Extraction and Antioxidant Activities of Magnolia kwangsiensis Figlar & Noot. Leaf Polyphenols

Microwave-assisted extraction was employed to extract polyphenols from the leaf of Magnolia kwangsiensis Figlar & Noot. The yield of polyphenols was 2.44±0.02 % under the optimal conditions of RSM: acetone concentration of 70 %, ratio of solvent to material of 21 mL⋅g^-1 and extraction time of 16 min. The antioxidant activities were evaluated in terms of total antioxidant ability, reducing power, DPPH^⋅ and ^⋅ OH scavenging activity. Results showed the polyphenols presented potential antioxidant activities, especially the stronger scavenging activity on ^⋅ OH. In term of ^⋅ OH scavenging activity, the IC₅₀ value of NKA-9 purification was 0.335 mg mL^-1 , equivalent to 35.23 % of V_C . The IC₅₀ values of crude extract and ethyl acetate extract were 0.580 and 0.828 mg mL^-1 , equivalent to 60.99 % and 87.07 % of V_C . Results indicated that M. kwangsiensis leaf polyphenols present potential antioxidant activities that make it beneficial for human health by preventing or reducing oxidative damage.