Photophysical studies, fluorescence imaging, single crystal X-ray structure analysis and DFT calculations revealed that compounds2and3show enhanced phototoxicity towardsCandida albicanscompared to compound1.

Tin(IV) porphyrin scaffolds having long-chain (C 8 and C 16 ) alkoxyphenyl group at one meso position were synthesized with axial dichloro and dihydroxo ligands. Modifications with respect to the alkoxy chain length and the axial ligands were investigated using UV−vis and fluorescence spectroscopy as well as cyclic voltammetry. Significantly higher molar absorption coefficients were noted with dichloro axial ligands whereas higher fluorescence quantum yields were observed for C 8 alkoxy chain substituents. Electrochemical redox data revealed that the porphyrin ring became difficult to reduce consequent to the presence of electron donating alkoxy chain. Evaluation of the aggregation behavior in different organic solvents and DMF-water mixture has been carried out. The singlet oxygen production and photostability data are supportive of their suitability for antibacterial photodynamic therapy. The antibacterial studies carried out in Gram negative (E. coli) and Gram positive (B. subtilis) bacteria using agar well diffusion and LB broth assay revealed selective toxicity in B. Subtilis cells. Fluorescence microscopy and competitive DNA binding studies with Hoechst 33342 revealed DNA binding at the minor groove which was further substantiated with molecular docking studies.

The unusual di-bromo product, 5b, confirmed by spectral analysis, showed the most potency with the lowest IC50 and MIC values, with excellent activity comparable to the standard antibacterial drug, tetracycline.

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Berberine has been used traditionally for its diverse pharmacological actions. It exhibits remarkable anticancer activities and is currently under clinical trials. In this study, we report that the anticancer activity of berberine could be partly due to its inhibitory actions on tubulin and microtubule assembly. Berberine inhibited the proliferation of HeLa cells with an IC of 18 μM and induced significant depolymerization of interphase and mitotic microtubules. At its IC, berberine exerted a moderate G2/M arrest and mitotic block as detected by fluorescence-activated cell sorting analysis and fluorescence microscopy, respectively. In a wound closure assay, berberine inhibited the migration of HeLa cells at concentrations lower than its IC, indicating its excellent potential as an anticancer agent. In vitro studies with tubulin isolated from goat brain indicated that berberine binds to tubulin at a single site with a K of 11 μM. Berberine inhibited the assembly of tubulin into microtubules and also disrupted the preformed microtubules polymerized in the presence of glutamate and paclitaxel. Competition experiments indicated that berberine could partially displace colchicine from its binding site. Results from fluorescence resonance energy transfer, computational docking, and molecular dynamics simulations suggest that berberine forms a stable complex with tubulin and binds at a novel site 24 Å from the colchicine site on the β-tubulin. Data obtained from synchronous fluorescence analysis of the tryptophan residues of tubulin and from the Fourier transform infrared spectroscopy studies revealed that binding of berberine alters the conformation of the tubulin heterodimer, which could be the molecular mechanism behind the depolymerizing effects on tubulin assembly.