Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
Journal of Science and Practice of Pharmacy
December 2017; 4 (1): 182-188
Available at http://www.jsppharm.org
ISSN: 2449-0458 (print); 2449-0466 (electronic)
©
Official Journal of the Nigerian Association of Pharmacists in Academia, University of Benin Branch, Benin City, Nigeria. All rights reserved.
Original Research Article
Preliminary investigation of the aphrodisiac potential of the
methanol extract and fractions of Rhaphiostylis beninensis Planch
ex Benth (Icacinaceae) root on male rats
Josephine O Ofeimun *, Buniyamin A Ayinde
Department of Pharmacognosy, Faculty of Pharmacy, University of Benin, University of Benin, PMB 1154, Benin City,
300001, Nigeria
* For correspondence: Email: jofeimun@uniben.edu. Tel: +2348064942568
Abstract
Purpose: The study investigated the claimed use of
the root of Rhaphiostylis beninensis (Rb) as an
aphrodisiac.
Methods: The methanol extract of the root of Rb as
well as the chloroform and aqueous fractions were
administered to male rats (100, 200, 400 mg/kg),
which were mated with female animals that had been
brought into oestrus by the sequential administration
of 100 µg/animal of ethinyl oestradiol orally 48 h
before
and
progesterone
(1.0
mg/animal)
subcutaneously, 6 h prior to mating. Tween 80 (5 %)
and 50 mg/kg sildenafil served as the negative control
and positive control respectively. Parameters
determined were; mounting latency (ML),
intromission latency (IL), ejaculation latency (EL),
mounting frequency (MF), intromission frequency
(IF), ejaculation frequency (EF), anogenital grooming
(AG), genital sniffing (GS).
Results: The methanol extract and aqueous fraction
were observed to show a dose dependent increase in
MF, IF, EF, AG and GS, while a dose dependent
decrease in ML, IL and EL was observed. The
chloroform fraction showed the same pattern of dose
dependent activity for all the parameters evaluated
except for the IL, where the effect produced by 200
mg/kg was higher than that produced by 400 mg/kg
dose.
Conclusion: This study provides evidence for theuse
of the root of Rb in ethno-medicine as an aphrodisiac.
Keywords: Male sexual dysfunction, impotence,
ethno-medicine, chloroform and aqueous fractions
Indexing: Index Copernicus, African Index Medicus
Introduction
Male sexual dysfunction (MSD) has been
defined as any condition that prevents the
attainment of sexual satisfaction in the male [1].
It has been identified as one of the common
causes of infertility and it is known to manifest
in various forms which includes; delayed or
inhibited ejaculation, premature or retrograde
ejaculation, low/inadequate libido and erectile
dysfunction [2]. Erectile dysfunction, also
sometimes referred as impotence is the
consistent inability to achieve or maintain an
erection sufficient for satisfactory sexual
intercourse. While not considered a threatening
health condition, it carries grave social and
medical implication as it may be an indication of
more worrisome health conditions such as
diabetes, hypertension, hormonal imbalance and
neurogenic diseases [3,4].
Aphrodisiacs are substances that arouse the
sexual instincts, increase pleasure and
performance and they have been used to treat
some form of erectile dysfunction [5]. Several
medicinal plants have been claimed to possess
pro-sexual properties in ethno-medicine. One of
such plant is Rhaphiostylis beninensis [6].
Rhaphiostylis beninensis Planch ex Benth (Rb) is
a woody climber that is native to tropical Africa.
In folkloric medicine, the leaf and root are used
in the management of arthritis and rheumatism
while the leaf decoction is used as a mouth wash
and a wash for sores. The bark is used as a
182
Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
laxative of choice for babies up to three months
old with chronic constipation [6]. A decoction of
the leaf is also taken for bronchial ailments while
the leaf bark and root decoctions are used to
expel roundworms. Goats forage the plant
evoking the epithet in Igbo “Ike” meaning
strong. The idea of impacting strength is also
manifest in the root and bark which are prepared
and sold to pregnant women to “strengthen the
fetus” and also convey the idea of making the
male organ strong, hence its use in ethno
medicine as an aphrodisiac [7].
The plant is known locally in Nigeria by various
names such as “Osumede” or “Usuende” (Bini),
“Ikpokirikpo” or “Kpolokoto” (Igbo), “Atapara”
or “Idiaapata” (Yoruba) [8]. Anti-inflammatory,
analgesic, anti-bacterial, antiproliferative and
growth inhibiting activities have been reported
for the plant [8-10]. A thiourea derivative
namely, N,N-di (4-methyoxybenzyl) thiourea
with anti-inflammatory activity have been
isolated from the root of the plant [11]. The
present study was undertaken to evaluate the
aphrodisiac potential of the plant with particular
reference to the methanol extract, chloroform
and aqueous fractions in male rats.
Methods
Plant collection and identification
Plant material was purchased at New Benin
market in Oredo Local Government Area of Edo
State in April 2014. It was identified at the
Forestry Research Institute of Nigeria (FRIN)
Ibadan by Dr Olufemi Shasanya, where a
voucher specimen was deposited and the number
(FHI-10068) allocated.
Preparation and extraction of the plant
material
The plant was washed free of earthy material and
the root bark was scrapped off and dried in the
laboratory at room temperature for 1 week and
thereafter in an oven maintained at 40 ⁰ C for 30
min. The dried plant material was milled and
subjected to extraction (1.0 kg) in a Soxhlet
extractor by defatting with petroleum ether (4060 ⁰ C); (3.5 L), followed by extraction of the
marc with methanol (2.5 L). The methanol
extract was concentrated under reduced pressure
using a rotary evaporator set at 40 ⁰ C and to
obtain a dark brown sticky mass. The extract (40
g) was dissolved in methanol/water (1:10) and
partitioned with chloroform exhaustively to yield
the chloroform and aqueous fractions. These
were concentrated by use of the rotary
evaporator set at 40 ⁰ C. The aqueous fraction
was further dried by placing it in an oven set at
40 ⁰ C.
Source and maintenance of animals
Adult albino rats of both sexes (180 - 220 g)
were obtained from the Animal House of the
School of Medicine, Ambrose Alli University
Ekpoma, Edo State, and housed in the Animal
House of The Department of Pharmacology,
Faculty of Pharmacy University of Benin. They
were allowed to acclimatize for two weeks, fed
with pelletized animal feed (Livestock Feed,
Lagos) and allowed access to water ad libitum.
They were equally subjected to natural 12 h
cycle of night and day. Handling was carried out
according to the guidelines of the European
convention for the protection of vertebrate
animals [12] and ethical approval was obtained
from the Ethical Committee of the Faculty of
Pharmacy, University of Benin.
Experimentation
The method according to Yakubu et al [13] with
a slight modification was adopted for this
evaluation. The female animals were artificially
brought into oestrus (heat) by the administration
of ethinyl oestradiol orally (100 µg/ animal) 48 h
before, and progesterone subcutaneously (1.0
mg/animal) 6 h prior to mating. The male
animals were grouped into five groups of five
animals each. Animals in group 1 received 10
ml/kg of 5 % Tween 80 and served as the
negative control, while group 2, 3 and 4 received
100, 200 and 400 mg/kg of the methanol extract,
chloroform or aqueous fraction. Group 5 animals
received 50 mg/kg of sildenafil in 5 % Tween 80
and served as the positive control. Twenty
minutes after administration of the negative
control, extract/fraction or positive control,
animals (one at a time) were placed in a plastic
cage (30 cm × 18 cm × 30 cm) and allowed 10
min to acclimatize following which the female
animals were introduced into the box (one male
to one female animal at a time). The animals
were observed for 30 min [14,15] with the aid of
a video recording camera and an independent
observer. Video camera recordings were
transcribed and matched with that of the
independent observer for the purpose of
accuracy and elimination of bias. Similar
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Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
procedures were used to evaluate the effect of
the chloroform and aqueous fractions.
The following male sexual parameters were
observed, recorded and evaluated: Mounting
frequency (MF), this is defined as the number of
times the male animal mount the female from the
time of introduction of the female without
achieving intromission. A mount is operationally
defined as the male assuming the copulatory
position by lifting its fore body over the hind
parts of the female by clasping her flanks with
his forepaw [13]. Mounting latency; this is
defined as the time interval between the
introduction of the female and the first mount by
the male [13].
Others parameters of sexual behavior observed
include; intromission frequency, intromission
latency, ejaculation frequency and ejaculation
latency. Intromission refers to the introduction of
one organ into another; operationally, the
introduction of the penis into the vagina.
Intromission frequency therefore refers to the
number of intromissions from the time the
female animal was introduced until ejaculation,
while intromission latency is taken as the time
interval between the introduction of the female
animal into the cage and the first intromission by
the male. This is usually characterizes by pelvic
thrusting and springing dismounts [16].
Ejaculatory frequency refers to the number of
times there was expulsion of semen by the male
following vaginal penetration. It is characterized
by longer, deeper pelvic thrusting and slow
dismount, followed by a period of inactivity or
reduced activity.
Ejaculation latency is defined as the time
interval between the first intromission and
ejaculation [16]. Also considered were
anogenital grooming and genital sniffing.
Anogenital grooming is the number of times the
male assumes a sitting position on its hind part
and scratches/rub its genital area. Genital
sniffing refers to the number of times the male
animal goes after the female and sniffs out its
anal area without mounting. Animals were taken
from the animal house to the laboratory for the
experiment with dim red light in place and
minimal disturbance daily for one week before
the experiment to acclimatize them to the
experimental
environment.
Equally
the
receptivity of the female animals was tested by
exposing them to other male animals outside the
test animals and only the most receptive females
were selected for the experiment. All
experiments were carried out between 2000 and
0300 h. Upon removal of each set of animals
from the cages, they were cleaned out before the
introduction of the next set.
Statistical analysis
Results were expressed as mean ± SEM of five
animals per group. One way analysis of variance
(ANOVA) was used to analyze the results, while
the Duncan’s multiple range test was used to
establish level of significance at p < 0.05.
GraphPad
Instat
software
incorporated,
California U.S.A was employed as the data
analysis tool.
Results
The methanol extract (100, 200, 400 mg/kg) was
observed to produce a dose dependent increase
in MF, IF, EF, AG and GS, while a dose
dependent decrease in ML, IL and EL was
observed compared to the negative control. The
highest activity was produced by the 400 mg/kg
dose of the extract, whose effect on IL and AG
were statistically significant (p < 0.05) (Table 1).
The chloroform fraction showed the least
activity in all the parameters determined,
however, activity equally followed a dose
dependent pattern except in the activity of the
fraction on IL, where it was observed that the
100 mg/kg dose of the chloroform extract
produced a lower value (763.32 ± 16.59)
compared to the 200 mg/kg dose which
produced a latency time of 854.37 ± 11.21 sec
(Table 2).
Similarly, the effect of the aqueous fraction was
observed to follow a dose dependent pattern as
the methanol extract and chloroform fraction.
The effect produced by 200 mg/kg of aqueous
fraction on mounting latency was statistically
significant (p < 0.05) compared to the negative
control (Table 3). Overall, the aqueous fraction
produced the highest activity in all the
parameters evaluated, with the chloroform
fraction showing the least activity. The activity
of the methanol extract was intermediate
between the two fractions. However the effect
produced by the aqueous fraction was less than
that produced by the reference drug.
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Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
Table 1: Aphrodisiac activity of methanol extract of Rhaphiostylis beninensis
MF
ML
IF
IL
EF
EL
AG
GS
Control
100 mg/kg
200 mg/kg
400 mg/kg
4.00 ± 0.12
6.50 ± 0.76
7.80 ± 0.22
9.00 ± 0.51
481.37 ± 9.30
316.27 ± 13.03 220.42 ± 6.41⃰
169.53 ± 6.29
2.60 ± 0.23
3.00 ± 0.29
3.20 ± 0.35
5.40 ± 0.76
748.34 ± 18.64 590.39 ± 17.30 437.21 ± 15.41
331.16 ± 13.30
1.20 ± 0.11
1.60 ± 0.41
2.20 ± 0.19
2.60 ± 0.34
367.24 ± 11.24 328.23 ± 13.41 258.41 ± 11.09
208.24 ± 10.56
9.34 ± 1.19
11.12 ± 1.31
13.52 ± 1.26⃰
15.80 ± 1.57
5.50 ± 1.28
7.57 ± 1.15
8.23 ± 0142
9.31 ± 2.31
Results are expressed as mean ± SEM, n = 5, p < 0.05⃰
Sildenafil
15.00 ± 3.17
69.20 ± 3.16
8.00 ± 1.46
183.29 ± 13.61⃰
5.10 ± 0.44
121.15 ± 10.36
21.95 ± 2.35
16.20 ± 0.81⃰
Table 2: Aphrodisiac activity of chloroform fraction of methanol extract of Rhaphiostylis beninensis
MF
ML
IF
IL
EF
EL
AG
GS
Control
100 mg/kg
200 mg/kg
400 mg/kg
4.00 ± 0.12
5.10 ± 0.32
5.80 ± 0.22
6.20 ± 0.35
402.11 ± 7.08
407.27 ± 11.03
342.15 ± 8.32
291 ± 7.11
2.40 ± 0.51
2.80 ± 0.21
3.00 ± 0.38
3.60 ± 0.29
748.34 ± 18.64 763.32 ± 16.59
854.37 ± 11.21
663.17 ± 15.42
1.20 ± 0.18
1.20 ± 0.13
1.40 ± 0.11
1.80 ± 0.21
392.85 ± 10.72 342.45 ± 10.53
307.38 ± 11.17
299.51 ± 9.27
10.02 ± 1.59
9.82 ± 1.09
11.20 ± 1.26⃰
11.75 ± 1.39
6.30 ± 1.28
6.30 ± 1.31
6.72 ± 1.42
7.46 ± 1.09
Results are expressed as mean ± SEM, n = 5, p < 0.05⃰
Sildenafil
15.30 ± 1.52
81.53 ± 3.22⃰
7.40 ± 0.35
192.72 ± 11.23⃰
6.60 ± 0.51
121.15 ± 10.36
21.95 ± 2.35
10.52 ± 2.22⃰
Table 3: Aphrodisiac activity of the aqueous fraction of Rhaphiostylis beninensis
MF
ML
IF
IL
EF
EL
AG
GS
Control
100 mg/kg
200 mg/kg
400 mg/kg
4.00 ± 0.12
7.20 ± 1.26
8.80 ± 1.32
10.00 ± 1.73
402.11 ± 7.08
235.33 ± 6.93
192.31 ± 4.38
156.54 ± 4.21
2.40 ± 0.51
4.00.20 ± 0.49
4.60 ± 0.35
5.10 ± 0.38
748.34 ± 18.64 312.17 ± 17.12 263.21 ± 15.41 213.16 ± 18.30⃰
1.20 ± 0.18
2.20 ± 0.13
2.60 ± 0.21
3.20 ± 0.19
392.85 ± 10.72 272.54 ± 10.32 251.41 ± 10.51 177.24 ± 11.69
10.02 ± 1.59
13.00 ± 0.93
15.50 ± 1.62⃰
18.20 ± 1.55
6.30 ± 1.28
8.40 ± 1.27
10.00 ± 1.68
10.60 ± 1.18⃰
Results are expressed as mean ± SEM, n = 5, p < 0.05⃰
Discussion
Generally, medicinal plants with aphrodisiac
activity have been shown to elicit their effect
through various mechanisms. This involves a
peripheral, hormonal, and neuronal component
with a possible integration of all these
mechanism [17,18]. The peripheral component
has to do with the relaxation of the penile
smooth muscle brought about by increased
generation and release of nitric oxide, activation
of cyclic adenosine monophosphate (cAMP),
and or activation of the efflux of potassium ion
with a resultant increase in the flow of blood to
the penis and the production of an erection
[19,20]. It has also been established that
increased serum level of androgens particularly
Sildenafil
15.30 ± 1.52
81.53 ± 3.22⃰
7.40 ± 0.35
192.72 ± 11.23⃰
6.60 ± 0.51
121.15 ± 10.36
21.95 ± 2.35
10.52 ± 2.22⃰
testosterone regulate the magnitude of penile
erectile response by regulating the venous out
flow from the cavernous spaces [21]. Equally
involved is the neural system that depends on the
stimulation and inhibition of dopamine receptors
in the central nervous system to either enhance
or impair sexual behavior [22].
Genital sniffing is a parameter used to measure
pre-copulatory sexual behavior, the purpose
being to stimulate sexual excitement. An
increase in the number of times the male seeks
out the female to sniff her odors is an indication
of pre-copulatory sexual stimulation in the male
[23]. In this study, the aqueous fraction of the
methanol extract of Rb, was observed to produce
an increase in GS that was statistically
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Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
significant compared to the control. This
increase was similar to that produced by the
reference drug, suggesting an increase in sexual
stimulation and excitement by this fraction of the
extract. Equally, increase in anogenital grooming
is indicative of increased sexual stimulation in
male rats. It plays a major role in the readiness
of the adult male rat for reproduction [24]. It is
also an important measure of the erectile status
of the penis [25]. In this study, the methanol
extract as well as the chloroform and aqueous
fractions of RB at varying concentrations were
observed to exhibit a dose dependent response in
AG, with that produced by the aqueous fraction,
at the highest dose (400 mg/kg) being higher
than that seen with the extract and chloroform
fraction. However, this was less than that seen
with the reference drug.
Mounting and intromission frequencies are
considered indices of libido and potency, while a
decrease in mounting and intromission latencies
are indicators of sexual arousability, motivation
and potency [26]. The methanol extract, aqueous
and chloroform fractions were observed to effect
a dose dependent increase in mounting,
intromission and ejaculatory frequencies,
whereas a dose dependent decrease in mounting,
intromission and ejaculation latencies was
observed suggesting that these have ability to
affect, arousal, motivation, potency and vigor
positively. However, for each of the parameters
considered, the aqueous fraction was seen to
have a greater effect followed by the methanol
extract and lastly the chloroform fraction.
The purpose of fractionating the methanol
extract into the chloroform and aqueous phases
is to partition the constituents present in the
extract into non – polar (chloroform) and polar
(aqueous) constituents. From the result of the
study it can be deduced that the polar
constituents present in the plant have a higher
tendency to induce aphrodisiac effect in male
rats compared to the non-polar constituents.
Various phytochemicals have been reported to
be present in the plant. These include alkaloids,
tannins, flavonoids, saponins, steroids and
reducing sugars (5). Except for reducing sugars,
all the other constituents have been reported to
enhance sexual stimulation by increasing
endogenous testosterone level probably by
raising the level of luteinizing hormone [27].
Equally, alkaloids present in some plants such as
Mucuna prurienshave been credited with
estrogenic properties that manifest as
vasodilation of blood vessels of the penis with
resultant erection, as well as increased
spermatogenesis [28]. Saponins and particularly,
those with a steroidal nucleus are known to have
a nitric oxide like activity that bring about the
relaxation of the smooth muscle of the corpus
cavernosum. They are also known to produce
increases in the levels of circulating testosterone
with its resultant effect on male sexual behavior,
which is enhanced sexual stimulation and
excitement [29]. It is possible that the presence
of any or all of these components in the extract
and fractions are responsible for the observed
activity.
Conclusion
This study provides evidence for the use of the
root of R. beninensis in ethno medicine as an
aphrodisiac. The methanol extract, chloroform
and aqueous fractions of the plant revealed
varying degree of activity with the aqueous
fraction showing the highest activity. The effect
observed could be due to the presence of
constituents such as saponin, alkaloids,
flavonoids, tannin andsteroidal triterpenoids
reported to be present in the plant, and these may
have exerted their effect through central and /or
peripheral mechanisms. However, more work
still needs to be done to identify, isolate and
characterize constituent/s in the plant responsible
for the observed activity and to identify the exact
mechanism/s of action of extracts and such
isolated constituents.
Acknowledgement
We wish to acknowledge Pharmacist Fabian
Amaechina of the Department of Pharmacology
and Toxicology, Faculty of Pharmacy, Mr
Gabriel O. Benjamin of the Department of
Phytomedicine and Mr Benjamin O. Abhulimen
of the Department of Science Laboratory
Technology, Faculty of Life Sciences,
186
Ofeimun and Ayinde
Investigation of the aphrodisiac potential of Rhaphiostylis beninensis
University of Benin for their assistance with this
work.
Conflict of Interest
We declare that there is no conflict of interest
associated with this work.
Contribution to authorship
We declare that this work was done by the
authors named in this article and all liabilities
pertaining to claims relating to the content of this
article will be borne by us. The two authors
jointly conceived and designed the work, while
actual data collection and analysis was done by
the first author. Both authors jointly contributed
to the manuscript.
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