Synthesis and Properties of Amphipathic Fluorescent Dye Derived from Spiculisporic Acid Anhydride

Abstract

Pyrenacyl ester of spiculisporic acid anhydride (SAPE) was newly synthesized as an amphipathic fluorescent probe from a kind of microbial biosurfactant. SAPE was synthesized by the reaction of spiculisporic acid anhydride, which was derived from spiculisporic acid, with 1-bromoacetylpyrene. SAPE showed different fluorescent spectra by behaving as “finger prints” in response to various kinds of hydrophobic environments of solvents, molecular aggregates, and liposomes. SAPE gave different fluorescent patterns in solvents depending on the solubility parameter. On the ohter hand, excimer formation of SAPE was accelerated in larger micellar domains of heptaoxyethylene dodecyl ether (C₁₂E₇) than in sodium dodecylsulfate (SDS). The dependence of the spectrum on surfactant concentrations was also notable. Furthermore, SAPE was considered to have a larger membrane fluidity in liposomal bilayers than in micelles from the different emitting wavelengths of the respective excimers in liposome (511 nm) and micelles (440 or 453 nm).