New approach to the interaction between Folin-Ciocalteu reactive and sugars during the quantification of total phenols

Abstract

Phosphomolybdic and phosphotungstic acids mixture, known as Folin-Ciocalteu reactive, is one of the main methods for the quantification of polyphenolic compounds in vegetable extracts (FC reactive). However, as other spectrophotometric methods, it can be unspecific and interact with other molecules, such as sugars, present in vegetable extracts, modifying the obtained results. The aim of the present study was to evaluate the effect of glucose, sucrose, fructose, xylose, mannose, rhamnose and arabinose on the quantification of polyphenolic compounds by the FC method. Fructose and xylose showed the highest interaction with FC reactive, while sucrose, mannose, rhamnose and glucose showed the lowest effect. Fructose and mannose reacted differently with both gallic acid solutions and anise, jalapeño hot pepper and traditional Mexican spices (hoja santa and avocado leaves). Fructose increased the response of the method, and consequently overestimated the polyphenolic content, while mannose showed an underestimation. The obtained results showed that sugar content in vegetable extracts may interfere on the estimation of polyphenolic content, especially if high content of fructose is present in the samples.