Kyushu University · Medicine
Professor Toshiro Matsui's research lab specializes in the identification and characterization of bioactive natural compounds, particularly polyphenols such as anthocyanins, flavonoids, and phenolic acids, with a focus on their alpha-glucosidase (AGH) inhibitory activities. The lab investigates the postprandial blood glucose-lowering effects of these compounds using in vitro enzyme assays and in vivo animal models, aiming to develop functional foods or nutraceuticals for the prevention and management of type 2 diabetes. A key research direction involves structure-activity relationships of acylated anthocyanins and theaflavins, especially their selective inhibition of maltase over sucrase, which mimics physiological conditions in the small intestine.
Figures are computed from collected data and may differ slightly.
alpha-Glucosidase (AGH) inhibitory study by natural anthocyanin extracts was done. As the result of a free AGH assay system, 12 anthocyanin extracts were found to have a potent AGH inhibitory activity; in particular, Pharbitis nil (SOA) extract showed the strongest maltase inhibitory activity, with an IC(50) value of 0.35 mg/mL, as great as that of Ipomoea batatas (YGM) extract (IC(50) = 0.36 mg/mL). Interestingly, neither extract inhibited the sucrase activity at all. For the immobilized assay
To clarify the postprandial glucose suppression effect of flavonoids, the inhibitory effects of catechins and theaflavins against alpha-glucosidase (AGH) were examined in this study. It was initially demonstrated that theaflavins and catechins preferentially inhibited maltase rather than sucrase in an immobilized AGH inhibitory assay system. For the maltase inhibitory effects of theaflavins, the effects were observed in descending order of potency of theaflavin (TF)-3-O-gallate (Gal) > TF-3,3'-d
To clarify a postprandial glucose suppression effect of diacylated anthocyanin with alpha-glucosidase (AGH) inhibitory activity, a single oral administration study of it in male 8-week-old Sprague-Dawley rats was performed. The diacylated anthocyanin used in this study was peonidin 3-O-[2-O-(6-O-E-feruloyl-beta-D-glucopyranosyl)-6-O-E-caffeoyl-beta-D-glucopyranoside]-5-O-beta-D-glucopyranoside isolated from storage roots of the purple sweet potato (Ipomoea batatas cv. Ayamurasaki), which showed
A survey of food components with alpha-glucosidase (AGH) inhibitory activity was conducted to identify a prophylactic effect for diabetes in food. Sardine muscle hydrolyzed by alkaline protease showed potent activity (IC50 = 48.7 mg/ml) as well as green and oolong teas (IC50 = 11.1 and 11.3 mg/ml, respectively). Furthermore, hydrolyzates prepared by various proteases gave differing AGH inhibitory activity. DEAE-Sephadex chromatography of the alkaline protease hydrolyzate eluted potent AGH inhibi
Four diacylated pelargonidin (Pg: SOA-4 and SOA-6), cyanidin (Cy: YGM-3), and peonidin (Pn: YGM-6) 3-sophoroside-5-glucosides isolated from the red flowers of the morning glory, Pharbitis nil cv. Scarlett O'Hara (SOA), and the storage roots of purple sweet potato, Ipomoea batatas cv. Ayamurasaki (YGM), were subjected to an alpha-glucosidase (AGH) inhibitory assay, in which the assay was performed with the immobilized AGH (iAGH) system to mimic the membrane-bound AGH at the small intestine. As a
To clarify the suppression of postprandial blood glucose rise via alpha-glucosidase (AGH) inhibitory action by natural compounds, propolis was examined in this study. A single oral administration of propolis extract (50% methanol fraction on XAD-2 column chromatography) in Sprague-Dawley rats demonstrated a potent antihyperglycemic effect with the significant AUC(0-120 min) reduction of 38% at a dose of 20 mg/kg compared to that of controls. Among the active compounds isolated from the fraction,
The latent production of angiotensin I-converting enzyme (ACE) Inhibitors from tartary buckwheat (BW) was investigated, and the peptides responsible for ACE inhibition characterized. Intact buckwheat was found to exhibit ACE inhibitory activity having an IC50 value of 3.0 mg/ml. The activity of the protein fraction (IC50: 0.36 mg protein/ml) was not enhanced by pepsin treatment. Pepsin, followed by chymotrypsin and trypsin hydrolysis, resulted in a significant increase in the ACE inhibitory acti
Reported is the preparation of wheat germ (WG) hydrolyzate with potent angiotensin I-converting enzyme (ACE) inhibitory activity, and the characterization of peptides responsible for ACE inhibition. Successful hydrolyzate with the most potent ACE inhibitory activity was obtained by 0.5 wt.%-8 h Bacillus licheniformis alkaline protease hydrolysis after 3.0 wt.%-3 h alpha-amylase treatment of defatted WG (IC50; 0.37 mg protein ml(-1)). The activity of WG hydrolyzate was markedly increased by ODS a
Peptides have been demonstrated as potentially beneficial compounds against several life-style related diseases such as hypertension, hypercholesterolemia, and atherosclerosis, among others. However, limited research has been carried out on peptide absorption, resulting in a lack of understanding and control of this process. Therefore, this review discusses the recent insights gathered on in vitro and in vivo absorption of peptides across intestinal membranes, into blood circulation. Briefly, so
In order to evaluate the anti-hyperglycemic effect of natural compounds via the inhibition of alpha-glucosidase (AGH), the potential inhibitory effect of anthocyanins, caffeic acid analogs, and caffeoylquinic acid analogs have been reviewed. A new AGH assay system to mimic the membrane-bound AGH at the small intestine was proposed and evaluated.
We report here the antihypertensive effect of wheat germ (WG) hydrolysate and its dominant peptide, Ile-Val-Tyr (IVY), with potent angiotensin I-converting enzyme (ACE) inhibitory activity. The toxicity test of AG50W fraction purified from the WG hydrolysate and IVY in ddy mice revealed that 1 week median lethal concentrations of AG fraction and IVY were less than 100 and 10 mg/kg, respectively. As a result of an intravenous administration test of both inhibitors in spontaneously hypertensive ra
1. Intact absorption of the bioactive dipeptide Val-Tyr (VY), with in vivo antihypertensive ability in normotensive human subjects, was investigated. 2. As a result of a single oral administration of VY, the VY absorption curve occurred maximally over the second hour postprandially; a greater than 10-fold higher increment of VY following a dose of 12 mg was observed in the plasma at 2 h compared with the baseline concentration of VY at 0 h (1934 +/- 145 vs 159 +/- 11 fmol/mL plasma, respectively
The distribution of an antihypertensive dipeptide, Val-Tyr (VY), in the tissues of spontaneously hypertensive rats (SHR) was investigated in this study. A single oral administration of VY (10 mg/kg) to 18-week-old SHR resulted in a prolonged reduction of systolic blood pressure (SBP) up to 9 h (SBP0h 198.0+/-3.6 mmHg; SBP9h 154.6+/-3.5 mmHg). As a result of VY determination, a roughly 10-fold higher increment of plasma VY level was observed at 1 h than that at 0 h, whereas thereafter the level d
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