The Japanese encephalitis virus (JEV), a mosquito-borne flavivirus that causes viral encephalitis leading to neural damage, is a major threat in most Asian countries. The RNA-dependent RNA polymerase ...(RdRp) present in the viral genome is the key component for genome replication, making it an attractive target for antiviral drug development. In this study, the natural products from Echinacea angustifolia were retrieved for structure-based virtual screening against JEV–RdRp. The top six compounds (Echinacoside, Echinacin, Rutin, Cynaroside, Quercetagetin 7-glucoside, and Kaempferol-3-glucoside) were obtained based on the highest negative docking score, ADMET (absorption, distribution, metabolism, excretion, and toxicity), and molecular interaction. The computational analysis of these selected compounds against the co-crystallized ligands, i.e., ATP and GTP, were performed. Further, 100 ns molecular dynamic simulation and post-free binding energy calculation of all the selected compounds complexed with JEV–RdRP were performed to check the stability of the complexes. The obtained results showed considerable stability and intermolecular interaction with native ligand-binding site residues of JEV–RdRp. Hence, selected natural compounds are admissible inhibitors of JEV–RdRp protein and can be considered for future antiviral drug development studies.
The antioxidant properties of components of leaf extracts of the evergreen plant, Sempervivum tectorum (ST), have been evaluated using UV irradiated liposomal systems containing the spin trap ...5-(diethoxyphosphoryl)-5-methyl-pyrroline-N-oxide. Decreases in free radical activity in the liposomal systems as measured by electron paramagnetic resonance (EPR) spectroscopy demonstrate that the lipophilic ST juice components, kaempferol (KA) and kaempferol-3-glucoside (KG) contribute significantly to the antioxidant properties of the juice. EPR spectral simulation established the presence of oxygen and carbon centered free radical adducts. The mixtures with low pH, citric and malic acid, and ST juice reveal increased EPR signals from oxygen centered radicals in comparison to the control, pointing to the important role of pH in oxygen radical formation. Parallel assays that measured thiobarbituric acid related substances confirm the antioxidant effects of KA and KG and explain the results of spin trapping experiments complicated by low pH's. Keywords: Sempervivum tectorum extract; EPR; kaempferol; kaempferol-3-glucoside; liposomes; antioxidants
Four kaempferol glycosides, I, II, III, and IV, were isolated from the leaves of Clitoria ternatea L. (Leguminosae). Kaempferol 3-glucoside (I), 3-rutinoside (II), and 3-neohesperidoside (III) were ...identified by UV, PMR, and mass spectrometry. IV, C33H40O19, mp 198°, was characterized as kaempferol-3-O-rhamnosyl-(1→2)-O-rhamnosyl-(1→6)-glucoside from spectral data, and was named clitorin. In this connection, distinction between rutinosyl and neohesperidosyl by CMR spectrometry is discussed.
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