O A

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Advances in Environmental Biology, 5(9): 2626-2630, 2011
ISSN 1995-0756
This is a refereed journal and all articles are professionally screened and reviewed
ORIGINAL ARTICLE
Chemical Composition And Free Radical Scavenging Activity Of Leaf Essential Oils Of
Acalypha Torta
1
Patricia A. Onocha and 2 Ganiyat K. Oloyede
1
Nat ural p rodu cts/ Medic ina l C he mi st r y Un it , De part ment of Ch e mist r y, Uni ver sit y of
Ibadan , Nige ria .
Pa t ri cia A. Ono cha and Gani y at K. Oloy ede: Chemical Composition And Free Radical
Scavenging Activity Of Leaf Essential Oils Of Acalypha Torta.
ABST RACT
The colourless essential oils obtained by hydro-distillation from the leaves of Acalypha torta was analysed
using GC and GC/MS. It indicated the presence of thirty-four compounds. The major constituents of the oil
were (E,E,Z)-1,5,9-Cyclododecatriene (16.58%), Hexyltiglate (9.74%), N-(4-methoxyphenyl)nicotinamide
(8.86%), Spiro[3,3]heptane-2,6-dione (7.65%), (E)- β-Terpineol (6.72%), constituting 49.55% of the total
chemical composition. The oxygenated terpenes and other secondary plant metabolites which include alkenes,
alcohols, esters, amides, aldehydes and ketones, although present in individual minute quantities, constituted
50.44% of the total chemical composition of the oil. This shows that A. torta oil is rich in oxygenated
compounds. The presence of these compounds therefore accounted for the promising free radical scavenging
activity of the oil determined by scavenging effect on 2, 2-diphenyl-1-picrylhydrazyl radical method. At 0.1 and
0.2 mg/ml, the % inhibition of the essential oil (95.53% and 79.14 % respectively) was discovered to be higher
than the % inhibition of the standards - ascorbic acid, BHA and α-tocopherol – used in the assay.
Key words: GC/MS, essential oil, 2, 2-diphenyl-1-picrylhydrazyl, free radical, Acalypha torta.
Introduction
Man has always depended on plants for food,
drinks, shelter, clothing and medicine. Ancient man
knew that some plants extract had the ability to cure
diseases and or heal some form of ailments.
Nevertheless, the difficulty encountered with
alternative medicine is that of a reliable
documentation of known traditional herbal medicine
since uses differ from one tribe to another. Folk
medicine has therefore existed from the earliest time
[16,1,9,18,19,20,7] but only in recent times did
scientists especially organic chemists report that
various secondary metabolites such as essential oils,
flavonoids, alkaloids, mucilage, bitters, glycosides
and terpenoids are the active constituents responsible
for the medicinal effect of plants [22,5,15]. Search
for active chemical compounds especially from plant
is now on the increase because plants will continue to
serve as bio-renewable resources from which
chemical compounds which will form the basis for
the synthesis of new and effective drugs will arise.
Acalypha torta of the family Euphorbiaceae is
an erect shrub which grows not more than 5 feet. It
has a dark blotched olive-green leaves which are
curiously contorted. It is an ornamental plant used to
beautify homes, gardens etc. The plant is used
medicinally for the treatment of fungal skin diseases,
neonatal jaundice, and diarrhea amongst others.
Though this plant is not edible; it is found to contain
alkaloids, tannins and resins [6,21]. Not much
pharmacological research has been carried out on this
plant despite its importance in traditional medicine.
The aim of this research work therefore is to extract
the volatile oil of the leaves of Acalypha torta and
determine the chemical composition by carrying out
Gas Chromatography and Gas ChromatographyMass Spectrometry analysis. The oil was also
subjected to free radical scavenging activity by invitro assessment on DPPH (2, 2-diphenyl-1picrylhydrazyl) radical [4,3,12] using Ascorbic acid,
butylated hydroxylanisole and α- tocopherol as
antioxidant standards.
Materials and Methods
Plant Materials:
Fresh leaves of A. torta were collected in
September 2010 at the Botanical Gardens, University
of Ibadan. Specimens were identified by Mr E.
Donatus of the Botany and Microbiology
Corresponding Author
Patricia A. Onocha, 1 N a t u r a l p r o d u c t s / M e d i c i n a l C h e m i s t r y U n i t , D e p a r t m e n t o f
C h e m i s t r y , U n i v e r s i t y o f I b a d a n , N i g e r ia .
E-mail: [email protected]; Tel: +234 703 6015339
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Adv. Environ. Biol., 5(9): 2626-2630, 2011
Department, University of Ibadan, Oyo State, Nigeria
and confirmed at the Federal Research Institute,
Ibadan (FRIN) where a voucher specimen is
deposited (FHI 107324). The volatile oil was
immediately collected from the fresh plant material
by hydrodistillation using an all-glass scavenger
apparatus.
Reagents:
Hexane and methanol (BDH chemicals),
Butylated hydroxyanisole (BHA), α-Tocopherol and
2,2-diphenyl-1-picrylhydrazyl radical (DPPH) were
obtained from Sigma Chemical Co (Germany).
Reference Standards:
Ascorbic acid, Butylated hydroxyanisole
(BHA) and α-Tocopherol for antioxidant activity.
electronic integration measurements using flame
ionization detector (FID), set at 250 oC. The peak
numbers and relative percentages of the
characterized components are given in Table 1.
Gas Chromatography–Mass Spectrometry:
The essential oils were analysed by GC-MS on
an Agilent Technologies 7890A GC system coupled
to a 5975C VLMSD mass spectrometer with an
injector 7683B series device. An Agilent (9091)413:325 0C HP-5 column (30 m x 320 µm x 0.25
µm) was used with helium as carrier gas at a flow
rate of 3.3245 ml/min. GC oven temperature and
conditions were as described above. The injector
temperature was at 250 oC. Mass spectra were
recorded at 70 eV. Mass range was from m/z 30 to
500.
Identification of Components:
Major Equipments Used:
UV-Visible Spectrophotometer (Unico1200 &
Perkin Elmer lambda 25 models), GC-Mass
spectrophotometer (Agilent Technologies) and
Hydro distiller - Clavenger apparatus.
Isolation of Essential Oils:
The oil was obtained by hydro distillation on a
Clavenger type apparatus for 4 hours in accordance
with the British pharmacopoeia specifications
(1980). The essential oil was collected and stored at
4 0C prior to analysis. The oil yield was calculated
relative to the dry matter.
Analysis of the Essential Oils:
Gas chromatography:
GC-MS analysis of the essential oil was carried
out on an Agilent Technologies 7890A GC system
coupled to a 5975C VLMSD mass spectrometer with
an injector 7683B series device. An Agilent (9091)413:325 0C HP-5 column (30 m x 320 µm x 0.25µm)
was used with helium as carrier gas at a flow rate of
3.3245 ml/min. The GC oven temperature was
initially programmed at 500C (hold for 1min) and
finally at 300 0C (hold for 5min) at a rate of
800C/min while the trial temperature was 37.25 0C.
The column heater was set at 250 0C and was a split
less mode while the pressure was 10.153 psi with an
average velocity of 66.45 cm/sec and a hold-up time
of 0.75245 min was recorded. Mass spectrometry
was run in the electron impact mode (EI) at 70eV.
The percentage compositions were obtained from
Results And Discussion:
GC-MS Analysis of the Essential Oils:
The individual constituents of the oil were
identified on the basis of their retention indices
determined with a reference to a homologous series
of n-alkanes and by comparison of their mass
spectral fragmentation patterns (NIST 08.L
database/chemstation data system) with data
previously reported in literature (Adams 2001;
Joulain and Konig 1998; Mclafferty and Staufer
1989).
Free Radical Scavenging Activity:
Scavenging Effect on DPPH:
A 0.5 mM of 2, 2–diphenyl–1–picrylhydrazyl
radical (DPPH) solution in methanol was prepared
and 3ml of this solution was mixed with the oil
sample in methanol. The free radical scavenging
activity of the oil at various concentrations 0.1 and
0.2 mg/ml was then determined. The decrease in
absorption at 517 nm of DPPH was measured after
10min of incubation. The actual decrease in
absorption was measured against that of the control
and the percentage inhibition was also calculated.
The same experiment was carried out on ascorbic
acid, butylatedhydroxylanisole (BHA) and αtocopherol which are known antioxidant agents. All
test and analysis were run in triplicates and the result
obtained was averaged (Koleva et al, 2002; Oloyede
and Farombi, 2010). The activities were determined
as a function of their %Inhibition which was
calculated using the formula;
%I = Acontrol - Asample x 100
Acontrol
Essential oils from 400g of freshly collected
leaves of A. torta, obtained by means of
hydrodistillation gave 0.65% (w/w). The essential
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Adv. Environ. Biol., 5(9): 2626-2630, 2011
oils, colourless with characteristic smell were
analyzed by GC and GC/MS systems using a polar
column. 34 constituents representing 99.99% of the
total essential oils were identified in the plant. The
result of the analysis is presented in Table 1.
Table 1: Chemical Composition of Essential oil of A. torta from GC-MS analysis
S/N
RT(sec)
Chemical Composition
1
619.50
Camphene
2
735.90
(E)- β- Terpineol
3
918.18
Cis-Cinamaldehyde
4
922.32
Transe-Carveol
5
926.76
1-Isocyano-4-Methylbenzene
6
934.02
5,6-Diethenclcyclohexence
7
754.96
N-(4-Methoxpheny1) Nicotinamide
8
958.38
2,4-Dimethyl-1-Hexene
9
962.46
1H-1,3-Benzimidazole-2-Methonal
10
972.42
Pulegone
11
983.76
Carvone
12
998.52
(E,Z)-1,5-Cyclooctadiene
13
1034.58
Methylcitronellate
14
1038.36
(Z)-2,1-Octadien-1-ol,Acetate
15
1065.48
2-Methyl,p-Benzoquinone
16
1068.60
Isopulegylacetate
17
1077.18
Nopol
18
1080.24
6-Methylchrysene
19
1081.26
3-acetylphenoxathine
20
1091.22
Cis-Verbenylacetate
21
1097.40
Sipro[3,3]Heptane-2,6-Dione
22
1100.82
Safrole
23
1118.34
(Z)-3-Decen-1-ol,Acetate
24
1124.88
(E,E,Z)-1,5,9-Cyclododecatriene
25
1132.80
3-(Cyclohex-3-enyl)prop-2Enoic Acid
26
1191.48
Cis,Trans-5,9-Cyclododecadiene-Cic-1,2-Diol
27
1207.62
(E,E)-1,5-Cyclododecadiene
28
1216.86
Hexyltiglate
29
1223.04
3-Methyl-2-Norcaranone
30
1228.92
Cis-Isosafrole
31
1259.10
1,2-Nonadiene
32
1286.94
(E,E,E)-1,5,9-Cyclododecatriene
33
1309.92
Furfuylhexanoate
34
1342.56
Transe-Methylcinnamate
Total
T.P (%)
1.00
6.72
0.65
0.92
3.35
1.27
8.86
0.90
4.92
2.75
1.26
0.47
0.49
1.19
1.02
2.28
1.04
1.48
1.45
0.24
7.65
2.89
0.95
16.58
2.40
3.97
0.36
9.74
3.02
3.29
1.11
2.58
1.94
1.25
99.99%
*RT = Retention Time, T.P. = Total Percentage
A torta leave essential oil contains (E,E,Z)1,5,9-Cyclododecatriene (16.58%), Hexyltiglate
(9.74%),
N-(4-methoxyphenyl)nicotinamide
(8.86%), Spiro[3,3]heptane-2,6-dione (7.65%), (E)β-Terpineol (6.72%) as the major constituents.
Hydrocarbons like alkenes, terpenes and oxygenated
compounds like alcohols, esters, amides, aldehydes
and ketones are present in minute quantities.The
presence of this group of secondary plant metabolites
confirms the ethno medicinal application of A. torta
in traditional medicine practice .
Free Radical Scavenging Activity:
It was observed that the essential oil of A. torta
scavenged free radical generated by 2, 2-diphenyl-1picrylhydrazyl radical (DPPH) as there was decrease
in absorbance at 517 nm, 0.174±0.012 at 0.1 mg/ml
and 0.157±0.004 at 0.2 mg/ml respectively (Table 2).
Table 2: Scavenging Effect of A. torta Leave Essential Oils on DPPH at 517nm
CONC.
A. TORTA
ASCORBIC ACID
BHA
0.1mg/ml
0.174±0.012
0.0843±0.010
0.0370±0.006
0.2mg/ml
0.157±0.004
0.2893±0.128
0.0460±0.06
*Absorbance of essential oil, Ascorbic Acid, BHA and α- Tocopherol at 517nm.
α- TOCOPHEROL
0.6800±0.029
0.7040±0.003
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Adv. Environ. Biol., 5(9): 2626-2630, 2011
Fig. 1: % Inhibition of DPPH Free radical Scavenging activity of essential oils of A. torta*
*%inhibition of oil and reference standards.
The % inhibition of the essential oils decreased
with the increase in the concentration of the oils
(Figure 1). At 0.1 and 0.2 mg/ml, the % inhibition of
the essential oil (95.53 % and 79.14% respectively)
was discovered to be higher than the % inhibition of
all the standards -ascorbic acid, BHA and αtocopherol - used at 0.1 mg/ml. Overall, A. torta has
free radical scavenging activity in the reaction
involving DPPH radical. The essential oils from this
plant can therefore be a source of antioxidant agents.
References
Conclusion:
4.
5.
The essential oil contains thirty-four
compounds from the GC/GC-MS analysis.
UV/Visible analysis of free radical scavenging
activity of essential oils of A. torta revealed that the
oil has very good activity as a radical scavenger in
the experiment involving 2,2 – diphenyl – 1 –
picrylhydrazyl radical (DPPH). The percentage
inhibition was found to be higher than the three
antioxidant standards - ascorbic acid, BHA and αtocopherol - used at 0.1 mg/ml. This study has shown
that the essential oils from A. torta can be useful in
the therapy of diseases caused by free radicals. This
plant therefore has important application for the
pharmacological industries.
1.
2.
3.
6.
7.
8.
Acknowledgement
The authors appreciate the assistance of Mr.
Sunday Abimbade of the Department of Chemistry
University of Ibadan, Nigeria in carrying out the
antioxidant analysis. The Authors acknowledges the
financial support of the Senate Research Grant of the
University of Ibadan, Ibadan, Nigeria.
9.
Akube, P.I., 1990. Nigerian medicinal plants:
Pharmacology and toxicology; the state of
medicinal plant research in Nigeria, Spectrum
Books Ltd., 53-54.
Adams, R.P., 2001. Identification of essential
oils by ion trap Mass spectroscopy. Academic
press Limited. London.
Arouma, O., 1996. Characterization of drugs as
antioxidant prophylactics. Free Rad Biol. Med.,
20(5): 657-705.
Bors, W., M. Saran, 1991. Radical scavenging
activity by flavonoid antioxidants. Horticultural
science, 26: 66-68.
Burkill, H.M., 1994. The useful plants of West
Tropical Africa, Second edition, Vol. 2,
Families E-I. Royal Botanical Gardens, Kew,
Richmond, United Kingdom, pp: 636.
Iwu, M.M., 1993. Handbook of African
medicinal plants. CRC Press, Boca Raton,
Florida, United States, 464-472.
Jahan, F.I., M.S. Hossain, A.A. Mamun, M.T.
Hossain, S. Seraj, A.R. Chowdhury, Z. Khatun,
N.Z. Andhi, M.H. Chowdhury and M.
Rahmatullah, 2010. An evaluation of
antinociceptive effect of methanol extracts of
Desmodium gangeticum (L.) D.C. stems and
Benincasa hispida (Thunb.) Cogn. leaves on
acetic acidinduced gastric pain in mice.
Advances in Natural and Applied Sciences, 4:
365-369.
Mannan, A., H. Das, M. Rahman, J. Jesmin, A.
Siddika, M. Rahman, S. Rahman, M.H.
Chowdhury and M. Rahmatullah, 2010.
Antihyperglycemic activity evaluation of
2630
Adv. Environ. Biol., 5(9): 2626-2630, 2011
10.
11.
12.
13.
14.
15.
16.
Leucas aspera (Willd.) Link leaf and stem and
Lannea coromandelica (Houtt.) Merr. bark
extract in mice. Advances in Natural and
Applied Sciences, 4: 385-388.
Nawaz, A.H.M.M., M. Hossain, M. Karim, M.
Khan, R. Jahan and M. Rahmatullah, 2009. An
ethnobotanical survey of Rajshahi district in
Rajshahi division, Bangladesh. American
Eurasian Journal of Sustainable Agriculture,
3(2): 143-150
Joulain, D, W.A. Konig, 1998. The atlas of
Spectral Data of Sesquiterpenes Hydrocarbons.
E.B-Verlag Hamburg, Germany.
Koleva, II, T.A. Van-Beck, A. Evstaliva, 2002.
Screening of plant for antioxidant Activity. A
comparative study on three testing methods.
Phytochemical Analysis 13: 8-17.
Koppenol, W., 1993. The Centennial of Fenton
reaction. Free Rad Biol Med., 15: 645 -651.
Mclafferty, F.W., D.B. Stauffer, 1989. The
Willey/NBS Registry of Mass Spectral Data.
John Wiley & Sons, New York.
Mensor, L.L., F.S. Menezes, G.G. Leitão, A.S.
Reis, C. Tereca, C.S. Coube, S.G. Leirao
2001. Screening of Brazilian Plant Extracts
for Antioxidant Activity by the use of DPPH
Free Radical method. Phytotherapy Research,
15: 127-130.
Newmann, D.J., G.M. Cragg, K.M. Snader,
2000. The influence of Natural Products upon
drug discovery. Nat Prod Report 17: 215-234.
17. Oliver-Bever, B., 1986. Medicinal Plants in
Tropical West Africa, Cambridge, 125-129.
18. Oloyede, G.K., O.E. Farombi, 2010.
Antioxidant Properties of Crinum ornatum Bulb
Extract. World J Chem., 5(1): 32-36.
19. Rahmatullah, M., D. Ferdausi, M.A.H. Mollik,
M.N.K. Azam, M.T. Rahman and R. Jahan,
2009a. Ethnomedicinal Survey of Bheramara
Area in Kushtia District, Bangladesh. American
Eurasian Journal of Sustainable Agriculture, 3:
534-541.
20. Rahmatullah, M., A. Noman, M.S. Hossan,
M.H. Rashid, T. Rahman, M.H. Chowdhury
and R. Jahan, 2009b. A survey of medicinal
plants in two areas of Dinajpur district,
Bangladesh including plants which can be used
as functional foods. American Eurasian Journal
of Sustainable Agriculture, 3: 862-876.
21. Rahmatullah, M., A.K. Das, M.A.H. Mollik, R.
Jahan, M. Khan, T. Rahman and M.H.
Chowdhury, 2009c. An Ethnomedicinal Survey
of Dhamrai Sub-district in Dhaka District,
Bangladesh. American Eurasian Journal of
Sustainable Agriculture, 3: 881-888.
22. Sofowora, A., 2008. Medicinal plants of
Traditional Medicine in Africa. Spectrum
Books, Ibadan, Nigeria. 3rd edition, 181-199.
23. Trease,
G.E.,
W.C.
Evans,
1987.
Pharmacognosy, Sixth edition (ELBS) Volume
5 Bailliere tindall, London.