Simultaneous determination of four sesame lignans and conversion in Monascus aged vinegar using HPLC method

A simple, accurate and specific high-performance liquid chromatography (HPLC) method has been developed and validated for simultaneous determination of sesamol, sesamin, asarinin and sesamolin in Monascus aged vinegar. The effects of acid hydrolysis and four heating treatments on the components content in Monascus aged vinegar were discussed. The results showed that the isomerisation of sesamin to asarinin, and decomposition of sesamolin to sesamol significantly increased, regardless of heating or acid hydrolysis. Thermal processes and acid hydrolysis increased the content of sesamol and asarinin, respectively, but severe thermal processes resulted in the loss of total sesame lignans. Sesamol and asarinin reached the highest (2.720 +/- 0.202 mu g/mL and 2.064 +/- 0.075 mu g/mL) for autoclaving (125 degrees C, 15 min) and acid hydrolysis (25 degrees C, 15 min, nature pH), respectively. Therefore, autoclaving and acid hydrolysis were considered as the optimal way to obtain higher content of sesamol and asarinin.