FREE
SERUM TESTOSTERONE LEVEL IN MALE RATS TREATED WITH TRIBULUS ALATUS EXTRACTS
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WALID H. EL-TANTAWY,
ABEER TEMRAZ, OMAYMA D. EL-GINDI
Drug Bioavailability
Center, National Organization For Drug Control and Research, Cairo, Egypt,
Pharmacognosy Department, Faculty of Pharmacy for Girls, Al-Azhar University,
Cairo, Egypt
ABSTRACT
Objective:
The present study was undertaken to investigate the effect of Tribulus
alatus extracts on free serum testosterone in male rats.
Materials and Methods: Free serum testosterone
level was measured in male rats treated with alcoholic extracts of the
aerial part without fruits, fruits of Tribulus alatus and their fractions.
Results: All tested extracts showed significant
increase in the level of free serum testosterone when compared to that
of corresponding control, p < 0.05. Statistical comparison of all groups
revealed that the maximum level was found in groups treated with chloroformic
and ethanolic fractions of fruits extract.
Conclusion: Tribulus alatus extract appears
to possess aphrodisiac activity due to its androgen increasing property.
Key
words: Tribulus; testosterone; aphrodisiacs; rats
Int Braz J Urol. 2007; 33: 554-9
INTRODUCTION
In
traditional medicine a variety of plants have been used as sex stimulants
(1). For centuries, Arabs have made use of herbal drugs to improve sexual
performance and increase libido (2). In African traditional medicine,
especially in Cameroon, Zingiber officinale and Pentadiplan-dra brazzeana
are used as aphrodisiac and male sexual stimulation (3). In Egypt, the
pollen grains of dates (Phoenix dactylifera) and seeds of hermala (Peganum
harmala) are used to restore sexual potency (4).
The genus Tribulus of the Zygophyllaceae
comprises ca 20 species that grow as shrubs or herbs in subtropical areas
around the world (5).Among the Tribulus species T. terrestris, T. cistoides
and T. alatus have been phytochemically investigated and isolation of
steroidal saponins from these plants was reported (6-8).
The present study was undertaken to investigate
the effect of Tribulus alatus extracts on free serum testosterone in male
rats.
MATERIALS
AND METHODS
Plant
Material and Preparation of Extracts
Samples of Tribulus alatus were collected
from Al Azhar University, Nasr-city, Cairo and were kindly identified
by Department of Botany, Faculty of science, Cairo University. A voucher
specimen (number 3978/1) was deposited at Herbarium Horti Botanici Pisani
(Flora Aegyptiaca), Pisa, Italy.
The dried aerial parts and fruits (400g
and 100g, respectively) of Tribulus alatus were finely powdered and were
macerated separately in 70% methanol. The alcoholic extract was evaporated
to dryness under vacuum. The residues were combined, weighted (90g and
20g, respectively) suspended in distilled water and successively extracted
with chloroform, ethylacetate and n-butanol saturated with water. Each
extract was collected and evaporated to dryness under vacuum to give chloroformic
extract (4g and 2.1g, respectively ) ethylacetate extract (3.2g and 1.5g,
respectively) and n-butanolic extract (8g and 3.8g, respectively) then
the water was evaporated to dryness and the residue was macerated in absolute
ethanol several times. The alcoholic extracts were combined and evaporated
to dryness under vacuum to give ethanolic extract (30g and 8g, respectively)
Animals
Healthy, adult male Wistar albino rats weighing
200-250g, aged 4-5 months were used in this study. The animals had free
access to a standard commercial diet, water and were kept in rooms maintained
at 25 ± 1°C. The animals were divided randomly into different
groups; each group consisted of six rats. Control groups treated with
distilled water (2 mL/kg p.o.) only.
Toxicity
Study
On the basis of the toxicity study, the
LD50 value of the extract of the aerial part without fruits in mice was
812 and was 868 mg/kg body weight for the extract of fruits. On the other
hand, LD50 value for extract of different fractions ranged from 155-200
mg/kg body weight. The experiment was carried out on three steps.
First
Step
Control group: treated with distilled water
(2 mL/kg p.o.). Group 1: received 70% alcoholic extract of aerial part
without fruits (n = 6). Group 2: received 70% alcoholic extract of fruits
(n = 6). Group 3: received 70% alcoholic extract of total herb (n = 6).
Reference group: treated with 0.45 mg mestrolone (n = 6).
In the first step, groups received extracts
(suspended in water using Tween 20 as a surfactant) at a dose of 50 mg
/ kg body weight orally by orogastric catheter once a day for 40 days.
A reference group was treated with 0.45 mg mestrolone once a day for 40
days orally by orogastric catheter. After 40 days, blood samples were
collected from the tail veins of the rats at the same time of the day
and serum was separated.
Second
Step
Control group: treated with distilled water
(2 mL/kg p.o.). Group 4: received chloroformic fraction of aerial part
without fruits (n = 6). Group 5: received ethylacetate fraction of aerial
part without fruits (n = 6). Group 6: received butanolic fraction of aerial
part without fruits (n = 6). Group 7: received ethanolic fraction of aerial
part without fruits (n = 6). Reference group: treated with 0.45 mg mestrolone
(n = 6).
Third
Step
Control group: treated with distilled water
(2 mL/kg p.o.). Group 8: received chloroformic fraction of fruits (n =
6). Group 9: received ethylacetate fraction of fruits (n = 6). Group 10:
received butanolic fraction of fruits (n = 6). Group 11: received ethanolic
fraction of fruits (n = 6). Reference group: treated with 0.45 mg mestrolone
(n = 6).
On the other hand, in the second and third
steps the groups received dose 12.5 mg / kg body weight orally by orogastric
catheter once a day for 40 days. A reference group was treated with 0.45
mg mestrolone once a day for 40 days orally by orogastric catheter. After
40 days, blood samples were collected from the tail veins of the rats
at the same time of the day and serum was separated.
Determination
of Free Serum Testosterone
The level of free serum testosterone was
measured by Enzyme-linked immunosorbant assay (ELISA) according to (9),
KAPD29:040318/2KAPD2924 IN VITRO DIAGNOSTIC USEenBioSource Europe SA -
Nivelles, Belgium.
Statistical
Analysis
Data were presented as the mean ±
SE (n = 6). Statistical analysis used Student’s t-test to compare
differences between groups and the control. One-way analysis of variance
(ANOVA) was applied for comparison between different treatments. Differences
were considered statistically significant at P < 0.05.
RESULTS
Table-1
represents mean free serum testosterone level (pg/ mL) among group of
rats treated with 70 % alcoholic extracts of Tribulus alatus. Testosterone
level was significantly increased among all groups, when compared to that
of their corresponding control, P < 0.05. The highest level was found
in the group treated with the reference drug followed by the group treated
with fruits extract, followed by the one treated with the aerial part
without fruits and the lowest level was found in the group treated with
total herb.
Table-2 illustrates mean free serum testosterone
level (pg/mL) among groups of rats treated with different fractions of
70% alcoholic extracts of the aerial part without fruits of T. alatus.
Testosterone level showed significant increase among all groups, when
compared to that of their corresponding control, p < 0.05.
The level of testosterone in the group treated
with the reference drug showed a significant increase when compared to
that of all other groups. The level of testosterone in-group (5) showed
a significant increase when compared to that of other groups including
that treated by total aerial parts extract, group (1).
Table-3 illustrates mean free serum testosterone
level (pg/mL) among groups of rats treated with different fractions of
70 % alcoholic extracts of the fruits of T. alatus. Testosterone level
showed significant increase among all groups, when compared to that of
their corresponding control, p < 0.05.
Testosterone level showed significant increase
in groups 8 and 11. As compared with that of other fractions, total fruits
extract and the group treated with the reference drug.
COMMENTS
Some
causes that are responsible for low testosterone levels, include congenital
problems such as deficiencies of male hormones and rare malformation syndromes,
and acquired problems such as aging, chronic illness, drugs, starvation,
stress, head trauma, infections, cancers, surgeries, alcoholism, removal
or trauma to the testicles, and infection or twisting of the testicles
in their sack.
The use of testosterone is widespread in
the treatment of many problems including infertility, athletic enhancement,
erectile dysfunction and libido problems. Its application can have grave
consequences if not used properly. Androgen, or more specifically testosterone,
is widely utilized to treat erectile dysfunction (10).
Various neurotransmitters and their inter/intracellular
signaling are responsible for the relaxation of corpus cavernosal smooth
muscle. Androgens influence these neurotransmitters and contribute to
the regulation of penile erection. The classic theory about testosterone
treatment is that it stimulates the sex drive and, by doing so, restores
erectile functioning (11).
Once a man is diagnosed as hypogonadic,
or having a low testosterone level, the next step is to choose which form
of treatment to utilize. As with all medications, benefits should be evaluated
against potential risk. Age is one important factor in making this decision.
In men less than fifty years old, the goal
is to restore libido and erections. Testosterone also improves strength,
physical stamina, and health status (10). Many people are now relying
on herbal medicines for health care (12). Since other treatments applied
are becoming more expensive and often carry serious side effects, there
should be scientific dissemination of information on the therapeutic efficacy
of these plants. Aphrodisiacs are substances that enhance sex drive and/or
sexual pleasure or can arise sexual desire or libido (13). They are also
agents that can be used to modify impaired sexual functions.
Studies have implicated the saponin component
of plants in enhancing aphrodisiac properties due to their stimulatory
effect of androgen production (11).
A survey concerning the secondary metabolites
of genus Tribulus showed that steroidal saponins are the typical constituents
of the genus, and in particular of T. terrestris (14). Saponins have been
implicated as possible bioactive agent responsible for the aphrodisiac
effect in Tribulus terrestris extract (11). These saponins were found
to increase the levels of testosterone and luteinizing hormone (15).
It was reported that Tribulus alatus contained
steroidal saponins (8), which might contribute to increasing endogenous
testosterone levels by raising the level of luteinizing hormones (LH)
as reported for saponins isolated from T. terrestris (15).
In the present study, the significant increase
in the level of free serum testosterone is an indication of the aphrodisiac
potential of Tribulus alatus extract.
CONCLUSION
The
alcoholic extracts of both parts of Tribulus alatus produced a significant
increase in the level of free serum testosterone at dose 50 mg/Kg body
weight. Also different fractions of both parts of the plant revealed significant
increase in the level of free serum testosterone at dose 12.5 mg/Kg body
weight when compared to their corresponding controls. It is concluded
that Tribulus alatus extract appears to possess aphrodisiac activity due
to its androgen increasing property.
CONFLICT
OF INTEREST
None
declared.
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____________________
Accepted after revision:
December 23, 2006
_______________________
Correspondence address:
Dr.Walid Hamdy Ali El-Tantawy
Drug Bioavailability Center
National Organization for Drug Control and Research
Dokki, P.O. 29, Cairo, Egypt
Fax: + 002023379445
E-mail: wldhmdy@yahoo.com
EDITORIAL COMMENT
In
this manuscript, the authors evaluated the effect of Tribulus alatus extracts
on free serum testosterone in male rats. The authors found that the alcoholic
extracts of both parts of Tribulus alatus produced a significant increase
in the level of free serum testosterone at dose 50 mg/kg body weight.
Also different fractions of both parts of the plant revealed significant
increase in the level of free serum testosterone at dose 12.5 mg/kg body
weight. From these studies, the authors concluded that the alcoholic extract
of the Tribulus alatus might thus be used to modify impaired sexual functions,
especially those arising from hypotestosteronemia. The paper is very original
and most part is carefully carried out. It presents some interesting observations.
Dr. Q. T. Yang
Department of Urology
Second Affiliated Hospital
Shantou University Medical College
Shantou, 515041, China
E-mail: yang2001tao@126.com
EDITORIAL COMMENT
Male
reproductive disorders and sexual dysfunction is a serious problem of
recent society. In this respect the current paper deal with topical question
of increasing incidences of male sexual dysfunction and potential risk
of application of synthetic hormonal drugs. There is limited understanding
in the literature on aphrodisiac effect of plants, namely, Tribulus on
man and primates. The study is interesting and informative and adds to
our knowledge about aphrodisiac properties of species belonging to genus
Tribulus. The authors develop a proper experimental model on rat and provide
useful data on the ways for stimulation of androgen production by natural
sources. The article contains new facts about isolation of different organic
fractions from fruits and aerial part of Tribulus and their comparative
effect on testosterone production. The data are useful for clinical practice
and treatment of male sexual dysfunction. They will encourage further
studies on finding natural products for stimulation of testicular endocrine
function that would be of interest for pharmacology.
Dr. Nina
Atanassova
Inst. of Exp. Morphology & Anthropology
Bulgarian Academy of Sciences
Sofia, Bulgaria
E-mail: ninaatanassova@yahoo.com
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