Food plant with antioxidant, tyrosinase inhibitory and antimelanoma activity: Prunus mahaleb L

Abstract

Prunus mahaleb L. seeds are used as spice and folk remedies in many countries. The aim of this study was bioactivity guided isolation and characterization phytoconstituents of P. mahaleb which have been studied very limited so far. The antioxidant capacities of seed and kernel (endocarp) extracts were studied by DPPH, nitric oxide (NO), superoxide (SO), TEAC, CUPRAC methods. The antiproliferative activity were investigated for the first time against B16F10, A2058, HeLa and L929 cell lines using MTT assay. Gallic acid and ursolic acid which have strong antioxidant and cell growth inhibitory effect, were isolated from the most active fractions. From the inactive fractions, quercetin-3-O-(2-O,6-O-α-dirhamnopyranosyl β-glucopyranoside), kaempferol-3-O-(2-O,6-O-α-dirhamnopyranosyl β-glucopyranoside) and β-sitosterol 3-O-β-glucopyranoside were isolated. Our study is the first record for the isolation of ursolic acid from all parts of P. mahaleb, gallic acid from P. mahaleb kernels, two flavonol triglycosides from the Prunus species and their analysis by advanced NMR spectroscopic methods. Ursolic acid (IC50: 170.2 μM) and gallic acid (IC50: 10.5 μM) showed strong tyrosinase inhibition, gallic acid being 5.4 times more effective than standard compound. Kernel extracts have strong antioxidant activity, showed high growth inhibitory activity with dose-dependent manner on melanoma cells but no growth inhibitory on healthy L929 and HeLa cancer cells. The high antioxidant capacity of kernel, its selective growth inhibition of B16F10 and A2058 melanoma cells and its strong tyrosinase inhibitory compounds suggest that it could be a new, non-toxic and inexpensive resource for melanoma treatment and cosmetic industry.