Some plants, apart from serving as food, have also been known to exhibit
medicinal properties (Borget, 1993; Ozuola et al., 2006). Over
400,000 species of tropical flowering plants have medicinal properties,
a factor that may have made traditional medicine cheaper than modern medicine
(Akpulu et al., 1994; Aibinu, 2004).
Although plant based natural medicines are popularly acclaimed to be
safe, scientists advocate for proper toxicological studies (Oyewole et
al., 2007; Ozolua et al., 2006) in other to ensure safety in
the use of natural medicines. Toxicity is the undesirable property of
any drug or chemical capable of producing injurious or detrimental effects
on a living organism. Whether or not these injuries occur depend on the
amount of chemical absorbed (Gossel and Bricker, 1990; Betram, 1998).
The toxic effect caused by a drug is similar in man and some other animals,
a premise for use of animal models in toxicological studies (Range et
al., 1995). Most toxic effects of drugs occur at a predictable time
after administration. However, the target organ of toxicity is not necessarily
the site of accumulation of the chemical (Curtis, 2001).
Jatropha tanjorensis belongs to the Family Euphorbiaceae, it is
a common weed of field crops, bush re-growth, road sides and disturbed
places in the higher rainfall forest zones of west Africa. It is commonly
called hospital too far, catholic vegetable, iyana-ipaja, lapalapa (Iwalewa
et al., 2005). The leaf is a commonly consumed vegetable in many
parts of Southern Nigeria. It is also popular as a natural remedy against
diabetes in this region (Olayiwola et al., 2004). Phytochemical
screening of J. tanjorensis leaf revealed that it contains bioactive
principles such as alkaloids, flavonoids, tannins, cardiac glycosides,
anthraquinones and saponins (Ehimwenma and Osagie, 2007).
It is popular as a natural remedy against malaria infection and hypertension
in some parts of Nigeria, however there is dearth in scientific validation
of these claims.
In the present study, we investigated the toxicity profile of J. tanjorensis
by examining the body and organ weights, hematology and histopathology
of rabbits treated with the leaves of the plant.
MATERIALS AND METHODS
The plant material used in this study was harvested in the month of March,
2007 from the vicinity of a home garden in BDPA, Ugbowo, Benin City, Nigeria.
The plant was identified as J. tanjorensis by Professor MacDonald
Idu of the Botany Department, University of Benin, Benin City, Nigeria.
Voucher specimen was deposited in the herbarium of Botany Department,
University of Benin, Benin City, Nigeria.
The harvested leaves were air-dried for 2 days then further dried in
an oven at 40 °C for 24 h. before grinding. The ground leaves were
preserved in moisture-free, airtight laboratory containers for further
use. Forty rabbits (20 male and 20 female) weighing between 1.3 and 1.5
kg were bought from Aduwawa Market in Benin City and acclimatized in the
Animal House, for 2 weeks. The rabbits were divided by sex into 4 groups
of 5 animals per cage. They were provided with commercial feed-mash and
water ad libitum. Colored marker pen was used to distinctly label
each animal for easy identification.
Jatropha tanjorensis powder was mixed with commercial feed and
administered to the rabbit treatment groups viz., 5:95, 10:90 and 25:75%
of plant to feed mash representing groups B, C and D, respectively. While
the control (group) was administered feed-mash only (0:100).
Physical characteristics such as agility, appetite and eye color were
closely observed through out the period. The average weekly weight of
rabbit in each group was recorded. After the 5th week period, blood samples
were collected through the marginal ear vein of each rabbit with small
needles and 5 mL of the blood sample was kept in EDTA (ethylenediaminetetra
acetic acid) bottles for analysis. The hematological examination was performed
using an automatic multichannel blood cell counter (Systemx Kx 21 Haematology
Analyser). The parameters included hematocrit value (HCT), red blood cell
count (RBC), white blood cell count (WBC), hemoglobin (HG), mean corpuscular
volume (MCV) mean corpuscular hemoglobin concentration (MCHC), platelets
(PLT), lymphocytes (LYMPH), neutrophils (NEUT), mixed (MXD), red cell
distribution width (RDW) and platelet cell distribution width (PDW).
The animals were then sacrificed by cervical dislocation and immediately
dissected in order to collect the relevant organs, which were fixed in
formaldehyde before weighing. The organs were dehydrated in different
stages of alcohol concentration and cleared in toluene. The tissues were
then impregnated in molten paraffin and embedded. Sectioning was done
at 3 μ and stained using eosin and haematoxylin. The samples were
finally cleared in xylene and mounted in paraffin wax.
The mean, standard deviation and standard error and the level of significance
for the differences between means were calculated by using SPSS 10. The
level of significance was at p = 0.05
RESULTS AND DISCUSSION
Table 1 reports on physical observations. Only the
female groups B, C and D had moderate appetite for the feed preparation
when compared with the control and other treatment groups.
Table 2 shows there was no significant difference in
average body weight between the treatment groups and the control and between
Table 3 shows that HGB, HCT and PLT values in female
Group D were significantly higher, 11.83 ± 0.69, 36.03 ±
1.87 and 394.00 ± 103.41 than those of the control, 5.47 ±
3.37, 16.13 ± 10.41 and 94.33 ± 47.90, respectively.
|| Effect of 5 weeks consumption of J. tanjorensis on
some physical parameters in rabbits
|+++ : High appetite, ++ : Moderate appetite
|| Effect of intake of J. tanjorensis leaves on the average
body weights of rabbits
|Values and expressed as Mean ± SD with similar
superscript within a row are not significantly different, p>0.05
Table 4 reveals that apart from the female spleen,
significant differences were recorded in all other isolated organs between
the control and treated rabbits. Spleen weight of the male control (0.23
± 0.15) was significantly lower than Groups B, C and D (0.5 ±
0.15, 0.43 ± 0.57 and 0.53 ± 0.11, respectively). However,
the treatments were not significantly different for the same organ.
Table 5 reveals that most the organs showed very mild
histopathologic changes compared with the control. Severe triaditis was
however observed in the liver of female treatment group compared with
that of the male treatment group.
The observations of behavioral, hematological and histological parameters
have been employed in toxicological studies (Basu and Arivukkarasu, 2006).
Decrease in body weight could either be due to the effect of a plant material
on the internal organs or to general discomfort resulting in lowered feeding
in treated animals (Brodie et al., 1970).
In the present study, the agility, the treatments did not appear to have
any observable influence on the agility, eye colour and appetites of the
rabbits and there was no significant difference (p>0.05) in the average
body weight of treatment groups compared with the control group after
5 weeks (Table 1, 2).
The significantly higher HGB, HCT and PLT values in the female Group
D of 11.83 ± 0.69, 36.03 ± 1.87 and 394.00 ± 103.41,
respectively compared with 5.47 ± 3.37, 16.13 ± 10.41 and
94.33 ± 47.90 (Table 3) for the control may be
an indication of improvement in the bone marrow function. This is in line
with the views of Oduola et al. (2007).
Although significant differences were recorded in the weights of most
of the isolated organs, no regular pattern could however be established
in both sexes (Table 4). Whereas the weight of the right
kidney in the 25% treatment male group was significantly lower (4.23 ±
0.32) than the control (5.92 ± 0.36), the reverse was recorded
for the female rabbits as similar treatment recorded a significantly higher
value (4.23 ± 0.32) than the control (3.70 ± 0.17).
|| Effect of Jatropha tanjorensis leaves on hematological
parameters of rabbits
|n = 5 replicates, Mean ± SE with similar superscript
within a row are not significantly different at p>0.05, Mean ±
SE with different Superscript within a row are significantly different
at p<0.05 HT: Hematocrit value RBC: Red blood cell count, WBC:
White blood cell count, HGB: Hemoglobin level, MCV: Mean corpuscular
volume, MCHC: Mean corpuscular hemoglobin concentration, PLT: Platelets,
LYMPH: Lymphocytes, neutrophils, MXD: Mixed, RDW: Red cell distribution
width and PDW: Platelet cell distribution width
|| Organ weights in rabbits given feed containing varying concentrations
of J. tanjorensis leaves
|n = 5 replicates Mean ± SE with different superscript
within a row are significantly different, p<0.05. Mean ±
SE with similar superscript within a row are not significantly different,
|| Incidence of histopathologic findings in rabbits given feed
containing J. tanjorensis leaves for 5 weeks
|+= Moderate, ++= Severe, n = 5 replicates
The histopathology revealed that the heart, liver and kidney showed areas
of mild necrosis (Table 5). Although there was severe
triaditis in the liver of the female treatment group compared with that
of the male, such isolated event cannot sufficiently be interpreted as
meaningful toxicological effect.
There was no noticeable neurological sign in the 25% group in the present
study suggesting that the possibility of the induction of neurotoxic effects
of J. tanjorensis is quite low even with the ingestion of up to
25% of the plant.
In conclusion, this study reveals that the toxicity profile of J.
tanjorensis is low since no observable adverse effect (NOAE) was recorded
in this study. However, specific dose preparation and administration using
syringe (oral, intramuscular or intravenous) may yield more precise results
compared with the challenge of differential appetite observed in the present