Melanogenesis inhibitors from Coix lacryma-jobi seeds in B16-F10 melanoma cells

Abstract

An adenine derivative, 9-β-D-glucopyranosyl adenine, reported for the first time from a natural source, in addition to nine known compounds were isolated from the seeds of Coix lacryma-jobi. Their structures were elucidated based on extensive spectroscopic and chemical studies. The isolated compounds and the ethanol extract have been assayed for melanin inhibition using B16-F10 melanoma cell line. The results of our study suggested the potential use of Coix lacryma-jobi seeds as a skin whitening agent and reveal the seeds to be a rich source of important phytochemicals with melanogenesis inhibitory activity. Among the isolated compounds, coixol (2) and 2-O-β-glucopyranosyl-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (8) exhibited potent melanogenesis inhibitory activity with no obvious melanocytotoxicity. The rest of the compounds showed weak to moderate activity.

Keywords:

• Poaceae
• adlay
• Coix lacryma-jobi
• melanogenesis
• coixol
• 9-β-D-glucopyranosyl adenine

Acknowledgements

The Egyptian Government is acknowledged for the fellowship support to Yhiya Amen. We acknowledge the help of Shinnihonseiyaku Co., Ltd. (Japan) for providing the extract material. We would like to thank Research and Education Support Center of the faculty of Agriculture, Kyushu University for supporting facilities for ESI-IT-TOF analysis. The authors are indebted to Dr. Shingo Yokota, Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Japan for carrying out the IR measurement. This work was performed under the Cooperative Research Program of ‘Network Joint Research Center for Materials and Devices’, Kyushu University.