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The optical band positions (or crystal field energy levels) of manganese (IV) ions in trigonal barium titanium hexafluoride and barium silicon hexafluoride crystals are computed from the full diagonalization (of energy matrix) method founded on the two-spin-orbit-parameter model which consists of the effects from both the spin-orbit parameters of dn ion and ligand ions. The computed results are in rational agreement with the experimental values. It is found that the large difference of first excited state splitting ΔE (2E) between the manganese (IV)-doped barium titanium hexafluoride and barium silicon hexafluoride crystals is owing mainly to the great difference of trigonal distortion between the fluorine octahedral clusters in the two host crystals. [ABSTRACT FROM AUTHOR]

Human CYP1A2 is an important enzyme for drug metabolism and procarcinogen activation. This study aimed to explore the binding mode of ligands with CYP1A2 and to screen potential inhibitors from a library of herbal compounds using computational and in vitro approaches. The heme prosthetic group and six residues (Thr124, Phe125, Phe226, Phe260, Gly316, and Ala317) in the active site of CYP1A2 were identified as important residues for ligand binding using the LIGPLOT program. Ala317 in helix I immediately above heme was highly conserved in most human CYPs with known crystal structures. In molecular docking, 19 of the 56 herbal compounds examined were identified as potential inhibitors of CYP1A2. Up to 21 of the 56 herbal compounds were hit by the pharmacophore model of CYP1A2 inhibitors developed and validated in this study. In the in vitro inhibition study, 8 herbal compounds were identified as moderate to potent inhibitors of CYP1A2. Five of the 8 herbal compounds predicted to be potential inhibitors were confirmed as CYP1A2 inhibitors in the in vitro study. A combination of computational and in vitro approaches, represent a useful tool to identify potential inhibitors for CYP1A2 from herbal compounds. [ABSTRACT FROM AUTHOR]