Effects of Solvents on Total Phenolic Content and Antioxidant Activity of Ginger Extracts

Ginger (Zingiber officinale) is a popular spice which is used for the treatment of different gastrointestinal and inflammatory discomfort. In the present study, the total phenolic content (TPC) and antioxidant activity of ginger extract using four solvents (ethanol, methanol, acetone, and ethyl acetate) were determined. Among the four solvents, methanol extract showed the maximum phenolic content (1183.813 mg GAE/100 g at Ayikel and 1022.409 mg GAE/100 g at Mandura) and the least phenolic content was found in acetone extract (748.865 mg GAE/100 g at Ayikel and 690.152 mg GAE/100 g at Mandura). In addition, the highest DPPH radical scavenging activity (84.868% at Ayikel and 82.883% at Mandura) was observed in methanol. However, acetone showed the least DPPH radical scavenging activity (73.864% at Ayikel and 70.597% at Mandura). Antioxidant activities of ginger extracts were also expressed as IC50 values, and acetone extract has maximum IC50 value (0.654 and 0.812 mg/mL) followed by ethyl acetate and ethanol, while being the lowest for methanol (0.481 and 0.525 mg/mL). The result of this study showed that extraction solvents significantly affected the total phenolic content and antioxidant activities of ginger. Thus, ginger can be regarded as promising candidates for natural sources of antioxidants with a high value of phenolic contents.