Antioxidative Activities and Active Compounds of Extracts fromCatalpaPlant Leaves
In order to screen theCatalpaplant with high antioxidant activity and confirm the corresponding active fractions fromCatalpa ovataG. Don,C. fargesiiBur., andC. bungeiC. A. Mey., total flavonoid contents and antioxidant activities of the extracts/fractions ofCatalpaplant leaves were determined. The determined total flavonoid content and antioxidant activity were used as assessment criteria. Those compounds with antioxidant activity were isolated with silica gel column chromatography and ODS column chromatography. Our results showed that the total flavonoid content inC. bungeiC. A. Mey. (30.07 mg/g·DW) was the highest, followed by those inC. fargesiiBur. (25.55 mg/g·DW) andC. ovataG. Don (24.96 mg/g·DW). According to the determination results of total flavonoid content and antioxidant activity in 3 clones of leaves ofC. bungeiC. A. Mey., the total flavonoid content and antioxidant activity in crude extracts fromC. bungeiC. A. Mey. 6 (CA6) leaves were the highest. Moreover, the results showed that the total flavonoid content and antioxidant activities of ethyl acetate (EA) fraction in ethanol crude extracts in CA6 leaves were the highest, followed byn-butanol, petroleum ether (PE), and water fractions. Two flavonoid compounds with antioxidant activity were firstly isolated based on EA fraction. The two compounds were luteolin (1) and apigenin (2), respectively.