ABSTRACT
Objective: To investigate the impact of compatibility ratios of rhubarb-gardenia herbal pair and extraction techniques on anthraquinone dissolution, and to explain the bases of different compatibility of rhubarb-gardenia in the prescriptions of Chinese materiamedica from chemical composition. Methods: Anthraquinones were extracted from rhubarb-gardenia herbal pair of different compatibility ratios by water decoction method and ultrasonic extraction with alcohol. Free and total anthraquinones were analyzed by HPLC and the contents of binding anthraquinones were equal to the total minus the free anthraquinones. Results: The contents of various types of anthraquinones extracted by water decoction method increased and binding anthraquinone content increased significantly after rhubarb was compatible with gardenia. This suggested that gardenia was benefit for binding anthraquinone dissolution. Decocting order (Rhubarb cooked first, last, and at the same time) also affected the content of anthraquinones in water decoction method. Separate ultrasonic extraction was benefit for total and free anthraquinone dissolution. Separate ultrasonic extraction was benefit for total and free anthraquinones dissolution. Simultaneous ultrasonic extraction was benefit for binding anthraquinone dissolution. The extraction effect of ultrasonic method was significantly higher than that of water decoction method. Conclusion: Rhubarb-gardenia herbal pair in different compatibility proportion plays different role in different prescriptions because of the different composition and content of anthraquinones,which proves the rationality of the classic formula.