Antioxidant properties of the extracts from different parts of broccoli in Taiwan

The flowers, stems, and leaves of broccoli (Brassica Oleracea L var italica Plenca) cultivated in Taiwan were freeze-dried and extracted with methanol, water, or acetone. The antioxidant properties, including reducing power. ferrous ion chelating ability, and alpha,alpha -diphenyl-beta -picrylhydrazyl (DPPH) radical scavenging activity, were tested in this study. The above antioxidant properties of broccoli extracts along with alpha-tocopherol and butylated hydroxyanisole (BHA) were compared. Results showed that the methanol and water extracts exhibited a higher reducing power in all three parts; while the acetone extract was the least. The stem extracts showed the highest reducing power, which was 1.3 times those alpha-tocopherol and BHA extract,, followed by the leaf extracts, which exhibited similar reducing power to alpha-tocopherol and BHA. The lowest reducing power was observed on flower extracts, which was only three fourth of the reducing power as compared to alpha-tocopherol and BHA. The methanol and water extracts of broccoli also exhibited high chelating ability; while the acetone extracts showed the lowest. The broccoli stem exhibited the highest chelating ability among three parts of broccoli, The acetone extracts from stems hardly showed any chelating ability as compared to alpha-tocopherol and BHA. The methanol extracts of broccoli showed the highest DPPH radical scavenging activity (>90%) among three different solvent extracts. Its DPPH radical scavenging activity was close to BHA and alpha-tocopherol. The water extracts showed only 43% DPPH radical scavenging activity; while the acetone extracts barely showed any DPPH radical scavenging activity.