Rapid Quantification of Bioactive Lentinan with an Aniline Blue Fluorescent Method

Lentinan is a clinically approved immune modulator and its anticancer and immunomodulatory bioactivity is found to be dependent on its triple helical conformation. Therefore, the development of rapid and convenient method for determination of bioactive lentinan with triple helical conformation holds great promise for the quality control of lentinan healthy products. In this work, an aniline blue fluorescent method was optimized and established to accurately and rapidly detect bioactive lentinan. In the presence of lentinan, the fluorescence intensity of aniline blue with 404 nm excitation and 492 nm emission dramatically enhanced within 15 min in pH 10 glycine-NaOH buffer solution, which allowed the analysis of lentinan in a very simple and fast manner. The method allowed for the sensitive determination of lentinan in the range of 1 to 60 μg/mL with a detection limit of 0.25 μg/mL. Notably, the protocol exhibited excellent selectivity for the determination of triple helical lentinan over other saccharides. The method was successfully applied to the detection of bioactive lentinan in health tonic solution, which demonstrated the method had great potential for quality control of lentinan contained products.