Abstract:
Ginger (Zingiber officinale Roscoe) contains the biological properties of the major
standard non–volatile pungent compounds of ginger, namely, [6]–, [8]–, and [10]–
gingerols, as well as [6]– , [8]–, and [10]–shogaols. So far, the comparative antioxidant
potencies among shogaols and gingerols have not been studied in detail and reported.
Accordingly, this study aimed to examine and compare the antioxidant abilities of the six
main compounds. Results showed that [6]–, [8]–, and [10]–gingerols, as well as [6]–, [8]–,
and [10]–shogaols exhibited substantial in vitro antioxidant activities. The DPPH•
, ABTS•+
,
and FRAP assays results showed that the antioxidant abilities of [6]–shogaol were greatest
among the six gingerols and shogaols studied (P< 0.05), and those of [6]–, [8]–, and [10]–
shogaols were greater than those of [6]–, [8]–, and [10]–gingerols, respectively, which can
be attributed to the presence of α, β–unsaturated ketones moieties. Moreover, the
observation that the antioxidant abilities of [6]–gingerol were greater than those of [8]–
and [10]–gingerols (P< 0.05) indicated that the short carbon chains of [6]–gingerol and
[6]–shogaol played a significant role in making them more potent antioxidants than the
other four longer carbon chain compounds. This finding can be attributed to gingerols
undergoing dehydration transformations into shogaols during oven drying. Our results
provided some new information on the antioxidant abilities of gingerols and shogaols.
Keywords: α, β–unsaturated ketones moieties, Antioxidant potency, Gingerol, Shogaol,
HPLC–UVD
