Variations in the contents of gingerols and chromatographic fingerprints of ginger root extracts prepared by different preparation methods.

In the present study, an HPLC-DAD method was optimized for the quantitative determination of 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol in ginger extracts. A chromatographic fingerprinting method was also established to differentiate and evaluate the ginger extracts for bioactivity. Twenty-one extracts were prepared by methods differing in ginger type (fresh versus dried), solvent, and extraction methods. The ANOVA analysis showed the methods' influence on the mean extraction yields of gingerols increased in the order of: high pressure-high temperature (HP)>blender (BD)>low pressure (LP). The optimal solvent to extract gingerols was found to be 95% ethanol. The type of ginger used had significant effects on the content of gingerols, but its overall influence depended on the solvent used. In order to maximize the extraction efficiency of gingerols, a combination of dry ginger, 95% ethanol, and the HP extraction method should be employed. The chromatographic fingerprints were obtained to differentiate the unknown components from all ginger extracts. The similarity of the chromatographic fingerprints was used to evaluate the differences among all extracts. It can be concluded that the chromatographic fingerprints are able to ensure the stability of each extract and have some correlation with the observed bioactivity.