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Tyrosinase (EC 1.14.18.1) catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones that form brown or black pigments. In the present paper, cefotaxime, a cephalosporin antibacterial drug, was tested as an inhibitor of tyrosinase. The results show that cefotaxime inhibits both the monophenolase and diphenolase activities of tyrosinase. For the monophenolase activity, cefotaxime increased the lag time and decreased the steady-state activity with an IC50 of 3.2 mM. For the diphenolase activity, the inhibition by cefotaxime is reversible and mix-I type with an IC50 of 0.14 mM. The inhibition constants (K(I) and K(IS)) were determined to be 0.14 and 0.36 mM, respectively. The molecular mechanism of inhibition of tyrosinase by cefotaxime was determined by fluorescence quenching and molecular docking. The results demonstrated that cefotaxime was a static quencher of tyrosinase and that cefotaxime could dock favorably in the active site of tyrosinase. This research may offer a lead for designing and synthesizing novel and effective tyrosinase inhibitors in the future.

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To provide a quantitative synthesis of studies on the relationship between vision impairment (VI) and cognitive outcomes in older adults. A systematic search was undertaken of relevant databases for original articles published before April 2020. Random effect models were used to obtain pooled estimates of the associations between VI and cognitive outcomes (cognitive impairment and dementia) with subgroup analyses of VI measures, cross-sectional associations of VI with cognitive impairment, and longitudinal associations of baseline VI with incident cognitive impairment and dementia. Potential sources of heterogeneity were explored by meta-regression. Publication bias was evaluated with Egger's test. Sixteen studies including 76,373 participants were included in this meta-analysis, with five cross-sectional studies and eleven longitudinal studies. There was a significantly increased risk of cognitive outcomes with VI identified by subjective measures (odds ratio (OR)=1.63; 95% confidence interval (CI): 1.26–1.99) and objective measures (OR = 1.59; 95% CI: 1.40–1.78). The odds of baseline cognitive impairment were 137% higher in older adults with VI compared with those without VI (OR = 2.37, 95% CI: 1.84–3.03) at baseline. Compared with older adults without VI at baseline, those with baseline VI had a higher relative risk (RR) of incident cognitive impairment (RR = 1.41; 95% CI: 1.31–1.51) and dementia (RR = 1.44, 95% CI: 1.19–1.75). VI was associated with increased risks of cognitive impairment and dementia across cross-sectional and longitudinal studies. Additional research and randomized clinical trials are warranted to examine the implications of treatment for VI, such as wearing glasses and cataract surgery, to avoid cognitive impairment and dementia. [ABSTRACT FROM AUTHOR]