Changes in Human Erythrocyte Membrane Exposed to Aqueous and Ethanolic Extracts from Uncaria tomentosa

Effect of Uncaria tomentosa aqueous extract on the response to palmitate-induced lipotoxicity in cultured skeletal muscle cells

BACKGROUND

Type 2 diabetes mellitus (T2DM) is frequently associated with dyslipidemia, which corresponds to the increase in the triglycerides and fatty acid concentrations in tissues, such as the skeletal muscle. Also, T2DM molecular mechanism involves increasing in reactive oxygen species (ROS) production and oxidative stress. The use of herbal medicines such as Uncaria tomentosa (Ut) has been proposed as an auxiliary treatment for patients with T2DM. In this study, it was evaluated the effect of Ut aqueous extract on cell viability and ROS production, in skeletal myoblasts from C2C12 lineage exposed to the free fatty acid palmitate (PA).

METHODS

Cells were incubated with PA in different concentrations ranging from 10 to 1000 μM, for 24 or 48 h, for cytotoxicity assay. Cell death, DNA fragmentation and ROS production assays were performed in cell cultures incubated with PA for 24 h, in the pre (preventive condition) or post treatment (therapeutic condition) with 250 μg/ml Ut aqueous extract, for 2 or 6 h. Cell death was evaluated by MTT method or flow cytometry. ROS generation was measured by fluorescence spectroscopy using the DCFDA probe.

RESULTS

Cell viability was reduced to approximately 44% after the incubation with PA for 24 h from the concentration of 500 µM. In the incubation of cells with 500 μM PA and Ut extract for 6 h, in both conditions (preventive or therapeutic), it was observed an increase of 27 and 70% in cell viability respectively, in comparison to the cultures incubated with only PA. Also, the incubation of cultures with 500 μM PA, for 24 h, increased 20-fold the ROS formation, while the treatment with Ut extract, for 6 h, both in the preventive or therapeutic conditions, promoted decrease of 21 and 55%, respectively.

CONCLUSION

The Ut extract was efficient in promoting cell protection against PA lipotoxicity and ROS generation, potentially preventing oxidative stress in C2C12 skeletal muscle cells. Since T2DM molecular mechanism involves oxidative stress condition and it is often associated with dyslipidemia and fatty acid accumulation in muscle tissue, these results open perspectives for the use of Ut as an auxiliary strategy for T2DM management.

Uncaria tomentosa extract (AC-11) improves pregnancy hypertension together with suppression of sFlt-1 and sEng

Disruption of well-controlled reproductive functions leads to pregnancy complications such as hypertensive disorders of pregnancy (HDP). Uncaria tomentosa (Wild), known as cat's claw, is widely used for the treatment of a various types of health problems; AC-11 (AC-11®, hot-water extract of U. tomentosa) is unique phytochemical compound and has potential roles as anti-inflammatory or anti-oxidant processes. We investigated whether AC-11 has a protective effect on pathogenesis of HDP in vivo and production of anti-angiogenic factors (sFlt-1 and sEng, major factors for the onset of HDP) in in vitro. Non-pregnant or pregnant mice were administered AC-11 (4 mg/mL), then, angiotensin II (Ang II) was subcutaneously infused to increase blood pressure. Human placental tissues or human umbilical vein endothelial cells (HUVECs) were incubated with or without AC-11. Treatment with AC-11 significantly reduced blood pressure induced by Ang II infusion. The population of CD8⁺T cells, the ratio of CD8/CD4, and plasma interleukin-6 levels were increased by Ang II infusion, and were decreased by AC-11 both in pregnant and non-pregnant mice. In pregnant mice, plasma levels of sFlt-1 and sEng were decreased by AC-11. In in vitro cell culture of HUVECs or placental tissue culture, treatment with AC-11 significantly inhibited secretion of sFlt-1 and sEng. We suggest a novel role of AC-11 in regulating blood pressure by controlling the balance of T cell population and inflammatory cytokine production both in non-pregnant and pregnant conditions. In addition, AC-11 inhibits HDP-related factors, including sFlt-1 and sEng, suggesting that AC-11 may useful for relieving HDP.

An In Vitro Comparative Study of the Effects of Tetrabromobisphenol A and Tetrabromobisphenol S on Human Erythrocyte Membranes-Changes in ATP Level, Perturbations in Membrane Fluidity, Alterations in Conformational State and Damage to Proteins

Brominated flame retardants (BFRs) are substances used to reduce the flammability of plastics. Among this group, tetrabormobisphenol A (TBBPA) is currently produced and used on the greatest scale, but due to the emerging reports on its potential toxicity, tetrabromobisphenol S (TBBPS)—a compound with a very similar structure—is used as an alternative. Due to the fact that the compounds in question are found in the environment and in biological samples from living organisms, including humans, and due to the insufficient toxicological knowledge about them, it is necessary to assess their impacts on living organisms and verify the validity of TBBPA replacement by TBBPS. The RBC membrane was chosen as the research model. This is a widely accepted research model for assessing the toxicity of xenobiotics, and it is the first barrier to compounds entering circulation. It was found that TBBPA and TBBPS caused increases in the fluidity of the erythrocyte membrane in their hydrophilic layer, and conformational changes to membrane proteins. They also caused thiol group elevation, an increase in lipid peroxidation (TBBPS only) and decreases in the level of ATP in cells. They also caused changes in the size and shape of RBCs. TBBPA caused changes in the erythrocyte membrane at lower concentrations compared to TBBPS at an occupational exposure level.