Takeshi Takaku

Anti-obesity action of oolong tea

OBJECTIVE:Oolong tea is traditionally reported to have anti-obesity and hypolipidaemic effects. The present study was performed to clarify whether oolong tea prevented obesity induced in mice by the oral administration of a high-fat diet for 10 weeks.DESIGN: High-fat diet-induced obese mice were treated with oolong tea for 10 weeks. The effects of various active fractions isolated from oolong tea on noradrenaline-induced lipolysis were examined with isolated fat cells and a cell-free system consisting of lipid droplets and hormone-sensitive lipase (HSL).RESULTS: The mean food consumption was not significantly different between high-fat diet-treated mice and high-fat plus oolong tea diet-treated mice. Oolong tea prevented the obesity and fatty liver induced by a high-fat diet. A water extract of oolong tea enhanced noradrenaline-induced lipolysis, and the active substance was identified as caffeine. Caffeine enhanced noradrenaline-induced lipolysis in fat cells without a concomitant increase in HSL activity and also accelerated the hormone-induced lipolysis in a cell-free system consisting of lipid droplets and HSL, but not in the cell-free system with sonicated lipid droplets and HSL. Oolong tea extract inhibited pancreatic lipase activity.CONCLUSION: It was demonstrated that the anti-obesity effects of oolong tea in high-fat diet-treated mice might be due partly to the enhancing effect of caffeine isolated from oolong tea on noradrenaline-induced lipolysis in adipose tissue, and to the inhibitory action of some other substance in oolong tea on pancreatic lipase activity. Caffeine was found to enhance lipolysis through acting on lipid droplets but not on HSL. The results suggest that oolong tea may be an effective crude drug for the treatment of obesity and fatty liver caused by a high-fat diet.

Anti-obesity effects in rodents of dietary teasaponin, a lipase inhibitor

OBJECTIVE: Based on the inhibitory effects of teasaponin on pancreatic lipase activity in vitro, this study was performed to clarify whether teasaponin prevented obesity induced in mice by a high-fat diet for 11 weeks.DESIGN: For in vitro experiments, assay for the inhibitory effects of teasaponin on pancreatic lipase activity was performed by measuring the rate of release of oleic acid from triolein in an assay system using triolein emulsified with lecithin, gum arabic, Triton X-100 or 4-methylumbelliferyloleate. For in vivo experiments, female ICR mice were fed a high-fat diet with or without 0.5% teasaponin for 11 weeks.RESULTS: Teasaponin competitively inhibited the hydrolysis of triolein emulsified with lecithin, gum arabic, Triton X-100 or 4-methylumbelliferyloleate. Teasaponin inhibited the elevations of plasma triacylglycerol levels 3, 4 and 5 h after oral administration of lipid emulsion containing corn oil. Teasaponin suppressed the increases in body, parametrial adipose tissue weights and diameter in adipose cell size induced by a high-fat diet. Furthermore, feeding a high-fat diet plus teasaponin had no effect on stool frequency and content, but significantly increased triacylglycerol contents in feces as compared to feeding a high-fat diet.CONCLUSIONS: The anti-obesity effects of teasaponin in high-fat diet-treated mice may be partly mediated through delaying the intestinal absorption of dietary fat by inhibiting pancreatic lipase activity.

Isolation of an anti-angiogenic substance from Agaricus blazei Murill: its antitumor and antimetastatic actions.

We previously found that ergosterol isolated from Agaricus blazei inhibited tumor growth through the inhibition of tumor‐induced neovascularization. In the present study, we isolated further anti‐angiogenic substances (A‐1 and A‐2) from this fungus using an assay system of angiogenesis induced by Matrigel supplemented with vascular endothelial growth factor, and A‐1 was identified as sodium pyroglutamate. Next, we examined the antitumor and antimetastatic actions of A‐1 using Lewis lung carcinoma (LLC)‐bearing mice. A‐1 (30, 100 and 300 mg/kg) inhibited tumor growth and metastasis to the lung. The reduction of the numbers of splenic lymphocytes, CD4+ and CD8+ T cells in LLC‐bearing mice was inhibited by the oral administration of A‐1 (30, 100 and 300 mg/kg). Further, A‐1 increased the number of apoptotic cells of tumors and the numbers of CD8+ T and natural killer cells invading the tumors, and inhibited the increase of von Willebrand factor expression (a measure of angiogenesis) in the tumors. These results suggest that the antitumor and antimetastatic actions of A‐1 (sodium pyroglutamate) may be associated with inhibition of the reduction of immune response caused by the tumor growth and tumor‐induced neovascularization. This is the first report showing that sodium pyroglutamate isolated from A. blazei as an anti‐angiogenic substance has potent antitumor and antimetastatic actions, as well as immune‐modulatory activity, in tumor‐bearing mice.

Antiobesity action of ε-polylysine, a potent inhibitor of pancreatic lipase

In vitro, ϵ-polylysine (EPL) strongly inhibited the hydrolysis of trioleoylglycerol emulsified with phosphatidylcholine (PC) and taurocholate by either pancreatic lipase or carboxylester lipase. The EPL concentration required for 50% inhibition of pancreatic lipase, 0.12 μM, was eight times lower than the concentration of orlistat required for the same effect. The 50% inhibition concentration by EPL was affected by emulsifier species: it was increased ∼150 times, 70 times, and 230 times on gum arabic, phosphatidylserine, and phosphatidic acid emulsion, respectively, compared with PC emulsion. The 50% inhibition concentration by orlistat was little changed by emulsifier species. Gel-filtration experiments suggested that EPL did not bind strongly to pancreatic lipase, whereas orlistat did. To test the effect of EPL on obesity, mice were fed a high-fat diet containing 0.1, 0.2, or 0.4% EPL. EPL prevented the high-fat diet-induced increase in body weight and weight of the liver and visceral adipose tissues (epididymal and retroperitoneal). EPL also decreased plasma triacylglycerol and plasma cholesterol concentrations and liver triacylglycerol content after they had been increased by the high-fat diet. The fecal weights of mice were increased by the high-fat diet containing EPL compared with the high-fat diet alone. Fecal lipid was also increased by the diet containing EPL. These data clearly show that EPL has an antiobesity function in mice fed a high-fat diet that acts by inhibiting intestinal absorption of dietary fat.

Fibrinogen-induced erythrocyte aggregation: erythrocyte-binding site in the fibrinogen molecule

The effect of fibrinogen and fibrinogen-derived products on the velocity of rouleau formation of human erythrocytes was quantitatively examined with a rheoscope combined with a video-camera, an image analyzer and a computer. (i) The velocity of rouleau formation by naturally occurring low-molecular-weight fibrinogen of 305 kDa and by desialylated fibrinogen was the same as that by native fibrinogen of 340 kDa. (ii) Concerning fibrinogen degradation products by plasmin, the velocity of rouleau formation decreased upon going from fibrinogen greater than fragment X greater than fragment Y (the ratio of molar concentration of fibrinogen, fragment X and fragment Y for giving a certain velocity of rouleau formation was approx. 1:2:5). The effect of fragments X and Y on the fibrinogen-induced rouleau formation was additive. (iii) Fragments D and E could not induce rouleau formation and did not affect the fibrinogen-, fragment X- and fragment Y-induced rouleau formation. (iv) Fibrinopeptides A and B and artificial tetrapeptides (Gly-Pro-Arg-Pro and Gly-His-Arg-Pro) did not affect the fibrinogen-induced rouleau formation. (v) The possible erythrocyte-binding site in fibrinogen molecule for leading to rouleaux was proposed to be in A alpha-chain (probably, around residues No. 207-303) near the terminal domain of the trinodular structure of fibrinogen.

Inhibition of lipase activities by basic polysaccharide

Basic polysaccharide strongly inhibited the hydrolysis of trioleoylglycerol (TO) emulsified with phosphatidylcholine and taurocholate by either pancreatic lipase or carboxylester lipase. DEAE-Sephadex dose-dependently inhibited the hydrolysis of TO by pancreatic lipase and carboxylester lipase; however, carboxymethyl-Sephadex and Sephadex G-50 did not inhibit the hydrolysis. Polydextrose (PD), a soluble polysaccharide, was a very weak inhibitor of pancreatic lipase. However, when a basic group, a DEAE group, was attached to PD, lipase inhibition by DEAE-PD was increased, and this was dependent on the substitution ratio of DEAE groups. The number of positive charges per PD molecule is important in lipase inhibition. Similar substitution effects were observed with other basic groups, such as piperidinoethyl and 3-triethylamino-2-hydroxypropyl. The natural basic polysaccharide, chitosan, also inhibited pancreatic lipase activity. Gel-filtration experiments suggested that DEAE-PD did not bind strongly to pancreatic lipase. The effect of DEAE-PD on TO hydrolysis by pancreatic lipase was studied using various emulsifiers: DEAE-PD (50 μg/ml) did not inhibit the hydrolysis of TO emulsified with arabic gum, phosphatidylserine, or phosphatidic acid. In vivo, oral administration of DEAE-PD to rats reduced the peak plasma triacylglycerol concentration and increased fecal lipid excretion. These results suggest that basic polysaccharide is able to suppress dietary fat absorption from the small intestine by inhibiting pancreatic lipase activity.

Effects of Carp and Tuna Oils on 5-Fluorouracil-Induced Antitumor Activity and Side Effects in Sarcoma 180-Bearing Mice

In this study, we examined the effects of fish oils on 5-fluorouracil (5-FU)-induced antitumor activity in mice. First, we examined the antitumor activity of the oral administration of two fish oils (carp oil and tuna oil) in sarcoma 180-bearing mice. Carp oil (0.2 and 0.4 mL/mouse) and tuna oil (0.2 and 0.4 mL/mouse) had no effects on tumor growth. Next, we examined the combined effects of 5-FU plus two fish oils (carp oil and tuna oil) on the antitumor activity and side effects compared to the effects of 5-FU alone (12.5 mg/kg/d). We found that carp oil (0.4 mL/mouse) or tuna oil (0.2 or 0.4 mL/mouse) enhanced the ability of 5-FU (12.5 mg/kg/d) to prevent tumor growth, without increasing side effects such as myelotoxicity and immunocompetent organ toxicity. Tuna oil (0.2 mL/mouse) slightly reduced body weight as compared to the effects of 5-FU alone and water alone (control). The area under the curve (AUC) (0–120 min) of blood 5-FU levels was reduced by the oral co-administration of 5-FU with carp oil or tuna oil. Apparent Tmax was shortened by the oral co-administration of 5-FU with carp oil or tuna oil. On the other hand, AUC (0–4 h) of 5-FU incorporation into tumor RNA fraction was not affected by the oral co-administration of 5-FU with carp oil or tuna oil.

Purification and Characterization of Polyphenols from Chestnut Astringent Skin

Polyphenolic compounds from chestnut astringent skin (CAS) were purified by dialysis, using Diaion HP-20 and Sephadex LH-20 columns. During purification, specific α-amylase inhibitory activities were increased about 3.4-fold, and the 50% inhibition value was 5.71 μg/mL in the Sephadex LH-20 fraction (SE-fraction). The SE-fraction contained about 67% of the total polyphenols, 57.3% of the flavanol-type tannins, and 51.3% of the procyanidins. Strong antioxidant activity was observed in the SE-fraction. Oral administration of the SE-fraction in rats fed corn starch significantly suppressed an increase in blood glucose levels. The SE-fraction contained gallic acid and ellagic acid. The MALDI-TOF spectrum showed a peak series exhibiting a mass increment of 288 Da, reflecting the variation in the number of catechin/epicatechin units. Our results suggest CAS contains polyphenols with strong α-amylase inhibitory activity. The data also suggest CAS polyphenols might be oligomeric proanthocyanidins with gallic acid and ellagic acid.

Identification of a peptide sequence in albumin that potentiates superoxide production by microglia

Abstract: Microglial activation has recently been recognized as acause of damage in various neurodegenerative diseases. A possible mechanismunderlying this damage is the activation of microglia by serum factors leakedthrough a disruption of the blood—brain barrier, which in turn triggermicroglial cell proliferation and the release of various substances toxic toneurons, such as superoxide (O2‐). We recently reportedthat serum albumin enhanced O2‐ producation in culturedrat microglia stimulated by phorbol ester. In the present report, we identifythe active site of this enhancement within the albumin molecule. We purifiedan active subfragment from trypsin‐treated bovine serum albumin that wascomposed of 12‐mer and 33‐mer peptides connected by a disulfide bond. Thechemically synthesized 12‐mer peptide showed activity within a concentrationrange (∼10‐7M) equivalent to that of albumin. Theactivities of a series of synthesized peptides conclusively indicated that theminimum active sequence was Leu‐His‐Thr‐Leu. The present study may shed lighton the mechanism of neuronal cell damage in various neurodegenerativediseases.

Inhibition by ε-polylysine of fat digestion in the stomach and intestine of rats.

In vitro, the inhibition by ε-polylysine depends on how the substrate is presented to the lipase. We therefore examined whether ε-polylysine can interact with the lipid emulsion and prevent lipase activity in digestive organs. To confirm lipase inhibition by ε-polylysine, a 14C-trioleoylglycerol emulsion with or without ε-polylysine was orally administered to rats, and the radioactive lipid distribution determined at regular intervals. The radioactive plasma lipid was decreased, and radioactive fecal lipid was increased by the administration of ε-polylysine. The peak of radioactive lipids in the intestine was delayed by the administration of ε-polylysine. We used 20-week-old rats as a model for the middle-aged and elderly to test the effect of ε-polylysine on the body weight increase. ε-Polylysine significantly prevented any elevation in body weight and weight of the liver and epididymal adipose tissues. These data show that ε-polylysine inhibited the lipase activity in the digestive organ and had an anti-obesity function in the middle-aged rats.