Fluorophore–quencher complexes (Cu2+/Al3+) of coumarin Schiff bases as chemosensors for the detection of L-glutamic acid and L-arginine: in vitro and in vivo studies.

This study reports the development of new probes RR1 ((1E)-1-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)ethyl thiosemicarbazone) and RR2 ((1E)-1-(1-(6-bromo-2-oxo-2H-chromen-3-yl)ethylidene)phenyl thiosemicarbazone), which selectively showed fluorescence turn 'OFF' response towards Cu2+ and Al3+. Further, complexes of RR1-Cu2+ and RR2-Al3+ acted as chemosensors for the detection of L -amino acids. RR1-Cu2+ selectively detected L -arginine (fluorescence turn 'ON'), and RR2-Al3+ selectively detected L -glutamic acid (fluorescence turn 'ON'). The existence of the fluorophore–quencher complexes RR1-Cu2+ and RR2-Al3+ was confirmed by theoretical studies. Further, the chemosensors RR1-Cu2+ and RR2-Al3+ have three possible structural isomers (RR1-Cu2+- L -arginine – A, B and C) and (R2-Al3+- L -glutamic acid – D, E and F), as confirmed by theoretical studies. In vitro bio-imaging of the probes (RR1 and RR2), complexes (RR1-Cu2+ and RR2-Al3+) and complexes associated with L -arginine (RR1-Cu2+- L -arginine) and L -glutamic acid (R2-Al3+- L -glutamic acid) was performed in the MDA-MB-231 cell line using their IC50 concentrations. In addition, in vivo live cell imaging studies were conducted using C. elegans as the model organism. [ABSTRACT FROM AUTHOR]