African Journal of Biomedical
Research, Vol. 7, No. 1, Jan, 2004, pp. 31-33
Short
communication
EFFECTS OF AQUEOUS
EXTRACTS OF HIBISCUS
SABDARIFFA CALYCES AND OCIMUM GRATISSIMUM LEAVES ON INTESTINAL
TRANSIT IN RATS
OWULADE M. O., EGHIANRUWA,
K. I.* AND DARAMOLA, F. O.
Department of Veterinary
Physiology
and Pharmacology, University of Ibadan, Ibadan, Nigeria.
* Correspondence.
Received: March
2001
Accepted in final form: January 2002
Code Number: md04008
The effects
of aqueous extracts of the leaves of Ocimum gratissimum and calyces of Hibiscus
sabdariffa on intestinal transit were determined in experimental rats The
leaves of Ocimum gratissimum were oven dried and then pulverized. The dried
calyces of Hibiscus sabdariffa were also pulverized. 10% extracts of both
powders were made and
administered orally to rats at varying doses. Test rats were given the 10% extracts
of Ocimum gratissimum and Hibiscus sabdariffa at 0.5/100g, 1ml/100g, 2ml/100g
body weight. Control rats received saline instead of extracts. After 30 minutes,
each animal was then given 1.5 ml of a dye solution orally. 1 hour after administering
the dye each rat was sacrificed and the intestine carefully dissected out. The
length of the intestine and the transit point of the orally administered dye
were then measured. The transit point was calculated as a percentage of the total
length of the intestine. The extracts of both Ocimum gratissimum and Hibiscus
sabdariffa caused a reduction in the transit points of the dye. The extract of
Hibiscus sabdariffa was more effective. The reduction in transit point, and hence
the increase in transit time by both extracts indicates that the plants could
be useful at appropriate doses in the control
of diarrhea. Hibiscus sabdariffa would be more effective in this regard.
Key Words: Hibiscus
sabdariffa, Ocimum
gratissimum, intestinal
transit, aqueous extract.
INTRODUCTION
The consumption of a variety
of local herbs and vegetables by man is believed to contribute significantly
to the improvement of human health, in terms of prevention, and or cure of
diseases because plants have long served as a useful and rational source of
therapeutic agents [Roberts
and Tyler 1999]. Hibiscus sabdariffa and Ocimun gratissimum are
popular plants whose products are used by virtually every Nigerian. Ocimum gratissimum is
a shrub commonly found around village huts and in gardens [Iwu, 1993]. It is
known as Efinrin ajase in Yoruba, Ebavbokho in Bini, Aai doya
ta gida in Hausa, Nchonwu in Igbo. The leaves are used locally for
soup. It is also used to treat cases of stomach upset and
diarrhea
MATERIALS AND METHODS
Animals: Albino
rats of both sexes and weighing between 100-1 25g were used. These rats were
obtained from the
Department of Physiology, University of Ibadan. They were randomly selected and
kept in seven groups of five rats per group. Each group was kept in a separate
cage. All animals were fed with commercially formulated rat feed and water was
given ad libitum. Their cages were cleaned daily and food and water changed
daily. Food was withdrawn from the animals 24 hours before experiment but water
was allowed.
Preparation
of aqueous Extract.: The leaves of Ocimum grattissimum were
collected from Arulogun in Oyo state and were identified at the Department
of Botany, University of Ibadan, Nigeria. The calyces of Hibiscus
sabdarlffa were collected from Toro in Bauchi state and Identified at the
Department of Botany, Abubarka Tafawa Balewa University, Bauchi, Nigeria, The
respective parts of both plants were oven dried
separately at 80°C, pulverized and then sieved. Twenty-five grams of the powdered
leaf was weighed out and dissolved in 250 ml of distilled water to make 10% extract.
This was filtered and the residues discarded. The resultant extracts were stored
in capped bottles and kept in refrigerators before use.
Preparation
of Dye: The dye was prepared by a modified method of Uwagboe and
Orimilikwe (1995). 95 mIs of 10% aqueous suspension of
charcoal (BDH, England) was mixed with 5 ml of giemsa stain
(BDH, England).
Studies of Intestinal Transit:
Table 1 shows the groups of animals and the treatment each group received.
24 hours before experiment, food was withdrawn from the animals but water was
freely allowed. During the experiment, each rat received the appropriate dose
of the respective extracts. The extracts were administered orally using an
oral cannula.
Table 1. Animal groupings and treatments
Group
|
n
|
Dose of 10% O.G.
(ml/100g)
|
Dose of 10% H.S
(ml/100g)
|
Dose of 0.9% NaCl
(ml/100g)
|
1
|
5
|
0.5
|
Nil
|
Nil
|
2
|
5
|
1.0
|
Nil
|
Nil
|
3
|
5
|
2.0
|
Nil
|
Nil
|
4
|
5
|
Nil
|
0.05
|
Nil
|
5
|
5
|
Nil
|
1.0
|
Nil
|
6
|
5
|
Nil
|
2.0
|
Nil
|
7
|
5
|
Nil
|
Nil
|
1.0
|
The control group (Group 7) received
normal saline. Thirty minutes after the administration of the extract, 1.5ml
of the dye was administered orally to each rat using an oral cannula. The rats
were then kept without food and water for 1 hour before the determination of
transit point of the dye. At the end of this time, the rats were sacrificed
by an overdose of chloroform. Their peritoneum was opened and the entire length
of the small intestines were carefully stretched and cut open. The lengths
of the intestines from the pyloric junction were measured; the distance transverse
by the dye
from the pyloric unction was also measured,
Analysis of Results:
The distance transversed by the
dye from the pyloric junction was calculated as percentages of the entire length
of the intestines. This was regarded as the percentage transit point of the
dye at each dose of an extract. The means and standard errors of the means
[SEM] of these percentages were calculated for each group. Data from the control
group were regarded as zero administration of the extracts. These data were
then fed into the computer using the computer software, Microsoft excel [Microsoft
Incorporation, USA] to obtain graphic representations. The levels of significance
between the transit points of each dose were determined using
Students t- test.
RESULTS AND DISCUSSION
The results are presented
in Table 2. Extracts from Hibiscus sabdariffa caused dose-dependent
reduction in the percentage transit point of the dye. The reduction of percentage
transit point by extract of Ocimun
gratissimum was not dose-dependent. However, the reduction was significant
(P < 0.05) when compared to the percentage transit in normal rats.
Zobo, the aqueous
extract of the calyces of Hibiscus sabdariffa caused a reduction
in the percentage transit point indicating a reduction in intestinal motility,
and increased transit time.
The mechanism by which Hibiscus sabdariffa caused
this action cannot be ascertained from this study but studies carried out by
other workers (Obiefuna, 2001; and Odebiyi and Sofowora, 1978) on the phytochemical
constituents of the plant indicate the presence of pectin, a known protectant
and adsorbent (Swinyard, 1975). Pectin dissolves in water to form viscous colloidal
solution and was once used widely in the treatment of diarrhea (Swinyard, 1975).
Obiefuna et al., (1994) also observed that the petal extract of the
plant produced relaxation of isolated rat aorta. Relaxation of the intestinal
smooth muscle would cause increased transit time. At appropriate dose, zobo
could therefore become a constipating agent. It could also be effective in
reducing the intensity of diarrhea.
Table 2. Mean percentage
transit points of dye in the intestines of
rats administered extracts of Ocimun gratissimum and Hibiscus sabdariffa [n
=5 in each case].
EXTRACT
|
DOSE [Ml/100g]
|
MEAN % TRANSIT POINT
|
Ocimun gratissimum
|
0.5
|
68.88 ± 6.21**
|
1.0
|
72.48 ± 1.78*
|
2.0
|
69.10 ± 4.64*
|
Hibiscus sabdariffa
|
0.5
|
83.70 ± 5.55NS
|
1.0
|
78.60 ± 4.78*
|
2.0
|
60.66 ± 3.24**
|
CONTROL Normal saline
|
1.0 ml
|
85.14 ± 4.53
|
*NSNot significant;
*P<0.05; **P<0.01 (c.f.
control)
Although, a reduction in
motility was evident
between control and test rats, the leaf extract of
Ocimun gratissimum did
not produce a dose-dependent effect. The leaf extract of
Ocimun
gratissimum is therefore not as effective an inhibitor of intestinal motility
as
Hibiscus sabdariffa.
The effectiveness of the
leaf extract of Ocimun
gratissimum in controlling gastrointestinal upset (Oliver, 1969; Schippers,
2000; Lewis and Elvin-Lewis, 1977) may not be due to a direct relaxation of the
intestinal smooth muscle. A fraction of the crude extract has been shown to contract
guinea pig ileum and rat colon [Onojobi, 1986]. This action cannot be associated
with reduced intestinal motility. The antispasmodic action of thymol contained
in the aromatic volatile oil obtained from the leaves of Ocimun
gratissimum could be associated with reduced intestinal motility [Iwu, 1993].
This action in conjunction with antibacterial property of the plant may be responsible
for its observed action in diarrhea.
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