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 (IC₅₀ < 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 IC₅₀ 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 (IC₅₀-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.     

BMSC enhance the survival of paclitaxel treated squamous cell carcinoma cells in vitro

The 5-year survival rate of patients suffering from head and neck squamous cell carcinoma (HNSCC) is unsatisfying despite the advances in carcinoma treatment. Recent studies suggest that stem cells can be used as a gene therapy carrier for cancer treatment. Stem cells produce different cytokines such as growth factors in a paracrine manner and cancer cells may show drug resistance in the presence of such growth factors. Reports in the literature concerning treatment of cancer using bone marrow derived stem cells (BMSC) are controversial, which led us to investigate the effects of paclitaxel on human HNSCC cell lines (FaDu and HLaC 78) cultivated simultaneously with BMSC in a transwell system (co-culture). Co-culture and HNSCC cell lines were treated with 10nM of paclitaxel for 24h. Morphology, viability and apoptosis were measured by microscopy, the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the Annexin V-propidium iodide test. The survival of HNSCC cell lines treated with paclitaxel in co-culture increased significantly compared to control cells. Apoptosis of HNSCC cell lines in co-culture was attenuated significantly. In conclusion, BMSC increase HNSCC resistance to treatment with paclitaxel in vitro. Tumor-stroma interactions are critical components of tumor biology including tumor invasion and metastatic potential. Therefore particular attention must be paid to the complex tumor-stroma interactions to fully understand how tumor cells become chemoresistant.     

Overweight children and adolescents – is there a subjective need for treatment?

Objectives:  We report on the first months of recruitment for a study to evaluate outpatient training for moderately overweight youths. Methods:  Various recruitment strategies were employed, including media exposure, paediatricians, school events, and the distribution of flyers. Roughly 6 160 overweight and 4 720 obese children and adolescents of the target age range were estimated to live in the study area. Results:  Altogether, 172 families enrolled for participation. Only 38 enrolled children (22.1%), however, were overweight and thereby eligible for participation, 132 children (76.7%) were obese and two were normal weight. Most eligible participants were recruited via media or paediatricians. Conclusions:  Reaching overweight, but not obese, children and adolescents for intervention is difficult, where a low recognition of the condition in its less extreme form might be a particular problem. Submitted: 15 Januar 2008; revised: 25 September 2008, 15 December 2008; accepted: 18 January 2009     

Psychometric properties of the German version of the Motivational Interviewing Treatment Integrity Code

Motivational interviewing (MI) is effective in the treatment of addictions. To evaluate MI adherence of therapists, the Motivational Interviewing Treatment Integrity Code (MITI) was developed. MI is used in German-speaking countries, but there is no equivalent to the MITI. Our aim was to adapt the MITI for use in German language settings (MITI-d). Twenty-eight session tapes of Alcoholism Specific Psychotherapy utilizing MI were rated by two student raters and the MITI-d instructor. To evaluate interrater reliability, intraclass correlation coefficients (ICCs) were computed. ICCs were good to excellent for relevant MI constructs, except for Complex Reflections, MI-nonadherent Behaviors, Empathy, and MI Spirit. The evaluation of test-retest reliability for the student raters showed good to excellent results. The MITI-d is a psychometrically sound instrument for evaluating basic MI competence in German language settings.     

Alginate-poloxamer microparticles for controlled drug delivery to mucosal tissue

Purpose: The aim of this study was to prepare and characterize novel hydrogel-based delivery systems allowing for the controlled release of drugs to mucosal surfaces. Methods: Terbutaline sulfate and bovine serum albumin (BSA)-loaded alginate-poloxamer microparticles were prepared by a w/o-emulsion- and external gelation method. The microparticles were characterized by optical and scanning electron microscopy, laser light diffraction, atomic absorption spectroscopy, energy-dispersive X-ray analysis, via complexation with 1,9-dimethyl methylene blue and using dialysis bags as well as modified Franz diffusion cells for in vitro drug-release measurements. Results: Using heptane as organic phase, homogeneous and almost spherical microparticles were obtained with a high-loading efficiency (>90%). The resulting drug-release patterns could effectively be adjusted by varying the “alginate:poloxamer” blend ratio. In addition, the particle size, morphology, calcium and chloride content as well as alginate-release rates could be altered. Erosion was the predominant release mechanism for BSA. Special attention needs to be paid to the microparticle recovery procedure, which can significantly affect key properties such as the resulting drug-release patterns. Conclusions: The novel hydrogel-based microparticles offering mild conditions for incorporated drugs (e.g., proteins) provide an interesting potential as controlled delivery systems for mucosal surfaces.     

l-Arginine enhances the triglyceride-lowering effect of simvastatin in patients with elevated plasma triglycerides

We recently noticed a possible triglyceride-lowering effect during dietary supplementation with l-arginine. The major limitation of prior studies on l-arginine, however, was that triglyceride levels were not the primary end point, and patients were not necessarily hypertriglyceridemic. Therefore, we conducted a 2-arm, randomized, double-blind study in 33 hypertriglyceridemic patients to investigate the hypothesis that oral l-arginine may lower serum triglyceride levels in hypertriglyceridemic patients on and off statins. The study consisted of a 6-week run-in phase, 6 weeks of treatment with l-arginine (n = 22, 1.5 g bid) or placebo (n = 11), and a 6-week extension period where simvastatin (20 mg qd) was added. All patients received dietary advice during each study visit. Routine and lipid laboratory parameters were determined in the local routine clinical laboratory. Treatment with l-arginine alone had no effects on serum lipids compared to placebo. The combination of l-arginine with simvastatin led to a significantly stronger reduction in triglycerides compared to placebo plus simvastatin (−140.5 ± 149.2 mg/dL vs −56.1 ± 85.0 mg/dL; P = .048). In addition, we found simvastatin-induced increases in aspartate transaminase and fibrinogen to be attenuated by l-arginine as compared to placebo. We conclude from our data that l-arginine enhances the effects of simvastatin on lipid metabolism, but it has no triglyceride-lowering effects when given alone.     

COX-2 oxidative metabolism of endocannabinoids augments hippocampal synaptic plasticity

Endocannabinoids (eCBs) are important endogenous lipid mediators in synaptic transmission and plasticity and are oxygenated by cyclooxygenase-2 (COX-2) to form new types of prostaglandins. However, little is known about whether COX-2 oxidative metabolism of eCBs and their metabolites alter synaptic signaling. Here we demonstrate that increased COX-2 expression significantly enhances basal synaptic transmission and augments long-term potentiation (LTP) in the mouse hippocampus. This augmentation was inhibited in the presence of a selective COX-2 inhibitor or with deletion of the COX-2 gene. The CB₁ receptor-mediated depolarization-induced suppression of inhibition (DSI) was diminished when COX-2 expression was increased either with lipopolysaccharide (LPS) stimulation or transgenic neuronal over-expression of COX-2. Conversely, DSI was potentiated when COX-2 activity was pharmacologically or genetically inhibited. Interestingly, COX-2 oxidative metabolites of eCBs elevated LTP, an effect opposite to that of their parent molecules 2-arachidonoylglycerol (2-AG) and arachidonoyl ethanolamide (AEA). In addition, the ERK/MAPK and IP₃ pathways were found to mediate PGE₂-G-induced enhancement of LTP. Our results indicate that COX-2 oxidative metabolism of eCBs is an important signaling pathway in modulation of synaptic transmission and plasticity.