Melanin formation assay

Since the melanin formation assay was run against a cell viability assay, the activity peak maximum at fraction Dll was most likely due to cytotoxicity. The dereplication of another active peak located from fractions D7 to D2 is illustrated in Figure 9. Every active fraction was analyzed by HPLC/PDA/MS. There was a peak located at Rt=16.33 min in the LC/MS total ion chromatogram of active fractions. This peak showed the same pattern of increasing to decreasing intensity as the trend exhibited by the melanin inhibition activities of those fractions. 

The following example describes the results of the dereplication of an HTP fraction library for inhibition of melanin formation in an in vitro assay with a B16 cell line [54]. Briefly, following the inhibition and cell viability assay, the active organic extract from the whole plant of Mallotus repandus was fractionated with HTP. All of the HTP fractions were tested for melanin inhibitory activities. As shown in Figure 8, there are three major peaks exhibiting > 50% inhibitions of melanin synthesis and seven minor peaks exhibiting weaker inhibitions. The sharp activity peaks indicate the quality of the separations, which distributed the active components in three to five cells. 

Chen YM, Chavin W (1965) Radiometric Assay of Tyrosinase and Theoretical Consideration for Melanin Formation. Analyt Biochem 13 234... 

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