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Pak. J. Biochem. Mol. Biol. 2009; 42(4): 136-140
Antiobesity, antihyperlipidemic and hypoglycemic effects of the aqueous extract of
Nigella Sativa seeds (Kalongi)
Farhat Bano1*, Maliha Wajeeh2, Nadeem Baig3, Hajra Naz2 and Naheed Akhtar1
1Biophysics Research Unit, Department of Biochemistry, University of Karachi, Pakistan
2Neuropharmacology Research Unit, Department of Biochemistry, University of Karachi, Pakistan
3Karachi Medical and Dental College, CDGK, Karachi, Pakistan
Abstract: Obesity is a cluster of risk factors for cardiovascular disease, dyslipidemia and type II Diabetes. The seeds of Nigella Sativa
plant have been used to promote health and fight diseases for centuries especially in the Middle East and South Asia. The aim of the
present study was to assess the effects of aqueous extract of Nigella Sativa seeds on food intake, body weight and certain biochemical
parameters. The aqueous extract of Nigella Sativa was administered to obese rats weighing (250-300g) for 6 weeks. Body weight, food
intake and water intake were monitored weekly. At the end of the 6th week the rats were decapitated and blood was stored for biochemical
analysis. Statistical analysis showed that Nigella Sativa decreased body weight and food intake without decreasing water intake. Blood
glucose, serum cholesterol, triglycerides and low density lipoproteins (LDL) were significantly decreased and high density lipoprotein
HDL was significantly increased. On the basis of these results and the previous studies we can suggest the use of black seed for its role in
weight reduction and holistic effects on health.
Keywords: Nigella Sativa, kalongi, hypophagic, obesity, hypoglycemia.
Received: September 17, 2009 Accepted: November 22, 2009
*Author Correspondence: Farhatbano_2000@yahoo.com.
INTRODUCTION
Obesity has been called the “disease of
diseases” because of the diversity of complications
it produces; insulin resistance, diabetes,
hypertension and dyslipidemia that ultimately
increase the risk of cardiovascular disease1-3. The
seed of Nigella Sativa commonly known as black
seed, black cumin or Habba Sawada in Arabic are
used in folk medicine all over the world for
treatment and prevention of diseases4,5. It is narrated
by Abu Hurairah, the Prophet Mohammad (Peace be
Upon Him) said:
“Use this Black seed; it has a cure for every
disease except death.” (Sahih Bukhari)
The seeds contain numerous esters of
structurally unusual unsaturated fatty acids with
terpene alcohols (7%); furthermore traces of
alkaloids are found which belong to different types:
isochinoline alkaloids are represented by nigellimin
and nigellimin-N-oxide, and pyrazol alkaloids
include nigellidin and nigellicin. In the essential oil
(average 0.5%, max 1.5%), thymoquinone was
identified as the main component (up to 50%).
Other terpene derivatives were found in trace
amount: Carvacrol, carvone, limonene, 4-terpineol
and citronellol. The Nigella Sativa seeds are a
source of calcium, iron and potassium6. Currently a
new acetylated triterpene saponin (penta hydroxyl
pentocyclic triterpene) has been isolated from
Nigella sativa7.
Nigella Sativa has been reported to be used in
Egyptian folk medicine as carminative8. The
ethanolic extract of Nigella Sativa was shown to
have outstanding in vitro antibacterial activity
against methicillin resistant and sensitive strains of
staphylococcus aureus9. The ether extract of the
seed and its active principle, thymoquinone
produced minimum inhibitory concentrations
(MICs) against 8 species of dermatophytes. This
supports its use in folk medicine for the treatment of
fungal infections10. Nigella sativa extract using CO2
as solvent11, as well as methanolic extract possess
anti-oxidant activity12.
Anti-oxidants present in Nigella Sativa seeds
include Selenium, DL-α- and DL-γ-tocopherol, all-
trans retinol, thymoquinone and thymol13. The
aqueous and methanolic extracts of Nigella sativa
showed analgesic effect in mice as it produced
significant increases in reaction times in hot plates
and pressure tests14, 15. Both extracts also reduced
the normal body temperature15, the oil and seed
constituents of Nigella sativa showed anti-tumor
effects in vitro and in vivo16, 17. Studies have shown
that Nigella Sativa causes morphological
improvement in chronic toluene induced
neurodegenerative changes in the hippocampus,
frontal cortex and brain stem. Nigella sativa has
been shown to generate homogeneous cardiac
hypertrophy similar to that provoked by exercise
training18.
Since obesity is a risk factor leading to a
number of chronic and fatal diseases, many people
employ different methods to combat obesity and its
associated adverse effects. Although exercise is
regarded as one of the effective tools for weight
reduction and maintenance, but its compliance is
very low. People seemed to be more inclined to use
herbal medicines for reducing their weight which is
an easy approach in the busy lifestyles.
Therefore the present study was designed to
investigate the hypophagic, antiobese and
antihyperlipidemic effects of the widely used
Bano et al.
medicinal herb Nigella sativa in experimental
animals.
MATERIAL AND METHODS
Animals
Locally bred male Albino Wistar rats weighing
250-300 g, purchased from Hussain Ebrahim Jamal
institute (HEJ) University of Karachi were used for
the experiment. The rats were housed individually in
transparent cages with saw dust-covered floor, in
quiet room, with free access to standard diet and tap
water for one week before starting the experiment
for the purpose of acclimatization.
Herb
The seeds of the Nigella Sativa were purchased
from local herb store and authenticated by the
botanist “Saleem Shahzad” of Agriculture
department, University of Karachi.
Preparation of Nigella Sativa extract
Seeds of Nigella Sativa were washed and dried
and 25g of seeds were crushed in a grinder
according to the traditional mode of preparation19.
The powder was soaked in 50 ml distilled water and
left at room temperature for 24 hours. The filtered
extract was stored at 4 °C until use.
Experimental design
Fourteen male Albino Wistar rats were
randomly divided into two groups control and test, 7
in each. Both control and test animals were given
tap water to drink. 2 ml of extract of Nigella Sativa
was administered orally to the test animals with
feeding tubes at 10:30 a.m. daily. Body weights of
the test and control were recorded before starting the
experiment which served as pre-treatment body
weights. Body weights, food intake and water
intake were monitored after completion of every one
week. The experiment lasted for six weeks, at the
end of the sixth week animals were decapitated and
their blood was collected from cervical region.
Serum was extracted and stored at -70 °C which was
used for Biochemical analysis.
The biochemical analyses were done with the
help of the chemical analyzer. The kit for glucose
was supplied by Merck Qualitrol (R) and the kit for
cholesterol and triglycerides was supplied by
Elitech. Statistical analysis was done using t-test.
Differences between control and test animals were
considered statistically significant when P<0.05 and
when P<0.01.
RESULTS
Figure 1 shows the effects of Nigella Sativa on
weekly food intake in rats. The data statistically
analyzed by t-test revealed that administration of
Nigella Sativa significantly increased food intake in
first week (P<0.01), the increases were not
significant in the second, third and fifth week
(P>0.05) and decreased it in fourth week (P<0.05)
and sixth week (P<0.01) as compared to control
animals.
Figure 1: Effects of Nigella Sativa on weekly food intake (g) in
rats. Values are means ±S.D (n=7). Significant differences by t-
test (*P<0.05) and (**P<0.01) from respective water treated rats.
Figure 2: Effects of Nigella Sativa on weekly body weight (g) in
rats. Values are means ±S.D (n=7). Significant differences by t-
test (*P<0.05) and (**P<0.01) from respective water treated rats.
Figure 3: Effects of Nigella Sativa on weekly water intake (g) in
rats. Values are means ±S.D (n=7). Differences by t-test were
not significant.
Figure 2 shows the effects of Nigella Sativa on
weekly body weight in rats. The data statistically
analyzed by t-test revealed that administration of
Nigella Sativa significantly decreased body weight
in the first week (P<0.05), fifth week (P<0.01) and
sixth week (P<0.01) as compared to the control
animals. The decreases in body weights were not
significant in the second, third and fourth week
(P>0.05).
Antidiabetic, antihyperlipidemic and hypoglycemic effects of Nigella Sativa
Figure 4: Percentage decreases in food intake and body weight
after six weeks of Nigella Sativa administration. Values are
means ±S.D (n=7) from initial weeks food intake and initial day's
body weight. Decreases are shown in terms of percentage.
Figure 5: Effects of Nigella Sativa on blood glucose,
triglyceride, LDL, HDL and cholesterol levels. Values are means
±S.D (n=7). Significant differences by t-test (*P<0.05) and
(**P<0.01) from respective water treated rats.
Figure 3 shows the effects of Nigella Sativa on
weekly water intake in rats. Administration of herb
produced no significant effect in water intake
(P>0.05). Figure 4 shows the percentage decreases
in food intake and body weight after six weeks of
Nigella Sativa administration. The percentage
decrease in food intake in Nigella Sativa treated rats
was 44.93% and the percentage decrease in body
weight in Nigella Sativa treated rats was (17.31%).
Figure 5 shows the effects of Nigella Sativa on
different Biochemical parameters in rats.
The data statistically analyzed by t-test revealed
that administration of Nigella Sativa significantly
decreased blood glucose level (P<0.05),
triglycerides (P<0.01), LDL (P<0.01), cholesterol
(P<0.01) and increased HDL (P<0.01), as compared
to control animals.
DISCUSSION
The present study was designed to investigate
and evaluate the weight reducing effects of the herb
Nigella Sativa (Black cumin) in experimental
animals. A number of studies have assessed the
effectiveness of other weight loss herbal
supplements from rigorous clinical trials. A number
of herbs such as Aloe vera20, Dandelion21, Guarana22
are used for weight reduction. Anorectic effects of
Nigella Sativa of the present study are consistent
with the reports of Le and his co-workers23.
The findings in the present study strengthen the
notion that Nigella Sativa could be used as an anti-
diabetic remedy as present study reveals that
administration of Nigella Sativa decreased blood
glucose levels in animals. Black cumin or Black
seeds have been found to rank high among the anti-
diabetic plants most recommended by traditional
practitioners24. Previous reports have shown that
crude aqueous extract of Nigella Sativa restores
glucose homeostasis23. Nigella Sativa was shown to
enhance liver cell insulin sensitivity23. The ethanolic
extract of Nigella Sativa has shown to exhibit
insulin like activities25. Thus we can suggest that
Nigella Sativa in the present study could have
decreased blood glucose levels either or by restoring
glucose homeostasis or by enhancing liver cells
insulin sensitivity.
Our reports are in agreement with the previous
authors26, 27 that supplementation of Nigella Sativa
seeds in the diet had a favorable effect on the lipid
profile by decreasing TG, total cholesterol and LDL
cholesterol and increased HDL cholesterol as
compared to controls. Previous authors have
reported that hypotriglyceridaemic effects of Nigella
Sativa are possibly due to its cholerectic activity28.
In the present study cholesterol lowering effect of
Nigella Sativa could be due to cholerectic functions.
Cholerectic functions could be explained in terms of
reduced synthesis of cholesterol by hepatocytes or
by decreased fractional re absorption from small
intestine28. Reduction in LDL cholesterol consistent
with the previous study29 could be due to increased
production of LDL receptors.
Currently available anti-obesity medications
attack the body fat dilemma in three different ways.
They can stimulate metabolism for e.g.: Ephedra30,
Slimax31; impede digestion of fat for e.g.:
Pomegranate leaf32, Oolong tea33; or suppress
appetite for e.g.: tree-peony34. On the basis of the
current data we can suggest that Nigella Sativa
decrease body weight by suppression of appetite.
Suppression of appetite could be associated to the
neural circuits that regulate catecholaminergic,
serotonergic and peptidergic system or via
circulating leptin hormone signaling the brains
Bano et al.
satiety centre to produce hypophagic effects35 which
is translated into weight loss in the experimental
animals. However, none of the above mentioned
were monitored in the present study but detailed
study of these mechanisms would provide us a
detailed insight into the anorectic mechanism of
Nigella Sativa.
ACKNOWLEDGMENT
We are thankful to the Dean, University of
Karachi for the grant.
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