Tyrosinase-based TLC Autography for anti-melanogenic drug screening.

Tyrosinase-based TLC (thin layer chromatography) was developed for screening of anti-melanogenic drugs. In particular, this technique enables researchers to identify melanogenic inhibitor(s) in tested mixtures with the naked eye. In comparison with traditional colorimetric screening assays for tyrosinase inhibitor(s), not only is tyrosinase-based TLC a more cost-effective option (nearly one-tenth the enzyme cost of colorimetric methods) but also is a more sensitive detection approach for kojic acid (KA), a standard anti-melanogenic drug. The detection limit of tyrosinase-based TLC and colorimetric tyrosinase assay for KA was 0.0125 and 1.25 µg, respectively, demonstrating that the former was 100-fold more sensitive than the latter to determine the tyrosinase inhibitory rate of KA. Furthermore, the results of this method have demonstrated excellent precision by Gage Repeatability and Reproducibility (Gage R&R), with the variation of total Gage R&R being 28.24%. To verify the applicability of tyrosinase-based TLC, this platform was employed to screen melanogenic inhibitor(s) from Ganoderma formosanum extracts and two of all fractions (GFE-EA F4, F5) obtained showed depigmenting activity. It is noteworthy that these two fractions also exerted anti-melanogenesis activity on zebrafish, therefore verifying the credibility of tyrosinase-based TLC. In sum, this technique provides new insight into the discovery of novel melanogenic inhibitor(s).

[An epidemiological study on the ecological environment related to Nontuberculous mycobacteria in Shenzhen city of Guangdong province].

OBJECTIVE: To investigate the distribution of Nontuberculous mycobacteria in the environment of Shenzhen city and its related sensitivity to drugs. METHODS: 145 samples in the environment of Shenzhen city were collected and the samples were isolated, identified and its drug sensitivity were detected according to the "Procedure of Bacteriological Determination Regulation for Tuberculous Diagnosis", issued in 1995 by the Antituberculosis Association of China. RESULTS: All together, 53 strains of Mycobacteria were detected from the 145 sample, including 6 of them isolated from the polluted water in the hospital before disinfected, 4 from the polluted water in the hospital after disinfected, 4 from the dirt of air condition in the hospital, 34 from the polluted water in the residential area, 3 from the ocean water and 2 from the fountain. M. nonchromogenicum, M. avium, M. fortuitum, M. gordonae, M. genavense, M. chelonae and M. intracellulare were identified. CONCLUSION: Nontuberculous mycobacteria seemed to widely exist in the environment of Shenzhen city and the ratio of drug-resistant was high. Attention should be paid to the influence of Nontuberculous mycobacteria on humans in order to formulate effective control measure.