Piceatannol (trans-3,3',4,5'-tetrahydroxystilbene), a natural analogue of resveratrol, has multiple biological functions. Nevertheless, piceatannol's biological fate is yet to be determined. In this study, we evaluated the absorption and metabolism of piceatannol in rats. Furthermore, the area under the plasma concentration curves (AUC) and metabolic pathway of piceatannol were compared with those of resveratrol. We determined the plasma concentrations of piceatannol, resveratrol, and their respective metabolites following their intragastric administration. Resveratrol metabolites were only conjugates, whereas piceatannol metabolites were piceatannol conjugates, O-methyl piceatannol, and its conjugates. The AUC for piceatannol, resveratrol, and their metabolites increased in a dose-dependent manner (90-360 μmol/kg). The AUC for total piceatannol was less than that for total resveratrol, whereas the AUC for piceatannol (8.6 μmol·h/L) after piceatannol and resveratrol coadministration was 2.1 times greater than that for resveratrol (4.1 μmol·h/L). The greater AUC for piceatannol was a result of its higher metabolic stability.

We previously found that passion fruit (Passiflora edulis) seeds contained a high amount of piceatannol (3,5,3′,4′-trans-tetrahydroxystilbene), a natural analog of resveratrol (3,5,4′-trans-trihydroxystilbene). Resveratrol has been proposed as a potential anti-metabolic disorder compound, by its activation of sirtuin and AMP-activated protein kinase. Many reports show that resveratrol ameliorates diet-induced obesity and insulin resistance. However, it is not known whether piceatannol also affects diet-induced obesity. We explored the effect of piceatannol on high fat diet-fed mice. The results showed that piceatannol did not affect high fat diet-induced body weight gain or visceral fat gain in mice. However, piceatannol did reduce fasting blood glucose levels. Furthermore, to explore the potential of passion fruit seed extract containing piceatannol as a functional food, passion fruit seed extract was administered in a genetic diabetic mouse model (db/db mice). Single administration of passion fruit seed extract, as well as piceatannol reduced the blood glucose levels of these db/db mice. These results suggest that piceatannol and passion fruit seed extract may have potential application in the prevention of diabetes.Key words piceatannol; passion fruit seed; antidiabetic activity; high fat diet; db/dbThe incidence of metabolic syndrome is increasing worldwide due to aging and changes in lifestyle. In particular, this increase is largely attributed to the rise in the prevalence of obesity, and this common metabolic disorder is associated with increased risk of cardiovascular diseases and type II diabetes, and the latter substantially decreases quality of life and increases health care costs. It is difficult to strictly control blood glucose levels over the long term, even though many anti-diabetic medications are clinically available. Therefore, the development of functional foods that can prevent or improve type II diabetes is an urgent matter.Resveratrol is a natural component of several plants, including grapes, berries, and peanuts. Resveratrol displays widespread functions and has several health-promoting effects owing to its anti-cancer, anti-inflammation, and antioxidant activity.1) Recently, resveratrol has been proposed as a potential anti-metabolic syndrome compound because of its role in activating sirtuin and AMP-activated protein kinase (AMPK).2-5) Indeed, several studies have shown that resveratrol protects mice against diet-induced obesity.6-8) Resveratrol has also been shown to have a favorable effect on glucose metabolism in humans.9,10) However, it should be noted that no weight loss has been reported after resveratrol treatment in any human study. 11)Piceatannol is a hydroxylated analog of resveratrol and is also found in various plants, including grapes and rhubarb. Although piceatannol shows activities similar to resveratrol, its levels in plants are significantly lower than those of resveratrol, 12) and it has therefore received far less research attention. We previously found that passion...

( )-Epigallocatechin-3-O-(3-O-methyl)gallate (EGCG3″Me) and ( )-epigallocatechin-3-O-(4-O14 L/kg). These results suggested that the higher AUC of EGCG3″Me after oral administration was related to its high bioavailability and low distribution volume. These findings supported the stronger bioactivity of EGCG3″Me in vivo.

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Piceatannol is polyphenolic antioxidant found in passion fruit (Passiflora edulis) seeds. The aim of this study was to improve the absorption of piceatannol using α-cyclodextrin (αCD). The solubility of piceatannol in neutral and acidic solutions increased in an αCD concentration-dependent manner. The maximum plasma concentration of intact piceatannol and the time-to-maximum plasma concentration of O-methylated piceatannol metabolites increased in rats administered αCD-piceatannol inclusion complexes (PICs). Administering the αCD inclusion complexes significantly increased the area under the concentration-time curve of total stilbene derivatives (0-3 h) in terms of the total amount of intact piceatannol, O-methylated piceatannol, conjugated piceatannol, and isorhapontigenin. Gastrointestinal ligation experiments demonstrated that substantially higher levels of piceatannol metabolites were present in the lower intestine (the ileum) at 1 h postintragastric αCD-PICs administration as compared to those observed following piceatannol administration only. These results suggested that αCD enhanced piceatannol movement and absorption in the small intestine.

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BackgroundEnzymatically modified isoquercitrin (EMIQ) is produced from rutin using enzymatic hydrolysis followed by treatment with glycosyltransferase in the presence of dextrin to add glucose residues. EMIQ is absorbed in the same way as quercetin, a powerful antioxidant reported to prevent disused muscle atrophy by targeting mitochondria and to have ergogenic effects. The present study investigated the effect of EMIQ on skeletal muscle hypertrophy induced by functional overload.MethodsIn Study 1, 6-week-old ICR male mice were divided into 4 groups: sham-operated control, sham-operated EMIQ, overload-operated control, and overload-operated EMIQ groups. In Study 2, mice were divided into 3 groups: overload-operated whey control, overload-operated whey/EMIQ (low dose), and overload-operated whey/EMIQ (high dose) groups. The functional overload of the plantaris muscle was induced by ablation of the synergist (gastrocnemius and soleus) muscles. EMIQ and whey protein were administered with food. Three weeks after the operation, the cross-sectional area and minimal fiber diameter of the plantaris muscle fibers were measured.ResultsIn Study 1, functional overload increased the cross-sectional area and minimal fiber diameter of the plantaris muscle. EMIQ supplementation significantly increased the cross-sectional area and minimal fiber diameter of the plantaris muscle in both the sham-operated and overload-operated groups. In Study 2, EMIQ supplementation combined with whey protein administration significantly increased the cross-sectional area and minimal fiber diameter of the plantaris muscle.ConclusionEMIQ, even when administered as an addition to whey protein supplementation, significantly intensified the fiber hypertrophy of the plantaris muscle in functionally overloaded mice. EMIQ supplementation also induced fiber hypertrophy of the plantaris in sham-operated mice.

Amazake is a traditional Japanese beverage. Its main ingredients are sake cake and rice malt. In this study, we examined the effect of sake cake and rice malt on the intestinal barrier function and gut microbiota. BALB/c mice were fed a control diet or a diet containing a mixture of sake cake and rice malt powder (SRP) for four weeks. Fecal IgA values did not change between groups, but the fecal mucin level was significantly greater in the SRP-fed group. Gene expression analysis in the ileum by real-time PCR demonstrated Muc2 expression did not change, while the Muc3 expression was upregulated in the SRP-fed group. Furthermore, microbiota analysis demonstrated a change by SRP intake at the family level, and the proportion of Lactobacillaceae significantly increased in the SRP-fed group. At the genus level, the proportion of Lactobacillus also significantly increased in the SRP-fed group. These results suggest that the intake of a mixture of sake cake and rice malt improves intestinal barrier function by increasing mucin levels and inducing changes in intestinal microbiota.