In vitro leishmanicidal activity of 16 N-benzylcytisine derivatives has been evaluated using Leishmania donovani axenic amastigotes. In general, halogen (bromo-, chloro-) derivatives appeared to be more toxic against parasites than their parent compounds. Quantum-chemical calculations helped to recognize certain patterns in the structure of frontier orbitals related to bioactivity of compounds. Thus, the presence of halogen atom is shown to have a significant effect on both distribution and the energy of LUMOs thereby on potent activity that was also confirmed by Quantitative-Structure Activity Relationship (QSAR) analysis. Experimentally and theoretically observed structure-cytotoxicity relationships are described.
The title molecular salt, C15H21N2O+·ClO4
−, crystallizes with four cations (A, B, C and D) and four anions in the chiral unit cell (space group P21). The alkaloid was isolated from the aerial parts of Genista Hispanica collected in the Samarkand region of Uzbekistan. Each cation is protonated at the N atom that bridges the alkaloid rings C and D. In each cation, ring A is almost planar and ring B adops a sofa conformation with the methylene group bridging to the C ring as the flap. Rings C and D adopt chair conformations with a cis ring junction in all four cations. In the crystal, A+B and C+D dimeric pairs linked by pairs of N—H⋯O hydrogen bonds are observed, which generate R
2
2(16) loops in each case. The dimers are consolidated by weak aromatic π–π stacking interactions between the A rings [centroid–centroid distances = 3.913 (3) and 3.915 (3) Å].
The alkaloid triacanthine was isolated from Gleditschia triacanthos and its di- and tribenzyl derivatives were synthesized. Both compounds are crystallized in the R-3 space group with same unit cell parameters. A channel is formed in the crystals, in which water molecules with large thermal parameters located on the c axis on H-bonds distances. In the dibenzyl derivative of triacanthine, the prenyl group is disordered in two positions in a ratio of 0.65:0.35, which makes it possible to fill voids in the crystal packing. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H…H (about 57.9% and 51.4% for di- and tribenzyl derivatives respectively) and H…C/C…H (around 14.9% and 19.2%) interactions.
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