[Optimization of parameters for stir-frying of Kansui Radix with vinegar based on conversion of toxic components]

This study aims to optimize the parameters for stir-frying of Kansui Radix with vinegar based on the conversion of representative toxic diterpenes, which is expected to serve as a reference for the standardized production of Kansui Radix stir-fried with vinegar. To be specific, the toxic components [3-O-(2'E,4'Z-decadienoyl)-20-O-acetylingenol(3-O-EZ), kansuiphorin C(KPC)] in Kansui Radix and the products(ingenol, 20-deoxyingenol) after the stir-frying with vinegar were selected. The toxicity to intestine and water-draining activity were evaluated with NCM460(normal human colon mucosal epithelial cell line) and HT-29(a human colorectal adenocarcinoma cell line). An HPLC method was then developed to assess the conversion of toxic components. On this basis, temperature, time, and amount of vinegar for the processing of Kansui Radix were optimized with the Box-Behnken design and the content of ingenol and 20-deoxyingenol as evaluation index. The results showed that after the stir-frying of Kansui Radix with vinegar, 3-O-EZ and KPC were first converted to monoester 3-O-(2'E,4'Z-decadienoyl)ingenol(3-EZ) and 5-O-benzoyl-20-deoxyingenol(5-O-Ben) and finally to almost non-toxic ingenol and 20-deoxyingenol, respectively. Meanwhile, the water-draining activity was retained. Six compounds had a good linear relationship with the peak area in the corresponding concentration ranges(R~2≥0.999 8), and the average recovery fell in the range of 98.20%-102.3%(RSD≤2.4%). The content of representative diterpenes and intermediate products was 14.78%-24.67% lower in the Kansui Radix stir-fried with vinegar than in the Kansui Radix, while the content of the conversed products was 14.37%-71.37% higher. Among the process parameters, temperature had significant influence on the total content of products, followed by time. The optimal parameters were 210 ℃, 15 min, and 30% vinegar. The relative error between the experimental results and the predicted values was 1.68%, indicating that the process was stable and reproducible. The strategy of screening optimal parameters for stir-frying of Kansui Radix with vinegar based on the transformation of toxic components can help improve the production stability, reduce the toxicity, and ensure the efficacy of Kansui Radix stir-fried with vinegar, which can serve as a reference for the process optimization of similar toxic Chinese medicinals.