Journal of Medicinal Plants Research Vol. 4(24), pp. 2674-2679, 18 December, 2010
Available online at http://www.academicjournals.org/JMPR
ISSN 1996-0875©2010 Academic Journals
Full Length Research Paper
Chemical composition and antioxidant properties of
ginger root (Zingiber officinale)
Shirin Adel P. R.* and Jamuna Prakash
Department of Food Science and Nutrition, University of Mysore, Manasagangotri, Mysore 570 006, India.
Accepted 13 October, 2010
The chemical composition and antioxidant activity (in aqueous and solvent extracts) of Ginger root
(Zingiber officinale) were determined. The antioxidant components analysed were polyphenols, vitamin
C, β carotene, flavonoids and tannins. Antioxidant assays such as free radical scavenging activity,
reducing power and total antioxidant activity were carried out for ethanol, methanol, acetone, 80%
methanol and 80% ethanolic extracts. Protein and fat of sample were 5.08 and 3.72 g/100 g respectively.
Ash, minerals namely iron, calcium, phosphorous, zinc, copper, chromium and manganese) and vitamin
C were 3.85 (g), 8.0 (mg), 88.4 (mg), 174 (mg), 0.92 (mg), 0.545 (mg), 70 (µg), 9.13 (mg) and 9.33 (mg) per
100 g of sample, respectively. Antioxidant components (polyphenols, flavonoids and total tannin) were
higher in hot water (100°C) extract than other solvent extracts and 30°C water extract. Antioxidant
activity by 3 different methods showed higher activity in solvent extract than water extract. Order of
antioxidant activity by reducing power and free radical scavenging activity by DPPH was as follows,
80% methanolic > 80%ethanolic > methanolic > ethanolic > 30°C water >100°C water > acetonic extract.
Key words: Flavonoids, medicinal plant, polyphenol, spice, tannin.
Until synthetic drugs were developed in nineteenth
century, herbs were the basis for nearly all medicinal
therapy. Today, herbs are still found in 40% of
prescriptions, and the interest for use of herbal remedies
instead of chemical drugs is increasing because of lesser
side effects (Craig, 1999). A remarkable increase in the
use of medicinal plant products has been observed in the
past decade. Due to their properties, medicinal plants are
used as primary health care aid among 80% of the
world’s population in the form of plant extracts or their
active components (Word Health Organisation, 2008).
In the last decade, studies have also focused on new
group of bioactive components in some foods which have
protective effects against cell oxidation. These food
groups have been classified as functional foods. The
value of functional foods has been recognised for their
health benefits (Klein et al., 2000). Heart diseases
*Corresponding author. E-mail: Shirin59s@yahoo.com. Tel:
continue to be a major cause of death; cancer,
osteoporosis and arthritis remain highly prevalent.
Though, genetics play a major role in the progress of the
diseases mentioned, by and large most are considered
preventable or could be minimized by activity, a proper
diet, physical activity, weight management and a healthy
lifestyle. Functional foods can prevent or delay the onset
of chronic diseases and also provide basic nutritional
requirements (Medoua et al., 2009).
Ginger has been used as a spice and as natural
additives for more than 2000 years (Bartley and Jacobs,
2000). Also, ginger has many medicinal properties.
Studies have shown that, the long term dietary intake of
ginger has hypoglycaemic and hypolipidaemic effect
(Ahmed and Sharma, 1997). Ginger has been identified
as an herbal medicinal product with pharmacological
effect. Ginger suppresses prostaglandin synthesis
through inhibition of cyclooxygenase- 1 and
cyclooxygenase- 2. In traditional Chinese and Indian
medicine, ginger has been used to treat a wide range of
ailments including stomach aches, diarrhea, nausea,
asthma, respiratory disorders (Grzanna et al., 2005). As
ginger is widely used both as a spice and for its medicinal
properties, the present study was undertaken to
determine the nutritional composition of dry ginger as well
as its antioxidant activity and components. An attempt
was also made to investigate association between the
antioxidant activities and components of dry ginger
extracted in different solvents.
MATERIALS AND METHODS
Fresh ginger root (Zingiber officinale) were procured from local market,
washed with distilled water and dried in oven at 40°C, then ground and
stored in air tight container under refrigeration.
Chemical reagents and solvents
The chemicals used for the study were procured from Qualigen
Company Mumbai, India, Himedia Company, Mumbai, India and Sigma
Company, USA. They were all of analytical grade. Double distilled
water, methanol, ethanol, acetone, 80% methanol and 80% ethanol
were used for extraction.
Extraction of the sample
One gram of s ample was weighed accurately and suspended in 100 ml
of solvent. It was shaken for 3 h in an electronic s haker at room
temperature, unless otherwise specified, centrifuged at 4000 rpm for 20
min and filtered with Whatman No. 1 filter paper. For all experiments
fresh extracts were used.
Sample preparation for determination of antioxidant activity
250 mg of sample were mixed with 25 ml of extracting solvent and
extracted for 3 h, centrifuged at 4000 rpm for 20 min, and passed
through filter paper (Whatman No.1) to get clear extract. Water extracts
were taken at 30 and 100°C.
Proximate composition and trace element estimation
Nutritional composition -Moisture, total protein, f at, ash, calcium,
phosphorus, iron, vitamin C (Horwitz and Latimer, 2005), dietary fibre
(Asp et al., 1983) - of all the samples were estimated with standard
techniques. The ash s olutions were prepared with wet digestion
(Ranganna, 1986) and analyzed for zinc, c opper, c hromium and
manganese using atomic absorption spectrophotometer (AAS) (GBC
Scientific equipment, Australia). Instrument parameters such as
resonant wavelength, slit width and air-acetylene flow rate that are
appropriate for each element were selected (AOAC, 2000). The
instrument was set up and calibrated as per the guidelines in the
manual provided by the manufacturer. A calibration curve
(Concentration Vs absorbance) for each mineral to be determined was
prepared using a range of working standards. The flame paramet ers
were optimized in accordance with the instrument manufacturer’s
The standard s olutions were read before estimation of each mineral.
The burner was flushed with water between samples and zero was re-
established each time. Suitable dilutions of the ash solutions were made
to read the contents of the minerals in the ash solution. The
concentration of metals in the ash solutions of samples as well as in the
blank solutions were read from the calibration curve and the
concentration in the test samples was calculated taking into account the
dilutions and the weight of the samples taken.
Shirin and Jamuna 2675
Antioxidant components estimation
Total phenolic compound analysis
Total polyphenol content was estimated using Folin-Ciocalteu (FC)
assay which is widely used in routine analysis (Wright et al., 2000; Atoui
et al., 2005). A known amount of extract (10 mg/ml) was mixed with 1.0
ml of FC reagent and 0.8 ml of 2% Na2Co3 was added and the volume
was made up to 10 ml using water- methanol (4:6) as diluting fluid.
Absorbance was read at 740 nm after 30 min using spectrophotometer.
Tannic acid (0 - 800 mg/L) was used to produce standard calibration
curve. The total phenolic content was expressed in mg of Tannic acid
equivalents (TAE) /100 g of sample (Matthaus, 2002).
Determination of total flavonoids
The total flavonoid content was determined using the Dowd method as
adapted by (Arvouet-Grand et al., 1994). A 5.0 ml of 2% aluminium
trichloride (AlCl3) in methanol was mixed with the same volume of the
extract solution (10 mg/ml). Absorption readings at 415 nm using Perkin
Elmer UV-VIS spectrophotometer were taken after 10 min against a
blank sample consisting of extract s olution with 5.0 ml methanol without
AlCl3. The total flavonoid content was determined using a standard
curve with quercetin. Total flavonoid c ontent is expressed as g of
quercetin equivalents / 100 g of sample.
Total tannin estimation
Colorimetric estimation of tannins is based on the measurement of blue
colour formed by the reduction of phosphotungstomolybdic acid by
tannin like c ompounds in alkaline solution (R anganna, 1986). A known
amount of extract was mixed with 5.0 ml of Folin- Denis reagent (FD)
and Na2Co3 solution and made up to 100 ml, mixed well and
absorbance was read at 760 nm after 30 min using spectrophotometer.
Total tannin c ontent as expressed as mg tannic acid equivalent /100 g
Determination of antioxidant activity of different extract
Radical scavenging activity by DPPH (2, 2-diphenyl-1-
Effect of different extracts on DPPH free radical was measured
according to Lee (Lee et al., 1996). Positive control (standard) was
prepared by mixing 4.0 ml of ascorbic acid (0.05 mg/ml) and 1.0 ml of
DPPH (0.4 mg/ml) for water extract, and negative control (blank) was
prepared by mixing extract base (water/methanol/ethanol/acetone) with
1.0 ml of DPPH. Four different c oncentrations of extract was mixed with
4.0 ml of DPPH, the volume made up to known volume, mixed well and
left to stand at room temperature in a dark place for 30 min. Absorbance
was read us ing a spectrophotometer at 520 nm. The ability of extract to
scavenge DPPH was calculated using the following equation:
Control OD − Sample OD
Radical scavenging activity % =
A spectrophotometric method was used for the measurement of
reducing power. Different concentrations of extracts were mixed with
2.5 ml phosphate buffer (0.2 M, pH 6.6) and 2.5 ml of 1% potassium
ferricyanide (10 mg ml-1). The mixture was incubated at 50°C for 20 min,
then rapidly cooled, mixed with 2.5 ml of 10% trichloroactic ac id and
centrifuged at 6500 rpm for 10 min. The supernatant (2.5 ml) was mixed
with distilled water (2.5 ml) and then ferric chloride (0.5 ml, 0.1%) was
added and allowed to stand for 10 min. The absorbance was read
spectrophotometrically at 700 nm (Oyaizu, 1986).
2676 J. Med. Plant. Res.
Table 1. Nutritional composition of ginger (per 100g).
Constituent Value Constituent Value
Moisture 15.02 ± 0.04 Ash (g) 3.85 ± 0.61 (4.53)
Protein (g) 5.087 ± 0.09(5.98) Calcium (mg) 88.4 ± 0.97 (104.02)
Fat (g) 3.72 ± 0.03 (4.37) Phosphorous (mg) 174±1.2 (204.75)
Insoluble fibre (%) 23.5 ± 0.06 (27.65) Iron (mg) 8.0 ± 0.2 (9.41)
Soluble fibre (%) 25.5 ± 0.04 (30.0) Zinc (mg) 0.92 ± 0 (1.08)
Carbohydrate (g) 38.35 ± 0.1 Copper (mg) 0.545 ± 0.002 (0.641)
Vitamin C (mg) 9.33 ± 0.08 (10.97) Manganese (mg) 9.13 ± 001 (10.74)
Total carotenoids (mg) 79 ± 0.2 (9296) Chromium (µg) 70 ± 0 (83.37)
All value in this table represent the mean ± SD (n = 4). Figures in the parenthesis represent the dry weight values.
Total antioxidant activity by phosphomolybdenum method
The extract (0.1 ml) (10 mg/ml) was mixed with reagent solution (0.6 M
sulphuric acid, 28 mM s odium phosphate and 4 mM ammonium
molybdate in 100 ml). The tubes were capped and incubated in boiling
water bath at 95°C for 90 min, then cooled to room temperature and
absorbance was read at 695 nm with spectrophotometer against blank.
Water s oluble antioxidant capacity expressed as equivalent of ascorbic
acid (µmol/g of sample) (Prieto et al., 1999).
Data were expressed as mean ± SD. (n = 4) in all the experiments. To
determine the extent of association between antioxidant activity and
antioxidant components in different extracts, data were subjected to
correlation coefficient in Excel 2007.
RESULTS AND DISCUSSION
The nutritional composition of dry ginger was determined
with standard techniques and results are shown in (Table
1). Protein and fat content was found to be 5.98 and 4.37
g /100 g DW. The reported values for composition of
ginger by various authors are in the following range; for
protein, 7.2 to 8.7, fat, 5.5 to 7.3 and ash, 2.5 to 5.7 g/100
g DW (Nwinuka et al., 2005; Hussain et al., 2009;
Odebunmi et al., 2010). In our study, ash, iron, calcium
and phosphorous contents were 4.53 g, 9.41 mg, 104.02
mg, 204.75 mg/100 g DW, respectively. Ash content was
in the range of reported values and calcium content, that,
104.02 mg/100 g DW was very close to the value
reported for Indian foods (Gopalan et al., 2004).
Trace minerals namely zinc, copper, manganese and
total chromium were estimated with atomic absorption
spectrophotometer and found to be 1.08 mg, 0.641 mg,
10.74 mg and total chromium was 83.37 µg/100g DW,
respectively. Vitamin C and total carotenoids content
were found to be 10.97 and 92.96 mg/100 g, respectively.
Soluble and insoluble fibre of sample was determined
and as shown in Table 1, soluble fibre was slightly higher
than insoluble fibre. Antioxidant components were
estimated in seven extracting media and results are
shown in Table 2. Total polyphenols, tannin and
flavonoids were found to be more in 100°C water extract
than other extracts. It can be because of more solubility
of these components in hot water than other solvents.
Total polyphenols were highest in aqueous extract with
almost similar amounts at different temperatures (840
and 830 mg/g). Least polyphenols were seen in acetonic
extract. Antioxidant activities of plant extracts were
usually linked to their phenolic content. Hydrogen
donating characteristics of the phenolic compounds is
responsible for the inhibition of free radical induced lipid
ability to scavenge free radicals and give oxygen species
such as singlet oxygen, superoxide free radicals and
hydroxyl radicals (Hall, 1997), though, it is well accepted
that non phenolic antioxidants might also contribute to the
antioxidant activity of plant extract (Hassimotto et al.,
2005; Harish and Shivanandappa, 2006). In a study,
researchers estimated total polyphenol content of 35
different herbs and medicinal plants in 80% methanolic
extract. The polyphenol content was between 0.8 to 42.1
mg of gallic acid equivalent /g dry weight (DW)
(Kahkonen et al., 1999). Hinneburg et al. (2006) found
the total phenolic content of aqueous ginger extract to be
23.5 mg gallic acid/g of sample. Another researcher
(Rababah et al., 2004) estimated the total phenolic
content of 60% ethanolic extract of ginger to be 39.9 mg
of chlorogenic acid equivalent/g DW. In our study, when
we calculated total polyphenols content in 80%
methanolic extract/g of DW ginger, it showed 780 mg of
TAE/ 100 g of sample.
Flavonoids were estimated in all the extracts and data is
shown in Table 2. Highest flavonoid content was reported
in 30 and 100°C aqueous extract at 1.37 and 2.98 g/100
g of sample, respectively. Flavonoid content of 80%
methanolic extract and 80% ethanolic extracts were
Shirin and Jamuna 2677
Table 2. Antioxidant c omponents and total antioxidant activity of ginger in different solvent extracts.
Antioxidant components Water Methanol Ethanol Methanol
Total polyphenols mg/100 g 840 ± 2.1 838 ± 3.0 510 ± 2.2 565 ± 4.1 780 ± 5 800 ± 4.3 325 ± 1.9
Tannin g/100 g 1.51 ± 0.05 1.34 ± 0.08 1.12 ± 0.05 0.98 ± 0.03 1.28 ± 0.01 1.15 ± 0.1 0.67 ± 0.08
Flavonoids g/100 g 2.98 ± 0.06 1.371 ± 0.01 0.685 ± 0.005 0.278 ± 0.003 0.404 ± 0.002 0.352 ± 0.002 0.249 ± 0.002
Total antioxidant activity µmol/ g of sample 73529.4 ± 121 79400 ± 88 98822.5 ± 74 91176.25 ± 66 85294 ± 47 80000 ± 38 32056 ± 27
All values in this table represent the mean ± SD (n = 4).
Table 3. Correlation between antioxidant activity and antioxidant component of sample in different solvent extracts.
values) Water extract Solvent extract
Antioxidant components Method of assay Method of assay
DPPH Reducing power Total antioxidant DPPH Reducing power Total antioxidant
Flavonoids -1 -1 -1 0.493 0.505 0.613
Polyphenols 1 1 1 0.901 0.847 0.579
Total tannin -1 -1 -1 0.985 0.887 0.885
For solvent extract in DPPH method, 80% methanolic extract was not included for statistical analysis since the concentration did not match with other extracts.
found to be more than methanolic and ethanolic
extracts,respectively, but lesser than aqueous
extract. It can be due to higher solubility of ginger
flavonoids in water than other solvents.
Tannin was also estimated in all seven different
extracts (Table 2). As was observed for the other
antioxidant components, 30 and 100°C aqueous
extract had the highest tannin (1.34 and 1.51
g/100 g of sample, respectively) and acetonic
extract showed the least content (0.67 g/100 g).
As shown in Tables 2 and 3, tannin content did
not show any correlation with antioxidant activity
in aqueous extract, but high correlation was seen
with solvent extract.
Estimation of antioxidant activity
Antioxidant activity of dry ginger was estimated
with three different methods.
Total antioxidant activity
Total antioxidant activity (Table 2) was highest in
methanolic extract at 98822 µmol/g followed by
ethanolic extract at 91176 µmol/g. Least total
antioxidant activity was found in acetonic extract.
Free radical scavenging activity
DPPH is a stable free radical in methanol or
aqueous solution and accepts an electron or
hydrogen radical to turn into stable diamagnetic
molecule. It is usually used as a substrate to
evaluate the antioxidative activity of antioxidants
(Duh et al., 1999), thus we have estimated the
antioxidant activity through free radical
scavenging of ginger. Free radical scavenging
potency of sample is shown in Figure 1 which
showed the highest DPPH radical scavenging
activity in 80% methanolic extract followed by
80% ethanolic extract. In a study, by Chen et al.
(2008), DPPH radical scavenging activity of
methanolic extract was found to be in a range of
2678 J. Med. Plant. Res.
Figure 1. Free Radical sc avenging activity of ginger in different solvent extracts. Concentration of sample (in mg):
In 80% methanolic extract, A: 0.4, B: 0.6, C: 0.8 and D: 1.0. For all other extracts, A: 2.5, B: 5.0, C: 7.5, D: 10.
Figure 2. Reducing power of ginger in different solvent extracts.
32 to 90.1% in 100 mg of 18 different ginger species. In
the present study, DPPH free radical scavenging activity
of methanolic extract was 39.6, 64.7, 77.6 and 84.4% in
0.25, 0.5, 0.75 and 1.0 mg of sample, respectively, which
is higher than the reported values.
It has been reported that the reducing power of bioactive
compounds is associated with antioxidant activity (Yen et
al., 1993; Siddhuraju et al., 2002). Hence, it is essential
to determine the reducing power of phenolic constituents
to explain the relationship between their antioxidant effect
and their reducing power. The reducing power of different
solvent extracts of ginger was estimated. Highest
reducing power was also in 80% methanolic extract
followed by 80% ethanolic extract (Figure 2). As reported
by Chen et al. (2008), the reducing power of methanolic
extract of 18 different species of ginger ranged from 0.34
to 1.6 nm in 100 mg of sample. In our study, methanolic
extract of sample showed much higher activity of 0.208,
0.393, 0.558, 0.681 nm for 2.0, 4.0, 6.0 and 8.0 mg of
Antioxidant components and activity are highly
dependent on extracting solvent and concentration of
solvent (Turkmen et al., 2006), but they also vary within
the samples. Many researchers have reported the
relationship between phenolic content and antioxidant
activity. In some studies, they found a correlation
between the phenolic content and antioxidant activity
(Velioglu et al., 1998), whereas others found no
relationship (Kahkonen et al., 1999). As it is shown in
Table 3, in this study we also found high correlation
between polyphenol content and antioxidant activity in
both water extract (R2 = 1) and solvent extract (DPPH, R2
= 0.901, reducing power, R2 = 0.847 and total antioxidant
activity R2 = 0.579). Total tannin and flavonoids did not
show any correlation with antioxidant activity in aqueous
extract. In solvent extract, total tannin showed high
correlation with reducing activity (R2 = 0.887), total
antioxidant activity (R2 = 0.885) and free radical scavenging
activity (R2 = 0.985). Flavonoids showed correlation with
reducing power (R2 = 0.505), total antioxidant (R2 = 0.613)
and DPPH (R2 = 0.493). Since the antioxidant activity was
higher in alcoholic extract than aqueous extract, it is
advisable to use the extracting media capable of extracting
the lipophilic antioxidant compounds from ginger.
It can be concluded that ginger is a good source of
antioxidant and most of the antioxidant components
exhibit higher activities in alcoholic media as determined
by different assays. Hence, apart from its medicinal
properties, ginger can also be used as an antioxidant
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