Quantification of neomangiferin in rat plasma by liquid chromatography–tandem mass spectrometry and its application to bioavailability study

Neomangiferin, a natural C-glucosyl xanthone, has recently received a great deal of attention due to its multiple biological activities. In this study, a rapid and sensitive ultra-high performance liquid chromatography tandem mass spectrometry(UHPLC–MS/MS) method for the quantification of neomangiferin in rat plasma was developed. Using chloramphenicol as an internal standard(IS), plasma samples were subjected to a direct protein precipitation process using methanol(containing 0.05% formic acid). Quantification was performed by multiple reactions monitoring(MRM) method, with the transitions of the parent ions to the product ions of m/z 583.1-330.9 for NG and m/z 321.1-151.9 for IS. The assay was shown to be linear over the range of 0.2–400 ng/m L, with a lower limit of quantification of 0.2 ng/m L. Mean recovery of neomangiferin in plasma was in the range of 97.76%–101.94%. Relative standard deviations(RSDs) of intra-day and inter-day precision were both o 10%. The accuracy of the method ranged from94.20% to 108.72%. This method was successfully applied to pharmacokinetic study of neomangiferin after intravenous(2 mg/kg) and intragastric(10 mg/kg) administration for the first time. The oral absolute bioavailability of neomangiferin was estimated to be 0.53% 7 0.08% with an elimination half-life(t_(1/2)) value of 2.747 0.92 h, indicating its poor absorption and/or strong metabolism in vivo.

Sex-biased single-cell genetic landscape in mice with autism spectrum disorder

Autistic spectrum disorder(ASD)is a male-biased,heterogeneous neurodevelopmental disorder that affects approximately 1%e2%of the population.Prenatal exposure to valproic acid(VPA)is a recognized risk factor for ASD,but the cellular and molecular basis of VPA-induced ASD at the single-cell resolution is unclear.Here,we aim to compare the cellular and molecular differences in the hippocampus between male and female prenatal mice with ASD at the single-cell transcriptomic level.The transcriptomes of more than 45,000 cells are assigned to 12 major cell types,including neurons,glial cells,vascular cells,and immune cells.Cell type-specific genes with altered expression after prenatal VPA exposure are analyzed,and the largest number of differentially expressed genes(DEGs)are found in neurons,choroid plexus epithelial cells,and microglia.In microglia,several pathways related to inflammation are found in both males and females,including the tumor necrosis factor(TNF),nuclear factor kappa B(NF-kB),toll-like receptor(TLR),and mitogen-activated protein kinase(MAPK)signaling pathways,which are important for the induction of autistic-like behavior.Additionally,we note that several X-linked genes,including Bex1,Bex3,and Gria3,were among the male-specific DEGs of neurons.This pioneering study describes the landscape of the transcriptome in the hippocampus of autistic mice.The elucidation of sexual differences could provide innovative strategies for the prevention and treatment of ASD.

Voltage-dependent blockade by bupivacaine of cardiac sodium channels expressed in Xenopus oocytes

Bupivacaine ranks as the most potent and efficient drug among class I local anesthetics, but its high potential for toxic reactions severely limits its clinical use. Although bupivacaine-induced toxicity is mainly caused by substantial blockade of voltage-gated sodium channels （VGSCs）, how these hydrophobic molecules interact with the receptor sites to which they bind remains unclear. Navl.5 is the dominant isoform of VGSCs expressed in cardiac myocytes, and its dysfunction may be the cause of bupivacaine- triggered arrhythmia. Here, we investigated the effect of bupivacaine on Navl.5 within the clinical concentration range. The electrophysiological measurements on Navl.5 expressed in Xenopus oocytes showed that bupivacaine induced a voltage- and concentration-dependent blockade on the peak of/Na and the half-maximal inhibitory dose was 4.51 pmol/L. Consistent with other local anesthetics, bupivacaine also induced a use-dependent blockade on Navl.5 currents. The underlying mechanisms of this blockade may contribute to the fact that bupivacaine not only dose-dependently affected the gating kinetics of Nay1.5 but also accelerated the development of its open-state slow inactivation. These results extend our knowledge of the action of bupivacaine on cardiac sodium channels, and therefore contribute to the safer and more efficient clinical use of bupivacaine.