Reverse Phase Compatible TLC-Bioautography for Detection of Tyrosinase Inhibitors

RAMALLO, IA; GARCIA, P; FURLAN, RLE

PHYTOCHEMICAL ANALYSIS

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2017 vol. 28 p. 101 - 105

0958-0344

Introduction ? Reverse phase chromatography and bioautographic assays are key tools for natural product bioguided isolation;however, their direct coupling has not been fully achieved.Objectives ? To develop a bioautographic assay to detect tyrosinase inhibitors present in complex matrices sorbed on reversephase (RP) TLC-plates that can be used for bioguided isolation of bioactive compounds.Methods ? Enzyme gel entrapment with an amphiphilic copolymer was used for assay development. The gel turns into a brown?skin like? colour due to tyrosinase catalysed oxidation of L-tyrosine. The inhibitors are visualised as clear spots against a browncoloured background.Results ? The assay was able to localise cinnamaldehyde in Cinnamomum cassia essential oil, as its main constituent with knowntyrosinase inhibition properties. The assay allowed the detection of 0.03% (w/w) of kojic acid co-spotted with a methanolic extractof Sphaeralcea bonariensis and chromatographed on RP-TLC.Conclusion ? The developed assay is able to detect, with high sensitivity, tyrosinase inhibitors present in complex matrices thatwere chromatographed in RP-TLC. Results can be easily read by colour change, inhibitors appear as clear spots in a darker background.