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- Complementary Medicine -
Aphrodisiac potentials of the aqueous extract of Fadogia agrestis (Schweinf. Ex Hiern) stem in male albino rats
M. T. Yakubu, M. A. Akanji, A. T. Oladiji
Medicinal Plants Research Laboratory, Department of Biochemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria
Aim: To evaluate the phytochemical constituents and the aphrodisiac potential of the aqueous extract of
Fadogia agrestis (Rubiaceae) stem in male albino rats.
Methods: The aqueous stem extract of the plant was screened for
phytochemical constituents. Male rats were orally dosed with 18 mg/kg, 50 mg/kg and 100 mg/kg body weight,
respectively, of the extract at 24 h intervals and their sexual behavior parameters and serum testosterone
concentration were evaluated at days 1, 3 and 5.
Results: Phytochemical screening revealed the presence of alkaloids and
saponins while anthraquinones and flavonoids are weakly present. All the doses resulted in significant increase in
mount frequency, intromission frequency and significantly prolonged the ejaculatory latency
(P < 0.05) and reduced mount and intromission latency
(P < 0.05). There was also a significant increase in serum testosterone concentrations
in all the groups in a manner suggestive of dose-dependence
(P < 0.05). Conclusion: The aqueous extract of
Fadogia agrestis stem increased the blood testosterone concentrations and this may be the mechanism responsible for
its aphrodisiac effects and various masculine behaviors. It may be used to modify impaired sexual functions in
animals, especially those arising from hypotestosteronemia.
(Asian J Androl 2005 Dec; 7: 399-404)
Keywords: Fadogia agrestis; aphrodisiacs; sexual behavior; testosterone; erectile dysfunction
Correspondence to: Dr M. T. Yakubu, Medicinal Plants Research
Laboratory, Department of Biochemistry, University of Ilorin,
PMB 1515, Ilorin, Nigeria.
Tel: +234-803-3578-658, Fax: +234-31-221-593
Received 2004-09-24 Accepted 2005-03-21
Male impotence or erectile dysfunction (ED) is a
significant problem that may contribute to infertility .
There has been a worldwide increase in the incidence of
ED, probably due to aging populations and other risk
factors such as the presence of chronic illnesses (e.g.
heart disease, hypertension, diabetes mellitus), smoking,
stress, alcohol, drug abuse and sedentary lifestyles. ED
is defined as the consistent inability to achieve an
erection sufficient for the purpose of satisfactory
sexual intercourse, or the inability to ejaculate, or both .
Management therapies include the use of psychotherapy,
vacuum devices, surgery, penile implants and drugs .
Some of these are too expensive and not easily affordable.
In many localities in Nigeria, Fadogia
agrestis, a shrub with a yellowish stem and leaves, 1-3 feet high, is one
of several plants commonly used in the management of
However, the validity of the claimed aphrodisiac
activity (the ability to arouse sexual desire ) has not been
proven scientifically. This study was carried out to
provide information on its acclaimed aphrodisiac
properties. Previous workers [5, 6] had shown that male sexual
behavior parameters (mount frequency, mount latency,
intromission frequency, intromission latency and
ejaculatory latency) and serum testosterone levels could be used
to assess the aphrodisiac potential of the plant extract,
hence these indices were used in the present study.
2 Material and methods
2.1 Animals and reagents
Healthy, sexually experienced, white male albino rats
(Rattus novergicus) weighing 270 g-300 g, aged 5-5.5
months and female albino rats weighing 150 g-180 g,
aged 3.5-4 months were obtained from the Small
Animal Holding Unit of the Department of Biochemistry,
University of Ilorin, Ilorin, Nigeria. They were kept in
well-ventilated house conditions (temperature: 28
°C-31 °C; photoperiod: 12 h natural light and 12 h dark;
humidity: 50 %-55 %) with free access to rat pellets
(Bendel Feeds and Flour Mills Ltd., Ewu, Nigeria) and
tap water. Estradiol benzoate was purchased from Sigma
Chemical (St. Louis, USA) and progesterone from Shalina
Laboratories (Mumbai, India). The testosterone assay kit was procured from Immunometrics (London, UK).
2.2 Plant authentication, preparation of plant extract
and phytochemical analysis
The plant sample bought from the herb sellers at
Kulende Market, Ilorin, Nigeria was authenticated at the
Department of Horticulture and Landscape Technology,
Federal School of Forestry, Jos, Nigeria with a voucher
number 2:108. The plant stem was cut into pieces,
oven-dried at 40 °C to a constant weight. The dried pieces
were then pulverized using an electric blender
(Blender/Miller III, model MS-223, Taiwan, China) and the
powder obtained was stocked in a plastic container from
which varying amounts were taken and extracted in
distilled water for 48 h at room temperature (26 °C-28 °C).
This was then filtered using filter paper (Whatman
No. 1). The filtrate was then concentrated in stem bath and the
resulting brownish black residue was reconstituted in
distilled water to give the equivalent dose of 18 mg/kg body
weight (value originated from ethnobotanical survey),
while higher doses of 50 mg/kg body weight and
100 mg/kg body weight were also used in this study. The
reconstituted aqueous extract was administered orally using plastic
syringes to all animals in different groups. The aqueous
extract was subjected to chemical tests for the
qualitative and quantitative analyses of alkaloids, tannins,
phlobatannins, anthraquinones, cardiac glycosides,
saponins, cardenolides and dienolides, phenolics, flavonoids, caffeine, triterpenes and steroids [7, 8].
2.3 Evaluation of male sexual behavior
A total of 60 male rats of proven fertility were
housed individually in metabolic cages of dimensions
33.0 cm × 20.5 cm × 19.0 cm, with cleaning of the cages done
once daily. The rats were randomly divided into four
groups (A, B, C and D) of 15 animals each. Rats
in groups A, B and C were administered with the plant
extract (1mL) once daily at 24 h intervals at the dose of
18 mg/kg, 50 mg/kg and 100 mg/kg body weight
respectively. Group D served as the control and received appropriate volume
(1mL) of the vehicle (distilled water) in a similar manner.
Five rats from each of the groups were monitored for
sexual behavior after 1, 3 and 5 daily doses respectively.
Sixty female rats were brought to oestrus by the se
quential administration of estradiol benzoate (10 μg/100 g)
and progesterone (0.5 mg/100 g) through subcutaneous
injections, 48 h and 4 h respectively prior to pairing .
Sexual behavior studies were monitored in a separate room
for 2 h following the administration and were given
20 min adaptation period, after which a primed female
was placed in the same cage with the male. On days 1,
3 and 5, sexual behaviors were monitored, including:
· Mount frequency (MF): the number of mounts
without intromission from the time of introduction of the
female until ejaculation.
· Intromission frequency (IF): the number of
intromissions from the time of introduction of the female until
· Mount latency: the time interval between the
introduction of the female to the first mount by the male.
· Intromission latency: the interval from the time of
introduction of the female to the first intromission by the
· Ejaculatory latency: the time interval between the
first intromission and ejaculation. This is characterized
by longer, deeper pelvic thrusting and slow dismount
followed by a period of inactivity .
All sexual behavior studies were carried out between
13:00 and 16:00 at room temperature 26 °C-28 °C.
2.4 Testosterone assay
The same set of animals used for sexual behavior
parameters were also used for the testosterone assay;
the animals were sacrificed 24 h after the extract
dosing. Under ether anesthesia, the neck areas were quickly
cleared of fur and skin to expose the jugular veins. The
jugular veins were slightly displaced from the neck
region (to prevent contamination of the blood with
interstitial fluid) and then cut with a sharp sterile blade. The
rats were made to bleed into clean, dry corked
centrifuge tubes which were left at room temperature for
10 min. After that, the tubes were centrifuged at
33.5 × g for 15 min using uniscope Laboratory Centrifuge (model
SM800B, Surgifriend Medicals, England).
The sera were thereafter collected using Pasteur
pipettes into clean, dry, sample bottles and were then stored
frozen overnight  before being used for the
The serum testosterone concentration was quantitatively determined using the direct human serum
testosterone enzyme immunoassay kit as outlined in
the manu- facturer¡¯s protocol. The determination was based on
the principle of direct assay of a limited (competitive)
type following the general antibody-antigen reaction based
on enzyme linked immunoabsorbent assay as described
by Tietz  using Serozyme IÔ Serono (Diagnostics,
Freiburg, Germany). The serum testosterone concentration was then interpolated from a standard calibration
2.6 Statistical analysis
Data were presented as the mean ± SD (n
= 5). Statistical analyses used one-way analysis of variance
(ANOVA) to account for the different treatments and
were complemented with unpaired t-test.
Differences were considered statistically significant at
P < 0.05 .
3.1 Phytochemical analysis
Phytochemical screening of the aqueous extract of
Fadogia agrestis stem showed the presence of
alkaloids and saponins, while anthraquinones and flavonoids are
present in a small amount (Table 1). All other
phytoche-micals analyzed were not detected.
3.2 Male sexual behavior
Increase in the sexual vigor of MF (Figure 1) and IF
(Figure 2) were observed in all three dosed groups
(namely 18 mg/kg, 50 mg/kg and 100 mg/kg body weight)
in a dose dependent manner that was statistically
significant (P < 0.05) when compared with the control. By
the last day of the experimental period (day 5) in the
highest dosed group (100mg/kg), both MF and IF had
increased to 3.7 times of their respective control values.
In addition, pre-copulatory behavior such as anogenital
sniffing and nosing were less prominent with the
100 mg/kg body weight group while chasing was more pronounced.
In contrast, the mount latency (Figure 3) and
intromission latency (Figure 4) decreased significantly with the doses
and as the experimental period increased (P < 0.05). There
was also statistically significant prolongation of ejaculatory
latency (P < 0.05) following the administration of various
doses of the plant stem extract (Figure 5).
3.3 Serum testosterone
The administration of various doses of the plant
extract resulted in a significant increase in serum
testosterone concentration throughout the period of
administration (P < 0.05). The various doses (18 mg/kg, 50
mg/kg and 100 mg/kg body weight) produced two-, three- and
six-fold increases compared with the control by the end
of the experimental period (Figure 6).
Since many people are now relying on herbal
medicines for health care , possibly because the other
treatment options available are becoming more
expensive and often carry serious side effects, there should be
scientific dissemination of information on the
therapeutic efficacy of these plants. The aqueous extract of
Fadogia agrestis stem has been in use by many people in
our local population as a means of treating sexual
inadequacy and stimulating sexual vigor even without recourse
to the scientific validity of the claim. Aphrodisiacs are
substances that enhance sex drive and/or sexual
pleasure or can arouse sexual desire or libido . They are
also agents that can be used to modify impaired sexual
Phytochemical screening can help to reveal the chemical constituents of the plant extract and the one
that predominates over the others. It may also be used
to search for bioactive agents for starting products used
in the partial synthesis of some useful drugs .
Phytochemical screening of the plant stem showed the
presence of major metabolites of alkaloids and saponins, while
anthraquinones and flavonoids are weakly present
(Table 1). Saponins have been implicated as possible bioactive agent
responsible for the aphrodisiac effect in Tribulus
terrestris extract .
The significant increase in the indices of sexual vigor
(i.e. mount and intromission frequency [Figures 1, 2])
and the significant decrease in mount and intromission
latencies (Figures 3, 4) are indications of the aphrodisiac
potential of Fadogia agrestis stem extract. In this study,
the marked effects on the sexual behavior parameters,
compared with the control, are indications of stimulation
in the desire component of sexuality. Apart from the
desire that is essential for initiation of sex, penile
tumescence and rigidity as well as the accessory muscles that
help in providing additional penile rigidity and ejaculation
are dependent on testosterone for normal sexual activity
. Such increase in the frequency of mount and
intromission suggests that libido, sexual vigor and sexual
performance were unimpaired . The prolonged
ejaculatory latency indicates enhancement of sexual function
and suggests an aphrodisiac action.
It has been documented previously that sexual
behavior and erection are dependent on an androgen that
may be acting both centrally and peripherally .
Testosterone supplementation has previously been shown to
improve sexual function and libido , in addition to
the intensity of orgasm and ejaculations which might also
be expected to improve . The continued
administration of the plant extract for five days at various doses
which led to the significant increase in serum
testosterone may be responsible for the marked effect on sexual
behavior indices of the male rats. Increase in
testosterone levels in the present study may thus account for the
observed masculine behavior.
Studies have implicated the saponin component of
plants in enhancing aphrodisiac properties due to its
androgen increasing property . Saponins present in the
aqueous extract of this plant might have assisted in
stimulating an increase in the body natural endogenous
testosterone levels by raising the level of leutinizing hormones
(LH). This LH released normally by the pituitary gland
helps to maintain testosterone levels; as LH increases, so
does the testosterone . The increase in testosterone
seemed to have translated into the male sexual
competence observed in this study. Furthermore, this study
suggests that the aphrodisiac action may be mediated
through a change in the blood testosterone level.
In conclusion, results of this study have provided
evidence to support the acclaimed role of Fadogia agrestis
as an aphrodisiacs in traditional medicine. It has also
provided scientific evidence as to its purported
aphrodisiac effect. The aqueous extract of the
Fadogia agrestis stem may be adduced to increase
in the testosterone level of the blood, which may be due to its
saponin component. Theaqueous extract of the
Fadogia agrestis stem may thus be used to modify impaired sexual functions in
animals, especially those arising from hypotestoster-onemia.
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