ABSTRACT
Objective:To investigated the activity inhibition and inhibitory type of polyphenol oxidase (PPO) induced by galangin and the interaction mechanism of galangin with polyphenol oxidase was preliminarily indicated,and prove the related mechanism of galangin on proliferation of on human melanoma A375 cells.Methods: The activity inhibition and inhibitory type of PPO induced by galangin were investigated by spectrophotometric method,and interation mechanism of galangin with PPO was preliminarily indicated by fluorescence quenching and molecular docking,and chelating copper ions with the inhibitory mechanism of galangin on polyphenol oxidase was measured.Results: Galangin was a competitive inhibitor,the IC50 and Ki on PPO were obtained to be (47.86±3.33) and (24.83±1.45)μmol/L,respectively.Fluorescence spectrum indicated the fluorescence of PPO was quenched effectively by galangin and the binding constant Ka was obtained to be (4.67±0.43)×104 L/mol.Chelating copper ions and molecular simulation further showed that galangin was combined with active center of copper ions,and formed hydrogen bonds with catalytic site His259.Luteolin could induce the apoptosis of A375 cells significantly,and the tyrosinase activity and melanin synthesis were decreased.Conclusion: Galangin as a competitive polyphenol oxidase inhibitor and reduced the activity of polyphenol oxidase.which provides the theoretical basis for the clinical anti skin cancer.
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A sensitive colorimetric method for the detection of copper ions (Cu2+) was developed based on the surface modification of silver/platinum nanoclusters (Ag/Pt NCs) and regulation of peroxidase-like activity. It was found that 3-mercaptopropionic acid (MPA) could inhibit the catalytic ability of Ag/Pt NCs; however, it lost the inhibition toward catalytic ability of Ag/Pt NCs after oxidized by oxygen through the catalysis of Cu2+. On the basis of this, a colorimetric method was developed for the detection of Cu2+ through measuring the colorimetric signal variation of the TMB-H2O2 reaction. This method exhibited high sensitivity and selectivity toward Cu2+ over a panel of other metal ions. The linear range was 10-100 nmol/L and the detection limit was 5.0 nmol/L (3σ). The above method was also applied to detect real water samples and spiked samples, and the results demonstrated that this method was simple with low cost.
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Objective To investigate the tissue stimulation of copper ions to the smooth muscle of murine terminal rectum.Methods In this study copper needle used for electrochemical therapeutic equipment was punctured into submucosal smooth muscle tissue of terminal rectum above the dentate line in 65 male rats.Rats were then divided into 5 groups (10 rats in each group) at random and sacrificed at 1, 3, 4, 6, 8 weeks after respectively, samples were sent for observation of macroscopic and microscopic tissue reaction.Results Rats had no abnormal histological change in the puncture points grossly. Undor microscope, mild edema was detected in the submucosal layer in 1 week group. Remarkable infiltration of inflammatory cells and lymphocytes subsided 3 weeks after, and disappeared five weeks after.Smooth muscle was normal microscopically in all groups.In contrast, platinum and steel needles caused infiltration of plasma cells and neutrophils, ulcers and small abscess formation in around puncture points.Conclusion Inflammatory reaction was induced after puncturing of copper needle into the tissues and the tissue reaction disappeared after 5 Ws.In contrast with platinum and steel needles, copper needle was non-traumatic to the smooth muscle tissue.