Tyrosinase is a key enzyme that catalyzes melanogenesis in human skin. It oxidizes tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) and subsequently to dopachrome, which further polymerizes to melanin pigments. Therefore finding an effective tyrosinase inhibitor, either from synthetic or natural sources, is not only useful as skin whitening agents in cosmetic application, but also beneficial in treating melanin-related disorders. The present study reports of the optimized and validated results of a cell-based tyrosinase assay using B16F10 murine melanoma cell line, which produces melanin pigments and has been used extensively in antimelanogenesis studies. The optimization studies involved 3 parameters (1) optimal seeding cell number per well for total protein extraction; (2) optimal dopachrome formation from enzymatic reaction between total protein (tyrosinase source) and L-DOPA (substrate); and (3) optimal incubation period after the addition of substrate. The present study demonstrates that using seeding cell number of 2 × 105 cells/well, total protein of 40 μg, L-Dopa of 5 mM,and at an incubation period of 1 hour at 37°C provided the optimal response on cultured melanoma cells. Kojic acid, a standard tyrosinase inhibitor, was used as a positive control in the optimized cell-based tyrosinase assay to validate the usefulness of the assay. CONCLUSION: The use of the mentioned protocol is sensitive to determine changes in melanoma cells as the result of tyrosine inhibitors.
Introduction: Hypercholesterolemia is an important modifiable risk factor for coronary heart disease. Lifestyle changes in diet and physical activity can improve cholesterol levels. This study aimed to compare the fruits and vegetables (FV) intake and physical activity (PA) between hypercholesterolemic adults and non- hypercholesterolemic adults in Malaysia, and to investigate factors associated with meeting the recommended levels of FV intake and PA in a hyper- cholesterolemic population. Methods: This study was based on 17,988 participants (response rate 98.7%) aged 18 years and above who responded to the hypercholesterolemia questionnaire in the 2011 Malaysian National Health and Morbidity Survey (NHMS), a cross-sectional study with two-stage stratified sampling design. Data were obtained by trained enumerators via face-to-face interviews and were analysed by descriptive analysis, chi-square test, and univariable and multivariable logistic regression. Results: Out of the total population assessed, 39.0% had hypercholesterolemia. The prevalence of consuming five or more servings of FV per day is low (7.8%) while 36.0% were physically inactive among the hypercholesterolemic adults. No significant differences were observed in FV intake and PA between hypercholesterolemic and non-hypercholesterolemic populations. Gender, age and educational levels were associated with FV intake and PA among hypercholesterolemic adults. Hypercholesterolemic adults who were underweight or obese were less likely to consume FV, while those who were former smokers and those who had diabetes and heart disease were less likely to be physically active. Conclusion: These findings are relevant for future health promotion strategies, suggesting that more intensive interventions are needed to increase FV intake and PA level in hypercholesterolemic population and in the general population.
Study name: National Health and Morbidity Survey (NHMS-2011)