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Twelve polyphenols (1-12) possessing tyrosinase inhibitory properties were isolated from the methanol (95%) extract of Morus lhou. The isolated compounds consisted of four flavanones (1-4), four flavones (5-8), and four phenylbenzofuranes (9-12). Moracin derivative 12 proved to be new a compound which was fully characterized. Compounds 1-12 were evaluated for both monophenolase and diphenolase (the two steps catalyzed by tyrosinase) inhibition to identify the structural characteristics required for mushroom tyrosinase inhibition. We observed that all parent compounds (1, 5, and 9) possessing an unsubstituted resorcinol group were highly effective inhibitors of monophenolase activity (IC(50) values of 1.3, 1.2, and 7.4 microM). The potency of the inhibitors diminished with alkyl substitution on either the aromatic ring or the hydroxyl functions. Interestingly, flavone 5 was shown to possess only monophenolase inhibitory activity, but flavanone 1 and phenylbenzofuran 9 inhibited diphenolase as well as monophenolase significantly. The inhibitory mode of these species was also dependent upon the skeleton: phenylbenzofuran 9 manifested a simple competitive inhibition mode for monophenolase and diphenolase; on the other hand flavanone 1 (monophenolase, k(3) = 0.1966 min(-1) microM(-1), k(4) = 0.0082 min(-1), and K(i)(app) = 0.0468 microM; diphenolase, k(3) = 0.0014 min(-1) microM(-1), k(4) = 0.0013 min(-1), and K(i)(app) = 0.8996 microM) and flavone 5 both showed time-dependent inhibition against monophenolase. Compound 1 operated according to the simple reversible slow binding model whereas compound 5 operated under the enzyme isomerization model.

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Abstract:The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0

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ObjectivesEndonasal dacryocystorhinostomy (DCR) is a well-established treatment method in patients with nasolacrimal duct obstruction. However, there are a few reports about the overall management of failed endonasal DCR. We investigated the causes and management strategies of failed endonasal DCR.MethodsThis retrospective review included 61 patients (61 eyes) who had undergone revision surgery by the same surgeon after failed endonasal DCR between January 2008 and December 2012. The appropriate revision method was determined after analysis of the etiology of failure by the fluorescein dye disappearance test, nasal endoscopy, lacrimal irrigation, and probing. The criteria for success of the revision surgery were defined by the passage of fluid without resistance upon lacrimal irrigation and normalization of the tear meniscus height.ResultsThe mean duration between the primary endonasal DCR and revision surgery was 15.3 months. The average follow-up period after revision surgery was 12.2 months. The most common cause of endoscopic revision surgery was membranous obstruction. Endoscopic revision surgery was performed in 48 patients, while lacrimal silicone tube intubation under endoscopy was performed in 13 patients. The most common indication for lacrimal silicone tube intubation was functional epiphora. The overall success rate of the revision surgery was 89%.ConclusionThe most common cause of failed endonasal DCR was membranous obstruction. When patients with failed endonasal DCR presented at the clinic, it is important to identify the cause of the failure. Revision surgery could increase the final success rate of endonasal DCR.

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