Extraction of gingerols and shogaols from ginger (Zingiber officinale Roscoe) through microwave technique using ionic liquids

An ionic liquid-based microwave-assisted extraction (ILMAE) method was developed to extract 6-, 8-, 10-gingerols and 6-, 8-, and 10-shogaols from ginger (Zingiber officinale Roscoe). A series of water-miscible ionic liquids (ILs) with different kinds of anions and cations were investigated. Results indicated that among the investigated ILs, the carbon chains of alkyl cations remarkably affected the extraction efficiency of the six compounds and 1-decyl-3-methylimidazolium bromide ([C10MIM]Br) was the optimal IL. The selected conditions for ILMAE were as follows: [C10MIM]Br concentration, 0.80 M; extraction temperature, 75 degrees C; irradiation time, 30 min; and irradiation power, 400 W, in the case of solid liquid ratio of 0.1:10 g/mL. This study showed that compared with the total extraction yield of 0.595 +/- 0.031% by methanol marinated extraction and 0.673 +/- 0.043% by methanol-based microwave-assisted extraction, ILMAE attained higher yield of 0.716 +/- 0.051%; and ILMAE obtained a shorter time of 30 min for extraction of gingerols and shogaols from ginger. This study provides a basis for separating and purifying bioactive components from ginger. Moreover, the use of small amounts of [C10MIM]Br as extraction solution in the method was considered environmentally friendly.