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 & Graphene. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Protein Tyrosine Phosphatase 1B and α-Glucosidase Inhibitory Phlorotannins from Edible Brown Algae, Ecklonia stolonifera and Eisenia bicyclis

Abstract: The present work investigates protein tyrosine phosphatase 1B (PTP1B) and the α-glucosidase inhibitory activities of two edible brown algae, Ecklonia stolonifera and Eisenia bicyclis, as well as in their isolated phlorotannins. Since the individual extracts and fractions showed significant inhibitory activities, column chromatography was performed to isolate six phlorotannins, phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofurofucoeckol-A (4), dieckol (5), and 7-phloroeckol (6). Phlorotannins 3-6 were potent and noncompetitive PTP1B inhibitors with IC(50) values ranging from 0.56 to 2.64 µM; 4-6 exhibited the most potent α-glucosidase inhibition with IC(50) values ranging from 1.37 to 6.13 µM. Interestingly, 4 and 6 were noncompetitive, while 5 exhibited competitive inhibition in an α-glucosidase assay. E. stolonifera and E. bicyclis as well as their isolated phlorotannins therefore possessed marked PTP1B and α-glucosidase inhibitory activities; this could lead to opportunities in the development of therapeutic agents to control the postprandial blood glucose level and thereby prevent diabetic complications.

Citrate-assisted hydrothermal synthesis of single crystalline ZnO nanoparticles for gas sensor application

Abstract: ZnO nanoparticles (NPs) were synthesized from Zn(OH) 2 using trisodiumcitrate-assisted hydrothermal process. The structure, surface morphology, optical property and surface area of ZnO NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy and BET-surface area analyzer, respectively. XRD results confirmed the complete conversion of wulfingite structure of Zn(OH) 2 into the hexagonal wurtzite structure of ZnO after hydrothermal process. SEM and TEM images showed the formation of 100–150 nm ZnO NPs which were single crystalline in nature. PL spectroscopy showed only UV emission and no defect related visible emission in ZnO NPs. Experimental results showed that trisodiumcitrate suppressed the growth of ZnO along [0 0 0 1] direction which resulted into the formation of ZnO NPs. Gas response was examined for four gases namely CO, ethanol, acetaldehyde and NO 2 . Response increased with temperature for all gases except NO 2 . ZnO NPs showed response at room temperature for 5 ppm of NO 2 gas. The results demonstrate that these ZnO NPs have some sort of selectivity for NO 2 at low while for acetaldehyde at high working temperature.