Tetrahydro- β-Carboline alkaloids from Carthamus tinctorius L. with tyrosinase inhibitory activity

Publication date: December 2017 Source:Phytochemistry Letters, Volume 22 Author(s): Li-Li Lou, Sen Liu, Zhi-Yang Yan, Bin Lin, Xiao-Bo Wang, Xiao-Xiao Huang, Shao-Jiang Song Phytochemical research on the dry flower of Carthamus tinctorius L. led to the isolation of two new epimeric tetrahydro-β-carboline alkaloids (1 and 2), together with three known analogues (3–5). Their planar structures were determined by comprehensive 1D, 2D-NMR, and HR-ESI–MS spectroscopic data analyses. The absolute configurations of alkaloids 1 and 2 were assigned by comparing their experimental electronic circular dichroism (ECD) curves with the calculated ECD data. To investigate their impact on melanogenesis, all of the alkaloids isolated were tested for their tyrosinase inhibitory activity and alkaloid 4 was found to inhibit tyrosinase with an IC50 value of 0.17mM, compared with 0.18mM for arbutin. The putative binding interactions between the compounds and tyrosine were studied by molecular docking to provide an explanation for their inhibitory activities, and the results obtained indicated that hydrophobic interactions played a very significant role in the combination. Graphical abstract

Source: Phytochemistry Letters - September 29, 2017 Category: Chemistry Source Type: research