N-Alkylamides from Piper longum L. and their stimulative effects on the melanin content and tyrosinase activity in B16 melanoma cells

Abstract

Piper longum L., known as long pepper, is an edible and medicinal plant used as spice and for the treatment of stomach disease and analgesia in traditional Chinese medicine. N-Alkylamides are the major secondary metabolites in this plant. Sixteen known N-alkylamides were isolated from P. longum. Their structures were established on the basis of spectroscopic data and comparison to reported literatures. Among them, five compounds were isolated from this plant for the first time. Ethanol extract, compounds 1, 2, 3, 7 and 11 exhibited potent ability to increase the melanin content and weak stimulative effect on the tyrosinase activity in a concentration-dependent manner. Moreover, compound 2 also presented strong capacity to increase the tyrosinase activity in a concentration-dependent manner. These results indicated that P. longum might be a good natural source of lead compound for skin disorder diseases.

Graphical Abstract

Keywords:

• Piper longum L.
• N-alkylamides
• melanin content
• tyrosinase activity

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The financial support of this research was provided by the Natural Science Foundations of China. [grant number 31500273], the West Light Foundation of the Chinese Academy of Science [Grand No. 2015-XBQN-B-08], and the CAS-TWAS President’s Fellowship Programme.