Polyphenol contents and radical-scavenging activity of extracts from fruits and vegetables in cultivated in Okinawa, Japan

Abstract

The extracts from 66 species of fruits and vegetables cultivated in Okinawa region of Japan were prepared by sequential extraction with acetone at 30°C and 80% ethanol solution at 80°C, and their polyphenol contents and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities were measured. The total polyphenol contents of both extracts from edible parts varied in the range of 0.35 to 142.04 μ mol-gallic acid equivalent/g-fresh weight. The plants with higher polyphenol content showed a consistent tendency to exhibit higher radical-scavenging activity. Sapodilla (Manikara zapora), canistel (Pouteria campechiana), guava (Psidium guajava) and starfruit (Averrhoa carambola), originally came from the tropical zone, showed both higher level of polyphenol content and radical-scavenging activity, and they contained proanthocyanidin. The following higher group composed of bayberry (Myrica rubra), red cabbage (Brassica oleracea), suizenjina (Gynura bicolor) and purple-fleshed sweet potato (Ipomoea batatas), which contained anthocyanins. Nigana (Crepidiastrum lanceolatum), botanboufuu (Peucedanum japonicum) and nishiyomogi (Artemisia Indica), cooked only in Okinawa region within the country, also showed a high polyphenol content and radical-scavenging activity. In addition, there were some extracts from inedible parts of fruits, which possessed almost the same or higher level of polyphenol content and radical-scavenging activity, compared to their edible parts.