Abstract:In order to explore the optimal extraction conditions, composition and antioxidant capacity of total saponins from Clinacanthus nutans, single factor and response surface methodology were used to optimize the ultrasonic-assisted extraction conditions of total saponins from Clinacanthus nutans. The composition of total saponins under the optimal extraction conditions was analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) and the antioxidant activity was detected. The results indicated that the optimal extraction parameters included 92% volume fraction of ethanol, solid-liquid ratio of 1 g∶44 mL, extraction time of 0.6 h, and extraction temperature of 66 ℃, which yielded a total saponin extraction rate of 2.30%. Five triterpene saponins were then identified. The antioxidant experiment showed that the total saponins of Clinacanthus nutans had strong antioxidant activity, and there was a good correlation between their mass concentration and their ABTS+ scavenging rate, DPPH+ scavenging rate, and Fe3+ reduction ability. The corresponding semi-inhibitory concentrations to free radical scavenging rate were 0.407 mg/mL and 0.562 mg/mL, respectively. The results provide beneficial reference information for further development and utilization of saponins from Clinacanthus nutans.
