OBJECTIVETo confirm the inhibitory effect of Chinese herbs of acid taste on melanin synthesis.

METHODSActive ingredients of 22 kinds Chinese herbs of acid tastes were extracted by alkali extraction and acid precipitation, alcohol extraction, and water extraction, respectively, which was then dispensed into 25.00, 12.50, and 6.25 g/L suspension. Their effects on activities of tyrosinase were detected using mushroom-tyrosinase-DOPA speed oxidation. Their inhibition rates on activities of tyrosinase were respectively compared with inhibition rates of 1.0, 0.5, and 0.1 mmol/L arbutin.

RESULTSThe 22 kinds Chinese herbs of acid taste included Cornus Officinalis, Crataegus pinnatifida, dark plum fruit, Schisandra Chinensis, Chaenomeles sinensis Koehne, Reynoutria japonica Houtt, Achyranthes Bidentata, Sanguisorba officinalis L., Semen Ziziphi Spinosae, Herba Ecliptae, blueberry, immature bitter orange, submature bitter orange, Prunus mume Var, Hovenia acerba Lindl., Fructus Mori, Pomegranate Rind, white paeony root, Rosa laevigata Michx., Portulaca oleracea L, Terminalia chebula Retz, Rhus chinensis Mill. Their alkaline extractions showed inhibition to activities of tyrosinase to different degrees except Herba Ecliptae. Of them, the highest inhibition rate (88.49% ± 9.98%) was got by dark plum fruit at 25 g/L, while the lowest inhibition rate (11.22% ± 3.36%) was got by immature bitter orange at 6.25 g/L. Their alcohol extractions showed inhibition to activities of tyrosinase to different degrees except Herba Ecliptae. Of them, the highest inhibition rate (75.92% ± 5.57%) was got by Hovenia acerba Lindl. at 25 g/L, while the lowest inhibition rate (9.60% ± 1.15%) was got by submature bitter orange at 6.25 g/L. Their water extractions all had inhibition on activities of tyrosinase. Of them, the highest inhibition rate (54.23% ± 3.56%) was got by Fructus Mori at 25 g/L, while the lowest inhibition rate (10.25% ± 1.83%) was got by Semen Ziziphi Spinosae at 6.25 g/L. Compared with 1 mmol/L arbutin water solution, alkaline extractions of dark plum fruit, Schisandra Chinensis, Rhus chinensis Mill., Rosa laevigata Michx., blueberry, Chaenomeles sinensis Koehne, Portulaca oleracea L, Fructus Mori, Achyranthes Bidentata, Pomegranate Rind; alcohol extractions of dark plum fruit, Rhus chinensis Mill., Pomegranate Rind, Hovenia acerba Lindl., Crataegus pinnatifida, Achyranthes Bidentata; water extractions of Chaenomeles sinensis Koehne, blueberry, and Fructus Mori at 25 g/L got obviously higher inhibition rates (P < 0.05, P < 0.01). Compared with 0.5 mmol/L arbutin water solution, alcohol extraction of Chaenomeles sinensis Koehne and alcohol extraction of dark plum fruit at 12.5 g/L got obviously higher inhibition rates (P < 0.05, P < 0.01).

CONCLUSIONChinese herbs of acid taste could inhibit melanin synthesis, and its mechanism was related to inhibiting activities of tyrosinase.