Tomohiro Toida

New Biological Function of Bovine α-Lactalbumin : Protective Effect against Ethanol- and Stress-induced Gastric Mucosal Injury in Rats

Although several studies have shown that milk protein components have a wide range of biological activities, the potential role of these proteins in the gastrointestinal mucosal defense system is less well elucidated. In this study, we investigated the effect of the major proteins in cow’s milk on gastric mucosal injury by using two acute ulcer models in Wistar rats. Gastric mucosal injury was induced by either intragastric 60% ethanol-HCl or water-immersion restraint stress (23°C, 7 h). Each test milk protein was orally administered 30 min before the induction of gastric injury. Among the major milk proteins, α-lactalbumin (α-LA) is demonstrated to have a marked protective effect against ethanol-induced gastric injury, with the same potency as that of the typical antiulcer agent, Selbex. Whey protein isolate (WPI), which contained 25% α-LA, also protected against gastric injury, while casein showed no effect. Comparative studies on the protective effect of the four major components of WPI, β-lactoglobulin, α-LA, bovine serum albumin and γ-globulins (immunoglobulins), on the basis of their contents in WPI revealed that α-LA was responsible for the protective effect of WPI, being about 4-fold more effective than WPI itself. α-LA showed dose-dependent protection against gastric injury induced by stress as well as ethanol. Pretreatment with indomethacin (10 mg/kg body weight, s.c.), which is a potent inhibitor of endogenous prostaglandin synthesis, resulted in a significant reduction in the protective effect of α-LA. These results indicate that α-LA has marked antiulcer activity as an active component of cow’s milk protein, and suggest that α-LA intake may serve to protect against gastric mucosal injury, in part through endogenous prostaglandin synthesis.

Oral Ingestion of Aloe vera Phytosterols Alters Hepatic Gene Expression Profiles and Ameliorates Obesity-Associated Metabolic Disorders in Zucker Diabetic Fatty Rats

We investigated the effects of the oral administration of lophenol (Lo) and cycloartanol (Cy), two kinds of antidiabetic phytosterol isolated from Aloe vera , on glucose and lipid metabolism in Zucker diabetic fatty (ZDF) rats. We demonstrated that the administrations of Lo and Cy suppressed random and fasting glucose levels and reduced visceral fat weights significantly. It was also observed that treatments with Lo and Cy decreased serum and hepatic lipid concentrations (triglyceride, nonesterified fatty acid, and total cholesterol). Additionally, Lo and Cy treatments resulted in a tendency for reduction in serum monocyte chemotactic protein-1 (MCP-1) level and an elevation in serum adiponectin level. Furthermore, the expression levels of hepatic genes encoding gluconeogenic enzymes (G6 Pase, PEPCK), lipogenic enzymes (ACC, FAS), and SREBP-1 were decreased significantly by the administrations of aloe sterols. In contrast, Lo and Cy administration increased mRNA levels of glycolysis enzyme (GK) in the liver. It was also observed that the hepatic β-oxidation enzymes (ACO, CPT1) and PPARα expressions tended to increase in the livers of the Lo- and Cy-treated rats compared with those in ZDF-control rats. We therefore conclude that orally ingested aloe sterols altered the expressions of genes related to glucose and lipid metabolism, and ameliorated obesity-associated metabolic disorders in ZDF rats. These findings suggest that aloe sterols could be beneficial in preventing and improving metabolic disorders with obesity and diabetes in rats.

Administration of phytosterols isolated from Aloe vera gel reduce visceral fat mass and improve hyperglycemia in Zucker diabetic fatty (ZDF) rats

SUMMARY We examined the effects of lophenol (Lo) and cycloartanol (Cy), minor phytosterols of Aloe vera gel, in obese animal model of type II diabetes, Zucker diabetic fatty (ZDF) rats. Male ZDF rats were administered Lo and Cy at 25 μg/(kg day) daily for 44 days. Consecutive treatment of phytosterols suppressed the hyperglycemia, and random blood glucose levels after 35 days of treatment were 39.6 and 37.2% lower than the control, in Lo and Cy treatment groups, respectively. Consistent with the random blood glucose level, hemoglobin A1c (HbA1c) values of phytosterols treated rats were also lower than the control (Lo: 5.5 ± 0.8, Cy: 4.6 ± 0.7 vs. control: 7.2 ± 1.5). In the oral glucose tolerance test (OGTT) after 28 days of administration, the glucose intolerance was improved in phytosterols treatment groups. Additionally, the continuous administration of Lo and Cy also reduced the serum free fatty acid (FFA) and triglyceride (TG) levels except total cholesterol (T-Cho). Furthermore, the weights of total abdominal fat tissues were significantly lower than the control in ZDF rats with Lo (27.7%) and Cy (26.3%) treatment. These observations suggest that Aloe vera-derived phytosterols could reduce visceral fat accumulation, and would be useful for the improvement of hyperlipidemia and hyperglycemia.:

Aloe vera phytosterols act as ligands for PPAR and improve the expression levels of PPAR target genes in the livers of mice with diet-induced obesity

SUMMARY Lophenol (Lo) and cycloartanol (Cy), minor phytosterols of Aloe vera gel, were previously identified as anti-diabetic compounds, and these compounds also reduced body fat in a type 2 diabetic model animal. In this study, we investigated the effects of Lo and Cy on peroxisome proliferator activated receptors (PPAR) using a luciferase reporter assay. DNA microarray and real-time quantitative RT-PCR (qPCR) analyses were also performed in a diet-induced obesity (DIO) mouse model. The Aloe phytosterols activated PPAR in a dose-dependent manner. The expression levels of many PPAR target genes were changed in the Aloe phytosterol group compared with those in the control high-fat diet (HFD) group. In particular, the expression levels of Fatp1, Acox1, Cpt1, and Hmgcs2 were significantly increased in the Aloe phytosterol group compared with those in the control HFD group; however, the expression level of ApoCIII was significantly decreased in the Aloe phytosterol group. We confirmed that Aloe phytosterols activate PPAR transcription in vitro. In addition, quantitative gene expression analysis in DIO mice suggested that Aloe phytosterols improve fatty acid metabolism in the liver.:

Effects of Bovine α-Lactalbumin on Gastric Defense Mechanisms in Naive Rats

We recently investigated the effects of the major proteins in cows milk on gastric mucosal injuries in rat ulcer models. We found that α-lactalbumin (α-LA) has marked preventive effects against gastric mucosal injuries and that prostaglandin (PG) synthesis may contribute to these effects [Matsumoto et al., Biosci. Biotechnol. Biochem., 65, 1104-1111, 2001]. In this study, we investigated the effects of α-LA on several defense mechanisms of gastric mucosa by evaluating gastric PGE2 content, gastric mucin content, gastric luminal pH, gastric fluid volume, and gastric emptying in naive rats. Oral administration of α-LA (200, 500, and 1000 mg/kg) elevated endogenous PGE2 levels in gastric tissue and increased the gastric mucin contents of both the gastric fluid and the adherent mucus gel layer. In addition to these PG-related responses, α-LA also caused PG-independent responses such as elevation of gastric luminal pH, increase in gastric fluid volume, and delay in gastric emptying. These responses were observed to be dose-dependent (200-1000 mg/kg of α-LA). Thus, we demonstrated that α-LA enhances both PG-dependent and PG-independent gastric defense mechanisms in naive rats. Both of these mechanisms are probably involved in its gastroprotective action.

ADJUVANT ACTIVITY OF THE CELL WALL OF BIFIDOBACTERIUM INFANTIS FOR IN VIVO IMMUNE RESPONSES IN MICE

We examined the adjuvant activity of the Bifidobacterial Cell Wall preparation (WPG) for in vivo immune responses in mice. We studied three classical immune responses, which are thought to be T-cell mediated responses, to evaluate the adjuvant activity of WPG. The delayed type hypersensitivity (DTH) responses of sheep blood red cell (SRBC)-sensitized mice were significantly augmented by WPG, although the enhancement varied with the timing, route and dosage of injection. The adjuvant activity of WPG was also confirmed by using a glutaraldehyde treated- and Concanavalin A associated- tumor vaccine (G-Con A tumor vaccine) system. BALB/c mice sensitized with G-Con A tumor vaccine and WPG improved synergistically in survival time and cure rate compared with those given G-Con A vaccine alone. Spleen cells of Meth A tumor-bearing mice induced antitumor neutralizing activity with the growth of tumor but the activity declined and disappeared at the late stage of tumor growth (over 28 days after tumor transplantation). On the other hand, antitumor neutralizing immunity was prolonged for as long as 33 days in mice inoculated with Meth A tumor and WPG. The requirement of a T-cell subpopulation in the spleen cells of tumor plus WPG treated mice was confirmed using anti-Thy 1.2 antiserum + complement to deplete them. The adjuvant activities of the Bifidobacterial cell wall demonstrated by the in vivo immune responses predict that Bifidobacteria may play a role as an immunomodulator in human and animal intestines.

Safety Evaluation of Supercritical Carbon Dioxide Extract of Aloe Vera Gel

UNLABELLED The gel of the Aloe vera plant has been used safely for oral and external applications. Previously, we found phytosterols derived from an extract of Aloe vera gel obtained with an organic solvent to have hypoglycemic and antiobesity effects. While developing of functional foods using Aloe vera gel, we produced an active Aloe vera gel extract (AVGE) using a supercritical carbon dioxide (CO₂) extraction procedure. In this study, we tested the safety of AVGE in vitro and in vivo. In an acute oral toxicological test in which AVGE was administered to rats at a dose of 150 mg/kg body weight, there were no deaths or apparent abnormalities at necropsy. In a 90-d toxicity test in which rats were continuously administrered AVGE at 30 or 150 mg/kg, euthanized, and subjected to pathological examinations, no abnormalities attributable to the AVGE were found. AVGE was nonmutagenic in the Ames test and a chromosomal aberration test at concentrations of up to 5000 μg/plate and 1600 μg/plate, respectively, and in an in vivo bone marrow micronucleus test at up to 150 mg/kg/d. PRACTICAL APPLICATION AVGE can be safely used as a functional food material.

Antibacterial activity of the lactoperoxidase system combined with edible Laminaria hot-water extract as a source of halide ions.

Hot-water extracts prepared from nine out of 12 samples of dried edible Laminaria reduced the viable numbers of Aggregatibacter actinomycetemcomitans, Staphylococcus aureus, and Esherichia coli below the detection limit after incubation for 5 min when combined with lactoperoxidase, glucose oxidase, and glucose. Some extracts showed higher bactericidal activity and a higher OI− concentration in the assay mixture after ultrafiltration.