Ginger was steamed at 121 o C and 1.5 lb/in 2 for 30 min, dried at 60 o C for 12 h, and each step was repeated nine times. During processing, the lightness (L* value) and yellowness (b* value) decreased from 85.65±0.33 and 26.99±0.20 in the non-treated ginger to 56.91±0.25 and 16.69±0.06 in ginger treated for the ninth treatment. On the other hand, redness (a* value) increased from -1.51±0.03 to 7.34±0.08 on the eight treatment and then decreased to 7.21±0.04 on the ninth theatment. The contents of 6-gingerol decreased from 3.257±0.067 mg/g in the non-treated ginger to 0.567±0.036 mg/g on the theatment, whereas the contents of 6-shogaol increased from 1.299±0.050 mg/g to 2.999±0.089 mg/g on the sixth treatment and decreased to 2.099±0.039 on the ninth treatment. The contents of 10-gingerol decreased slightly from 1.106±0.125 mg/g to 0.806±0.026 mg/g. Unlike the 6- and 10-gingerol, the contents of 8-gingerol did not change greatly, with values between 0.916±0.005 mg/g and 1.106±0.005 mg/g being observed during processing. The tyrosinase inhibitory activities were increased from 43.42±11.45% in the non-treated ginger to 100% on the sixth treatment and then decreased to 51.98±7.36% on the theatment. The antioxidative activity was retained during processing.

Background : Ginger has been extensively used in foods and traditional medicines in Asian countries. Despite its frequent consumption in daily life, the mechanism of potential interactions between ginger components-drug has not been examined. To elucidate the mechanism of governing the effects of 6-shogaol, a primary constituent of dried ginger, on human cytochrome P450 (CYP) isoenzymes an incubation studies were carried out using pooled human liver microsome (HLM). Methods and Results : CYP isoenzyme specific substrate was incubated with multiple concentrations of inhibitor, HLM and cofactors. 6-shogaol showed a potent inhibitory effect on CYP2C9, CYP1A2 and CYP2C19 with half maximal inhibitory concentration (IC50) values of 29.20, 20.68 and 18.78 μM respectively. To estimate the value of the inhibition constant (Ki) and the mode of inhibition, an incubation study with varying concentrations of each CYP isoenzyme-specific probe was performed. 6-shogaol inhibited CYP2C9 and CYP2C19 noncompetitively (Ki = 29.02 and 19.26 μM respectively), in contrast, the inhibition of CYP1A2 was best explained by competitive inhibition (Ki = 6.33 μM). Conclusions : These findings suggest that 6-shogaol may possess inhibitory effects on metabolic activities mediated by CYP1A2, CYP2C9 and CYP2C19 in humans.