Correlation between color of Scutellariae Radix pieces and content of five flavonoids after softening and cutting by different methods

Abstract

Scutellariae Radix is one of the commonly used heat-clearing and damp-drying drugs in clinical practice. Establishment of the quality evaluation system for Scutellariae Radix is of great significance to ensure safety and effectiveness of clinical drug use.Scutellariae Radix pieces were prepared under different processing conditions with 3 softening methods: boiling,atmospheric steaming and pressurized steaming. High performance liquid chromatography( HPLC) method was used to determine the content of five flavonoids in Scutellariae Radix,and L*,a*,b*values representing color chromaticity of Scutellariae Radix powder were measured by colorimeter,then total color value E*was calculated. Simple correlation and canonical correlation analysis was used to explore the correlation between color of Scutellariae Radix powder and content of five flavonoids. The results showed that the contents of baicalin and wogonoside were significantly positively correlated with L*,b*and E*values,but negatively correlated with a*value. The contents of wogonin,apigenin,and melaleuca A were positively correlated with a*value,but negatively correlated with L*,b*,and E*values( P<0. 01). There was a significant negative correlation between the content of flavonoid glycosides and flavonoid aglycones( P<0. 01).All of these indicated that the color of Scutellariae Radix powder was significantly correlated with content of five flavonoids. The experiment results proved that when color difference between Huangqin pieces and medicinal materials was kept at ΔL*<6,Δb*<3,ΔE*<6,the total amount of the two glycosides in the pieces was about ±1. 5% of the medicinal materials; in this case,the total amount of the two glycosides was relatively high and stable,indicating that the color of Huangqin decoction pieces is a concrete manifestation of its intrinsic quality,and the chromaticity value detected by colorimeter can be used as a means to quickly evaluate the quality of Scutellariae Radix pieces. The results provide a new detection index for the characteristic quality evaluation system of Scutellariae Radix pieces.