Seasonal variation in flavonoid contents of green pepper and other vegetables

The flavonoid contents in the vegetables have the possibility to vary according to seasons. The flavonoid contents about 15 kinds of vegetables circulated in June were examined by HPLC after hydrolysis. In addition, the amounts of quercetin and luteolin in the green pepper during the year were studied with the main production area; Miyazaki and Kochi. The content of quercetin in green pepper, was 3.15 +/- 1.77mg (aggregate average) and luteolin content was 8.15 +/- 4.10mg per 100g of fresh weight. Flavonoid contents were increased in October to December, and the tendency to decrease in May to June. The relations with the amount of the ultraviolet rays irradiation was suggested. Moreover, a significant difference was observed among homes at time when a lot of contents were different. The contents of quercetin in June and in January in vegetables (kale, komatsuna, spinach, chin-gen-sai, and perilla) were not different significantly except for kale. Therefore, it was concluded that the changes of the amount of flavonoid in the vegetables were two ways, one of which was few changes and the other showed the maximum content in autumn during year.