Novel aliphatic N-oxide of naphthalimides as fluorescent markers for hypoxic cells in solid tumor

A series of novel aliphatic N-oxide of naphthalimides (A1–A5) were designed and prepared. The N–O group was firstly introduced into the amine side chain tailed to planar naphthalimide chromophore as hypoxic bioreductive marker. Fluorescence image analysis showed that the compounds could be used as potential markers for hypoxic cells (V79) in vitro especially for A1 with 17 times hypoxic-oxic fluorescence differential, which was probably due to the bis-bioreduction mechanism.

Graphical abstractThe N–O group was introduced into the amine side chain of chromophore as a hypoxic marker for the first time to identify hypoxic cells in solid tumor.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Novel aliphatic N-oxide of naphthalimides were designed and prepared. ► The N–O group was introduced into the amine side chain as bioreductive marker. ► Compounds A1–A5 could be used as potential markers for hypoxic cells (V79) in vitro. ► Compound A1 showed 17 folds hypoxic-oxic fluorescence differential.