Antioxidant Activity in the Petal Extract of PAP1 Transgenic Tobacco

Flavonoids are compounds which act as antioxidants in both plant and human. These substances are found in reproductive tissues. Tobaccos expressing ORF of PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) involved in flavonoid biosynthesis were used for investigating the flavonoid profiles and antioxidant activity of petals and compared to wild type (WT) tobacco. Approximately two months, the tobacco grown in a culturing room had produced flowers for harvesting. The petal tissues were extracted with the solvent of acidic methanol and water. These extracts were measured the specific wavelength of flavonoid derivatives by using a spectrophotometer. The petal extract of H7 line showed the highest content of all detected flavonoid subgroups. However the petal extract of transgenic line H5 and H7 had significantly higher levels of anthocyanin (pelargonidin) than those of the other transgenic and WT tobaccos. An antioxidant activity of the petal extract was evaluated by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) assay. An effective concentration of the extract which scavenged DPPH radical by 50% (EC50) was presented. EC50 of the H5 and H7 transgenic extracts was approximately two folds less than that of WT extract Therefore anthocyanin may highly affect on antioxidant activities.