COMPARATIVE ANALYSIS OF PHYTOCHEMICAL AND ANTIOXIDANT ACTIVITY OF SOME SELECTED MEDICINAL PLANTS FRESH TUMERIC (CURCUMA LONGA) AND GINGER (ZINGIBER OFFICINALE)
Abstract
Turmeric and ginger which are both Zingiberaceae rhizomes, are widely used as
spices, traditional medicines and functional foods. Their value is largely due to
diverse phytochemicals (polyphenols, phenolic ketones, and volatile oils) that
exhibit antioxidant, anti-inflammatory and other bioactivities. The purpose of this
study was to evaluate phytochemical constituents and antioxidant potential of
fresh tumeric and fresh ginger. The qualitative and quantitative phytochemical
analysis of fresh turmeric and fresh ginger extracts revealed the presence of
phenols, flavonoids, tannins, alkaloids, reducing sugars, proteins, and phytates in
varying concentrations across the two solvent systems (aqueous and methanolic
extracts). In fresh turmeric, methanolic extraction significantly increased the
concentration of all major antioxidant-related phytochemicals when compared
with the aqueous extract. (p < 0.05). These results indicate that methanol
(ethanol) was a more efficient solvent for extracting most antioxidant
phytochemicals from turmeric. In fresh ginger, a similar pattern was observed
where the methanolic extract exhibited significantly higher levels of most
phytochemicals than the aqueous extract (p < 0.05). Estimated DPPH radicalscavenging
assays, simulated from measured phytochemical concentrations,
showed that methanolic extracts of both plants displayed markedly greater
predicted scavenging activity than their aqueous counterparts. The methanolic
extract of fresh turmeric exhibited the highest predicted antioxidant potency with
an estimated IC₅ ₀ of approximately 18.0 μg/mL, achieving simulated DPPH
inhibition of 58.1% at 25 μg/mL and 91.7% at 200 μg/mL. The methanolic extract
of fresh ginger was the second most potent with an estimated IC₅ ₀ of 25.3
μg/mL, producing simulated inhibitions of 49.7% at 25 μg/mL and 88.8% at 200
μg/mL. Both aqueous extracts demonstrated substantially higher estimated IC₅ ₀
values and correspondingly lower simulated scavenging: turmeric aqueous
(IC₅ ₀ ≈ 69.3 μg/mL) and ginger aqueous (IC₅ ₀ ≈ 67.4 μg/mL) each gave
predicted inhibitions of approximately 26–27% at 25 μg/mL and 74–75% at 200
μg/mL. More research is required to see if this plants can be used to treat
ailments, and the amount to be consumed by users.
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