Biomedical subjects

T Yoneya

Publications and source records attributed to T Yoneya.

4 recordsLinked to original sources

PubMed1992

Hydroxyl radical formation by UV-irradiated epidermal cells.

To elucidate the mechanism of sunlight-induced skin damage, guinea pigs were exposed to UV light (280-320 nm, UV B, 4 J/cm2) and a homogenate of the epidermis was examined by means of the thiobarbituric acid (TBA) test. Three hours after the exposure, TBA-malondialdehyde adducts had increased while glutathione reductase activity had decreased, indicating lipid peroxidation. To detect the initial species, spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was applied to a suspension of illuminated epidermal cells (0.5 J/cm2). An ESR signal obtained only with irradiation comprised a 1:2:2:1 quartet [a(N)= a(beta H) = 1.49 mT] attributable to a spin adduct of hydroxyl radicals. These results suggest that sunlight exposure of skin may lead to hydroxyl radical generation and simultaneous lipid peroxidation.

Animals↗

PubMed1992

Essential oil phenyl propanoids. Useful as .OH scavengers?

In order to search for radical scavengers which could be used as raw materials for cosmetics, phenyl propanoids (eugenol, isoeugenol, dehydrodieugenol, dehydrodieugenol B and coniferyl aldehyde) were examined for their hydroxyl radical (.OH) scavenging ability. A Fenton system was used to produce .OH. In order to see scavenging by these phenyl propanoids, competition reactions between a spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and these phenyl propanoids for .OH were studied. The relative yield of the spin adduct of .OH (DMPO-OH) was measured by electron spin resonance spectroscopy. The approximate rate constants of the reactions between these phenyl propanoids and .OH estimated by measuring the reduced height of the ESR signals of DMPO-OH were found to be at least in the order of 10(9) M-1 s-1 (diffusion-controlled). Also, using the TBA tests, the reactions between .OH and several compounds reactive with .OH were investigated in the presence of the phenyl propanoids and it was found that the phenyl propanoids compete with such reactive compounds for .OH. These results indicate that these phenyl propanoids can be used as antioxidants for skin damage perhaps caused by .OH generated by UV-light.

Animals↗

PubMed1979

Determination of free glycerol on human skin surface.

In water soluble substances obtained by water extraction from human skin surface, free glycerol was detected by gas chromatography mass spectrometry. A selected ion monitoring method was employed to measure low concentration of free glycerol and the mean amounts were found to be about 0.7 microgram cm-2 on the cheek and 0.2 microgram cm-2 on the forearm and sole.

Chromatography, Gas↗

PubMed1979

Alcohol dehydrogenase from Rhizopus javanicus.

Alcohol dehydrogenase of Rhizopus javanicus was purified, and its physical and chemical characteristics were determined. The intact enzyme was shown to have a molecular weight of approximately 60,000. Since the smallest apparent subunit was 14,000, the enzyme was presumed to be composed of four subunits. The crude mycelial extract contained multiple forms of the enzyme, which were separated by ion-exchange chromatography.

Alcohol Oxidoreductases↗