The antioxidation capacities of green `Welcome', green and white `Gijnlim', and purple `Purple passion' asparagus spears were evaluated. Analyses of rutin and total polyphenols, and assays of DPPH radical absorbing and low-density lipoprotein (LDL) antioxidation were conducted. Varietal differences associated with the colors of spears were observed both in the amounts of rutin, total polyphenols and in DPPH radical absorbing activities, although not in LDL antioxidation activities. DPPH radical absorbing activities seemed to be affected by both rutin and other polyphenolic compounds. However, LDL antioxidation activities were likely to be influenced more by other polyphenolic compounds than by rutin. Total polyphenol content showed a fairly close relationship with rutin content, DPPH radical absorbing activity and LDL antioxidation activity. To determinate total polyphenol content using the Folin–Denis' method seemed to be useful for selecting the breeding lines that show high antioxidative capacities.
Asparagus is a popular vegetable rich in healthy functional components. Asparagus spears are known to contain a large amount of rutin, which has been found to possess anti-inflammatory, antitumor, and antibacterial/viral properties, and protodioscin, which is an antitumor substance and present in the bottom parts (8 cm from the cut end). However, the process of its production leaves fern in the aboveground parts and roots in the underground parts as significant amounts of nonusable parts, and this issue should be solved. This study was conducted to examine the distributions of rutin and protodioscin, representative functional components in different parts of asparagus. The results suggested that large amounts of rutin were noted in the cladophylls and storage roots (brown and epidermis), and the protodioscin content was high in the buds, the soil-covered section of the spear, and the rhizome. A significant amount of rutin was detected in the aboveground parts, which is consistent with the results of previous studies, but it was also found in the storage roots. The largest amount of protodioscin was found in the buds, as well as in young fruits and seeds of the aboveground parts. Injury by continuously cropping asparagus may be associated with high rutin content in the storage roots of asparagus.