Abstract: The purpose of this study was to optimize the extraction process of two forms of Monacolin K from highland barley Monascus,and to establish their content determination method.On the basis of single factor experiment,and adopting the Box-Benhnken central composite experiment and response surface analysis to determine the optimal extraction technology.The HPLC method for the determination of two forms of Monacolin K was as follows:with ZORBAX Eclipse XDB-C₁₈ column (4.6 mm×250 mm,5 μm),in the mobile phase of acetonitrile-0.1% phosphoric acid water (60:40, v/v),the flow rate was 1.0 mL/min,the detection wavelength was 238 nm.The results showed that the linearity,precision,repeatability,stability and recovery of the developed HPLC method were good.The optimized extraction conditions were finally determined to be:using methanol as extraction solvent,with extraction temperature of 60 ℃,liquid-solid ratio of 20:1 (mL/g) and ultrasonic extraction of 1 h.Under the optimized extraction,the contents of acid form and lactone form of Monacolin K were 2.51mg/g and 1.65 mg/g,respectivly.

Key words: highland barley Monascus, Monacolin K, response surface analysis, high performance liquid chromatography, determination