Zeolitic imidazolate framework-8 for selective extraction of a highly active anti-oxidant flavonoid from Caragana...

The medicinal compositions or active components in medicinal plants are the major sources to find new drugs or lead compounds. Exploring novel sorbents with good selectivity for extraction and separation of medicinal compositions or active components from complex medicinal plants are interesting and challenging. Metal-organic frameworks (MOFs) show great potential in adsorption and extraction recently. Herein, we report our primary attempt of zeolitic imidazolate framework-8 (ZIF-8) as a model MOF for selective extraction of a flavonoid named 3,4-dihydroxy-8,9-methylenedioxypterocarpan (compound 1) from a traditional medicinal plant Caragana Jubata. The enrichment factor of ZIF-8 for compound 1 is 57.7. The recoveries of compound 1 at three spiked levels (50, 100, 150 mg L^-1) in Caragana Jubata dichloromethane extract are 62.1%, 66.4%, and 75.4%, respectively, with the relative standard deviations of less than 2.9%. The compound 1 also gave good linearity (R² of 0.999) in the concentration range of 5-1000 mg L^-1. The obtained compound 1 gave highly antioxidant activity (DPPH radical scavenging rate of 79.03%, inhibitory rate on lipid peroxidation of 75.30%, which were higher than the positive controls Vitamin C and BHT) and low IC₅₀ values (5.438 ± 0.068, 20.970 ± 0.083 μg mL^-1 for DPPH radical scavenging activities and inhibitory effects on lipid peroxidation, respectively). These results demonstrated the feasibility of MOFs in selective extraction of medicinal compositions or active components from complex medicinal plants. The current work may open a new way of MOFs in selective extraction of pharmacological active components from medicinal plants.