Publications by authors named "Gwan Sub Sim"

To develop a new potent anti-melanogenic agent, we have conjugated lipoic acid (LA) to poly (ethylene) glycol (PEG) of molecular weight 2000 and examined the effects on inhibition of tyrosinase activity and melanin synthesis in B16F10 melanoma cells. The water-soluble LA-PEG 2000 was synthesized from LA and methylated PEG by an esterification reaction in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. Synthetic LA-PEG 2000 was confirmed by IR and (1)H-NMR spectroscopy.

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Flavonoids and related compounds exhibit a wide range of useful pharmacological properties but present challenges related to their stability and solubility in commonly available solvents. In this study, polymethyl methacrylate (PMMA) microcapsules were prepared using a novel polyol-in-oil-in-polyol (P/O/P) emulsion solvent evaporation method as a means of stabilizing the flavonoids, using quercetin as a model flavonoid drug. The morphology of the microcapsules was evaluated using a scanning electron microscope, revealing a spherical shape with a smooth surface.

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Free radicals and reactive oxygen species (ROS), which are generated by UV irradiation, may cause serious injury to skin cell membranes, DNA and functional proteins. In addition, these agents stimulate the expressions of matrix metalloproteinases (MMPs), which can degrade most components of the extracellular matrix (ECM), including collagen. In order to develop new anti-photoaging agents, five major components from the extract of Fraxinus chinensis extract (FCE) were identified.

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Superoxide radical scavenging activity and DPPH radical scavenging activity were assessed in order to evaluate the antioxidant effect of the Sorbus commixta Hedl. extract (SCoE). SCoE was also treated with several carbohydrate-hydrolytic enzymes that significantly increased the total phenol and flavonoid composition of SCoE.

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Collagenase, a matrix metalloproteinases (MMPs), is a key regulator in the photoaging process of skin due to the reactive oxygen species generated after exposure to ultraviolet A (UVA). Flavonoid compounds have been demonstrated to possess antioxidant properties, and could be useful in the prevention of photoaging. In this study, to investigate the structure-activity relationship of flavonoid compounds on their antioxidant property and inhibitory effects against the MMP activity, the effects of several flavonoids; myricetin, quercetin, kaempferol, luteolin, apigenin and chrysin, on the reactive oxygen species scavengering activity and inhibitory effect against the MMP activity were examined in vitro and in human dermal fibroblasts induced by UVA.

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Exopolysaccharide (EPS) was prepared by submerged mycelial culture of a newly isolated mushroom Grifola frondosa HB0071 in a 5-l stirred-tank fermenter. This fungus produced a high concentration of biomass (24.8 gl(-1) at day 4), thereby achieving high EPS concentration (7.

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Free radicals and reactive oxygen species (ROS) caused by UV exposure or other environmental factors are critical players in cellular damage and aging. In order to develop a new anti-photoaging agent, this work focused on the antioxidant effects of the extract of tinged autumnal leaves of Acer palmatum. One compound was isolated from an ethyl acetate soluble fraction of the A.

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