Available via license: CC BY-NC-ND
Content may be subject to copyright.
Vol. 64 No. 3 2018
From Botanical to Medical Research
EXPERIMENTAL PAPER
Phytochemical characterisation and bioactive
properties of Solanum sodomaeum L. fruits at two
stages of maturation
INES OUERGHEMMI1,2, MOUNA BEN FARHAT3,*, HELA HARBEOUI1,2, MAJDI HAMMAMI1,
GHAITH HAMDAOUI4, BRAHIM MARZOUK1, MOUFIDA SAIDANE TOUNSI1
1Laboratory of Aromatic and Medicinal Plants
Centre of Biotechnology of Borj-Cedria
BP 901, Hammam-Lif 2050, Tunisia
2Department of Biology
Faculty of Sciences of Bizerte, University of Carthage
Jarzouna, Bizerte, Tunisia
3Laboratory of Extremophile Plants
Centre of Biotechnology of Borj-Cedria
BP 901, Hammam-Lif 2050, Tunisia
4Unit of Support for Research and Technology Transfer
Technopole of Borj-Cedria
BP 901, Hammam-Lif 2050, Tunisia
*corresponding author: e-mail: mounabenfarhat@hotmail.fr
Summary
Introduction: Solanum sodomaeum L. has been observed to have several medicinal properties, in particular,
in the treatment of several types of human skin cancer.
Objective: The influence of the maturation stage of S. sodomaeum fruits on the total lipid contents, fatty
acid profiles, essential oil yields and compositions, as well as the antibacterial and antioxidant activities of
the essential oils, was investigated.
Methods: The fatty acid and essential oil constituents were identified using gas chromatography (GC) and
GC–mass spectrometry (GC–MS). The antioxidant properties of essential oil and vegetal oil were assessed
using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging and reducing power assays. The antibacterial ac-
Herba Pol 2018; 64(3): 20-30
Received: 2018-01-18
Accepted: 2018-07-04
Available online: 2018-09-28
DOI: 10.2478/hepo-2018-0015
Unauthenticated
Download Date | 10/23/18 2:53 PM
21
Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
Vol. 64 No. 3 2018
INTRODUCTION
e genus Solanum is widespread in temperate and
tropical areas and includes about 1700 species. Spe-
cies of the genus Solanum produce a class of useful
biologically active secondary metabolites, the gly-
coalkaloids [1]. ese nitrogen-containing steroi-
dal glycosides have revealed antibiotic, antifungal,
antimicrobial and antiviral properties [2] and show
signicant cytotoxicity against several human can-
cer cell lines and skin tumours [3]. Glycoalkaloids
are toxic compounds at certain levels considering
their role as plants’ defensive allelochemicals against
a number of pathogens and predators [4].
Among the numerous species of the genus, Sola-
num sodomaeum L. is common in Tunisia [5]. e
fruits of S. sodomaeum are used in the treatment of
external warts and eczema. e species is a source of
solasodine, a raw material for the hemisynthesis of
steroid hormones [5]. S. sodomaeum glycoalkaloids
have been shown to be ecient in several types of
human skin cancer therapies [6]. Steroidal glyco-
sides extracted from the roots of the species exhibit
antiproliferative activity in resistance to human pro-
myelocytic leukaemia (HL-60) cells [7].
Previous investigations on S. sodomaeum have fo-
cussed on its alkaloids [7, 8]; therefore, the present
paper attempts to valorise S. sodomaeum in relation
to its contents of fatty acids and essential oil. Accord-
ing to our bibliographic investigation, the current
study could be the rst report on the variation of the
fatty acid and essential oil compositions of S. sod-
omaeum fruits according to the maturation stage,
as well as evaluation of the antibacterial properties
of the essential oil and the antioxidant properties of
both essential and vegetal oils.
MATERIAL AND METHODS
Plant material
S. sodomaeum fruits were arbitrarily harvested from
several individual plants in Borj-Cédria (Hammam-
Lif, northeast of Tunisia, 36°3´48˝N, 0°21´0˝E) in
the months of January and February 2012. Samples
were collected at two phases of maturation on the
basis of their colour. Full green fruits represented the
immature stage and yellow ones, the mature stage.
e harvested S. sodomaeum fruits were freeze-
dried, powdered by using an electric mill and were
preserved in a desiccator at ambient temperature
(25°C) in darkness. A voucher specimen was stored
at the Herbarium of the Laboratory of Aromatic and
Medicinal Plants at the Centre of Biotechnology
of Borj-Cédria (Hammam-Lif, Tunisia) under the
number SS-2012-07.
Extraction and analysis of fatty acids
By using the slightly modied procedure of Bligh
and Dyer [8], lipids of triplicate sub-samples (1 g) of
S. sodomaeum fruits were extracted. Briey, samples
were kept in boiling water for 5 min, then ground
with a mixture of chloroform-methanol-hexane
tivity of essential oil was tested using the disc diffusion assay for resistance in human pathogenic bacteria.
Results: Mature fruits showed higher total lipid content (17%) and were characterised by polyunsaturated
fatty acids (53.87%), represented mainly by linoleic acid (53.11%). Similar yields of essential oils were de-
tected for immature (0.43%) and mature (0.45%) fruits. Tetrahydronaphthalene (41.79%) was detected as
the major essential oil component at the immature stage versus dihydrocoumarin pentane (18.27%), hexa-
decanoic acid (17.43%) and 2-undecanone (13.20%) in mature fruits. The DPPH test showed that essential
oils had better antioxidant properties; however, the vegetal oils showed better performance in the reducing
power assay. Moreover, the essential oil of S. sodomaeum mature fruits was active against bacterial strains.
Conclusions: S. sodomaeum fruits could be a valuable source of natural antioxidants and antibacterial
agents.
Key words: antibacterial activity, antioxidant activity, essential oils, fatty acids, fruit maturation, Sola-
num sodomaeum
Słowa kluczowe: aktywność antybakteryjna, aktywność antyoksydacyjna, olejki eteryczne, kwasy
tłuszczowe, dojrzewanie owoców, Solanum sodomaeum
Unauthenticated
Download Date | 10/23/18 2:53 PM
22
I. Ouerghemmi, M. Ben Farhat, H. Harbeoui, M. Hammami, G. Hamdaoui, B. Marzouk, M. Saidane Tounsi
(2:1:1, v/v/v) and washed using the xing water.
e organic layer including lipids was recovered
and dried using a nitrogen stream. Total fatty ac-
ids (TFAs) were trans-methylated by using sodium
methylate solution (3%) according to the procedure
of Cecchi et al. [9]. Methyl heptadecanoate (C17:0)
was used as an internal standard.
e resulting fatty acid methyl esters (FAMEs)
were analysed using a Hewlett-Packard (HP)
6890 gas chromatograph series II (Agilent Tech-
nologies, Palo Alto, CA, USA) supplied with a ame
ionisation detector (FID) and an electronic pressure
control (EPC) injector. Separation of individual con-
stituents was made by using a polar HP INNOWax
capillary column (30 m × 0.25 mm, coated with pol-
yethylene glycol lm of 0.25 µm thickness; Hewlett-
Packard, Palo Alto, CA, USA). e temperature
of the oven was set at 150°C for 1 min, elevated to
200°C at the rate of 15°C/min, maintained for 3 min
and nally increased to 242°C at a rate of 2°C/min.
e carrier gas was nitrogen with a ow rate of
1.5 ml/min, and the split ratio was 60:1. Tempera-
tures were set at 250°C and 275°C for the injector
and detector, respectively. Identication of FAMEs
was performed by comparing their retention times
with those of the co-injected authentic standards.
Isolation and analysis of essential oil
Hydro-distillation of S. sodomaeum fruits (100 g)
at each stage of maturation was made by using a
Clevenger-type apparatus for 3 h. Essential oils were
dried over anhydrous sodium sulphate and stored at
4°C until analysis.
An aliquot (0.5 µl) of each essential oil sample
was analysed using gas chromatography–mass spec-
trometry (GC–MS). e GC analysis was performed
by using a HP-5890 Series II instrument equipped
with HP-INNOWax and HP-5 capillary columns
(30 m × 0.25 mm, 0.25 μm lm thickness for both).
e temperature programme was as follows: the
initial oven temperature was set at 60°C for 10 min,
then raised to 220°C at the rate of 5°C/min. e tem-
peratures of the injector and the detector were set
at 250°C. Nitrogen was the carrier gas, with a ow
rate of 2 ml/min, the detector was dual FID and the
split ratio was 1:30. e FID peak area normalisa-
tion yielded the percentages of the essential oil con-
stituents. GC–MS analyses were conducted using a
Varian CP3800 gas chromatograph equipped with a
HP-5 capillary column (30 m × 0.25 mm; coating
thickness: 0.25 μm) and a Varian Saturn 2000 ion-
trap mass spectrometer. e injector and transfer
line temperatures were 220°C and 240°C, respec-
tively. e temperature of the oven was raised from
60°C to 240°C at 3°C/min. Helium was the carrier
gas, with a ow rate of 1 ml/min. e split ratio was
1:30. e essential oil constituents were identied
by comparison of their retention times with those
of authentic samples, by comparing their linear in-
dices relative to a series of n-hydrocarbons and by
computer conformity with commercial standards
(National Institute of Standards and Technology,
1999). In addition, identication was achieved using
a homemade library of mass spectra built up from
pure substances and components of known oils and
mass spectra literature data [10-11]. Furthermore,
GC–chemical ionisation MS (CIMS) permitted the
conrmation of molecular weights of all identied
substances, using methanol as CI ionizing gas.
Screening of antibacterial activity
e disc diusion method was adopted to evaluate
the antibacterial activity [13] against several human
pathogenic bacteria, namely, Bacillus cereus ATCC
10876, methicillin-resistant Staphylococcus aureus
ATCC 25922, Listeria monocytogenes ATCC 15313,
Salmonella DMS 560 and Pseudomonas aeruginosa
ATCC 27853. All bacteria were grown on Mueller–
Hinton plate at 30°C for 18–24 h before inoculation
into the nutrient agar. A loop of bacteria from the
agar slant stock was cultivated in nutrient broth
overnight; a sample of this culture was streaked with
a sterile cotton swab onto Petri dishes containing
10 ml of API suspension medium and adjusted to
the 0.5 McFarland turbidity standards with a Den-
simat (BioMerieux). Sterile lter paper discs (6 mm
diameter) soaked in essential oils of S. sodomaeum
fruits were put on the culture plates. Aer 1–2 h at
4°C, the treated Petri dishes were incubated at 25°C
or 37°C for 18–24 h. Tetracycline was used as the
positive control. e antimicrobial activity was as-
sessed by measuring the diameter of the growth in-
hibition zone surrounding the discs. Triplicates of
each experiment were performed.
1,1-Diphenyl-2-picryl-hydrazyl radical
(DPPH•)-scavenging activity
e activity of S. sodomaeum samples against free
radicals was evaluated according to the procedure
of Hanato et al. [14]. Accordingly, 0.5 ml of a meth-
anolic solution of DPPH (0.2 mM) was added to the
essential oil and vegetal oil of S. sodomaeum fruits.
Unauthenticated
Download Date | 10/23/18 2:53 PM
23
Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
Vol. 64 No. 3 2018
e mixture was incubated for 30 min at room tem-
perature, and the absorbance was read against a
blank at 517 nm; the positive control was butylated
hydroxytoluene (BHT).
e equation adopted to assess the inhibition per-
centage (I%) of DPPH free radical was as follows:
I% = [(A0 – A1)/A0] × 100,
where A0 is the absorbance of the control and A1 is
the absorbance of the samples in the mixture.
Reducing power assay
e procedure proposed by Oyaizu [15] was used
to evaluate the reducing power of S. sodomaeum
samples. us, 1 ml of essential oil or vegetal oil was
added to 2.5 ml of a solution of sodium phosphate
buer (0.2 M, pH 6.6) and a solution of potassium
ferricyanide (2.5 ml of 1% solution). e mixture
was incubated in a water bath at 50°C for 20 min.
Subsequently, 2.5 ml of 10% trichloroacetic acid was
added, and the mixture was submitted to centrifuga-
tion at 650 g for 10 min. ereaer, 2.5 ml of distilled
water and 0.5 ml of a solution of iron (III) chloride
(0.1%) were mixed with 2.5 ml of supernatant. e
Table 1.
Variations in total lipid contents and fatty acid compositions during the maturation process of Solanum sodomaeum fruits
Parameters Maturation stage
Immature fruits Mature fruits
Total lipid content [%, w/w] 12% 17%
C 12:0 0.48±0.31 a 0.46±0.12 a
C 14:0 1.32±0.56 a 0.86±0.35 a
C 16:0 21.96±1.60 a 15.63±1.17 b
C 16:1 0.34±0.01 a 0.42±0.02 a
C 18:0 33.32±11.19 a 14.45±4.84 b
C 18:1 5.06±2.07 b 11.69±1.75 a
C 18:2 34.017± 4.11 b 53.11±7.89 a
C 18:3 1.75±0.58 a 0.76±0.11 b
C 18:4 0.38±0.05 ND
C 20:0 1.01±0.24 a 0.54±0.18 b
C 20:1 0.26±0.07 a 0.64±0.60 a
C 22:0 0.44±0.03 b 1.09±0.26 a
C 22:1 0.33±0.13 b 0.53±0.13 a
Saturated fatty acids 58.52 33.03
Monounsaturated fatty acids 6.01 13.28
Polyunsaturated fatty acids 36.30 53.87
Compounds are listed in order of their elution in the HP-INNOWax column; values are represented as mean values ± standard
deviation of three independent replicates (n=3); values followed by the same letter did not share signicant dierences at 5% (Duncan
test); ND: not detected
absorbance was read at 700 nm, and vitamin C was
adopted as the positive control.
Statistical analysis
Results were expressed as mean values ± standard
deviation of triplicates. Dierences between groups
were analysed by analysis of variance (ANOVA)
procedure, and signicant (p<0.05) dierences were
evaluated according to Duncan’s multiple-range test.
Ethical approval: e conducted research is not re-
lated to either human or animal use.
RESULTS AND DISCUSSION
Total lipids and fatty acid constituents
Total lipids and percentages of the identied fatty
acids of S. sodomaeum fruits at the two phases of
maturation are shown in Table 1. e level of total
Unauthenticated
Download Date | 10/23/18 2:53 PM
24
I. Ouerghemmi, M. Ben Farhat, H. Harbeoui, M. Hammami, G. Hamdaoui, B. Marzouk, M. Saidane Tounsi
oil reached 12% in the immature stage (green fruits)
and then sharply increased to ~17% at the mature
stage (yellow fruits). ere are no investigations on
the total lipid accumulation during the course of the
maturation process of S. sodomaeum. Nevertheless,
several researchers have focussed on the eect of the
stage of maturation on the accumulation of lipids
in diverse species. In accordance with our results,
Glew et al. [16] demonstrated low accumulation of
total lipids at an earlier stage of the development of
date plum persimmon, while the level was enhanced
quickly in the course of the last stage. e same be-
haviour was also observed in juçara (Euterpe edulis
Martius) fruits [17] and Rhus tripartitum fruits [18].
To our knowledge, the current study is the rst
investigation on fatty acid accumulation in S. sod-
omaeum fruits. Totally, 13 fatty acids were deter-
mined in the vegetal oils. e fatty acid proles were
qualitatively similar, but they displayed signicant
(p<0.05) quantitative dierences, in particular for
the most abundant constituents, according to the
maturation phase (tab. 1). In the immature phase,
the vegetal oils of the S. sodomaeum fruit were de-
ned by the preponderance of saturated fatty acids
(SFA), with a level of 58.52% of TFAs. e latter
fraction is mainly represented by stearic acid (C18:0;
33.32%) and palmitic acid (C16:0; 21.96%). In addi-
tion, linoleic acid (C18:2; 34.17%) was detected as
one of the most abundant fatty acids in immature
fruits, and it increased considerably to reach the
level of 53.11% at the mature stage. Linoleic acid ac-
cumulation could be explained by the activity of the
Δ12-desaturase, a membrane-bound enzyme, which
ensures the desaturation of oleic to linoleic acid [19].
It is an essential fatty acid for humans, and it is pref-
erentially used in industries for hydrogenation of
oils [20]. In addition, S. sodomaeum fruits showed a
more-than-twofold increase in the level of oleic acid
(C18:1; 11.69%) and a signicant (p<0.05) reduc-
tion in the contents of stearic (C18:0; 14.45%) and
palmitic (C16:0; 15.63%) acids at the mature phase.
e unsaturated fatty acid fraction was the most
abundant fraction (67.15%) of the fruits’ vegetal
oil, in particular, polyunsaturated fatty acids (PU-
FAs) were highly represented (53.87%). It is worth
noting that increased attention to PUFA as healthy
components in the diet is due to their multiple ben-
ets such as their role in relieving cardiovascular,
inammatory and heart disorders, atherosclerosis,
autoimmune disease, diabetes and other health is-
sues [21]. Furthermore, palmitic acid could cause
several damages, such as oxidative DNA damage,
human cell necrosis and apoptosis. ese damages
could be repressed by consuming – in parallel – oth-
er fatty acids, in particular PUFAs [22]. In regard to
the context of the fatty acid contents, mature fruits
seemed to be healthier since they contained higher
percentages of PUFA and lower content of palmitic
acid.
Essential oil composition
e essential oil yields of S. sodomaeum fruits ranged
from 0.43% for immature fruits to 0.45% for mature
fruits (v/w), and the dierences in yield between the
stages of maturation were not signicant (p>0.05).
e composition of the essential oils of the S. sod-
omaeum fruits at two dierent maturation stages is
illustrated in table 2. irty components were iden-
tied, with percentages of 99.61% and 95.10% of
the total oil, respectively, for immature and mature
fruits. e stage of immature fruits showed tetrahy-
dronaphthalene (41.79%) as the major constituent
of the essential oils. Considerable percentages of
hexadecanoic acid (24.15%), dihydrocoumarin pen-
tane (8.23%), tridecanone (3.61%) and 2-undecan-
one (2.69%) were also detected. Dihydrocoumarin
pentane, hexadecanoic acid and 2-undecanone were
found to be the most abundant components of es-
sential oils of S. sodomaeum mature fruits, with the
percentages of 18.27%, 17.43% and 13.20%, respec-
tively.
On the whole, acenes were the most abundant
chemical group at the immature stage (43.47%),
and their percentages showed a substantial de-
crease at the mature stage (7.93%). Conversely, ke-
tones (20.65%), aldehydes (9.32%), sesquiterpenes
(5.12%), alcohols (10.28%) and esters (1.76%) were
characterised by a signicant (p<0.05) augmenta-
tion of their values at the mature phase.
It is worth noting that the ketone fraction, in par-
ticular, 2-undecanone and tridecanone, have been
widely reported to be toxic for several arthropod
pests [23]. Also, hexadecanoic acid, a monocar-
boxylic acid, contributes to the aromatic character
of several plants. is acid has been evaluated for
inducing resistance in crop plants, such as tomato,
against Botrytis cinerea [24], and citrus, against the
fungus Alternaria alternata [25]. Aldehydes are
reported to be responsible of the oral and fruity
aroma of citrus [26]. It must be taken into consid-
eration that the components in lower amounts, such
as α-pinene, β-pinene, D-limonene, camphene, p-
cymene and β-thujone, contribute to the antifungal
property of the essential oils, as previously dem-
onstrated by Sacchetti et al. [27]. Additionally, the
Unauthenticated
Download Date | 10/23/18 2:53 PM
25
Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
Vol. 64 No. 3 2018
Table 2
Variations in the essential oil composition [% total peak area] at the two stages of maturation of Solanum sodomaeum fruits
Components IR Immature fruits Mature fruits
α-Pinene 935 0.54±0.13 ND
Camphene 951 0.40±0.08 ND
β-Pinene 980 ND 0.54±0.06
p-Cymene 1023 0.29±0.06 ND
D-Limonene 1027 1.11±0.13 b 1.39±0.16 a
2, 6-Dimethyl-5-heptenal 1053 1.39±0.52 b 3.83±1.03 a
2-Nonanone 1094 0.26±0.03 ND
β-ujone 1107 0.73±0.14 a 0.57±0.29 a
Camphor 1142 0.66±0.12 ND
Decanal 1206 0.51±0.18 b 1.24±0.14 a
1-Decanol 1269 1.50±0.55 b 3.93±0.91 a
Undecanal 1290 0.73±0.24 b 1.88±0.31 a
2-Undecanone 1295 2.69±0.39 b 13.20±1.32 a
Carvacrol 1303 2.01±0.15 a 2.41±0.39 a
Dodecanal 1410 1.51±0.23 ND
Caryophyllene 1428 0.92±0.19 b 1.46±0.17 a
Pentadecanone 1454 0.83±0.20 b 2.55±0.15 a
Dihydrocoumarin pentane 1486 8.23±1.88 b 18.27±1.90 a
Tridecanone 1497 3.61±0.49 a 4.33±0.38 a
1-Tridecanol 1553 0.38±0.09 b 1.00±0.17 a
Z-3-Hexenyl benzoate 1564 0.50±0.13 b 1.76±0.18 a
Caryophyllene alcohol 1572 0.48±0.10 b 1.19±0.34 a
Humulene oxide 1607 1.00±0.11 b 2.19±0.47 a
Tetradecanal 1621 0.56±0.12 b 1.22±0.30 a
Pentadecanal 1719 ND 1.15±0.03
Trimethyl hexanol 1820 0.51±0.12 b 4.17±0.66 a
7,11,15-Trimethyl neophytadiene 1837 1.68±0.42 a 1.58±0.33 a
Cyclopropanaphthalene 1919 0.67±0.12 b 1.59±0.12 a
Tetrahydronaphthalene 1920 41.79±5.58 a 6.36±0.96 b
Hexadecanoic acid 1965 24.15±9.11 a 17.43±1.63 a
Total 99.61±1.46 a 95.10±5.33 a
Chemical classes [%]
Acenes – 43.47±5.84 a 7.93±0.78 b
Acids – 24.15±9.11 a 17.43±1.63 a
Phenols – 2.01±0.15 a 2.41±0.39 a
Ketones – 8.78±0.79 b 20.65±2.06 a
Aldehydes – 4.70±1.04 b 9.32±1.56 a
Monoterpenes – 2.34±0.40 a 1.93±0.17 a
Sesquiterpenes – 2.59±0.41 b 5.12±0.50 a
Alcohols – 2.86±0.58 b 10.28±0.91 a
Esters – 0.50±0.13 b 1.76±0.18 a
Others – 8.23±1.88 b 18.27±1.90 a
Compounds are listed in the order of their elution on a HP-INNOWax column; values followed by the same letter did not share
signicant dierences at 5% (Duncan test); ND: not detected; values are represented as mean values ± standard deviation of three
independent replicates.
Unauthenticated
Download Date | 10/23/18 2:53 PM
26
I. Ouerghemmi, M. Ben Farhat, H. Harbeoui, M. Hammami, G. Hamdaoui, B. Marzouk, M. Saidane Tounsi
minor components might contribute to some type
of synergism with other dierent bioactive compo-
nents [28].
According to our bibliographic investigation,
there is no previous survey on the variation of the
chemical composition of essential oils of S. sodomae-
um during fruit maturation. Nevertheless, such stud-
ies have been undertaken for several medicinal and
aromatic plants, which showed signicant changes
in the composition of the oils according to the matu-
ration phase. ese changes could be due to varia-
tions in climatic conditions, such as temperature,
relative humidity, sunshine hours and precipitations
[29], and may be associated with metabolic changes
that precede the process of and prepare the fruit for
maturation.
Antioxidant activity
e evaluation of the total antioxidant property of
S. sodomaeum fruits cannot be estimated by using a
single method, because of the variety of phytochem-
icals and the related chemical moieties [30]. So, in
the present study, two methods – including DPPH
test and reducing power assay – were used to assess
the antioxidant activity of the essential oil and veg-
etal oil of immature and mature fruits.
Results of the DPPH radical scavenging and re-
ducing power tests are given in Figure 1. As shown
in Figure 1a, the oils of S. sodomaeum fruits at the
two maturation phases revealed much lower ca-
pacity to reduce the DPPH radical to the yellow-
coloured diphenylpicrylhydrazine, as compared
with BHT (IC50 = 10.77 µg/ml). e best activities
were observed for the essential oils with no sig-
nicant dierences (p>0.05) in levels between the
immature (IC50 = 6.73 mg/ml) and mature (IC50 =
6.71 mg/ml) stages of the fruits. Lower DPPH-scav-
enging activities were detected for vegetal oils in the
immature (IC50 = 28.50 mg/ml) and mature (IC50 =
28.47 mg/ml) phases of the fruits.
Reducing power is evaluated based on the meas-
urement of the conversion of ferric iron (Fe3þ) to
ferrous iron (Fe2þ) in the presence of antioxidants
[31]. Contrary to results obtained for the DPPH
assay (g. 1b), the reducing power test showed
higher antioxidant activity for vegetal oils with sig-
nicant dierences (p<0.05) in levels between the
two stages of fruit maturation. e immature fruits
(EC50=3.75 mg/ml) revealed better reducing power
compared with the mature ones (EC50=16.93 mg/ml)
and vitamin C (EC50=8.33 mg/ml).
Previous investigations have suggested that there
is an association between chemical composition and
antioxidant activity. In accordance with the study
by Hazzit et al. [33], the antioxidant capacity of es-
sential oils could be ascribed to the phenolic com-
ponents in plant oils, particularly thymol and/or
carvacrol. In coherence with the current study, the
Figure 1.
Antioxidant activity measured by the DPPH scavenging (a) and reducing power (b) assays at the immature and mature fruit stages.
Data are represented as mean values ± standard deviation of three independent replicates. Bars sharing the same small letter did not
share signicant dierences at p<0.05 (Duncan test)
EC50 (mg/ml)
IC50 (mg/ml)
Unauthenticated
Download Date | 10/23/18 2:53 PM
27
Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
Vol. 64 No. 3 2018
S. aureus was only observed for the oils extracted at
the mature phase. Moreover, it is worth noting that
the Gram-positive bacteria were more sensitive than
Gram-negative ones to the essential oils (tab. 3). Pre-
viously, some investigations have demonstrated that
Gram-negative bacteria were resistant to the eects
of essential oil and its constituents [37]. e resist-
ance has been ascribed to the existence of cell wall
lipopolysaccharides that can screen out the essential
oil [38].
Essential oils are a mixture of a variety of major
and minor chemical components. Along with major
components, previous investigations have reported
that the less representative components and a poten-
tial interaction between the constituents could also
inuence the antimicrobial activities [37].
Results of the current study support the use of es-
sential oils from the mature fruits of S. sodomaeum in
the treatment of diseases caused by the tested bacteria,
because of the natural origin of the remedy, the safety
for the consumers and the low risk of development of
resistance by pathogenic microorganisms [39].
CONCLUSION
e overall results permitted the valorisation of
S. sodomaeum fruits for their antioxidant and anti-
bacterial properties, which might lead to their poten-
tial use as nutraceuticals and agro-food supplements.
Conict of interest: Authors declare no conict of in-
terest.
REFERENCES
1. Al Sinani SSS, Eltayeb EA. e steroidal glycoal-
kaloids solamargine and solasonine in Solanum
plants. S Afr J Bot 2017; 112:253-69. doi: http://
dx.doi.org/10.1016/j.sajb.2017.06.002
moderate antioxidant capacity could be due to the
low amounts of phenolic and terpenic compounds.
However, it is worth noting that the antioxidant ac-
tivity of the essential oils is not ascribed exclusively
to the highly represented compounds and minor
ones also could be implied in the total antioxidant
activity; moreover, synergistic eects have also been
described [33]. In addition, previous investigations
have demonstrated that the antioxidant capacities of
vegetal oils could be attributed in most part to PU-
FAs, tocopherols and phenolics [34, 35].
According to our bibliographic research, there
is no previous investigation available regarding the
antioxidant activities of S. sodomaeum essential oil
and vegetal oil with respect to fruit maturation stages.
Antibacterial activity
Several essential oils and extracts from various plant
species have been shown to be capable of inhibiting
microorganisms in the contexts of skin infection,
dental caries and food spoilage. e antimicrobial
capacity of most essential oils or plant extracts is
substantially less eective than that of synthetic an-
tibiotics. However, they have diverse modes of ac-
tion and, therefore, may be able to combat the resist-
ant strains of microorganisms [36].
Results of the antibacterial activity analysis of the
essential oils of S. sodomaeum fruits at two matu-
ration phases against three Gram-positive bacteria
(B. cereus, L. monocytogenes and S. aureus) and two
Gram-negative bacteria (P. aeruginosa and Salmo-
nella DMS 560) are illustrated in table 3.
e essential oil of immature fruits showed in-
hibitory activity against Salmonella (2.5 mm) which
was lower by more than ten times than the activ-
ity of the control tetracycline (27.0 mm). e es-
sential oil of mature fruits was more ecient than
that of immature ones, since the growth inhibition
of P. aeruginosa, B. cereus, L. monocytogenes and
Table 3
Antibacterial activity of essential oils of Solanum sodomaeum fruits against three Gram-positive and two Gram-negative bacteria
Bacteria species Maturation stage
Immature Mature Tetracycline
Pseudomonas aeruginosa - 8.5±1.0 23.0
Salmonella DMS 560 2.5±1.0 7.5±1.0 27.0
Bacillus cereus - 16.0±2.0 22.0
Listeria monocytogenes - 18.5±1.0 36.0
Staphyloccun aureus ATCC 25922 - 20.5±1.0 35.0
(–) absence of activity; the diameter of inhibition is measured in millimetres; experiments were done in triplicate.
Unauthenticated
Download Date | 10/23/18 2:53 PM
28
I. Ouerghemmi, M. Ben Farhat, H. Harbeoui, M. Hammami, G. Hamdaoui, B. Marzouk, M. Saidane Tounsi
2. Lee MH, Cheng JJ, Lin CY, Chen YJ, Lu MK.
Precursor-feeding strategy for the production of
solanine, solanidine and solasodine by a cell cul-
ture of Solanum lyratum. Process Biochem 2007;
42:899-903. doi: http://dx.doi.org/10.1016/j.proc-
bio.2007.01.010
3. Maurya A, Gupta S, Negi S, Srivastava SK. pH-
zone-rening centrifugal partition chromatog-
raphy for preparative isolation and purication
of steroidal glycoalkaloids from Solanum xan-
thocarpum. J Sep Sci 2009; 32:3126-32. doi: http://
dx.doi.org/10.1002/jssc.200900323
4. Friedman M. Analysis of biologically active
compounds in potatoes (Solanum tuberosum),
tomatoes (Lycopersicon esculentum) and jim-
son weed (Datura stramonium) seeds. J Chro-
matogr A 2005; 1054:143-55. doi: http://dx.doi.
org/10.1016/j.chroma.2004.04.049
5. Jouzier E. Solanacées médicinales et philatélie.
Bull Soc Pharm Bordeaux 2005; 144:311-32.
6. Cham BE, Meares HM. Glycoalcaloids from
Solanum sodomaeum are eective in the treat-
ment of skin cancers in man. Cancer Lett 1987;
36:111-8. doi: http://dx.doi.org/10.1016/0304-
3835(87)90081-4
7. Ono M, Nishimura K, Suzuki K, Fukushima T,
Igoshi K, Yoshimitsu H et al. Steroidal glycosides
from the underground parts of Solanum sod-
omaeum. Chem Pharm Bull 2006; 54(2):230-3.
doi: http://dx.doi.org/10.1002/chin.200628178
8. Bligh EG, Dyer WJ. A rapid method of total lipid
extraction and purication. Can J Biochem Phys
1959; 37:911-7. doi: http://dx.doi.org/10.1139/
o59-099
9. Cecchi G, Biasini S, Castano J. Methanolyse rap-
ide des huiles en solvant. Note de laboratoire. Rev
Fr Corps Gras 1985; 4:163-164.
10. Laerty FW, Stauer DB. Wiley registry of mass
spectral data. 6th ed. Mass Spectrometry Library
Search System Bench-Top/PBM, Version 3.10d.
Neweld, UK. Palisade, 1994.
11. Adams RP. Identication of essential oil compo-
nents by gas chromatography/mass spectrom-
etry. 4th ed. Carol Stream, IL. Allured Publishing
Corporation, 2007.
12. König WA, Hochmuth DH, Joulain D. Terpe-
noids and related constituents of essential oils.
Hamburg. Library of Mass Finder, Institute of
Organic Chemistry, 2001.
13. Rios JL, Recio MC. Medicinal plants and antimi-
crobial activity. J Ethnopharmacol 2005; 100:80-4.
doi: http://dx.doi.org/10.1016/j.jep.2005.04.025
14. Hanato T, Kagawa H, Yasuhara T, Okuda T. Two
new avonoids and other constituents in licorice
root: their relative astringency and radical scav-
enging eect. Chem Pharm Bull 1988; 36:1090-
1097. doi: http://dx.doi.org/10.1248/cpb.36.2090
15. Oyaizu M. Studies on products of browning
reaction: antioxidative activity of products of
browning reaction. Jpn J Nutr Diet 1986; 44:307-
315. doi: http://dx.doi.org/10.5264/eiyogakuza-
shi.44.307
16. Glew RH, Ayaz FA, Millson M, Huang HS,
Chuang LT, Sanz C et al. Changes in sugars, ac-
ids and fatty acids in naturally parthenocarpic
date plum persimmon (Diospyros lotus L.) fruit
during maturation and ripening. Eur J Lipid Sci
Technol 2005; 221:113-118. doi: http://dx.doi.
org/10.1007/s00217-005-1201-9
17. Schulz M, Borges GSC, Gonzaga LV, Seraglio
Olivo SKT, Azevedo IS, Nehring P et al. Chemi-
cal composition, bioactive compounds and anti-
oxidant capacity of juçara fruit (Euterpe edulis
Martius) during ripening. Food Res Int 2015;
77:125-131. doi: http://dx.doi.org/10.1016/j.
foodres.2015.08.006
18. Tlili N, Tir M, Benlajnef H, Khemiri S, Mejri H,
Rejeb S et al. Variation in protein and oil con-
tent and fatty acid composition of Rhus triparti-
tum fruits collected at dierent maturity stages
in dierent locations. Ind Crops Prod 2014;
59:197-201. doi: http://dx.doi.org/10.1016/j.ind-
crop.2014.05.020
19. El Arem A, Flamini G, Saa EB, Issaoui M, Za-
yene N, Ferchichi A et al. Chemical and aroma
volatile compositions of date palm (Phoenix dac-
tylifera L.) fruits at three maturation stages. Food
Chem 2011; 127:1744-1754. doi: http://dx.doi.
org/10.1016/j.foodchem.2011.02.051
20. Msaâda K, Hosni K, Ben Taarit M, Chahed T,
Hammami M, Marzouk B. Changes in fatty acid
Unauthenticated
Download Date | 10/23/18 2:53 PM
29
Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
Vol. 64 No. 3 2018
composition of coriander (Coriandrum sativum
L.) fruit during maturation. Ind Crops Prod 2009;
29:269-274. doi: http://dx.doi.org/10.1016/j.ind-
crop.2008.05.011
21. Finley JW, Shahidi F. e chemistry, processing
and health benets of highly unsaturated fatty
acids: an overview. In: John WJ, Shahidi F, eds.
Omega-3 fatty acids, chemistry, nutrition and
health eects. Washington. American Chemical
Society, 2001:258-279.
22. Carvalho IS, Teixeira MC, Brodelius M. Fatty
acids prole of selected Artemisia ssp. plants:
health promotion. LWT Food Sci Technol
2011; 44:293-8. doi: http://dx.doi.org/10.1016/j.
lwt.2010.05.033
23. Kauman WC, Kennedy GG. Relationship be-
tween trichome density in tomato and parasitism
of Heliothis spp. (Lepidoptera: Noctuidae) eggs by
Trichogramma spp. (Hymenoptera: Trichogram-
matidae). Environ Entomol 1989; 18:698-704.
doi: http://dx.doi.org/10.1093/ee/18.4.698
24. Vicedo B, Flors V, Leyva MD, Finiti I, Kravchuk
Z, Real MD et al. Hexanoic acid-induced resist-
ance against Botrytis cinerea in tomato plants.
Mol Plant Microbe Interact 2009; 22:1455-65. doi:
http://dx.doi.org/10.1094/MPMI-22-11-1455
25. Llorens E, Vicedo B, Lopez MM, Lapena L, Gra-
ham JH, García-Agustín P. Induced resistance in
sweet orange against Xanthomonas citri subsp. cit-
ri by hexanoic acid. Crop Prot 2015; 74:77-84. doi:
http://dx.doi.org/10.1016/j.cropro.2015.04.008
26. Richard H. Connaissance de la nature des arômes.
In: Richard H, Multon JL, eds. Les arômes ali-
mentaires, Partie I, Généralités, Sciences et tech-
niques agro-alimentaires. Paris. Lavoisier TEC
and DOC-Apria, 1992.
27. Sacchetti G, Maietti S, Muzzoli MV, Scaglianti
M, Manfredini S, Radice M et al. Compara-
tive evaluation of 11 essential oils of dierent
origin as functional antioxidants, antiradicals
and antimicrobials in foods. Food Chem 2005;
91:621-32. doi: http://dx.doi.org/10.1016/j.food-
chem.2004.06.031
28. Marino M, Bersani C, Comi G. Impedance meas-
urements to study the antimicrobial activity of
essential oils from Lamiaceae and Compositae.
Int J Food Microbiol 2001; 67:187-95. doi: http://
dx.doi.org/10.1016/S0168-1605(01)00447-0
29. Dhouioui M, Boulila A, Chaabane H, Saïd Zina
M, Casabianc H. Seasonal changes in essen-
tial oil composition of Aristolochia longa L. ssp.
paucinervis Batt. (Aristolochiaceae) roots and
its antimicrobial activity. Ind Crops Prod 2016;
83:301-6. doi: http://dx.doi.org/10.1016/j.ind-
crop.2016.01.025
30. Chu YH, Chang CL, Hsu HF. Flavonoid con-
tent of several vegetables and their anti-
oxidant activity. J Sci Food Agric 2000;
80:561-5. doi: http://dx.doi.org/10.1002/
(SICI)1097-0010(200004)80:5<561::AID-
JSFA574>3.0.CO;2-#
31. Zhang Y, Yang L, Zu Y, Chen X, Wang F, Liu F.
Oxidative stability of sunower oil supplement-
ed with carnosic acid compared with synthetic
antioxidants during accelerated storage. Food
Chem 2010; 118(3):656-62. doi: http://dx.doi.
org/10.1016/j.foodchem.2009.05.038
32. Omar KA, Shan L, Wang YL, Wang X. Stabiliz-
ing axseed oil with individual antioxidants and
their mixtures. Eur J Lipid Sci Technol 2010;
112(9):1003-11. doi: http://dx.doi.org/10.1002/
ejlt.200900264.
33. Hazzit M, Baaliouamer A, Veríssimo AR, Falei-
ro ML, Miguel MG. Chemical composition and
biological activities of Algerian ymus oils.
Food Chem 2009; 116:714-21. doi: http://dx.doi.
org/10.1016/j.foodchem.2009.03.018
34. Peschel W, Sanchez-Rabaneda F, Diekmann W,
Plescher A, Gaetzia A, Gartzia I et al. An industri-
al approach in the search of natural antioxidants
from vegetable and fruit wastes. Food Chem
2006; 97:137-50. doi: http://dx.doi.org/10.1016/j.
foodchem.2005.03.033
35. Fruhwirth GO, Wenzl T, El-Toukhy R, Wagner
FS, Hermetter A. Fluorescence screening of anti-
oxidant capacity in pumpkin seed oils and other
natural oils. Eur J Lipid Sci Technol 2003; 105:266-
74. doi: http://dx.doi.org/10.1002/ejlt.200390055
36. Latif S, Anwar F. Aqueous enzymatic sesame
oil and protein extraction. Food Chem 2011;
125:679-84. doi: http://dx.doi.org/10.1016/j.
foodchem.2010.09.064
Unauthenticated
Download Date | 10/23/18 2:53 PM
30
I. Ouerghemmi, M. Ben Farhat, H. Harbeoui, M. Hammami, G. Hamdaoui, B. Marzouk, M. Saidane Tounsi
37. Głoniak P, Łos R, Skalicka-Wozniak K, Widelski
J, Burczyk J, Malm A. Activity of Crithmum mar-
itimum L. (Apiaceae) against Gram-positive bac-
teria. Lublin. Annales Universitatis Mariae Curie-
Sklodowska, 2006.
38. Dob T, Dahmane D, Benabdelkader T, Chelghoum
C. Studies on the essential oil composition and
antimicrobial activity of ymus algeriensis Bois-
set Reut. Int J Aromather 2006; 16:95-100. doi:
http://dx.doi.org/10.1016/j.ijat.2006.04.003
39. Kivrak I, Duru ME, Öztürk M, Mercan N, Har-
mandar M, Topçu G. Antioxidant, anticholineste-
rase and antimicrobial constituents from the es-
sential oil and ethanol extract of Salvia potentil-
lifolia. Food Chem 2009; 116:470-9. doi: http://
dx.doi.org/10.1016/j.foodchem.2009.02.069
Unauthenticated
Download Date | 10/23/18 2:53 PM
