Chonbuk National University

About: Chonbuk National University is a education organization based out in Jeonju, South Korea. It is known for research contribution in the topics: Apoptosis & Nanofiber. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Anti-inflammatory and antioxidant activities of constituents isolated from Pueraria lobata roots

Abstract: In order to evaluate the anti-inflammatory and antioxidant activities of Pueraria lobata roots and its active components, in vitro inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) protein expression, and tert-butylhydroperoxide (t-BHP)-induced reactive oxygen species (ROS) generation in RAW 264.7 cells, as well as in vitro scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH), peroxynitrite (ONOO(-)), nitric oxide (NO·), superoxide anion (·O(2)(-)) and total ROS, and inhibitory activities against ONOO(-)-mediated tyrosine nitration, were determined. Repeated column chromatography was performed to isolate four known compounds from the anti-inflammatory and antioxidant EtOAc fraction: daidzein; genistein; puerarin; (+)-puerarol B-2-O-glucopyranoside; four known compounds from the anti-inflammatory n-hexane fraction: lupenone; lupeol; puerarol; coumestrol; seven known compounds from the antioxidant n-BuOH fraction: allantoin; 3'-hydroxypuerarin; daidzein 8-C-apiosyl-(1→6)-glucoside; puerarin; genistin; 3'-methoxypuerarin; daidzin. Among these compounds, lupenone and lupeol reduced NO production, as well as iNOS and COX-2 protein levels in LPS-stimulated RAW 264.7 cells. Furthermore, lupeol showed significant inhibitory activity against intracellular ROS generation by t-BHP. Meanwhile, 3'-hydroxypuerarin showed marked ONOO(-), NO·, total ROS scavenging activities, and weak ·O(2)(-) scavenging activity, while 3'-methoxypuerarin showed ONOO(-) scavenging activity and weak NO· and O(2)(-) scavenging activities, suggesting that existence of the 3'-hydroxyl group in puerarin plays an important role in the scavenging of ONOO(-), NO·, and total ROS, as well as inhibiting the ONOO(-)-mediated tyrosine nitration mechanism. These results indicate that P. lobata roots and its constituents may be a useful therapeutic and preventive approach to various inflammatory diseases and oxidative stress-related disease.

Modular synchronization in complex networks.

Abstract: We study the synchronization transition (ST) of a modified Kuramoto model on two different types of modular complex networks. It is found that the ST depends on the type of intermodular connections. For the network with decentralized (centralized) intermodular connections, the ST occurs at finite coupling constant (behaves abnormally). Such distinct features are found in the yeast protein interaction network and the Internet, respectively. Moreover, by applying the finite-size scaling analysis to an artificial network with decentralized intermodular connections, we obtain the exponent associated with the order parameter of the ST to be beta approximately 1 different from beta(MF) approximately 1/2 obtained from the scale-free network with the same degree distribution but the absence of modular structure, corresponding to the mean field value.

Apoptotic effect of quercetin on HT-29 colon cancer cells via the AMPK signaling pathway.

Abstract: Activation of AMP-activated protein kinase (AMPK), a physiological cellular energy sensor, strongly suppresses cell proliferation in both nonmalignant and tumor cells. This study demonstrates the mechanism of quercetin-induced apoptosis in HT-29 colon cancer cells. Treatment of cells with quercetin significantly decreased cell viability in a dose-dependent manner. Notably, quercetin increased cell cycle arrest in the G1 phase and up-regulated apoptosis-related proteins, such as AMPK, p53, and p21, within 48 h. Furthermore, in vivo experiments showed that quercetin treatment resulted in a significant reduction in tumor volume over 6 weeks, and apoptosis-related protein induction by quercetin was significantly higher in the 100 mg/kg treated group compared to the control group. All of these results indicate that quercetin induces apoptosis via AMPK activation and p53-dependent apoptotic cell death in HT-29 colon cancer cells and that it may be a potential chemopreventive or therapeutic agent against HT-29 colon cancer.