Extraction and purification of limonene-1,2-diol obtained from the fungal biotransformation of limonene

Abstract

R-(+)-limonene is the main component of the orange peel oil, which is available in large amounts, at low cost, and can be employed in biotransformation processes as a precursor of different value-added aroma compounds. Limonene-1,2-diol is one of the oxyfunctionalyzed counterparts of limonene that can be obtained from the biotransformation process, but its biological properties and applications are still little investigated in literature. Thus, we aimed to study the recovery and purification of limonene-1,2-diol obtained from fungal biotransformation, which is an essential step for further investigations. First, liquid-liquid extractions were performed to select the most appropriate solvent, extraction time, and extracting material (whole fermented broth or supernatant) for recovering limonene-1,2-diol. Subsequently, sequential extractions with different solvents were considered for recovering larger amounts of limonene-1,2-diol as well as for removing the residual limonene. Finally, Open Column Chromatography procedures were evaluated for purifying limonene-1,2-diol originating from a limonene:limonene-1,2-diol mixture. According to the results, ethyl acetate was the most adequate solvent for recovering limonene-1,2-diol, and equilibrium was quickly reached (20 s in vortex). The extraction of the supernatant was repeated twice with hexane, followed by two sequential extractions with ethyl acetate, and was found to be the most suitable process for recovering limonene-1,2-diol in higher yields and purities. In addition, a silica-gel column chromatography was used for separating limonene from limonene-1,2-diol, but this procedure was deemed unnecessary, since better recovery and purification yields were obtained from the liquid-liquid extraction. The processes described in our study may be useful for researchers working with limonene-1,2-diol or other oxidized monoterpenoid as well as with downstream processing of biotransformation products.