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Abstract: Amyloid β-protein (Aβ), which is deposited in neurons as neurofibrillary tangles, is known to exert cytotoxic effects by inducing mitochondrial dysfunction. Additionally, the PI3K/Akt-mediated interaction between Bad and BclXL plays an important role in maintaining mitochondrial integrity. However, the application of therapeutic drugs, especially natural products in Alzheimer''s disease therapy via PI3K/Akt/Bad/BclXL-regulated mitochondrial apoptotic pathway has not aroused extensive attention. In the present study, we investigated the neuroprotective effects of hyperoside, a bioactive flavonoid compound from Hypericum perforatum, on Aβ25–35-induced primary cultured cortical neurons, and also examined the potential cellular signaling mechanism for Aβ detoxication. Our results showed that treatment with hyperoside significantly inhibited Aβ25–35-induced cytotoxicity and apoptosis by reversing Aβ-induced mitochondrial dysfunction, including mitochondrial membrane potential decrease, reactive oxygen species production, and mitochondrial release of cytochrome c. Further study indicated that hyperoside can activate the PI3K/Akt signaling pathway, resulting in inhibition of the interaction between Bad and BclXL, without effects on the interaction between Bad and Bcl-2. Furthermore, hyperoside inhibited mitochondria-dependent downstream caspase-mediated apoptotic pathway, such as that involving caspase-9, caspase-3, and poly ADP-ribose polymerase (PARP). These results demonstrate that hyperoside can protect Aβ-induced primary cultured cortical neurons via PI3K/Akt/Bad/BclXL-regulated mitochondrial apoptotic pathway, and they raise the possibility that hyperoside could be developed into a clinically valuable treatment for Alzheimer''s disease and other neuronal degenerative diseases associated with mitochondrial dysfunction. [Copyright &y& Elsevier]

Complex nuclear magnetic resonance (NMR) signals of organic compounds containing multiple analogous substructures or mixtures pose a significant challenge to structural identification, thus resulting in frequent misassignment of structures. The GEMSTONE method, a single-scan technique that selectively excites a specific proton signal among the crowded NMR signals, was recently proposed as a solution. However, its extension to the polarization transfer method for heteronuclear spin systems was unsuccessful. Herein, we present an extension method that addresses the altered heteronuclear polarization transfer efficiency and enables the acquisition of ultraselective 13 C and 1 H- 13 C correlation NMR subspectra with hertz-level signal selectivity in both dimensions. We demonstrate the effectiveness of this technique in the structural analysis of a chromopeptide pharmaceutical and a diastereomeric mixture of a fungicide., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Metabolomic isotopic tracing can provide flux information useful for understanding drug mechanisms. For that, NMR has the unique advantage of giving positional isotope enrichment information, but the current 13 C 1D NMR approach suffers from low sensitivity and high overlaps. We developed a new 2D heteronuclear NMR experiment incorporating J -scaling and distortion-free elements that allows for quantitative analysis of multiplets with high sensitivity and resolution. When applied to an old chemotherapeutic drug, the approach provided a quantitative estimation of TCA-cycle turns, confirming the conventional mechanism of its mitochondrial metabolic enhancement. Additionally, the approach identified a new mechanism of the higher contribution of the pentose phosphate pathway to serine synthesis in the cytosolic compartment, possibly explaining the broad pharmacological activities of the drug. Our approach may prove beneficial in helping to find new usages or metabolic mechanisms of other drugs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In NMR analysis of complex organic molecules, low natural abundance of 13 C and the low resolution of two-dimensional (2D) experiments are significant difficulties. Also challenging is the analysis of a mixture spectrum without separation, which has been limited to simple molecules. Through nonuniform sampling using modified heteronuclear multiple bond correlation combined with indirect covariance, a high-resolution  13 C- 13 C correlation spectrum was obtained with 1 H sensitivity. Built on the thus-obtained 13 C- 13 C connectivities, deconvolution of the mixture spectra was achieved through a new signal-processing procedure, termed DECODE, tailored to the indirect covariance eigendecomposition. When applied to a complex natural product mixture of rotenone and brucine with many quaternary carbons, the method resolved very close carbon peaks and extracted clean individual spectra. Essentially providing molecule-wide 13 C connectivities for complex molecules from 1 H-detected 2D spectra, our approach should prove useful in many areas of NMR analysis.