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Scientific Research and Essay Vol. 2 (6), pp. 191-194, June 2007
Available online at http://www.academicjournals.org/SRE
ISSN 1992-2248 © 2007 Academic Journals
Full Length Research Paper
Phytochemical constituents and antioxidant properties
of extracts from the leaves of Chromolaena odorata
Afolabi C. Akinmoladun
1*
, E.O. Ibukun
1
and I.A.
Dan-Ologe
2
1
Biochemistry Department, Federal University of Technology, Akure, Nigeria.
2
Department of Fisheries, College of Environmental Sciences, University of Agriculture, Abeokuta, Nigeria.
Accepted 16 April, 2007
Aqueous and methanolic extracts of Chromolaena odorata were screened for phytochemical consti-
tuents. The evaluation of the antioxidant potential of the methanolic extract was also carried out. Tests
for tannins, steroids, terpenoids, flavonoids and cardiac glycosides were positive in both methanolic
and aqueous extracts. Alkaloids were detected only in the methanolic extract. The total phenolic
content, reducing power and percent DPPH scavenging effect were 0.01 ±
±±
± 0.00 mg/g GAE, 0.22 ±
±±
± 0.01
and 28.85 ±
±±
± 0.99%, respectively. Against the backdrop of many known medicinal properties of this plant,
results from the present work suggest that relatively low values of antioxidant indices may not imply a
low medicinal value.
Key words: Chromolaena odorata, phytochemicals, antioxidant activity, reductive potential, medicinal plants
INTRODUCTION
Chromolaena odorata (L) King and Robinson Asteraceae
commonly known as Siam weed, is a fast-growing pere-
nnial and invasive weed native to South and Central
America. It has been introduced into the tropical regions
of Asia, Africa and other parts of the world. It is an aggre-
ssive competitor that occupies different types of lands
where it forms dense strands that prevents the establish-
ment of other flora. It is a menace in plantations and
other ecosystems. It suppresses young plantations, agri-
cultural crops and smothers vegetation as it possesses
allelopathic potentialities and growth inhibitors (Ambika
and Jayachandra, 1980; Ambika and Jayachandra, 1982;
Muniappan and Marutani, 1988). The economic value of
C. odorata is low. Consequently, there is a relative pau-
city of research works on it. It is a perennial shrub native
of South and Central America. In recent decades, it has
become a serious pest in the humid tropics of South East
Asia, Africa and Pacific Islands. It spreads rapidly in
lands used for forestry, pasture and plantation crops such
as rubber, coffee, coconut, cocoa and cashew. The plant
can be poisonous to livestock as it has exceptionally high
level of nitrate (5 to 6 times above the toxic level) in the
*Corresponding author. E-mail: akinmoladunfc@gmail.com.
leaves and young shoots; the cattle feeding on these die
of tissue anoxia (Sajise et al., 1974).
Despite the negative sides to the plant, it still has patro-
nage from practitioners of traditional medicine. It has
been reported to have antispasmodic, aniprotozoal, anti-
trypanosomal, antibacterial and antihypertensive active-
ties. It has also been reported to possess anti-inflamma-
tory, astringent, diuretic and hepatotropic activities (Watt
and Brandwijk, 1962; Feng et al, 1964; Weniger and
Robinean, 1988; Iwu, 1993). In the southern part of Nige-
ria, the leaves are used for wound dressing, skin infection
and to stop bleeding. Some specific phenolic compounds
have been isolated from the plant (Metwally and Ekejuba,
1981).
The medicinal values of plants lie in their component
phytochemicals such as alkaloids, tannins, flavonoids
and other phenolic compounds, which produce a definite
physiological action on the human body (Hill, 1952). A
systematic search for useful bioactivities from medicinal
plants is now considered to be a rational approach in
nutraceutical and drug research. Therefore, the present
work has been designed to evaluate the antioxidant pot-
ential of C. odorata with a view to contributing to the
search for beneficial uses of this invasive plant which is a
menace to farmers.
192 Sci. Res. Essays
Table 1. Phytochemicals detected in extracts of Chromolaena odorata.
Phytochemicals Methanolic extracts Aqueous extracts
Alkaloids + -
Saponins - +
Tannins + +
Phlobatannins + +
Anthraquinones - +
Steroids + +
Terpenoids + +
Flavonoids + +
Cardiac glycosides
With steroidal ring + +
With deoxy – sugar + +
+ = Present
- = Absent
MATERIALS AND METHODS
Chemicals
DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical, gallic acid, ascorbic
acid and Folin-Ciocalteau reagent were obtained from Sigma-Ald-
rich, USA. All other chemicals and reagents used were of analytical
grade.
Plant materials
Leaves of C. odoarata were collected from a farmland in Akure,
South-Western Nigeria and identified at the Department of Crop,
Soil and Pest Management, Federal University of Technology,
Akure. They were air dried, packed in paper bags and stored. The
dried leaves were pulverized and 196 g of the pulverized sample
was extracted with 500 ml of 80% methanol by maceration for 72 h.
The methanolic extract was concentrated in a rotary evaporator,
lyophilized and thereafter preserved for further use. An aqueous
extract was also prepared from the pulverized sample for the
purpose of comparison of the phytochemical constituents with that
of the methanolic extract.
Phytochemical screening
Chemical tests were carried out on the aqueous and methanolic
extracts for the qualitative determination of phytochemical
constituents as described by Harborne (1973), Trease and Evans
(1989) and Sofowora (1993). Total phenolic content was
determined using Folin-Ciocalteau reagent as previously described
(McDonald et al., 2001). Total phenol value was expressed as mg/g
gallic acid equivalent.
DPPH radical scavenging activity
The ability of the extract to scavenge DPPH radical was determined
according to the method described by Mensor et al. (2001). One ml
of a 0.3 mM DPPH methanol solution was added to a solution of the
extract or standard (250 µg/ml, 2.5 ml) and allowed to react at room
temperature for 30 min. The absorbance of the resulting mixture
was measured at 518 nm and converted to percentage antioxidant
activity (AA %). Methanol (1.0 ml) plus extract solution (2.5 ml) was
used as a blank. 1 ml of 0.3 mM DPPH plus methanol (2.5 ml) was
used as a negative control. Solution of gallic acid served as positive
control.
Reductive potential
This was determined according to the method of Oyaizu (1986).
The extract or standard (100 µg/ml) was mixed with phosphate
buffer and potassium ferricyanide. The mixture was incubated at
50˚C for 20 min. Tricloroacetic acid (10%, 2.5 ml) was added to the
mixture. A portion of the resulting mixture was mixed with FeCl
3
(0.1%, 0.5 ml) and the absorbance was measured at 700 nm in a
spectrophotometer. Higher absorbance of the reaction mixture
indicates higher reductive potential.
Statistical analysis
Data were expressed as mean ± SEM. A one-way analysis of
variance was used to analyze data. P<0.5 represented significant
difference between means (Duncan’s multiple range test).
RESULTS AND DISCUSSION
Table 1 shows the phytochemicals detected in C. odorata
leaf extract. Tests for tannins, steroids, terpenoids, flavor-
noids and cardiac glycosides were positive in both met-
hanolic and aqueous extracts. Alkaloids were detected
only in the methanolic extract. Phenolics, alkaloids, terpe-
noids and cardiac glycosides detected in the extracts are
compounds that have been documented to possess
medicinal properties and health-promoting effects (Salah
et al., 1995; Del-Rio et al., 1997; Okwu, 2004; Liu, 2004).
The total phenolic content in the methanolic extract was
0.01 ± 0.00 mg/gGAE; a rather low value. Phenolics are
the largest group of phytochemicals and have been said
to account for most of the antioxidant activity of plant
extracts (Thabrew et al., 1998).
The result of the DPPH scavenging assay is shown in
Figure 1. The percentage antioxidant activity of C. odora-
Akinmoladun et al 193
0
10
20
30
40
50
60
70
80
90
CO
GA
AA
% AA
*
# #
Figure 1. Antioxidant activity of CO compared with some standards. CO,
Chromolaena odorata; GA, gallic acid; and AA, ascorbic acid.
#
Not significantly
different, P>0.05 and *Significantly different, P<0.001.
0 0.2 0.4 0.6 0.8 1
1.2
AA
CO
Reductive Potential
`
*
#
Figure 2. Reductive potential of Chromolaena odorata. AA, Ascorbic acid; and
CO, Chromolaena odorata. *
#
Significantly different (P<0.001).
ta is about a third of the value for gallic acid and ascorbic
acid while the reductive potential is about a fifth of the
value for ascorbic acid. These values are appreciable
enough for a plant that has been tagged as an obnoxious
weed.
The relatively low values for the percentage antioxidant
activity (Figure 1) and the reductive potential (Figure 2)
are in harmony with the finding that a strong positive
association exists between total phenolic content and
DPPH scavenging effect and also between total phenolic
content and reductive potential (Miliauskas et al., 2004) ).
Low values in some antioxidant assays do not imply low
value in all other assays since many antioxidant assays
show no correlation (Schaich, 2006). Result of a parti-
cular antioxidant assay depends on the chemistry of the
assay and the nature and combination of bioactive princi-
194 Sci. Res. Essays
ples in the material under investigation.
Emerging trends in antioxidant research point to the
fact that low levels of phenolics (and other phytochemi-
cals) and low values of antioxidant indices in plants do
not translate to poor medicinal properties. Mineral ele-
ments, other secondary plant metabolites not detected or
evaluated and vitamins contribute to the synergy of phy-
tochemicals that confer medicinal properties on plants.
The present investigation indicates that though C. odora-
ta has been described as a plant of low economic value,
it is not worthless. Its use in traditional medicine attests to
this. There are prospects for its commercial utilization
especially in view of its abundant and widespread nature.
The toxic compounds in the plant could be removed
through appropriate extraction and processing methods
making extracts and products from the plant safe for the
utilization of animal and man. Control of this invasive and
notorious weed has been unsuccessful. Finding ways of
profitably utilizing it may be the best option left. Further
work is in progress in our laboratory along these lines.
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