Establishment of content determination and optimization extraction condition of total alkaloids in Maca

To establish a method for the assay of the total alkaloids in Maca,and investigate the contents from different origins. With the oxymatrine as reference,the method was established by purified acid dye colorimetry and optmized the extraction condition by response surface method. Acid dye colorimetric conditions was as follows : adding p H3. 5 buffer 3 m L and bromocresol green colour reagent 3 m L, then detemining at the wavelength 412 nm. The optimal extraction conditions was found to be ratio of liquid to solid 23 ∶1(m L/g),temperature 82 ℃,time 2.1 h. The extraction efficiency of total alkaloids from Yunnan yellow Maca under these conditions was 1.3 mg/g compared to 8.4 mg/g from Tibet black Maca,highest among the five species investigated. This method was simple,highly sensitive,accurate and reproducible,which could be used for determination of the total alkaloids in Maca.