3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P100 ChARACTERIZATION OF NEuTRAL LIPID
COMPOSITION OF NigellA sATivA L. SEEDS
OIL
CLAUDIA TOMA a , ADELA PInTEA, COnSTAnTIn
BELE and FRAnCISC V. DULF
a Department of Pharmacognosy Faculty of Pharmacy,
“Vasile Goldis” West University, 1 Feleacului Str., 300041,
Arad, Romania,
claudiatoma2004@yahoo.com
Introduction
Nigella sativa L. is an annual herbaceous plant which
belongs to the family of Ranunculaceae, widely cultivated
in Middle East, Asia and northern Africa. The seeds, known
as black cumin, are used for culinary purposes, as a spice for
pastry and bakery. Nigella seeds and oil are used in arabian
folk medicine for the treatment of asthma, as carminative,
diuretic or lactogogue 1,2 . More recently Nigella sativa fixed
oil showed gastroprotective, hepatoprotective and antitumour
effects in vivo 3,4 . The biological effects of the oil are mainly
atributable to thymoquinones, known as powerfull antioxidants.
Other components such are polyunsaturated fatty acids,
phytosterols and tocopherols can contribute to the beneficial
effects of the black cumin seeds.
The lipid composition, including lipid classes, fatty
acids and sterols of Nigella seeds of various geographical origins
were reported 5,6,7 . The fixed oil contains high levels of
unsaturated fatty acids and an unusual fatty acid – 20 : 2 (11c,
14c) – considered as a chemotoaxanomic marker for Nigella
species. The main sterols reported in black cumin seeds were
β-sitosterol, stigmasterol and campesterol 6,7 . The aim of this
work was the study of lipid fraction in the oil of Nigella seeds
cultivated in Romania, as a potential nutraceutical or ingredient
of functional food.
Experimental
E x t r a c t i o n a n d L i p i d F r a c t i o n a t i o n
Total lipids were extracted with chloroform : methanol
(2 : 1; v/v), evaporated to dry and kept –20 °C in use. neutral
lipids were separated by TLC with a solvent mixture of
hexane: ethyl ether: acetic acid (95 : 15 : 1).
F a t t y A c i d s A n a l y s i s
The fatty acids methyl esters of total lipids and lipid
fractions (FAME) were obtained by transesterification with
BF 3 /methanol. A Shimadzu GC 17A with FID detector and a
Crompack Silica 25 MXO capillary column (25 m × 0.25 mm
i.d., film thickness 0.25 µm) was used. The temperature
program was: 5 min at 150 o C, 4 o C min –1 to 235 o C (hold
5 min). The injector temperature was 260 °C and the detector
temperature –260 °C. The carrier gas was helium.
S t e r o l s A n a l y s i s
A part of total lipid extract was saponified by refluxing
with 1M KOH ethanol/water (8 : 2, v/v) solution for 1 h. The
s803
unsaponifiables were then extracted first with petroleum ether
and diethyl ether.
The sterols were derivatized BSTFA containing
1% TMCS in pyridine and separated on fused silica capillary
column coated with 5% phenyl/95% dimethylpolysiloxane
(30 m × 0.25 mm i.d., film thickness 0.25 µm; Rtx-5; Restek
Corporation, Bellefonte, PA, USA). The same GC system
mentioned above was used, with the following temperature
program: 5 min at 200 °C, 10 °C min –1 to 300 °C (hold
20 min).
FAME and sterols peaks were identified by comparison
of their retention times with those of commercially available
standards (Sigma). All extractions and GC-FID runs were
performed in triplicate and mean values were calculated.
Results
Nigella seeds are characterized by high oil content, ranging
between 30–40 % of fresh weight. The Romanian cultivar
investigated has a total lipid (TL) content of 30.1 g 100 seeds –1 .
For German cultivar a value of 39.2 % oil in fresh seeds was
reported 8 . The major fraction is the neutral lipids, representing
96.6 % of the oil while the polar lipids (PL) count for
3.4 %. The total sterols were found at 87 mg 100g –1 seeds,
value which is lower than those reported for German cultivar
but higher than for the Tunisian one (Table I) 6,7 .
Table I
nigella seeds oil composition
Fraction Amount
neutral lipids 29.1 ± 0.05 g 100 g –1 seeds
Polar lipids 0.9 ± 0.01 g 100 g –1 seeds
Total sterols 87.2 ± 0.02 mg 100 g –1 seeds
Total oil 30.1 ± 0.05 g 100 g –1 seeds
In the total lipids extract the major fatty acid was linoleic
acid – 56.6 %, followed by oleic acid – 23.5 %. The most
important saturated fatty acid was palmitic acid – 12.66 %.
Saturated fatty acids represent 16 %, monounsaturated fatty
acids – 23.8 % and polyunsaturated fatty acids account for
more than 59 % of total lipids. The unusual eicosadienoic
acid 20 : 2 (11c, 14c) was found at 2.5 %, value which is close
to that reported for other cultivars.
The fatty acids composition of triacylglycerols (TAG)
was closed to that of the TL. Diacylglycerols (DAG) and
monoacylglycerols (MAG) contains lower palmitic and linoleic
acid and higher oleic and eicosadienoic acid. The esterified
sterols (SE) and the polar lipds (PL) contain the highest
concentration of saturated fatty acids: palmitic (more than
17 %) and stearic (more than 4 %). The PL class also has the
highest level of eicosadienoic acid. Miristic, linolenic and
gadoleic acids were present in negligible amount in all lipid
classes (Table II). Only traces of arachidic acid 20 : 0 were
found. The sterol fraction contains: 37 % β-sitosterol, 11 %
stigmasterol and 10 % campesterol as major compunds.