Alpha-Glucosidase inhibitory activity was found in aqueous methanol extracts of tochu-cha, dried leaves of Eucommia ulmoides (Eucommiaceae). Five active principles against yeast enzyme were isolated and characterized. Among them, quercetin (1, Ki: 8.5 x 10(-6) M) was considered to contribute mostly to the activity of the tochu leaves. In regard to an animal alpha-glucosidase, rat intestinal sucrase activity was also inhibited by 1.

The apoptosis-inducing effect of fucoxanthin on human leukemic HL-60 cells was investigated. Fucoxanthin, which was obtained from the brown alga Undaria pinnatifida, inhibited the proliferation of HL-60 cells and induced DNA fragmentation on agarose gel electrophoresis, a typical characteristic feature of apoptotic cells. The results of sandwich ELISA using anti-biotin-antibody and anti-DNA-antibody also demonstrated DNA fragmentation in accordance with the increase in fucoxanthin concentration and incubation time. Since the level of DNA fragmentation did not increase after 24 h incubation, fucoxanthin appeared to have some effect on cell cycle. In contrast, β-carotene did not show an apoptosis-inducing effect on HL-60 cells. These results suggested that a carotenoid structure might be crucial for inducing apoptosis.Not