[Determination of artemisinic acid in Artemisia annua at different growth stages based on spot area].

OBJECTIVE: Based on the important medicinal applications of artemisinic acid and the superiority of Thin Layer Chromagraphy (TLC), the spot area method of TLC was presented to determine the content changes of artemisinic acid of Artemisia annua at different growing stages. METHODS: The separation conditions including chromatographic solutions and chromogenic agent were optimized. The detection limit and the linear concentration range were analyzed. And the content changes of artemisinic acid of Artemisia annua at different growing stages were detected. RESULTS: The results showed that artemisinic acid extracted from Artemisia annua could be separated completely by the chromatographic solutions composed by petroleum ether,acetone and ethyl acetate (80: 19: 1). The artemisinic acid was clearly colored using the chromogenic agent consisting by ethanol, bromophenol blue and sulfuric acid. The detection limit of TLC was 0.05 mg/mL. The spot area of TLC had a good linear relationship within the range of 0.05-0.6 mg/mL, accorded with regression equation of y = 11.162 x + 0.0823. The results showed that the content of artemisinic acid at 0.041 mg/g in April which below the detection limit of TLC had no color spot. Contrarily, the spots of artemisinic acid were obvious in materials growing from May to September, and content was about 0.7, 1.2, 2.1, 2.4 and 2.7 mg/g, respectively corresponding to results by HPLC. CONCLUSION: The method can be applied to the quantitative analysis of artemisinic acid in Artemisia annua.