Biomedical subjects

Kenjiro Tadera

Publications and source records attributed to Kenjiro Tadera.

8 recordsLinked to original sources

PubMed2006

Antioxidant and alpha-amylase inhibitory compounds from aerial parts of Varthemia iphionoides Boiss.

Various extracts of aerial parts of Varthemia (Varthemia iphionoides Boiss) were investigated for radical-scavenging activity, antioxidative activity, and porcine pancreas alpha-amylase inhibitory activity. The ethanol and water extracts showed a pronounced 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with inhibition of about 90% at a concentration of 100 microg/ml, and alpha-amylase inhibitory activity of about 70% at a concentration of 200 microg/ml by the 2-chloro-4-nitrophenyl alpha-maltotrioside (CNP-G3) degradation method. The ethanol extract was purified by column chromatography to give seven 3-methoxyflavones (1-7) and eudesmane sesquiterpene, selina-4,11(13)-dien-3-on-12-oic acid (8). The structures of these compounds were established by NMR, MS, and UV spectroscopy. Of 3-methoxyflavones, 5,7,4'-trihydroxy-3,6-dimethoxyflavone (1), 5,7,4'-trihydroxy-3,3'-dimethoxyflavone (2), and 5,4'-dihydroxy-3,7,3'-trimethoxyflavone (3,7,3'-tri-O-methyl-quercetin) (7) exhibited pronounced radical-scavenging activity. The antioxidative activity in the linoleic acid system was considerable in compounds 1, 2, and 5,4'-dihydroxy-3,6,7-trimethoxyflavone (4). Compounds 1, 2, 4, 5 (5,7,4'-trihydroxy-3-methoxyflavone), and 6 (5,4'-dihydroxy-3,7-dimethoxyflavone) showed markedly high inhibitory activity against porcine pancreas alpha-amylase. Eudesmane sesquiterpene did not show any activity.

Asteraceae↗

PubMed2006

Inhibition of alpha-glucosidase and alpha-amylase by flavonoids.

The inhibitory activity of six groups of flavonoids against yeast and rat small intestinal alpha-glucosidases and porcine pancreatic alpha-amylase was compared, and chemical structures of flavonoids responsible for the inhibitory activity were evaluated. Yeast alpha-glucosidase was potently inhibited by the anthocyanidin, isoflavone and flavonol groups with the IC50 values less than 15 microM. The following structures enhanced the inhibitory activity: the unsaturated C ring, 3-OH, 4-CO, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring. Rat small intestinal alpha-glucosidase was weakly inhibited by many flavonoids, and slightly by the anthocyanidin and isoflavone groups. 3-OH and the hydroxyl substitution on the B ring increased the inhibitory activity. In porcine pancreatic alpha-amylase, luteolin, myricetin and quercetin were potent inhibitors with the IC50 values less than 500 microM. The 2,3-double bond, 5-OH, the linkage of the B ring at the 3 position, and the hydroxyl substitution on the B ring enhanced the inhibitory activity, while 3-OH reduced it.

Animals↗

PubMed2005

Amino acid sequence and antimicrobial activity of chitin-binding peptides, Pp-AMP 1 and Pp-AMP 2, from Japanese bamboo shoots (Phyllostachys pubescens).

Two novel chitin-binding peptides, designated Pp-AMP 1 and Pp-AMP 2, which had antimicrobial activity against pathogenic bacteria and fungi, were purified from Japanese bamboo shoots (Phyllostachys pubescens) by a simple procedure based on chitin affinity chromatography. They had the common structural features of the plant defensin family, but they could not be grouped in any type of that family. They showed a high degree of homology to mistletoe toxins.

Amino Acid Sequence↗

PubMed2004

Purification, characterization, and sequencing of novel antimicrobial peptides, Tu-AMP 1 and Tu-AMP 2, from bulbs of tulip (Tulipa gesneriana L.).

Novel antimicrobial peptides (AMP), designated Tu-AMP 1 and Tu-AMP 2, were purified from the bulbs of tulip (Tulipa gesneriana L.) by chitin affinity chromatography and reverse-phase high-performance liquid chromatography (HPLC). They bind to chitin in a reversible way. They were basic peptides having isoelectric points of over 12. Tu-AMP 1 and Tu-AMP 2 had molecular masses of 4,988 Da and 5,006 Da on MALDI-TOF MS analysis, and their extinction coefficients of 1% aqueous solutions at 280 nm were 3.3 and 3.4, respectively. Half of all amino acid residues of Tu-AMP 1 and Tu-AMP 2 were occupied by cysteine, arginine, lysine, and proline. The concentrations of peptides required for 50% inhibition (IC(50)) of the growth of plant pathogenic bacteria and fungi were 2 to 20 microg/ml. The structural characteristics of Tu-AMP 1 and Tu-AMP 2 indicated that they were novel thionin-like antimicrobial peptides, though Tu-AMP 2 was a heterodimer composes of two short peptides joined with disulfide bonds.

Amino Acid Sequence↗

PubMed2003

Purification, characterization, and sequencing of a novel type of antimicrobial peptides, Fa-AMP1 and Fa-AMP2, from seeds of buckwheat (Fagopyrum esculentum Moench.).

Novel antimicrobial peptides (AMP), designated Fa-AMP1 and Fa-AMP2, were purified from the seeds of buckwheat (Fagopyrum esculentum Moench.) by gel filtration on Sephadex G75, ion-exchange HPLC on SP COSMOGEL, and reverse-phase HPLC. They were basic peptides having isoelectric points of over 10. Fa-AMP1 and Fa-AMP2 had molecular masses of 3,879 Da and 3,906 Da on MALDI-TOF MS analysis, and their extinction coefficients in 1% aqueous solutions at 280 nm were 42.8 and 38.9, respectively. Half of all amino acid residues of Fa-AMP1 and Fa-AMP2 were cysteine and glycine, and they had continuous sequences of cysteine and glycine. The concentrations of peptides required for 50% inhibition (IC50) of the growth of plant pathogenic fungi, and Gram-positive and -negative bacteria were 11 to 36 microg/ml. The structural and antimicrobial characteristics of Fa-AMPs indicated that they are a novel type of antimicrobial peptides belonging to a plant defensin family.

Actinomycetales↗

PubMed2003

Interaction between acidic polysaccharides and proteins.

There was an ionic interaction between acidic polysaccharides (APS) and proteins at the pH range in which APS were negatively charged and proteins were positively charged, and in enzymes the interaction was detected as a change in the enzyme activity. At pH 4.7, acid phosphatase (pI, 5.4), alpha-glucosidase (pI, 5.7), and beta-glucosidase (pI, 7.3) were inhibited by APS to various extents. On the other hand, alpha-glucosidase and alkaline phosphatase (pI, 4.5) were not inhibited by APS at pH 6.8 and 9.8, respectively, most of these two enzymes being negatively charged at the respective pHs. Sulfated polysaccharides combined with hemoglobin (pI, 6.8 to approximately 7.0) by an ionic bond at pH 2 to make hemoglobin unsusceptible to proteolysis by pepsin, but polyuronides which were not charged at this pH did not affect hydrolysis of hemoglobin.

Acid Phosphatase↗

PubMed2003

Synthesis and antioxidative activity of 6-hydroxypyridoxine.

An attempt to synthesize 6-hydroxypyridoxine (OPN), hydroxylation on C-6 of pyridoxine (PN) by hydroxyl radical (OH*). was conducted. Application of two well-known OH* generating reactions, i.e. the Fenton reaction and the Fe2+-EDTA/ascorbate reaction, were unsuccessful, as large amounts of by-products were formed. Although generation of OH* by autoxidation of ascorbic acid in the absence of metal ions was slow, by-products were formed in small quantities, and OPN was easily obtained in colorless crystals. Its structure was confirmed by spectral analyses. OPN was comparable to polyphenols such as (+)-catechin, rutin and gallic acid in the antioxidative activity against linoleic acid peroxidation, and was an effective DPPH radical scavenger, though the DPPH radical-scavenging activity of OPN was somewhat lower than that of the polyphenols. PN was relatively inactive under the conditions used here, indicating that the introduction of a hydroxyl group on C-6 of PN greatly enhanced both activities.

Antioxidants↗

PubMed1998

Degraded limonoids from Melia azedarach.

Two new degraded limonoids, azedararide and 12alpha-acetoxy fraxinellone, were isolated together with two known degraded limonoids, fraxinellone and fraxinellonone, as ichthyotoxic substances from the root bark of Melia azedarach. Their structures were elucidated by spectroscopic and chemical means.

Journal Article↗