Comparison of ultrasound and microwave-assisted extractions of bioactive components from lotus leaf and effect of the artificial gastric juice immersion on the antioxidant activities

In order to improve the extraction efficiency of lotus leaf antioxidants and explore the effect of artificial gastric juice immersion on the antioxidant activities, the extraction efficiency of lotus leaf antioxidants of ultrasound and microwave-assisted extractions by determining reducing power, total antioxidant power, scavenging percentage of hydroxyl radicals, DPPH radicals and the effect of the artificial gastric juice immersion on the antioxidant activities were studied.The results showed that the antioxidant activities (the reducing power, total antioxidant power, scavenging percentages of superoxide anion radicals and DPPH radicals) of the microwave-assisted extracts were stronger than those of ultrasound assisted extracts, the total flavonoids and polyphenols contents of the microwave-assisted extracts were higher than those of ultrasound assisted extracts.The antioxidant activities (the total antioxidant power, scavenging percentages of superoxide anion radicals, hydroxyl radicals and DPPH radicals) of lotus crude extracts were much improved after immersed by the artificial gastric juice.