Purification and characterization of a tyrosinase inhibitor from camellia pollen

- A tyrosinase inhibitor with an IC50 of 0.05 mg/mL is identified from Camellia pollen.
- The tyrosinase inhibitor was identified to be kaempferol by UV spectrum, NMR and MS spectrum.
- The procedure consisting of HSCCC, macroporous adsorptive resin and solvent fraction is effective to purify bioactive compounds from pollen.
- The kaempferol mainly exists in glycosidic forms.
- The kaempferol contributes 32.41% to the total tyrosinase inhibition activity of the pollen extract.

Bee pollen is an important bee-product that contains larger amount of bioactive compounds. In this paper, a tyrosinase inhibitor was separated from camellia pollen by the aid of high-speed counter-current chromatography (HSCCC), macroporous adsorptive resin chromatography and solvent fraction. The tyrosinase inhibitor was identified to be kaempferol by absorption spectrum, nuclear magnetic resonance and mass spectrum. The purity and recovery were 98.47% and 41.94%, respectively. The kaempferol was detected to have the IC50 of 0.05 mg/mL and mainly exists in glycoside forms. It had a concentration of 1.03 mg/g in the acidic hydrolysis of the ethanol extract (HEE), and contributed 32.41% to the total tyrosinase inhibition activity of HEE. This study demonstrates an effective procedure to purify bioactive compounds from bee pollen, and reveals kaempferol as a major tyrosinase inhibitor of camellia pollen, providing interesting information for in-depth study of bioactive compounds of pollen.