Zhibing Huang1, Baowei Su1, Yang Xu1, Laisheng Li2, Yanping Li1. 1. State Key Laboratory of Food Science and Technology, Sino-German Joint Research Institute, Nanchang University, Nanchang, China. 2. Center of Analysis and Testing, Nanchang University, Nanchang, China.
Abstract
BACKGROUND: We previously demonstrated that disruption of the pksCT gene of Monascus led to a greater than 98% decrease in its citrinin production capacity in Monascus (PHDS26). Two potentially toxic compounds, monascopyridine A (MPA) and monascopyridine B (MPB), were found in the fermentation products of the pksCT gene-disrupted Monascus. Moreover, a rapid and reliable high-performance liquid chromatography method was developed for the simultaneous determination of MPA and MPB. We studied the effects of various extraction parameters and designed an orthogonal experiment to investigate the importance of each factor. RESULTS: The optimal extraction conditions were: methanol concentration, 90%; extraction temperature, 40 °C; extraction time, 10 min; two extraction cycles; and a solid-liquid ratio of 1:25. Under the optimal chromatographic conditions, good linearity was reached over the concentration ranges 0.5-200 µg mL-1 and 0.5-300 µg mL-1 for MPA and MPB, respectively, and the corresponding determination coefficients were 0.9999 and 0.9997. The percentage relative standard deviation values of within-day and between-day precision for MPA were 2.0% and 2.1%, respectively; the corresponding values for MPB were 4.8% and 4.6%. The average recovery for MPA and MPB was 99.9% and 94%, respectively. CONCLUSION: Maximum MPA and MPB yields (2073.7 and 1961.7 µg g-1 , respectively) were observed after 16 days of cultivation.
BACKGROUND: We previously demonstrated that disruption of the pksCT gene of Monascus led to a greater than 98% decrease in its citrinin production capacity in Monascus (PHDS26). Two potentially toxic compounds, monascopyridine A (MPA) and monascopyridine B (MPB), were found in the fermentation products of the pksCT gene-disrupted Monascus. Moreover, a rapid and reliable high-performance liquid chromatography method was developed for the simultaneous determination of MPA and MPB. We studied the effects of various extraction parameters and designed an orthogonal experiment to investigate the importance of each factor. RESULTS: The optimal extraction conditions were: methanol concentration, 90%; extraction temperature, 40 °C; extraction time, 10 min; two extraction cycles; and a solid-liquid ratio of 1:25. Under the optimal chromatographic conditions, good linearity was reached over the concentration ranges 0.5-200 µg mL-1 and 0.5-300 µg mL-1 for MPA and MPB, respectively, and the corresponding determination coefficients were 0.9999 and 0.9997. The percentage relative standard deviation values of within-day and between-day precision for MPA were 2.0% and 2.1%, respectively; the corresponding values for MPB were 4.8% and 4.6%. The average recovery for MPA and MPB was 99.9% and 94%, respectively. CONCLUSION: Maximum MPA and MPB yields (2073.7 and 1961.7 µg g-1 , respectively) were observed after 16 days of cultivation.