionally, the optimized extract demonstrated potential to inhibit HT29 colorectal cancer cell growth (EC₅₀ = 2.432 μg mL^-1) without presenting cytotoxicity in confluent Caco-2 cells, a model of human intestinal epithelium. These results supply new information about the phenolic composition of Nerium oleander leaves and their antiproliferative effect.

Cardenolide and pregnatriene compounds from the roots of Nerium oleander

Cardenolide and pregnatriene compounds were isolated from the chloroform fraction of the 95% aqueous ethanolic extract of dried roots of Nerium oleander. The stereochemical structure of the cardenolide and pregnatriene compounds was determined to be 3β-O-(D-diginosyl)-14β-hydroxy card-20(22)-enolide and 12β-hydroxy pregna-4,6,16-triene-3,20-dione using spectroscopic methods including IR, HRMS and NMR spectroscopy.

Toxicity effects of Nerium oleander, basic and clinical evidence: A comprehensive review

Introduction:

Nerium oleander is a plant that is frequently grown in gardens and public areas. N. oleander is distributed originally in subtropical Asia but is now growing in many parts of the world, such as the United States, Australia, China, and Middle East countries. Pharmacological effects of plant including antinociceptive, anti-inflammatory, and anticancer activity were reported, but the potential toxic effects of all parts of the shrub either fresh or dried on animal and human body were documented.

Method:

The data of this review article were obtained from Medline/Pubmed, Scopusand Google Scholar databases in English until September 2019. To include all publications in this field, keywords such as N. oleander and toxicity were used.

Results:

The poisoning effects of plant or their active alkaloids induced infiltration of cells with hemorrhage and sever negative changes in the lung, induce lesions, and infiltration of inflammatory cells into the portal spaces with scattered necrosis of hepatocytes in the liver, cardiac toxicity of the plant in the heart were included, induced varying degrees of hemorrhage, myocardial degeneration, and necrosis. It also induced arrhythmia, sinus bradycardia, and prolonged P-R interval in electrocardiographic records.

Conclusions:

The toxic effects of N. oleander are mostly related to its inhibitory effects on the Na+-K+ ATPase pump in the cellular membrane. However, the exact molecular mechanism involved in the toxicity of N. oleander is not clear.

Circadian sensitivity to the cardiac glycoside oleandrin is associated with diurnal intestinal P-glycoprotein expression

The cardiac glycoside oleandrin is a main active constituent of the botanical anti-cancer drug candidate PBI-05204, an extract of Nerium oleander. Here, we aimed to determine the circadian sensitivity of mice to oleandrin, and to investigate the role of intestinal P-gp in generating rhythmic drug toxicity. Toxicity and pharmacokinetic experiments were performed with wild-type, Bmal1iKO (intestine-specific Bmal1 knockout) and Bmal1fl/fl (control littermates of Bmal1iKO) mice. The cardiac toxicity (reflected by plasma CK-MB, LDH and cTn-I levels) varied significantly with the times of drug dosing in wild-type mice (a lower toxicity at ZT10 and more severe at ZT2/22). Dosing at ZT2 generated a higher drug exposure than ZT10, supporting a lower toxicity at ZT10. Intracellular accumulation of oleandrin (2.5-10 μM) was reduced in MDCKⅡ-MDR1 than in parental cells. MDR1 overexpression decreased the cell sensitivity to oleandrin toxicity. The net flux ratio (MDCKⅡ-MDR1 versus parental cells) was 2.9 for oleandrin. These data indicated oleandrin as a P-gp substrate. Both mdr1a mRNA and P-gp protein oscillated with the times of the day in small intestine of Bmal1fl/fl mice. Intestinal ablation of Bmal1 down-regulated mdr1a mRNA and P-gp protein, and abrogated their rhythms. Likewise, Bmal1 silencing led to down-regulated mdr1a mRNA and to a loss of its rhythmicity in serum-shocked CT26 cells. Based on luciferase reporter assays, Bmal1 regulated rhythmic mdr1a transcription through the clock output genes Hlf and E4bp4. Intestinal ablation of Bmal1 exacerbated oleandrin toxicity and enhanced drug exposure. Moreover, time dependency of toxicity and drug exposure were lost in Bmal1iKO mice. In conclusion, diurnal intestinal P-gp is a critical factor influencing daily oleandrin exposure and toxicity. Our findings have implications in minimizing oleandrin (and possibly Nerium oleander) toxicity and improving drug efficacy via dosing time optimization.

Anti-poliovirus activity of Nerium oleander aqueous extract

Nerium oleander (NO), a member of the Apocynaceae family, is an ornamental plant. In this study, we evaluated the antiviral activity of hot and cold extract of NO against six different viruses such as herpes simplex virus type 1 (HSV-1), polio virus type 1 (Sb-1), vesicular stomatitis virus (VSV), reovirus type-1 (Reo-1), human immunodeficiency virus type-1 (HIV-1), and yellow fever virus (YFV). Interestingly the results of plaque reduction assay demonstrated that both, hot extract and cold extract (breastin) of NO inhibited Sb-1 viral infection.In order to identify the mechanism by which NO exerts its antiviral activity, the virucidal effect, the time of addition and the adsorption assay were carried out. Results demonstrated that NO exerts its effect after infection period, particularly during the first two hours post infection.

Green synthesis of Nerium oleander-conjugated gold nanoparticles and study of its in vitro anticancer activity on MCF-7 cell lines and catalytic activity

The phytochemicals present in the stem bark extract of Nerium oleander (commonly known as Karabi) have been utilized for the green synthesis of stable gold-conjugated nanoparticles at room temperature under very mild conditions. The green synthesized gold-conjugated nanoparticles were characterized by surface plasmon resonance spectroscopy, High resolution transmission electron microscopy, X-ray diffraction studies and dynamic light scattering. A mechanism for the synthesis and stabilization of gold-conjugated nanoparticles (AuNPs) has been proposed. Anticancer activity of the stabilized AuNPs studied against MCF-7 breast cancer cell line revealed that the stabilized AuNPs were highly effective for the apoptosis of cancer cells selectively. The antioxidant activity of the stem bark extract of Nerium oleander has also been studied against a long lived 2,2-diphenylpicrylhydrazyl radical at room temperature. Moreover, the utilization of the stabilized AuNPs as a catalyst has also been demonstrated.

Ethnopharmacology, phytochemistry, and biotechnological advances of family Apocynaceae: A review

The family Apocynaceae is one of the largest and important families in angiosperm. Several members of this family have medicinal properties and have been in the treatment of various ailments. Most of them are consumed as food by tribal people whereas a few plants are used as source of poison. Members of family Apocynaceae are rich in alkaloids, terpenoids, steroids, flavonoids, glycosides, simple phenols, lactones, and hydrocarbons. Other compounds such as sterols, lignans, sugars, lignans, and lactones have been isolated and systematically studied. Few studies have reported antioxidant, anti-inflammatory, antimicrobial, and cytotoxic activities of crude extracts as well as single compound(s) isolated from various members of the family Apocynaceae. Holarrhena antidysenterica, Rauvolfia serpentina, Carissa carandas, and Tabernaemontana divaricata are the extensively studied plants in this family. The present review provides a detailed outlook on ethnopharmacology, phytochemistry, and biological activities of selected members of this family. Moreover, it also covers the biotechnological advances used for large-scale production of bioactive compounds of therapeutic interest along with plant tissue culture-based approaches for conservation of this medicinally valuable family.

Synthetic Approach to the Core Structure of Oleandrin and Related Cardiac Glycosides with Highly Functionalized Ring D

The first synthetic approach to the core structure of cardiac glycoside oleandrin exhibiting a potent cytotoxic activity, starting from a common androstane derivative, has been accomplished. The synthesis is focused on stereoselective transformations in the densely substituted and sterically shielded five-membered ring (steroid ring D). The developed synthesis paves a route to the synthesis of related bufadienolides, i.e., constituents of traditional drug Ch'an Su, bufotalin, and cinobufagin.

Can Coffee Chemical Compounds and Insecticidal Plants Be Harnessed for Control of Major Coffee Pests?

Pests and pathogens threaten coffee production worldwide and are difficult to control using conventional methods, such as insecticides. We review the literature on the chemistry of coffee, concentrating on compounds most commonly reported from Coffea arabica and Coffea canephora. Differences in chemistry can distinguish coffee species and varieties, and plants grown under different biogeographic conditions exhibit different chemotypes. A number of chemical groups, such as alkaloids and caffeoylquinic acids, are known to be insecticidal, but most studies have investigated their effects on coffee quality and flavor. More research is required to bridge this gap in knowledge, so that coffee can be bred to be more resistant to pests. Furthermore, we report on some pesticidal plants that have been used for control of coffee pests. Locally sourced pesticidal plants have been underutilized and offer a sustainable alternative to conventional insecticides and could be used to augment breeding for resilience of coffee plants.

Exploring a natural MDR reversal agent: potential of medicinal food supplement Nerium oleander leaf distillate

OBJECTIVE

To investigate the molecular effects of Nerium oleander leaf distillate on paclitaxel and vincristine resistant (MCF-7/Pac and MCF-7/Vinc) cells and sensitive (MCF-7/S) cell lines.

METHODS

Nerium oleander (N. oleander) leaf extract was obtained by hydrodistillation method. The toxicological effects of N. oleander distillate, previously suggested as medicinal food supplement, on drug resistant cells were evaluated by XTT tests. MDR modulation potential of the plant material was evaluated by flow cytometry and fluorescent microscopy. Paclitaxel and vincristine were applied to the sublines in combination with N. oleander distillate.

RESULTS

Fractional inhibitory indices show that N. oleander distillate did not increase the antiproliferative effects of anticancer drugs. N. oleander treatment in to MCF-7/Pac and MCF-7/Vinc did not inhibit P-gp activity and MDR1 gene expression level.

CONCLUSIONS

As a result it may be suggested that although N. oleander distillate has some medicinal effects as food supplement it may not be suitable as an MDR modulator for drug resistant breast cancer cells.

Flavonoid and cardenolide glycosides and a pentacyclic triterpene from the leaves of Nerium oleander and evaluation of cytotoxicity

A pentacyclic triterpene, oleanderocioic acid, two flavonoidal glycosides, quercetin-5-O-[α-L-rhamnopyranosyl-(1→6)]-β-D-glucopyranoside and kaempferol-5-O-[α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside, and a cardenolide, oleandigoside, together with 11 known compounds, were isolated from the leaves of Nerium oleander. Their structures were elucidated on the basis of spectroscopic analysis. The growth inhibitory and cytotoxic activities of eight compounds were evaluated against the MCF-7 human breast cancer cell line using a sulforhodamine B assay. Three compounds, oleandrin, odoroside A and B were further assayed using a panel of 57 human cancer cell lines.

Acromyrmex octospinosus (Hymenoptera: Formicidae) management. Part 1: Effects of TRAMIL's insecticidal plant extracts

BACKGROUND

Leaf-cutting ants are considered to be one of the most important pest species of the New World. Until now, control strategies against these leaf-cutting ants have mainly been synthetic chemicals. The aim of the present study was to test the action of several plant extracts quoted as an example by TRAMIL participative surveys for their insecticidal properties on adult major workers of Acromyrmex octospinosus. Three tests were used to that end: contact toxicity, repellent test and ingestion bioassay. Six traditional plant uses recommended by interviewed people in surveys were tested: (1) maceration of Mammea americana fresh crushed seeds; (2) decoction of Nerium oleander fresh leaves; (3) Nerium oleander dried leaf water juice; (4) decoction of Nicotiana tabacum dried leaves; (5) Trichillia pallida dried leaf water juice; (6) decoction of Rollinia mucosa dried seeds.

RESULTS

Two plant extracts with contact toxicity (Mammea americana and Nicotiana tabacum), six plant extracts with repellent activity and four plant extracts with ingestion toxicity (Mammea americana, Nicotiana tabacum and both extracts of Nerium oleander) were found.

CONCLUSION

The data presented in this study showed that plant extracts cited by TRAMIL ethnopharmacological surveys have the potential to control the leaf-cutting ant, Acromyrmex octospinosus. In particular, the Mammea americana extract, with its natural low repellent effect and its high toxicity by ingestion, and Nerium oleander extracts, with their natural delay action, are possibly the best extracts for the control of these ants.

Nerium oleander Distillate Improves Fat and Glucose Metabolism in High-Fat Diet-Fed Streptozotocin-Induced Diabetic Rats

Diabetes was induced by intraperitoneal injection of streptozotocin (35 mg/kg bw) in all rats of five groups after being fed for 2 weeks high-fat diet. Type 2 diabetic Nerium-oleander- (NO-) administered groups received the NO distillate at a dose of 3.75, 37.5, and 375 μg/0.5 mL of distilled water (NO-0.1, NO-1, NO-10, resp.); positive control group had 0.6 mg glibenclamide/kg bw/d by gavage daily for 12 weeks. Type 2 diabetic negative control group had no treatment. NO distillate administration reduced fasting blood glucose, HbA1c, insulin resistance, total cholesterol, low density lipoprotein, atherogenic index, triglyceride-HDL ratio, insulin, and leptin levels. Improved beta cell function and HDL concentration were observed by NO usage. HDL percentage in total cholesterol of all NO groups was similar to healthy control. NO-10 distillate enhanced mRNA expressions of peroxisome proliferator-activated-receptor- (PPAR-) α, β, and γ in adipose tissue and PPAR-α-γ in liver. The findings from both in vivo and in vitro studies suggest that the considerable beneficial effect of NO distillate administration at a dose of 375 μg/0.5 mL of distilled water may offer new approaches to treatment strategies that target both fat and glucose metabolism in type 2 diabetes.

The structure of a new cardenolide diglycoside and the biological activities of eleven cardenolide diglycosides from Nerium oleander

A new cardenolide diglycoside (1) was isolated from Nerium oleander together with ten known cardenolide diglycosides 2-11. The structure of compound 1 was established on the basis of their spectroscopic data. The in vitro anti-inflammatory activity of compounds 1-11 was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). Compounds 2-5 were active at an IC(50) value of less than 0.8 µM. The cytotoxicity of compounds 1-11 was evaluated against three human cell lines normal human fibroblast cells (WI-38), malignant tumor cells induced from WI-38 (VA-13), and human liver tumor cells (HepG2). Compound 3 was active toward VA-13 cells, and compounds 2-5 were active toward HepG2 cells at IC(50) values of less than 1.3 µM. The multidrug resistance (MDR)-reversal activity of compounds 1-11 was evaluated on the basis of the amount of calcein in MDR human ovarian cancer 2780AD cells in the presence of each compound. Compounds 1 and 8 showed moderate effects on calcein accumulation.

Characterization of the anticancer properties of monoglycosidic cardenolides isolated from Nerium oleander and Streptocaulon tomentosum

AIM OF THE STUDY

For identification of the active constituents we investigated the anticancer activity of cardenolides from Streptocaulon tomentosum Wight & Arn. (Asclepiadaceae) and from Nerium oleander L. (Apocynaceae) which are both used against cancer in the traditional medicine in their region of origin.

MATERIAL, METHODS AND RESULTS

The antiproliferative activity of cardenolides isolated from roots of Streptocaulon tomentosum (IC(50)<1-15.3 μM after 2 days in MCF7) and of cardenolide containing fractions from the cold aqueous extract of Nerium oleander leaves ("Breastin", mean IC(50) 0.85 μg/ml in a panel of 36 human tumor cell lines), their influence on the cellular viability and on the cell cycle (block at the G2/M-phase or at the S-phase in tumor cells, respectively) were determined using different cell lines. The murine cell line L929 and normal non-tumor cells were not affected. Bioactivity guided fractionation of Breastin resulted in the isolation of the monoglycosidic cardenolides oleandrine, oleandrigeninsarmentoside, neritaloside, odoroside H, and odoroside A (IC(50)-values between 0.010 and 0.071 μg/ml).

CONCLUSIONS

The observed anticancer activities of extracts and isolated cardenolides are in agreement with the ethnomedicinal use of Streptocaulon tomentosum and Nerium oleander. The most active anticancer compounds from both species are monoglycosidic cardenolides possessing the 3β,14β-dihydroxy-5β-card-20(22)-enolide structure with or without an acetoxy group at C-16. The results indicate that the cytotoxic effects are induced by the inhibition of the plasma membrane bound Na(+)/K(+)-ATPase.

Nematicidal cardenolides from Nerium indicum Mill

Three nematicidal cardenolides were obtained from the AcOEt extract of Nerium indicum Mill. by bioassay-guided fractionation. They include a new compound, 3beta-O-(beta-D-diginosyl)-14,15alpha-dihydroxy-5alpha-card-20(22)-enolide (1), and two known compounds, uzarigenin (2) and cardenolide N-1 (3). The median lethal concentrations (LC(50)) of compounds 1-3 against the nematodes Bursaphelenchus xylophilus, Panagrellus redivivus, and Caenorhabditis elegans at 72 h were 103.3, 49.0, and 45.4 mg l(-1), 257.0, 62.7, and 177.8 mg l(-1), and 242.9, 29.1, and 41.7 mg l(-1), respectively. This is the first report about the nematicidal activity of cardenolides.

Acetylcholinesterase-inhibiting steroidal alkaloid from the sponge Corticium sp

A new stigmastane-type steroidal alkaloid, 4-acetoxy-plakinamine B (1), was isolated from the Thai sponge Corticium sp. The compound was subjected to the acetylcholinesterase inhibitory activity determination to reveal a high inhibitory activity (IC(50) 3.75+/-1.69 microM). The kinetics of enzyme inhibition showed a decrease in V(max), whereas K(m) was increased, thus suggesting an unusual mixed-competitive mode of inhibition. Compound 1 is the first steroidal alkaloid bearing a stigmastane skeleton ever been reported to exhibit such good potency in the acetylcholinesterase inhibition bioassay.

Bioactive cardenolides from the stems and twigs of Nerium oleander

Four new cardenolide monoglycosides, cardenolides N-1 (1), N-2 (2), N-3 (3), and N-4 (4), were isolated from Nerium oleander, together with two known cardenolides, 5 and 12, and seven cardenolide monoglycosides, 6-11 and 13. The structures of compounds 1-4 were established on the basis of their spectroscopic data. The in vitro anti-inflammatory activity of compounds 1-13 was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). Compounds 1, 5, 6, and 11-13 were active at an IC50 value of less than 1 microM. The cytotoxicity of compounds 1-13 was evaluated against three human cell lines, normal human fibroblast cells (WI-38), malignant tumor cells induced from WI-38 (VA-13), and human liver tumor cells (HepG2). Compounds 1, 4, 6, and 11-13 were active toward V-13 cells, and compounds 1, 11, and 12 were active toward HepG2 cells at IC50 values of less than 1 microM. Compounds 4, 5, 10, and 12 showed selective cell growth inhibitory activity toward V-13 tumor cells compared with that of parental normal WI-38 cells. The MDR-reversal activity of compounds 1-13 was evaluated on the basis of the amount of calcein accumulated in MDR human ovarian cancer 2780AD cells in the presence of each compound. Compounds 4, 9, and 10 showed significant effects on calcein accumulation, compound 4 showing stronger activity than that of verapamil.

Acute cattle intoxication from Nerium oleander pods

Seven outbreaks of acute intoxication from oleander (Nerium oleander) in cattle were reported in Northeast of Brazil. A total of 92 cattle were poisoned by oleander in 7 different herds; 57 animals died (67% of affected cattle). All cases reported here occurred during dry season. Two of the outbreaks resulted from offering oleander triturated and mixed with fodder. In the other cases, accidental ingestion of residual parts of oleander derived from pruning or cutting plants on grazing land were responsible. Clinical signs were diverse; the most common were locomotion disturbances, diarrhoea, depression and sudden death. Postmortem findings varied from no significant lesions to widespread haemorrhage. The presence of oleander leaves in the rumen was noted in all cases. The lack of information about the toxicity of oleanders was the main cause for the accident, which prompt us to stimulate wide divulgation of the common toxic plants.

Three new triterpenes from Nerium oleander and biological activity of the isolated compounds

New ursane-type triterpene 1, oleanane-type triterpene 2, and dammarane-type triterpene 15 were isolated from the leaves of Nerium oleander together with 12 known triterpenes, 3beta-hydroxy-12-ursen-28-oic acid (ursolic acid, 3), 3beta,27-dihydroxy-12-ursen-28-oic acid (4), 3beta,13beta-dihydroxyurs-11-en-28-oic acid (5), 3beta-hydroxyurs-12-en-28-aldehyde (6), 28-norurs-12-en-3beta-ol (7), urs-12-en-3beta-ol (8), urs-12-ene-3beta,28-diol (9), 3beta-hydroxy-12-oleanen-28-oic acid (oleanolic acid, 10), 3beta,27-dihydroxy-12-oleanen-28-oic acid (11), 3beta-hydroxy-20(29)-lupen-28-oic acid (betulinic acid, 12), 20(29)-lupene-3beta,28-diol (betulin, 13), and (20S,24R)-epoxydammarane-3beta,25-diol (14). On the basis of their spectroscopic data, the structures of the new compounds 1, 2, and 15 were established as 3beta,20alpha-dihydroxyurs-21-en-28-oic acid, 3beta,12alpha-dihydroxyoleanan-28,13beta-olide, and (20S,24S)-epoxydammarane-3beta,25-diol, respectively. The anti-inflammatory activity of the seven isolated compounds and methyl esters of ursolic acid and oleanoic acid in vitro was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). The anticancer activity of the 14 isolated compounds, including 1, 2, 15, and methyl esters of ursolic acid and oleanolic acid in vitro was examined on the basis of the cell growth inhibitory activities toward three kinds of human cell lines.

Murine pharmacokinetics and metabolism of oleandrin, a cytotoxic component of Nerium oleander

Pharmacokinetic studies of [3H]oleandrin, a cardiac glycoside component of Anvirzel, were conducted in mice after either an i.v. dose (40 micrograms/kg) or a p.o. dose (80 micrograms/kg). Oleandrin was rapidly absorbed after oral dosing (Cmax at 20 min) although the elimination half-life was longer (2.3 +/- 0.5 h) than that after i.v. dosing (0.4 +/- 0.1 h). The AUC0-infinity values obtained after i.v. and p.o. dosing were 24.6 +/- 11.1 and 14.4 +/- 4.3 (ng.h/ml), respectively, resulting in an oral bioavailability of approximately 30%. After i.v. administration, oleandrin concentration in liver was approximately twice that measured in heart or kidney tissue. Oleandrigenin, the aglycone of oleandrin, was also found in these tissues. At 5 min, > 60% of the total radioactivity in liver was due to oleandrin while 28% of the given dose was present as oleandrigenin. Twenty-four hours following injection, 8% of total radioactivity was excreted in urine and contained both oleandrigenin (4.4% of the injected dose) and oleandrin (1.9%). Sixty-six percent of injected radioactivity was found in feces and consisted of oleandrin and oleandrigenin in equal amounts. Uptake of oleandrin in brain after i.p. injection of oleandrin (3 mg/kg) or oleander extract (700 mg/kg) was examined. Measured by LC/MS/MS, oleandrin content in brain was higher following injection of extract than it was with an equivalent dose of oleandrin. The data suggest that components within oleander extract may enhance transport of oleandrin across the blood brain barrier.

LC/MS/MS analyses of an oleander extract for cancer treatment

An HPLC/MS/MS method has been developed for the characterization and quantification of the cardiac glycosides oleandrin, odoroside, neritaloside and the aglycone oleandrigenin, all contained in a patented-hot-water extract of Nerium oleander L (Anvirzel). Qualitative analysis of such extracts was achieved using a hybrid tandem quadrupole time-of-flight (QqTOF) mass spectrometer. Collision-induced dissociation (CID) mass spectra of oleandrin, oleandrigenin, odoroside, and neritaloside were obtained with greater than 5 ppm mass accuracy and resolution routinely in excess of 8000 (fwhm). The detection limit for oleandrin of 20 pg (injected) was realized when the precursor-to-product ion transition, m/z 577 --> 373, was monitored. We have also applied the analytical method to the determination of oleandrin, oleandrigenin, neritaloside, and odoroside in human plasma following an intramuscular injection of Anvirzel.