Natural Pyrethrin-Induced Oxidative Damage in Human Liver Cells through Nrf-2 Signaling Pathway.

Natural pyrethrins (NPs), one kind of bio-pesticide, have been widely used in organic agriculture and ecological environment studies. Studies have shown that NPs may affect the metabolism of rat liver and human hepatocytes; nevertheless, the toxic effects of NPs on the liver and the related mechanisms are still incompletely understood. In this research, we utilized three types of human liver cells to investigate the mechanism of NPs' induction of oxidative stress. The results showed that NPs exhibit noteworthy cytotoxic effects on human liver cells. These effects are characterized by the induction of LDH release, mitochondrial collapse, and an increased production of ROS and MDA content, subsequently activating the Kelch-like ECH-associated protein 1/Nuclear factor erythroid 2- related factor 2 (Keap1/Nrf-2) pathway. The ROS inhibitor N-acetyl-L-cysteine (NAC) can alleviate ROS/Nrf2-mediated oxidative stress. In addition, the siRNA knockdown of Nrf-2 exacerbated the injury, including ROS production, and inhibited cell viability. In summary, the ROS-mediated Keap1/Nrf-2 pathway could be an important regulator of NP-induced damage in human liver cells, which further illustrates the hepatotoxicity of NPs and thereby contributes to the scientific basis for further exploration.

Loureirin B promotes insulin secretion through inhibition of KATP channel and influx of intracellular calcium.

The development of new diabetes drugs continues to be explored. Loureirin B, a flavonoid, extracted from Dracaena cochinchinensis, has been confirmed to increase insulin secretion and decrease blood glucose levels. For searching the promotion of insulin secretion with the treatment of loureirin B, experiments were employed based on cell experiments and computational methods. First, promotion of insulin secretion was dependent on extracellular glucose concentration. At the genetic level, loureirin B enhanced the relative mRNA level of Pdx-1 and MafA. Meanwhile the intracellular level of ATP increased due to the continuous absorption of glucose. Further experiments showed that the currents of KATP channel on Ins-1 cells were inhibited and the voltage-dependent calcium channels were subsequently activated. The increase of Cx43 protein expression might mediate the Ca2+ to the intracellular. Through computational simulation, we hypothesized that loureirin B might interact with KATP channels to promote insulin secretion. In conclusion, it could be concluded that loureirin B promoted insulin secretion mainly through increasing mRNA level of Pdx-1, MafA, intracellular ATP level, inhibiting the KATP current, influx of Ca2+ to the intracellular.

The Interaction Mode of Groove Binding Between Quercetin and Calf Thymus DNA Based on Spectrometry and Simulation.

Quercetin, a ubiquitous flavanoid, has numerous pharmacological effects, such as antioxidant and antitumor. Previous studies showed nucleic acids were the potential biological targets for antitumor medicine. For exploring the mechanism of DNA-target medicine, the interaction between quercetin and calf thymus DNA was studied based on the method of spectrometry and simulation in our study. Firstly, the interaction between quercetin and calf thymus DNA was confirmed by fluorescence spectrometry. Furthermore, circular dichroism, fluorescence polarization, competitive displacement assay, and salt concentration dependence assay were applied to search the interaction mode of quercetin-calf thymus DNA, which proved the existence of groove binding and electrostatic interaction. Meanwhile, quenching constant Ksv , binding constant Ka and the number of binding sites n was calculated, inferring that the fluorescence quenching occurred by static quenching process, and the main acting force was hydrogen bond. Finally, molecular docking was used to simulate and analyze the interaction between quercetin and calf thymus DNA.

Comparison of three methods for analyzing loureirin B and human serum albumin interaction using capillary electrophoresis.

Loureirin B (LB), a bioactive drug, is widely used in the treatment of biological diseases. However, due to its poor solution in water, it is important to find the approach which helps LB to specific biological targets. As the most abundant protein in plasma, HSA plays the role of a carrier of numerous drug ligand. Thus, the interaction between LB and HSA was explored by ACE, CE frontal analysis, and pressure-mediated ACE under simulated physiological conditions (pH 7.4). The binding constants were calculated as 13.14 × 104 L/mol, 7.00 × 104 L/mol, and 2.78 × 104 L/mol for each method, respectively. At the same time, the binding site number (n = 1.429) could be only calculated by the CE frontal analysis method. Furthermore, good experimental repeatability was obtained by pressure-mediated ACE with RSDs for retention times and peak areas within 2.149 and 1.228, respectively.