Flavonoids are a large group of polyphenolic compounds ubiquitously present in plants. They are important components of human diet. They are recognized as potential drug candidates to be used in the treatment and prevention of a lot of pathological disorders, due to their protective effects. Baicalin (7-glucuronic acid 5, 6-dihydroxyflavone) is one of the main single active constituents isolated from the dried roots of Scutellaria baicalensis Georgi. The great interest on this flavonoid is due to its various pharmacological properties, such as antioxidant, antimicrobial, anti-inflammatory, anticancer and so on, and its high accumulation in the roots of S. baicalensis. The aim of our work was to analyze the geometric and electronic properties of baicalin conformers (BCL), thus performing a complete search on the conformational space of this flavonoid in gas phase and in aqueous solution. The results indicate that the conformational space of baicalin is formed by eight conformers in gas phase and five conformers in aqueous solution optimized at B3LYP/6-311++G** theory level. BCLa2 and BCLa1 conformers have low stability in gas phase and very high stability in aqueous solution. This variation is related to a modification in the τ angle that represents the relative position of the glucuronide unit respect to the central rings of the flavan nucleus (A and C). This modification was successfully explained by examining the changes in the hydrogen bond (HB) interactions that occur in the region around the hydroxyl group located in position 6 of ring A. Besides, the molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analyses indicate that BCLa2 and BCLa1 conformers are the most favorable conformers for interacting with positively charged species (such as metal ions) in aqueous media (such as biological fluids).
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http://dx.doi.org/10.1016/j.jmgm.2017.07.007 | DOI Listing |
Nat Commun
January 2025
Department of Chemistry, Theoretical Chemistry Institute, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Identifying transitional states is crucial for understanding protein conformational changes that underlie numerous biological processes. Markov state models (MSMs), built from Molecular Dynamics (MD) simulations, capture these dynamics through transitions among metastable conformational states, and have demonstrated success in studying protein conformational changes. However, MSMs face challenges in identifying transition states, as they partition MD conformations into discrete metastable states (or free energy minima), lacking description of transition states located at the free energy barriers.
View Article and Find Full Text PDFACS Nano
January 2025
Clinical Translational Research Center of Aggregation-Induced Emission, School of Medicine, The Second Affiliated Hospital, School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), Guangdong 518172, China.
Strategies to acquire high-efficiency luminogens that emit in the second near-infrared (NIR-II, 1000-1700 nm) range are still rare due to the impediment of the energy gap law. Herein, a feasible strategy is pioneered by installing large-volume encumbrances in a confined space to intensify the repulsive interactions arising from overlapping electron densities. The experimental results, including smaller coordinate displacement, reduced reorganization energy, and suppressed internal conversion, demonstrate that the repulsive interactions assist in the inhibition of radiationless deactivation.
View Article and Find Full Text PDFFeature selection is essential in the analysis of molecular systems and many other fields, but several uncertainties remain: What is the optimal number of features for a simplified, interpretable model that retains essential information? How should features with different units be aligned, and how should their relative importance be weighted? Here, we introduce the Differentiable Information Imbalance (DII), an automated method to rank information content between sets of features. Using distances in a ground truth feature space, DII identifies a low-dimensional subset of features that best preserves these relationships. Each feature is scaled by a weight, which is optimized by minimizing the DII through gradient descent.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
National Key Laboratory of Space Medicine, China Astronaut Research and Training Center, Beijing 100094, China.
TMEM16A, a key calcium-activated chloride channel, is crucial for many physiological and pathological processes such as cancer, hypertension, and osteoporosis, etc. However, the regulatory mechanism of TMEM16A is poorly understood, limiting the discovery of effective modulators. Here, we unveil an allosteric gating mechanism by presenting a high-resolution cryo-EM structure of TMEM16A in complex with a channel inhibitor that we identified, Tamsulosin, which is resolved at 2.
View Article and Find Full Text PDFBiophys Chem
December 2024
Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China; NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. Electronic address:
The inhibition of the TIGIT/PVR interaction demonstrates considerable anticancer properties by enhancing the cytotoxic activity of natural killer (NK) and CD8+ T cells. However, the development of small molecule inhibitors that target TIGIT is currently limited. In this study, small molecules with the capacity to bind TIGIT and block the TIGIT/PVR interaction were screened through an advanced computational process, subsequently confirmed by blocking assays.
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