Determination of Rutin and Isoquercetin Contents in Hibisci mutabilis Folium in Different Collection Periods by HPLC

Hibisci mutabilis Folium (HMF), the dried leaf of Hibiscus mutabilis (Malvaceae), is commonly used in traditional Chinese medicine. This article aimed to establish a high-performance liquid chromatography method for the determination of rutin and isoquercitrin contents in the HMF, and to compare the content variation in all the samples, including nearly withered yellow leaf, in different collection periods, so as to provide research basis for the quality evaluation and determination of the optimal collection period. A reversed-phase HPLC separation method was employed, with a BDS Hypersil C18 column (4.6 m × 250 mm, 5 μm), under the following conditions: acetonitrile-0.3% phosphoric acid (15:85, v/v) solution as the mobile phase, flow rate 1.0 mL/min at 30°C and detection wavelength 254 nm. The calibration curves for rutin and isoquercitrin were linear over the range of 1.5-48 and 0.25-8 μg/mL, and the average recoveries were 99.92 and 100.45% (RSD: 2.39% and 2.11%, respectively)]. Based on the analysis results, it was found that contents of rutin and isoquercitrin in HMF (mature green leaf) harvested in different periods had significant difference, and reached the highest in mid-December. It was also found that the contents of the two components in the mature green leaf were much higher than those in the nearly withered leaf from the same collection period. In conclusion, the results indicated that the HPLC method was easy-to-operate and precise, and could be applied for the determination of rutin and isoquercitrin contents in the HMF. The experimental data also showed that early winter should be the most suitable collection period for HMF.