Abstract:

Cheap and easily available Adinandra nitida leaves contain more than 20% flavonoid compounds that have numerous biological functions such as antioxidation, reducing blood lipid, lowering blood pressure, antimicrobial action, etc. Hot water was adopted to extract flavonoids from Adinandra nitida leaves in the present study. The extraction technique was optimized using response analysis methodology and antioxidant activities of the flavonoids extracted from Adinandra nitida leaves were evaluated by measuring DPPH and superoxide anion radical scavenging activity and reducing power. The optimal extraction conditions were as follows: extraction duration 36 min, water temperature 100 ℃, and ratio of water to material 20:1, and under such conditions the predicted and actual values (an average of three repeats) of flavonoids yield were 8.24% and 8.20%, suggesting that the validity of established regression model was good. HPLC Analysis indicated that the flavonoid extract contained 59.3% camellianin A. The flavonoid extract could significantly scavenge DPPH and superoxide anion free radicals in a dose-dependent manner, meanwhile a linear correlation between its concentration and reducing power was also observed (R2 = 0.9895).

Key words: Adinandra nitida, flavonoid, extraction, antioxidant activity