To search for plant foodstuffs with potent anti-obese activity, we conducted a large scale screening based on the inhibitory activity on adipogenesis and the facilitating activity on adipolysis in vitro. That is, inhibition of intracellular lipid accumulation and facilitation of lipid degradation in 3T3-L1 adipocytes were extensively screened from ethanol and hexane extracts of approximately 100 kinds of plant foodstuffs marketed in Okinawa prefecture, which has been famous for the highest prevalence of exceptionally long-lived individuals in the world. Among them thirty one foodstuffs showed potent inhibitory activity on intracellular lipid accumulation in 3T3-L1 adipocytes, whereas only four foodstuffs showed clear facilitating effect on lipid degradation in 3T3-L1 adipocytes. Although further study to examine the in vivo effects on adipogenesis and adipolysis is required, this is the first study to investigate anti-obese characteristics of wide range of traditional Okinawa foodstuffs so that the results give useful information to take another look at Okinawa food culture.

Okinawa is an isolated island prefecture of Japan and is known for the longest life expectancy and low disability rate. We therefore focused on the effects of traditional Okinawan fruits Citrus depressa and Annona atemoya consumed by the Okinawan population. Repeated oral administration of ethanol extracts of C. depressa and A. atemoya potently lowered the plasma triglyceride (TG) concentrations of KKAy mice fed a moderately high fat diet for 4 weeks. Since diet intake and body weight were not reduced following administration of the C. depressa extract, TG absorption from the intestine is unlikely inhibited by this extract. Our previous study showed that the A. atemoya extract possesses a potent inhibitory effect on adipogenesis of 3T3 adipocytes. Thus, reduced fatty acid mobilization from the adipose tissue by the A. atemoya extract may result in the reduction in TG synthesis in the liver. This is the first report on the hypolipidemic effects of C. depressa and A. atemoya. Their extracts of these fruits are expected to be useful for the prevention of life style-related diseases.