Lipolysis induced by various citrus fruits

Abstract

Lipolysis induced by extracts of various citrus fruits (47 cultivars) was investigated using rat fat cells. High lipolytic activity was observed in unripe fruits. Lipolytic activity was also detected in ripe fruits ; peel or segment wall extracts from ripe fruits induced lipolysis, whereas juice sac extract did not. The lipolytic activity of segment wall extract was about 27% of that of peel extract. In peel fractions, the lipolytic activity of flavedo fraction was about 3-fold higher than that of albedo fraction. Using the Citrus genus classification of Tanaka, high lipolytic activities were observed in group V [Aurantium Tanaka ; including Natsumikan (Citrus natsudaidai Hayata) and Iyokan (Citrus iyo Hort. ex Tanaka)] and group VII [Acrumen Tanaka ; including Satsuma mandarin orange (Citrus unshiu Marc.) and Ponkan (Citrus reticulata Blanco)], while group II [Limonellus Tanaka ; including Tahiti lime (Citrus latifolia Tanaka)], group III [Citrophorum Tanaka], including lemon (Citrus limon (L.) Tanaka)] and group IV [Cephalocitrus Tanaka ; including Buntan (Citrus grandis (L.) Osbeck) and grapefruit (Citrus paradisi Macf.)] tended to have low lipolytic activity. The concentration of synephrine in unripe fruit was proportional to lipolytic activity. These results suggest that the peel and segment walls of ripe fruit, which are generated in large quantities as a waste product from the citrus juicing process, may be useful as a functional food, especially as a fat reducing material.