A new phloroglucinol derivative (1) and two known compounds (2 and 3) were isolated from the brown alga Eisenia bicyclis. These isolates exhibit inhibitory activity on glycation and alpha-amylase. Their structures were determined on the basis of spectroscopic data.

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Licorice, the roots and long-stalks of various species of Glycyrrhiza genus, has been used as a traditional folk medicine and foodstuff all over the world.2) Isoliquiritigenin is one of the plant pigments of licorice, and is a simple chalcone derivative, 4,2Ј,4Ј-trihydroxy-chalcone (see Fig. 1). We have reported the isolation of this compound from Egyptian licorice (Glycyrrhiza grabla), along with new and known 3-arylcoumarins.3) Shibata reported the anti-tumor promoter effects of various chalcone derivatives in vitro, and isoliquiritigenin exhibited potential activity. 4) Other biological activities for this compound have also been reported. For example, antitumor promoting activity on two-stage mouse skin carcinogenesis, 5) inhibitory effect on aldose reductase activity, 6) antiplatelet aggregation effect, 7) antioxidative and superoxide scavenging activities, 8) etc. However, all these experiments were in vitro or topical application in vivo, and there is no reported data of the effect by oral administration in vivo.Repetitive treatment with the organotropic colon carcinogen, azoxymethane (AOM), produces colon tumors in rodents exhibiting pathological features that are similar to sporadic forms in human colon cancer.9) The AOM-induced colon cancer model in rat has been used to evaluate the potency of chemopreventive agents against colon cancer. 10)Aberrant crypt foci (ACF) were first identified in methylene blue stained, whole-mount preparations of colonic mucosa from carcinogen-treated rodents, 11) and ACF have also been found in the colons of patients both with or without colorectal cancer.12,13) McLellan et al. reported that ACF may be a significant biological lesion in the development of colon tumors, and aberrant crypt (AC) formation is specific for exposure to colon carcinogens. 14) From these findings, the colonspecific, carcinogen-induced ACF model in rodents has been used as a short term screening to identify chemopreventive agents for colon cancer. 15,16) In the present studies, the effect of isoliquiritigenin on the AOM-induced ACF formation model in mice was studied. Based on the data obtained, AOM-induced murine colon carcinogenesis experiment was also studied. MATERIALS AND METHODSChemicals AOM was purchased from Sigma Chemical Co., Ltd. (St. Louis, MO, U.S.A.). Isoliquiritigenin (ILG) was synthesized by the methods of Hulle et al. 17) and purified by column chromatography (silica gel with a mixture of nhexane and ethyl acetate). After recrystallization, the purity was quantificated by HPLC (octadecyl silica (ODS) with a gradient of acetonitrile and water) as over 99.8%. The yield of this material was 38.6%.Animals Five-weeks old ddY male mice were obtained from Shizuoka Laboratory Animal Center (Hamamatsu, Shizuoka, Japan). Effect of Isoliquiritigenin on Murine Colon Aberrant Crypt FociFive-weeks old ddY mice were housed in temperature-and humidity-controlled animal quarters with a 12 h light/dark cycle and fed CE-2 diet. (CLEA Japan Co., Ltd.) On the 1st and 8th days, AOM (10 mg/kg b.w.) was...

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Three new bromophenols, 2,2',3,6,6'-pentabromo-3',4,4',5-tetrahydroxydibenzyl ether (1), bis(2,3,6-tribromo-4,5-dihydroxyphenyl)methane (2), and 2,2',3,5',6-pentabromo-3',4,4',5-tetrahydroxydiphenylmethane (3), were isolated from the red alga Symphyocladia latiuscula. Two bromophenols, 2,3,6-tribromo-4,5-dihydroxymethylbenzene (4) and 2,3,6-tribromo-4,5-dihydroxybenzaldehyde (5), were also reported for the first time as natural products. Their structures were elucidated on the basis of chemical and spectroscopic methods including HREIMS, HRFABMS, and 1D and 2D NMR spectral techniques. Compounds 1-5 exhibited significant aldose reductase inhibitory activity.