Dimethyl-2-[(acridin-9-yl)methylidene]-malonate as fluorescent probe for histochemical analysis.

Fluorescent compounds have been widely used for biomolecule labeling in cytochemistry and histochemistry analysis. Here, it is described the optical properties of dimethyl 2-[(acridin-9-yl)methylidene]-malonate (LPSF/IP-81), an acridine derivative. This compound was conjugated to Concanavalin A (Con A) lectin and applied as sugar probe in lectin histochemistry. Evaluation of luminescent properties showed that LPSF/IP-81 is photoluminescent with excitation at 360 nm and emission at 428 nm. Con A hemagglutinating activity and LPSF/IP81 photoluminescence were unaltered after conjugation. Circular dichroism of Con A-LPSF/IP81 conjugate showed the maintenance of the Con A structure. Lectin histochemistry with Con A-LPSF/IP81 conjugate demonstrated different pattern recognition studying normal, fibroadenoma, and invasive ductal carcinoma of human breast. These findings indicate that LPSF/IP-81 can be proposed as an alternative probe for histochemical analysis.