Flaniostatin, a new isoflavonoid glycoside isolated from the leaves of Cudrania tricuspidata as a tyrosinase inhibitor

In the course of screening program for skin whitening compounds, flaniostatin (FST) was isolated from the leaves of Cudrania tricuspidata as a novel inhibitor of tyrosinase. The structure of FST was determined by ESI-MS and NMR spectroscopic analyses as a new isoflavone glycoside. The FST was exhibited a tyrosinase inhibitory effect in a dose-dependent manner. This effect was higher than that of arbutin at the same concentrations. These results indicated that FST isolated from C. tricuspidata may be a positive tool for skin-whitening agent research.     

Selective cytotoxicity of Saururus chinensis in glucose-deprived HT-29 human colon cancer cells

In this study, the selective cytotoxic activity of methanolic extracts of Saururus chinensis (SCE) was examined on glucose-deprived HT-29 cells. The effects of SCE on 2-deoxy-glucose (2DG) or glucose-free stressed HT-29 cells were evaluated through the MTT reduction assay, morphological observations, and the colony formation assay, in which SCE (5, 10 μg/mL) was found to be highly toxic to HT-29 cells only during glucose-deprived conditions. In addition, the mechanism of selective cytotoxic effects on SCE was assessed by Western blot analysis; SCE suppressed the accumulation of GRP78. Furthermore, apoptotic effects of SCE on glucose-deprived HT-29 cells were identified by Hoechst 33342 staining and flow cytometric analysis. In conclusion, SCE induced apoptosis in HT-29 cells under glucose-deprived conditions by down-regulation of GRP78. Cytotoxic effects on HT-29 cells were only observed during glucose deprivation, suggesting that SCE may be a target for novel therapeutic agents for treating colon cancer under glucose-deprived stress.     

Stable Switching PD Control Using Hunt-Crossley Model for a Press Platform

This study proposes a switching proportional-derivative (PD) controller for a press platform for inspecting the surfaces of a wind turbine blade. We use the Hunt-Crossley model to represent the probe shape or the nonlinearity of the inspection platform. This model consists of a nonlinear spring and a damper; therefore, it is more accurate than linear spring-damper models. We prove the global asymptotic stability of a PD force feedback controller and a PD position feedback (force) controller. However, both the controllers suffer from implementation-related problems. Specifically, the PD force feedback controller makes the impact force large, and the PD position feedback controller cannot easily measure small position changes when the platform contacts the surface. These problems of each controller are solved by switching the two controllers. The PD force feedback control and PD position feedback control are used when the platform is in the contact and noncontact states, respectively. We prove that the proposed switching PD force/position feedback controller is globally asymptotically stable. Further, simulations show satisfactory performance resulting from stable switching between the two control schemes.