Abstract:

The aim of the current study was to optimize the extraction conditions for total flavonoids from the fruit of black
mulberry (Morus nigra L.) by orthogonal array design and response surface methodology. The antioxidant activity of total
flavonoids from black mulberry fruits was assessed by hydroxyl radical and superoxide anion radical scavenging, and
reducing power assays. Ethanol concentration, extraction temperature and number of repeated extractions were identified as
main variables that affect extraction efficiency by orthogonal array design, and optimized by response surface methodology
to be 48%, 80 ℃ and 4, respectively. Under the optimized conditions, the predicted extraction yield of total flavonoids
was 2.32%, which was very close to the experimental value of 2.31%. The total flavonoids extracted from black mulberry
fruits had strong reducing power, and exhibited a more powerful scavenging effect against hydroxyl radical than against
superoxide anion radical.

Key words: Morus nigra L., orthogonal array design, response surface methodology, total flavonoids, antioxidation