Abstract
Background.
There are numerous medicinal plants including the leaves of
Methods.
The laxative activity of the leaves of
Results.
Significant increase was observed in the mean weight of wet fecal matter at 200 (1.00 ± 0.03 g,
Conclusion.
The results of the present study indicated that 80% methanol extract of the leaves of
Constipation is a common bowel problem with symptoms, including difficulty or infrequent passage of stool, hardness of stool or a feeling of incomplete stool evacuation and often associated with pain. 1,2 According to Rome III criteria, constipation is diagnosed if loose stools rarely present and 2 or more of the following symptoms are seen at least for 3 months: straining, lumpy or hard stool, sensation of incomplete evacuation, and anorectal obstruction or blockage of defecation and need of manual maneuvers to facilitate in 25% or more of defecation. 3 Constipation can be classified into primary and secondary depending on the cause. Primary causes are intrinsic problems of colonic or anorectal function, whereas secondary causes are related to disease or medications use. 4
Constipation affects people of all ages, but persons 65 years old or older are most affected. The occurrence of the disease becomes frequent with advancing age, but it should not be considered that it is necessarily a result of advancing age. A systematic review conducted in 2011 reported that worldwide prevalence rates of constipation ranging from 0.7% to 79% among the older population.
4
–6
Another systematic review and meta-analysis study showed that overall prevalence of chronic idiopathic constipation (CIC) was 14% and higher in women compared with men.
7
A survey done in Canada indicated that the rate of constipation for women was close to twice of the rate among men.
5
A study in Ethiopia reported that 56% of patients with acute abdominal pain showed symptom of constipation.
8
Other similar studies in Ethiopia also revealed that the prevalence of constipation among
In most cases, constipation is a symptom of other underlying conditions, not a disease by itself. The possible causes of constipation could be disease related like gastrointestinal disorders, endocrine and metabolic disorders and neurological disorders. Drugs having anticholinergic effect, antidepressants, oral iron supplements, aluminum-containing compounds, clonidine, calcium antagonists, and ganglionic blockers, which reduce smooth muscle contractility, can also cause constipation. 11 –13
Constipation is a predisposing factor to colorectal disorders such as enlarged hemorrhoids and colorectal cancer. 14 Chronic constipation significantly compromises health-related quality of life. 15 Compared with the general population, patients of constipation are generally with impaired quality of life. The effect of constipation on quality of life is comparable with the more recognized conditions such as osteoarthritis, osteoporosis, and chronic allergies. So the physical consequences and impact of constipation on quality of life should be given due attention. 6 The burden of chronic constipation also goes to a loss in work productivity and affects employment and social activities. 16
Constipation can be managed by using nonpharmacologic approaches and/or pharmacologic agents. The common nonpharmacologic management includes dietary (fiber and adequate fluid intake), life style modification, and surgery.
17
Pharmacologic agents used in the treatment of constipation include drugs such as laxatives, colonic secretagogues, opioid antagonists, and serotonin receptor agonists.
18
–24
However, studies showed that around 47% of patients are not satisfied with their current constipation treatments reflecting reasons for dissatisfaction such as efficacy related (less effective and inconsistent results), adverse effects and cost concerns.
25
As a result, there are number of herbal alternative remedies used for the treatment of constipation around the world. Some of the medicinal plants that are traditionally used for the treatment of constipation include
According to World Health Organization estimation, about 80% of Africans depend on plant based traditional medicine for their primary health care needs. 31 A study showed that approximately 80% of the population in Ethiopia depends on traditional medicines to treat different diseases, including constipation. 32 High percentages of useful drugs have been found from plants used in traditional medicine by scientific investigation; so it is a good approach to discover other useful drugs from plants. 33
The plant
Methods
Drugs and Chemicals
Methanol absolute (Loba Chemie), loperamide HCl (Macleods Pharmaceuticals Ltd), castor oil (Amman Pharmaceutical Industries Co), bisacodyl (Remedica), Tween 80 (Blulux Laboratories), and charcoal (Lab Reagents) were the drugs/chemicals used in the study. Additionally, the reagents used in phytochemical screening test included glacial acetic acid (Blulux Laboratories), Mayer’s reagent (Research Lab Fine Chemical Industries), ammonia (Loba Chemie), ferric chloride (Fisher Scientific), sulfuric acid (HiMedia Laboratories), and benzene (Blulux Laboratories).
The Plant Material
Fresh leaves and the aerial part of
Extraction of Plant Material
The leaves of the plant were cleaned by rinsing with tap water and dried under shade at room temperature. After drying, the leaves were crushed to coarse powder using mortar and pestle. Then 900 g of the powder was macerated with 80% methanol in 100 g to 500 mL ratio. The macerate was kept for 72 hours with occasional shaking. Then the extract was filtered using Whatman filter paper (grade 3) and the marc was remacerated and filtered 2 times with the same volume of solvent in each round. The filtrate was concentrated using rotary evaporator and freeze drier to remove methanol and aqueous parts of the solvent, respectively. Then the dried extract was weighed and transferred into vials and kept in refrigerator until used. The extract was reconstituted with 2% Tween 80 suspending agent for oral administration during the experimental procedure. 41
Experimental Animals
Swiss albino mice of either sex, weighing 20 to 30 g, were obtained from the Animal House Unit of Ethiopian Health and Nutrition Research Institute (EHNRI), Addis Ababa, Ethiopia. The mice were housed in plastic cages under standard environmental conditions with a 12-hour light and dark cycle. The animals were provided with the standard food and water ad libitum. They were acclimatized to the experimental environment for a period of 7 days before the beginning of the experiment. 42
Preliminary Phytochemical Screening Test
The crude extract of the leaves of
Acute Oral Toxicity Test
An acute oral toxicity test was conducted, as per OECD 425 guideline, using 2000 mg/kg body weight limit dose of the crude extract in mice. 47
Induction of Constipation
Loperamide, 5 mg/kg in 2% Tween 80 once daily, was given orally for 6 days to the mice to be included in constipated negative controls, test groups, or constipated positive controls. The normal control group was treated with 2% Tween 80, 10 mL/kg for the same duration. All animals were allowed to access food and water ad libitum. 48,49
Laxative Activity Test in Loperamide Constipated Mice
One group containing 5 mice was used as normal control. The constipated mice were divided into 5 groups, each containing 5 mice and assigned group numbers 2 to 6. Then all groups were treated once daily for 5 days as follows. Group 1 (normal control): received 10 mL/kg of 2% Tween 80 Group 2 (constipated negative control): received 10 mL/kg of 2% Tween 80 Groups 3, 4, and 5 (test groups): received 100, 200, and 400 mg/kg of crude extract, respectively Group 6 (constipated positive control): treated with 0.25 mg/kg of bisacodyl
The mice were fasted overnight before they received the fifth dose. Following administration of the fifth dose they were kept in separate cages with nonabsorbable paper. Then fresh fecal pellets/wet feces from individual mice were collected in a 2-hour interval over a 12-hour period and counted and weighed. The fecal matter was then dried for 24 hours at room temperature and reweighed to determine dry fecal weight. Then percent fecal water content was calculated using the following formula. 49
Gastrointestinal Motility Test in Loperamide Constipated Mice
The mice were grouped and treated as described above for laxative activity test in loperamide constipated mice. The mice were fasted for 12 hours prior to the fifth dose of Tween 80, the extract, or bisacodyl while free access to water was allowed. After 40 minutes of the fifth dose, each animal received 0.3 mL of freshly prepared 5% aqueous suspension of charcoal meal orally. Then the animals were sacrificed and the small intestine of each was dissected out from the pylorus to caecum after 30 minutes of charcoal meal administration. The ratio of distance traveled by the charcoal meal to the length of small intestine was calculated for each animal as follows.
50
Gastrointestinal Secretion Test in Normal Mice
Twenty-five albino mice were fasted for 18 hours and grouped into 5 groups each containing 5 mice. Group 1 (negative control) was treated with 2% Tween 80, 10 mL/kg while group 2 (positive control) was given castor oil 0.5 mL per animal. Groups 3, 4, and 5 (test groups) were given 100, 200, and 400 mg/kg of the crude extract, respectively. After 1 hour of administration, all the animals were sacrificed, and the small intestine of each mouse was cutout from the pylorus to the cecum and weighed immediately. Thereafter, its content was removed by milking and reweighed. Then the weight difference of small intestine before and after milking was calculated for each animal. 51
Statistical Analysis
SPSS version 20 was used for statistical analysis. The results were expressed as mean ± standard error of the mean (SEM). A difference between groups compared was determined by 1-way analysis of variance followed by post hoc Tukey’s multiple comparison test. At
Results
Phytochemical Screen Tests
The preliminary phytochemical screening test on the plant extract determined the presence of phenols, flavonoids, steroids, saponins, and tannins.
Acute Oral Toxicity
The animals given the limit dose, 2000 mg/kg, of the extract showed no sign of toxicity except hunched posture, erected furs and slight diarrhea during the first 4 hours. Furthermore, no animal died in the 14-day follow up.
Laxative Effect of the Crude Extract in Loperamide Constipated Mice
Loperamide was used to induce constipation and it clearly reduced number, weight, and water content of feces.
Laxative Effect of
* Results expressed as mean ± SEM (n = 5). 1
The Effect of the Crude Extract on Gastrointestinal Motility in Loperamide Constipated Mice
The effect of
Effect of
* Results expressed as mean ± SEM (n = 5). 1
Gastrointestinal Secretion Effect of the Crude Extract in Normal Mice
The crude extract showed significant increases in intestinal fluid accumulation at 200 mg/kg (0.48 ± 0.07 g,

Effect of
Discussion
A published ethnobotanical study conducted in Ethiopia reported that the leaf part of
In this study, loperamide was used for induction of constipation (except in intestinal fluid accumulation) because previous literatures indicated that the administration of 2 to 5 mg/kg body weight of loperamide through oral or subcutaneous route for 3 to 7 days can effectively induce constipation in rodents. 48,49,55 –57 The mice treated with loperamide showed decrease in frequency of defecation, weight of wet feces, and fecal moisture content compared with nonconstipated (normal control) group. These symptoms are manifestations of constipation. 58 So increments in these parameters by the plant extract could be considered because of the laxative activity of the plant extract counteracting the constipation induced by loperamide.
In loperamide-induced constipation model, the plant extract produced a significant increase in the mean weight (at 200 and 400 mg/kg) and percent water content of feces (at all doses) compared with the constipated control group. This might indicate the laxative activity of the plant extract, that is, the reversal of constipation produced by loperamide as a result of the treatment by the plant extract. The most significant increase in the wet fecal weight and fecal water content was produced by bisacodyl. This may be due to lower concentrations of the active principles responsible for the laxative activity of the plant extract rather than efficacy problem. As can be seen in Table 1, slight or significant increase in mean fecal weight and fecal water content was observed with increasing dose of the plant extract.
In the gastrointestinal motility test model, the extract was able to increase intestinal motility as revealed by significant increase in the intestinal length traveled by charcoal meal in the highest dose of the extract. Furthermore, the results in this model showed an increasing tendency of the stimulatory effect on the gastrointestinal motility as the dose of the plant extract increased. The significant increase in the gastrointestinal transit ratio value by the middle (
The third model was done to investigate the effect of
In the present study, even though there was no significant difference seen in the frequency of defecation, the crude extract still could be considered having benefit in treating constipation as statistically significant increases in fecal mass and fecal water content were scored at least at the middle and the highest doses compared to constipated control. Increasing in the frequency of defecation alone cannot determine the laxative activity of a given plant extract unless accompanied by increasing fecal mass and moisture. This can be best explained by the fact that some types of constipations are characterized by hard and dry stool with a normal frequency of defecation or small and incomplete evacuation with frequent bowel movement. It has been also shown that constipation is more related to a condition of inability to evacuate stool completely and easily in every toilet rather than to decreasing in the number of bowel movements. 4,61
The presence of phytochemicals like flavonoids, saponins, tannins, sterols, terpenoids, alkaloids, phenolic compounds in different plant extracts were reported to be responsible for stimulant, laxative, and gastrointestinal propulsive activities of the plants.
62
Saponins have been reported to have smooth muscle contraction effect.
63
Some types of flavonoids like naringenin and apigenin shown to increase Cl− secretion in colonic epithelia of loperamide induced constipated animals and have a good laxative profile.
64
Qualitative phytochemical screening test on methanol extract of the leaves of
Conclusion
The findings of the present study indicated that 80% methanol extract of the leaves of
Supplemental Material
Supplemental Material, Manuscript_data - Laxative Activities of 80% Methanolic Extract of the Leaves of Grewia ferruginea Hochst Ex A Rich in Mice
Supplemental Material, Manuscript_data for Laxative Activities of 80% Methanolic Extract of the Leaves of
Footnotes
Acknowledgments
We would like to acknowledge Amhara Regional State Health Bureau for some financial support to undertake this study as a thesis in partial fulfillment of the requirements for MSc degree in pharmacology of the first author. We are also thankful to University of Gondar, Department of Pharmacology for allowing us to use the laboratory facility. The authors are also grateful to Mr Zemene Demelash for his technical support during the laboratory activities and Mrs Banchamlak Demamu for caring the laboratory animals used for this study.
Author Contributions
All the authors participated in proposing the title, proposal preparation and writing up of the final report. MYT conducted the laboratory activities, data compilation, and analysis. The manuscript was prepared by ABA. Finally, MYT and ZBW reviewed the manuscript before submission for publication. Moreover, all authors are responsible regarding the originality and correctness of this work.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Amhara Regional State Health Bureau. Some financial support to purchase laboratory chemicals and animals used was received from Amhara Regional State Health Bureau as this work was the thesis for partial fulfillment of requirements for MSc degree in pharmacology for the first author. Amhara Regional State Health Bureau was a sponsor of the MSc study to the first author.
Ethical Approval
The animals used in this experiment were handled according to a guideline for the care and use of laboratory animals and the ethical clearance was obtained from the Experimental Animals Ethics Committee, Department of Pharmacology, University of Gondar prior to the study.
Supplemental Material
Supplemental material for this article is available online.
References
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