Objective:To study the influences of combination and pH of Aconiti Lateralis Radix decoction on the six ester alkaloids contents and probe into chemical essence of combination taboo of Aconiti Lateralis Radix.Method: The HPLC analytical method was established for quantifying the six ester alkaloids contents in decoctions when Aconiti Lateralis Radix combined with Pinelliae Rhizoma

Trichosanthis Fructus

Fritillariae Cirrhosae Bulbus

Fritillariae Thunbergii Bulbus

Ampelopsis Radix and Bletillae Rhizoma

respectively

or extracted with acidic

alkaline water of different pH or combined with acidic

alkaline traditional Chinese medicine.Result: For the co-decoctions of Aconiti Lateralis Radix combined with Pinelliae Rhizoma

Trichosanthis Fructus

Fritillariae Cirrhosae Bulbus

Fritillariae Thunbergii Bulbus

Ampelopsis Radix and Bletillae Rhizoma

the pH values were all less than that of single Aconiti Lateralis Radix decoction and the contents of diester alkaloids was more than that of the single decoction.The contents of diester alkaloids in decoctions was correlated with the decoction pH.When Aconiti Lateralis Radix was extracted with acidic water or combined with acidic traditional Chinese medicine

the contents of diester alkaloids obviously increased with the increment of decoction acidity.When Aconiti Lateralis Radix was extracted with alkaline water or combined with alkaline traditional Chinese medicine

the decoction pH was greater than 7

the diester alkaloids were completely hydrolyzed.Conclusion: The chemical essence of combination taboo of Aconiti Lateralis Radix was that the diester alkaloids contents and the toxicity increased with the reduction of decoction pH.The diester alkaloids were relatively stable in acidic conditions and unstable in alkaline conditions.