Identification of Insulin-Mimetic Plant Extracts: From an In Vitro High-Content Screen to Blood Glucose Reduction in Live Animals.

Type 2 diabetes mellitus (T2DM) is linked to insulin resistance and a loss of insulin sensitivity, leading to millions of deaths worldwide each year. T2DM is caused by reduced uptake of glucose facilitated by glucose transporter 4 (GLUT4) in muscle and adipose tissue due to decreased intracellular translocation of GLUT4-containing vesicles to the plasma membrane. To treat T2DM, novel medications are required. Through a fluorescence microscopy-based high-content screen, we tested more than 600 plant extracts for their potential to induce GLUT4 translocation in the absence of insulin. The primary screen in CHO-K1 cells resulted in 30 positive hits, which were further investigated in HeLa and 3T3-L1 cells. In addition, full plasma membrane insertion was examined by immunostaining of the first extracellular loop of GLUT4. The application of appropriate inhibitors identified PI3 kinase as the most important signal transduction target relevant for GLUT4 translocation. Finally, from the most effective hits in vitro, four extracts effectively reduced blood glucose levels in chicken embryos (in ovo), indicating their applicability as antidiabetic pharmaceuticals or nutraceuticals.

Influence of silibinin and ß-ß-dimethylacrylshikonin on chordoma cells.

BACKGROUND: Chordoma, slow growing bone tumours originating from remnants of the notochord, leave affected patients with a median survival of six years. The high recurrence rate of chordoma, together with limited treatment options and bad overall prognosis, make the development of new treatment options urgently necessary. PURPOSE: In this study, the potential of two natural products, silibinin and ß-ß-dimethylacrylshikonin (DMAS), was tested on clival (MUG-CC1 and UM-Chor1) as well as sacral (MUG-Chor1 and U-CH2) chordoma cell lines. The treatment was administered both as single- and combined therapy. METHODS: For investigation of cell viability, the Cell Titer 96 Aqueous Non-Radioactive Cell Proliferation Assay Kit was used. Apoptosis induction was studied by flow cytometry, (Annexin V/SYTOX Green, caspase-3) and RT-qPCR. Pathway analyses were performed by western blot. RESULTS: Both drugs were found to reduce cell viability alone as well as in combination in a dose dependent manner, with DMAS being more efficient than silibinin. The mode of cell death was mainly apoptosis in DMAS treated samples, while the combination therapy led to apoptosis as well as late-apoptosis/necrosis. Silibinin therapy alone, although reducing cell viability, did not lead to significant apoptotic effects in the performed assays. Focussing on the molecular mechanism of DMAS induced apoptosis, it was found that major genes of the mitochondrial apoptosis pathway, like NOXA and PUMA were overexpressed. Additionally, western blot experiments showed a decrease of ERK/pERK, STAT3/pSTAT3 (Tyr705) and AKT/pAKT expression/activation levels under DMAS treatment. CONCLUSION: DMAS is a promising new candidate for chordoma therapy, while silibinin or a combination of both is less favourable.