Photochemical & Photobiological Sciences 2012-07-01

Synthesis, photophysical, photochemical, DNA cleavage/binding and cytotoxic properties of pyrene oxime ester conjugates.

Nilanjana Chowdhury, Sansa Dutta, Swagata Dasgupta, N D Pradeep Singh, Mithu Baidya, S K Ghosh

Index: Photochem. Photobiol. Sci. 11(7) , 1239-50, (2012)

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Abstract

A new series of (E)-pyrene oxime ester conjugates of carboxylic acids including amino acids were synthesized by coupling with an environment sensitive fluorophore 1-acetylpyrene. (E)-Pyrene oxime esters exhibited strong fluorescence properties and interestingly their fluorescence properties were found to be highly sensitive to the surrounding environment. Direct irradiation of the (E)-pyrene oxime esters by UV light (≥350 nm) resulted in both the photo-Beckmann rearrangement product and products resulting from N-O bond homolysis. Photoproduct formation and their distribution were found to be solvent dependent. Further, we also showed (E)-pyrene oxime esters intercalated into DNA efficiently and photo-cleaved DNA. Finally we also showed these oxime esters can permeate cells efficiently and may cause cytotoxicity upon irradiation of light.