University of Madras

About: University of Madras is a education organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Ring (chemistry) & Lipid peroxidation. The organization has 8496 authors who have published 11369 publications receiving 211152 citations. The organization is also known as: Madras University & University of Chennai.

Synthesis and characterization of silver nanoparticles supported on surface-modified poly(N-vinylimidazale) as catalysts for the reduction of 4-nitrophenol

Abstract: Two types of bead-shaped stable heterogeneous nanoparticle catalysts, viz. polymer-supported poly(styrene) functionalized with poly(vinylimidazole) immobilized silver nanoparticles (PS-PVIm-AgNPs) were prepared from poly(styrene)-co-poly( N -vinylimidazole) polymer matrices derived from 2% (Type-I) and 10% (Type-II) cross-linking monomer divinylbenzene and AgNO 3 as a metal precursor. The appearance of surface plasmon resonance peak at 422 nm in UV and Ag N (str,ring) peaks noticed at 1664 cm −1 for Type-I and 1668 cm −1 for Type-II catalysts in FT-IR confirms the immobilization of AgNPs onto PS-PVIm. The SEM and EDAX results prove that the Type-I catalyst has heterogeneous morphology with more white patches and enhanced amount of surface nitrogen and AgNPs than Type-II. The size of the AgNPs on Type-I and Type-II catalysts was measured as 10 nm and 14.6 nm from XRD, respectively. The comparative catalytic study for the reduction of 4-nitrophenol reveals that the pseudo-first order rate constant ( k obs ) for Type-I catalyst was relatively superior ( k obs = 5.12 × 10 −4 ) than Type-II ( k obs = 1.20 × 10 −4 ) due to the addition of high cross-linking load in Type-II. For the same reaction with Type-I catalyst, the variation of [substrate], [catalyst] and [NaBH 4 ] was directly proportional to k obs . The stability and reusability of the catalyst were observed good and sustained even at six cycles.

Luteolin inhibits cell proliferation during Azoxymethane-induced experimental colon carcinogenesis via Wnt/ β-catenin pathway

Abstract: The protective role of Luteolin (LUT) against Azoxymethane (AOM)-induced mouse colon carcinogenesis has been documented earlier. The aim of this study is to investigate on the mechanism of chemopreventive action exhibited by LUT employing AOM-induced colon carcinogenesis in mice as an experimental model. LUT inhibited AOM-induced colon tumorigenesis by decreasing tumor incidence and size. LUT reduced the cell proliferation by decreasing the number of Argyrophillic nucleolar organizer region (AgNOR)/nucleus and Proliferating Cell Nuclear Antigen (PCNA) index. It was known that β-catenin is a key effector in Wingless and Int (Wnt) signaling pathway and 90% of colon tumors arise from mutations in this pathway. In this study, we show evidence that LUT inhibited colon carcinogenesis by decreasing AOM-induced cell proliferation through the involvement of β-catenin, Glycogen synthase kinase (GSK)-3β and cyclin D1, the key components in Wnt signaling pathway. In conclusion, the protective effect of LUT could be attributed to inhibition of AOM-induced cellular proliferation probably through the involvement of β-catenin, GSK-3β and cyclin D1.