• YAKHAK HOEJI
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• v.43 no.3
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• pp.342-350
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• 1999

The antibacterial activity against Propionibacterium acnes (P. acnes), $5{\alpha}-reductase$ inhibition and comedolytic effects are the important pharmacological target sites of antiacne drughs. We previously reported on the antibacterial activities against P. acnes by natural products. In the present study the screening of $5{\alpha}-reductase$ inhibition and comedolytic effects from natural products were performed. Seven natural products such as Angelica koreana, Sophora flavescens, Prunus persica, Bombyx mori, Areca catechu, Galla rhois and Gleditschia koraiensis perfectly inhibited the activity of $5{\alpha}-reductase$ at the concentration of 0.01% (w/v). Sixteen natural products which were shown to have the potent antibacterial activities against P.acnes or $5{\alpha}-reductase$ inhibition activities were assayed for the comedolytic test. In the results of comedolytic effects on experimentally-induced comedones (EIC), Sophora flavescens showed the strongest comedolytic effect on EIC, and Polygonum cuspidatum and Angelica koreana showed stronger comedolytic effects on EIC than azelaic acid used for a positive control at the concentration of 3% (w/v). These results suggest that several natural products including Sophora flavescens can be developed as noble antiacne agents.

• Elastomers and Composites
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• v.54 no.3
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• pp.225-231
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• 2019

Bio-based polyester polyol was synthesized via esterification between azelaic acid and isosorbide. After esterification, bio-based polyurethanes were synthesized using polyester polyol, 1,3-propanediol as the chain extender, and 4,4'-diphenylmethane diisocyanate, in mixing ratios of 1:1:1.5, 1:1:1.8, 1:1:2, and 1:1:2.3. The bio TPU (Thermoplastic Polyurethane) samples were characterized by using FT-IR (Fourier Transform Infrared Spectroscopy), TGA (Thermal Gravimetric Analysis), DSC (Differential Scanning Calorimetry), and GPC (Gel Permeation Chromatography). The mechanical properties (tensile stress and hardness) were obtained by using UTM, a Shore A tester, and a Taber abrasion tester. The viscoelastic properties were tested by an Rubber Processing Analyzer in dynamic strain sweep and dynamic frequency test modes. The chemical resistance was tested with methanol by using the swelling test method. Based on these results, the bio TPU synthesized with the ratio of 1:1:2.3, referred to as TPU 4, showed the highest thermal decomposition temperature, the largest molecular weight, and most compact matrix structure due to the highest ratio of the hard segment in the molecular structure. It also presented the highest tensile strength, the largest elongation, and the best viscoelastic properties among the different bio TPUs synthesized herein.