Chemical Composition and Antimicrobial Studies of the Essential Oils of Jatropha integerrima Jacq (Leaf and Seeds)

Abstract

The chemical composition of the essential oils of the leaves and seeds of Jatropha integerrima was investigated by GC and GC-MS. The results showed significant variation in the chemical constituents of the tissue/parts analyzed. The leaf has pentadecanal (32.4%), 1,8-cineole (11.2%) and β-ionone (10.8%) as the major components. On the other hand, the seed oil is comprised mainly of aliphatic hydrocarbons represented by pentacosane (13.6%), hexacosane (13.3%), octacosane (12.3%) and heptacosane (10.1%). However, the defatted seed oil was predominantly made up of the monoterpenes 1,8-cineole (35.5%), p-cymene (20.5%) and α-pinene (16.5%). The oils displayed weak antimicrobial activity against Bacillus cereus and Staphylococcus aureus.

Full text

Chemical Composition and Antimicrobial Studies of the
Essential Oils of Jatropha integerrima Jacq (Leaf and Seeds)
Adeolu O. Eshilokuna, Adeleke A. Kasalia*, Isiaka A. Ogunwandea, Tameka M. Walkerb and
Williams N. Setzerb
aDepartment of Chemistry, Lagos State University, Ojo, P.M.B 1087 Apapa Lagos, Nigeria
bDepartment of Chemistry, University of Alabama in Huntsville, Huntsville, AL 35899, USA
alekekasali@hotmail.com
Received: March 22nd, 2007; Accepted: June 20th, 2007
The chemical composition of the essential oils of the leaves and seeds of Jatropha integerrima was investigated by GC and
GC-MS. The results showed significant variation in the chemical constituents of the tissue/parts analyzed. The leaf has
pentadecanal (32.4%), 1,8-cineole (11.2%) and β-ionone (10.8%) as the major components. On the other hand, the seed oil is
comprised mainly of aliphatic hydrocarbons represented by pentacosane (13.6%), hexacosane (13.3%), octacosane (12.3%) and
heptacosane (10.1%). However, the defatted seed oil was predominantly made up of the monoterpenes 1,8-cineole (35.5%),
p-cymene (20.5%) and α-pinene (16.5%). The oils displayed weak antimicrobial activity against Bacillus cereus and
Staphylococcus aureus.
Key words: Jatropha integerrima, essential oil composition, aliphatic hydrocarbons, monoterpenes, antimicrobial effects.
Jatropha integerrima Jacq., commonly known as
‘Peregrina or spicy Jatropha’ belongs to the family
Euphorbiaceae. It is an evergreen shrub with glossy
leaves and clusters of star-shaped bright scarlet or
vermilion flowers. It originated from Cuba, but has
been introduced throughout the tropics.
Jatropha species are known to be abundant sources
of diterpenes with various skeletons. Previously
reported diterpene constituents from species of this
genus include the macrocyclic diterpenes jatrophone,
jatrophatrione, jatropholones A-B, riolozatrione,
curcusones A-D, rhamnofolane, lathyrane,
12-deoxy-16-hydroxyphorbol esters and the
cleistanthane series of diterpenes. On the other hand,
from the roots of J. integerrima, the isolation and
structural determination of a macrocyclic diterpene,
integerrimene, with a novel 8, 9-seco-rhamnofolane
skeleton and a new rhamnofalane endoperoxide,
2-epicaniojane, together with caniojane and
1,11-bisepicaniojane has been reported [1]. To the
best of our knowledge, no previous work on the
essential oil components of this plant has been
reported in the literature. This paper reports on the
compounds identified from the essential oils of
J. integerrima, which is part of an extensive research
program aimed at characterization of the components
of Nigerian medicinal plants and herbs [2].
The results from GC-MS showed that the studied
samples contained a high percentage of aliphatic and
aromatic compounds (38.3% for the leaves and
87.6% for the seeds with fats), while the terpenoid
percentages were 56.0%, 12.3% and 99.8% for
leaves, seeds with fats, and seeds with no fats,
respectively.
The main monoterpene hydrocarbons were α-pinene
(2.1-16.5%), β-cymene (2.5-20.5 %), and 1,8-cineole
(4.4-35.8%). The oxygenated monoterpenes were
represented mainly by β-cyclocitral (1.4%) and
geranyl acetone (1.3%). A further main constituent of
the leaf oil was the aromatic compound isoamyl
benzoate (3.1%). Interestingly, neither of the seed
oils contained oxygenated monoterpenes.
The sesquiterpene β-caryophyllene was found in each
of the samples (0.1-1.4 %), while the leaf oil alone
NPC Natural Product Communications 2007
Vol. 2
No. 8
853 - 855

854 Natural Product Communications Vol. 2 (8) 2007 Eshilokun et al.
Table 1: Chemical constituents of J. integerrima essential oils.
Compoundsa RI Leaf
oil
Seed
oil
with
fat
Seed
oil
with
no fat
Aliphatic compounds
trans-2-Hexenal 856 0.5 - -
Tetradecane 1401 0.4 - -
Tetradecanal 1613 3.3 - -
Hexadecane 1614 - 2.8 -
Pentadecanal 1714 21.4 - -
6,10,14-Trimethyl-2-
pentadecanone 1840 2.8 - -
Nonadecane 1897 - 2.9 -
Eicosane 1999 - 0.5 -
Heneicosane 2093 - 0.9 -
Tricosane 2292 - 4.2 -
Tetracosane 2399 - 4.8 -
Pentacosane 2505 - 13.6 -
Hexacosane 2607 - 13.3 -
Heptacosane 2708 - 10.1 -
Octacosane 2808 - 12.3 -
Nonacosane 2907 - 9.8 -
Triacontane 3004 - 7.5 -
Hentriacontane 3100 - 4.9 -
Aromatic Compounds
Benzaldehyde 968 8.5 - -
Isoamyl benzoate 1438 3.1 - -
Hexylbenzene 1579 1.4 - -
Monoterpene Hydrocarbons
-Thujene 936 0.4 0.1 1.1
-Pinene 941 5.8 2.1 16.5
Sabinene 979 - 0.2 1.7
β-Mycrene 995 - 0.2 1.2
-Phellandrene 1006 - 0.4 3.4
Δ3-Carene 1011 0.2 0.3 2.7
p-Cymene 1027 6.3 2.5 20.5
Limonene 1030 - 0.9 7.2
1,8-Cineole 1034 11.2 4.4 35.8
trans-β-Ocimene 1050 - 0.1 0.9
γ-Terpinene 1059 - 0.1 0.8
-Terpinolene 1088 - 0.1 0.9
Oxygenated Monoterpenes
β-Cyclocitral 1218 1.4 - -
Geranyl acetone 1455 1.3 - -
Sesquiterpene
Hydrocarbons
-Copaene 1374 0.9 - -
Cyperene 1397 0.2 - -
β-Caryophyllene 1417 1.4 0.1 0.7
Alloaromadendrene 1459 1.8 - -
γ-Gurjunene 1473 0.3 - -
Germacrene D 1479 1.0 - -
β-Ionone 1487 10.8 - -
Valencene 1494 1.2 - -
-Muurolene 1500 0.7 - -
γ-Cadinene 1514 1.8 - -
δ-Cadinene 1522 1.5 - -
Oxygenated sesquiterpenes
Caryophyllene oxide 1581 - 0.6 4.7
Unknown 1600 1.0 - -
τ-Cadinol 1640 0.5 0.1 0.7
-Cadinol 1655 - 0.1 1.0
Unknown 1659 1.5 - -
Acorenone 1687 0.7 - -
Diterpenes
(E)-Phytol 2111 2.0 - -
aElution from the HP-5ms capillary column
had a high percentage of β-ionone (10.8%). The
oxygenated sesquiterpenes identified were
caryophyllene oxide (0.6-4.7%), τ-cadinol (0.1-0.7%)
and α-cadinol (0.1-1.0%). The diterpene (E)-phytol
was also identified in the leaf oil.
Table 2: The MICs of the oils of J. integerrima (MIC µg/mL).
B.c, Bacillus cereus (ATCC No 14579); S.a, Staphylococcus (ATCC No
29213); P.a., Pseudomonas aeruginosa (ATCC No 27853).
Both the leaf and seed oils exhibited weak
antibacterial activities against the Gram-positive
bacteria, Bacillus cereus and Staphylococcus aureus
(MIC ≤ 625 µg/mL), but were ineffective against
the Gram-negative Pseudomonas aeruginosa
(MIC = 1250 µg/mL).
Experimental
Plant materials: Mature plants (leaves and seeds) of
J. integerrima were collected in June 2004 from
plants cultivated at the campus of Lagos State
University, Ojo, Lagos, Nigeria. The plant was
authenticated by Mr TK Odewo at the Forestry
Research Institute of Nigeria (FRIN), Ibadan, where a
voucher specimen (FHI 106608) was deposited in the
institute herbarium.
Extraction of the volatile oil: Samples were air dried
for five days in the laboratory. Each sample (400 g)
was then subjected to hydrodistillation in an all glass
Clevenger type apparatus for four h in accordance
with the British Pharmacopoeia [3]. The yields (v/w)
of volatile oils were 0.16% and 0.23% for leaves and
seeds, respectively.
The seed oil was subsequently defatted by refluxing
with dichloromethane, which was distilled off under
cold conditions.
Gas chromatography–mass spectrometry analysis
(GC-MS): The volatile oil samples were subjected to
GC-MS analysis on an Agilent system consisting of a
model 6890 Gas Chromatograph, a model 5973 Mass
Selective Detector (MSD) and an Agilent
Chemstation data system. The GC column was an
HP-5ms fused silica capillary with a (5% phenyl)-
methyl polysiloxane stationary phase, film thickness
0.25 µm, length 30 m, and an internal diameter of
0.25 mm. The carrier gas was helium with a
column head pressure of 7.07 psi and a flow rate of
1.0 mL/min. Inlet temperature was 200oC and MSD
detector temperature was 280oC. The GC oven
temperature program was used as follows: 40oC
initial temperature, hold for 10 min; increased at
3oC/min to 200oC; increased 2oC/min to 220oC. The
Sample B.c S.a P.a
Leaf oil 312.5 625 1250
Seed oil 625 625 1250

Jatropha integerrima Essential Oils Natural Product Communications Vol. 2 (8) 2007 855
sample was dissolved in CH2Cl2 and a split injection
technique was used.
Identification of the constituents: Identification of
the constituents of the essential oils was achieved
based on their retention indices (determined with
reference to a homologous series of normal alkanes),
and by comparison of their mass spectral
fragmentation patterns [NIST data base (G 1036A,
revision D. 01. 00/chemstation data system (G1701
CA, version C. 00. 01. 08)] and with data previously
reported in the literature [4-6].
Microbial screening: The essential oils were
screened for antimicrobial activity against the
Gram-positive bacteria Bacillus cereus (ATCC No
14579) and Staphylococcus aureus (ATCC No
29213), and the Gram-negative bacterial species
Pseudomonas aeruginosa (ATCC No 27853).
Minimum inhibitory concentrations (MIC) were
determined using the microbroth dilution technique
[7]. Dilutions of the oils were prepared in cation-
adjusted Mueller Hilton broth (CAMHB) beginning
with 50 µL of 1% w/w solutions of essential oils in
DMSO plus 50 µL CAMHB. The oil solutions were
serially diluted (1:1) in CAMHB in 96-well plates.
Organisms at a concentration of approximately 1.5 x
108 colony forming units (CFU)/mL were added to
each well. Plates were incubated at 37oC for 24 h;
the final minimum inhibitory concentration (MIC)
was determined as the lowest concentration without
turbidity. Gentamicin was used as a positive
antibiotic control, while DMSO was used as a
negative control.
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