Background
Peptic ulcer is a clinical defect in the gastrointestinal mucosa lining, characterized with sores that develop along the epithelial lining of the stomach, lower esophagus, or small intestine. The prevalence has been attributed to the changing prevalence of
Helicobacter pylori (
H. pylori) infection, the increasing use of non-steroidal anti-inflammatory drugs, and the aging population [
1‐
3]. Peptic ulcer was reported as one of the world’s major gastrointestinal disorders. It was reported to affect as high as 10% of the world population with a death rate of as high as 15,000 yearly [
1]. Although, the true prevalence of peptic ulcer in Nigeria is unknown, report showed that peptic ulcer disease is very common in Africa with an estimated prevalent rate of 70 to 90% especially among young adults contrary to what was obtainable in Europe where prevalence is higher among adults above 40 years of age [
2‐
5].
The medical intervention in the treatment of peptic ulcer is predicated on the prognosis. However, treatment includes the use of antibiotics, antiacids and discontinuation of the ue of non steroidal anti inflammatory drugs (NSAIDs) which could provoke its development. Disease causing microbes are fast developing resistance to the lines of antibiotics commonly prscribed [
6], and thus the quest for new and more effective drugs for use. Research work towards the development of new drugs from medicinal plants is thus attracting increasing interest. Many medicinal plants and other naturally products are continuously been screened for their potential in developing new and more effective drugs. Although, medicinal plants and other natural products may possess biological activities that are beneficial to humans, many are used in folk medicine without taking into account their toxicity and other related adverse effects [
7]. There is therefore the need to evaluate these products for possible toxic effect on the body systems when consumed by man or his animals.
Mystomate4® is a polyherbal formulation with claims of effectiveness in the treatment of ulcer. According to the manufacturer; Egflorence Biosciences Ltd., Lagos, the formulation contains grounded charcoal,
Brassica juncea (L.) Czern seed and sodium chloride suspended in edible oil. It is a formulation locally used in the treatment of peptic ulcer. There are few reports on possible anti-ulceractive activities of the constituents. Olive oil an edible oil was reported to express bacteriocidal effect against
H. pylori a major peptic ulcer causative agent [
8] while the
Brassica juncea seed has been reported to possess antioxidant and anti-colon cancer activity [
9,
10]. The objective of this study therefore, was to investigate the acute and sub-chronic toxicity effect of Mystomate4® as well as the gastroprotective activity or anti ulcerative activities in laboratory animals.
Materials and methods
The herbal formulation (Mystomate4®) contains ground charcoal (4000 mg), Brassica juncea seed (2500 mg) and sodium chloride (550 mg) all suspended in 15 ml of edible oil. Mystomate4® was obtained from Egflorence Biosciences Ltd., Lagos-Nigeria. The preparation has a stock concentration of 0.47 g/ml of edible oil.
Animal
Healthy male
Swiss mice (20–21 g) were used for the acute toxicity study while the male and female
Sprague Dawley rats weighing between 120 and 140 g were used for the sub-chronic and the gastro protective study. They were maintained under standard laboratory conditions in temperature-controlled rooms (24–28 °C), under a 12:12 h light–dark cycle, with access to water and food
ad libitum. Animal care and handling procedures were in accordance with the International Association for the Study of Pain guidelines for the use of animals in pain research [
11]. All experimental animals used in this study were obtained from the Animal house of the College of Medicicne, University of Lagos.
Toxicity study
Acute toxicity study
The acute toxicity study was performed according to the Organization of Economic Co-operation and Development (OECD) guideline for testing of chemicals (OECD, 2001). All methods used also comply with the ethical regulations as provided by College of Medicine, University of Lagos. The male mice were weighed and divided into eight groups containing eight mice each. The mice were given a single dose from graded doses that ranged from 1.28, 2.56, 5.12, 10.24, 20.48, 40.96, 81.92 to 163.84 g/kg of the formulation. The doses used were arrived at after an initial pilot study to determine an average dose at which lethality was first recorded. Doses used during the pilot study rangeds from 0.1 to 200 g/kg and thereafter doses were chosen around the dose obtained from the pilot study. The formulation was administered orally using a mice-size oral dosing needle after an overnight fast. The mice were thereafter monitored for 72 h for sign and symptoms of toxicity and till 7 days for delayed toxicity symptoms. Water and feed was provided ad libitum and number of death and life mice was recorded for each group within the observation period. All doses used were dispensed from the stock solution of 0.47 g/ml of edible oil.
Sub-chronic toxicity study
The sub-chronic toxicity study was designed to evaluate the system toxicity of doses of the Mystomate4® administered orally over a period of 3 months. The test was carried out in line with OECD guideline for testing of chemicals [
12]. The doses used (2.5 g/kg and 5.0 g/kg body weight) were arrived at by titrating down the LD
50 value obtained from the acute toxicity study [
13]. There were five groups of 6 rats each; control (CN), 2.5 g/kg male (LM), 2.5 g/kg female (LF), 5.0 g/kg male (HM) and 5.0 g/kg female (HF) groups. All doses used were dispensed from the stock solution of 0.47 g/ml of edible oil. All the laboratory rats used in the sub-chronic study were gavage the Mystomate4® for a period of 3 months (90 days), while the control received equal volume of the vehicle (edible oil). Weekly weight and daily feed consumption per rat was measured. At the end of the 3 months treatment, the rats were sacrificed by cervical dislocation followed by decapitation and blood samples collected into heparinised sample bottles. Blood samples were centrifuged at 3500 revolutions per min at a temperature of 25 °C for 20 min. The plasma was carefully separated with the aid of a sterile pasteur pipette and stored at − 80 °C.
Blood analysis for toxicity confirmation
The plasma collected was used for assessment of toxicity test and the plasma lipid profile respectively. The following toxicity biomarkers were analyzed from the blood samples collected from the different group of animals after the 3 months period; Blood Urea, Total Protein (TP), Albumin, Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Serum Alkaline Phosphatase (SAP), blood urea nitrogen (BUN) and blood and urine creatinine assay using ELISA assay kits produced by Sigma-Aldrich, Cayman Chemical USA and Elabscience China. The toxicity effects of the oral administration of the Mystomate4® on the liver and the kidney was evaluated in male and female Sprague-Dawley rats. Serum lipid profile level was also assessed using the appropriate ELISA lipid profile assay kits from Elabscience, China. Assay was carried out according to the manufacturer protocol.
Histopathologic studies of vital organs involved with body detoxification
The following organs were carefully harvested over ice and their wet weight taken; the liver, the kidney and the spleen. The kidney and the liver samples were placed in Boin solution for 2 days after which the Boin solution was replaced with 70% alcohol. The 70% alcohol was changed twice after every 3 three days. The tissue was passed through graded concentration of alcohol as follows; 80% alcohol for 1 h, (2x), 90% alcohol for 1 h (2x), 95% alcohol for 1 h, 100% alcohol for 1 h (2x), 50% + 50% xylene for 1 h, xylene for 45 min. The tissue was removed and placed in the metal tissue mould with molten wax in the oven (50 °C) for 45 min. After 45 min, the mould was removed and the mould basket placed on it and more molten wax added. The mold containing the waxed tissue was placed in a fridge at 0 °C to for 15 min to allow it to solidify. Five micrometer size of the tissue was prepared with a rotary microtome (LEICA RM 2235 rotary microtome) and placed on a glass slide pre-coated with lysine. The slides were thereafter stained with haematoxylin and eosin (H&E) and viewed under the microscope at a magnification of × 400.
Ulcer study
Ethanol-induced gastric ulcer model
The gastrointestinal protective potential of the formulation against ethanol-induced gastric ulcer model was investigated in rats. Prior to the experiment, male rats weighing between 110 and 130 g were fasted for 24 h. Thirty-five rats were divided randomly into 5 groups of 7 rats each and pre-treated orally with the vehicle (edible oil, 10 ml/kg), misoprostol (0.1 mg//kg) a standard antiulcer drug as control or Mystomate4® (1.14, 2.28 and 3.43 mg/kg,). After 1 h of pre-treatment, all the rats were gavage with 80% ethanol solution (1 mL/animal). The rats were sacrificed 1 h later by cervical dislocation and their stomachs were immediately excised, cut along greater curvature, rinsed with normal saline and ulcer scored according to the method of Galati et al. (2001) [
14]. Ethanol is a gastric acid secretagogue stimulating increase gastric acid secretion from the gastric gland.
Indomethacin-induced gastric ulcer model
Rats fasted for 36 h were treated with vehicle (edible oil, 10 ml/kg or Mystomate4® (1.14, 2.28 and 3.43 mg/kg,). One hour later, indomethacin was given to rats orally at the dose of 80 mg/kg [
15]. The animals were sacrificed after 6 h. The stomachs were removed, washed gently with saline (0.9%) and scored as referenced in ethanol-induced model. Indomethacin is a non steroidal anti inflammatory drugs (NSAIDs), induced gastric ulcer via inhibiting the release of cyclooxygenase-1 (COX-1), prostaglandin E2 (PGE2) [
16].
Pylorus ligation-induced gastric ulcer model
The animals were divided into 5 groups, each consisting of six rats. Group 1 serves as the control and received edible oil, 10 ml/kg only. Group II, III and IV received the Mystomate4® at the doses of 1.14, 2.28 and 3.43 mg/kg, while group V received cimetidine at the dose of 40 mg/kg. After 1 h of the treatment pylorus ligation was done. Ligation was done without causing any damage to the blood supply of the stomach. Six hours after the ligation, the animals were sacrificed and the stomach removed. The gastric contents were collected, centrifuged and the supernatant measured. The ulcer formed in the gastric mucosa were measured and scored as described earlier [
17].
Analysis of data
Data are expressed as mean ± SEM. Statistical analysis was performed with one-way analysis of variance followed by Tukey’s test as post hoc test using Graph Pad Prism version 5.0 for Windows (San Diego, CA, USA). The level of data significance was set at p ≤ 0.05. LD50 result was arrived at by plotting the nonlinear regression graph of percentage number of deaths with increasing doses of Mystomate4®using Graph Pad Prism version 5.0 for Windows (San Diego, CA, USA).
Compliance with ethical standards
All methods and procedures used in this study including the care and the use of laboratory animal for biomedical research were approved by the Health Research and Ethical Committee of the College of Medicine, University of Lagos, Nigeria (CM/HREC/12/16/094), and they are in accordance with International best practices in the use of laboratory animal in Biomedical research.
Discussion
Acute toxicity test is aimed at determining toxic manifestations of any test substance in animals that are exposed to graded doses of the test substance within a single 24-h period. Acute oral toxicity study of Mystomate4® revealed an oral LD
50 value of 22,837.21 g/kg body weight. The LD
50 result for Mystomate4® was far above the proposed 5000–15,000 mg/kg body weight value at which any substance can be said to be practically nontoxic [
18,
19]. The Mystomate4® was further subjected to a sub-chronic toxicity test with determination of serum level of some indicators of organ and tissue toxicity such as alanine amino transferase (ALT), alkaline phosphatase (Alk-Phos), creatinine, bilirubin, urea, uric acid and total protein. The weekly weight of all the treated rats showed a significant decrease in weight compared to control group all through the period of the experiment except for the HM-5 mg group whose body weight was not significantly different from control at the end of the 12 weeks of treatment (Fig.
2). The decreased weight gain was due to a decrease in feed consumption in all the affected group of rats (Tab.
1) as a result of decreased feed acceptability due to the effect of the polyherbral mixture on the animal taste taste bud. The coefficient of organ weight revelaed no significant changes in the weights of neither the liver, the spleen nor the kidney in all the treated groups. Liver, kidney and spleen are important detoxification organs of the body and they usually record hyperthrophy due to excessive detoxification activities whenever the body is under toxicity assult [
20].
The serum level of ALT was significantly elevated in the 5 mg/kg treated male and female rats as well as the 2.5 mg/kg treated male rats (Tab
3). ALT is an enzyme contained in the fluid found in the liver cells, with resultant increase in the blood level depending on the degree of damage to the liver tissue [
21]. Thus, the elevated level of ALT especially at 5 mg/kg showed a possible liver toxicity effect as a result of long period (12 weeks) of exposure despite the non significant change recorded in the weight of the liver from Mystomate4® treated rats. The alkaline phosphatase level was also significantly elevated in the serum samples from male rats exposed at 5 mg/kg body weight. The alkaline phosphatase enzyme is found primarily in the liver and bones but also in other tissues of the body. The significant increase in alkaline phosphatase level has been used as a biomarker of inflammation and possible damage to the tissue [
22,
23]. Further analysis of the serum level of AST and uric acid revealed no significant change in any of the treated groups compared to control. However, there was a significant decrease in the level of creatinine in the female groups treated with 2.5 mg/kg and 5 mg/kg, while the serum urea level was also signizficantly lowered in 2.5 mg/kg and 5 mg/ kg treated male rats.
Creatinine is a bye product of the breakdown of creatinine phosphate by the activities of creatinine phosphokinase [
24]. Blood creatinine level is a very useful biomarker of kidney functions [
25]. The decreased serum level of creatinine showed no adverse effect on the kidney function. The serum bilirubin level was significantly lowered compared to control group among the 2.5 mg/kg treated male and female rats. Bilirubin is a breakdown product of heme obtained from red blood cells. High concentration of bilirubin in the blood is an indication of possible increased destruction of red blood cells or compromise of the red cell membrane integrity [
26]. It could also give an indication of early liver deficiency in the conjugation process leading to removal of bilirubin from circulation for onward deposit into the gall bladder [
27].
Furthermore, there was a significant increase in the serum albumin level in the 2.5 mg/kg group. This was despite the non significant change recorded in the result of the total serum protein in the same group. The total blood protein includes clotting factors, enzymes, antibodies, transport substances, albumin and most of the alpha and beta globulins. The urea assay result however, was significantly reduced in the blood samples from male and female rats dosed with 5 mg/kg of the Mystomate4®. Urea is a by-product of the breakdown of protein in the liver. High level of blood urea indicates that the kidney is unable to properly clear urea from circulation [
28]. The significant decrease in the blood urea recorded in all the 5 mg/kg treated rats in this study portent no adverse effect on the liver function. An analysis of the blood urea, creatinine and the blood urea-creatinine ratio when considered together gives a good indicator useful in differentiating kidney disease from dietary protein metabolism problems as well as possible degree of bodily hydration. The blood urea-creatinine ratio results in this study were all significantly reduced compared with the control group again showing that the functions of the kidney was not compromised [
29].
The serum triglyceride level was significantly increased in all the Mystomate4® treated rats compared to the control. This was in addition to the significant decrease and increase recorded in the serum level of LDL in 2.5 mg/kg and 5 mg/kg treated male rats respectively. Triglyceride is a known independent indicator and risk factor for coronary heart diseases when LDL:HDL ratio is elevated [
30]. The results of the histological studies of the liver and kidney tissues (Figs.
3 and
4) from all treated animals and control revealed a normal architecture with intact cellular components. The results of the histological studies further buttress the results of the relative organ weight, biochemical analysis and the sub chronic toxicity studies in which the Mystomate4® showed no significant toxicity on the liver and kidney in all the exposed rats compared with the control.
The gastro protective activity of the Mystomate4® was investigated in three models of antiulcer assays; ethanol, indomethacin and pylorus ligated-induced models. Ethanol induced gastric ulcers have been widely used for evaluation of gastrointestinal protective activity [
31]. Ethanol directly induces injury to the mucosa of gastric, declining the bicarbonates secretion and the generation of mucus [
32]. In this model, the formulation showed a significant reduction in the mean ulcer score at all doses administered compared to control. These results indicate that Mystomate4® possess an antiulcer activity which could be related to cytoprotective activity.
Indomethacin like other NSAIDs such as aspirin, adversely affect the gastroduodenal mucus causing ulcerative lesions on the mucus membrane. One of the main factors of indomethacin-induced gastric damage is the inhibition of prostaglandin synthesis through the cyclooxygenase pathway. Other mechanisms include decreased blood supply to the gastric mucosa, increased gastric acid secretion, as well as inactivation of the growth factors involved in mucosa defense and repair [
33,
34]. The formulation significantly reduced mucosal damage in the indomethacin–induced ulcer model, suggesting the possible involvement of prostaglandin in the gastrointestinal protective effect of the polyherbal formulation.
The effect of the treatment of the polyherbal formulation on the parameters of gastric secretion was also determined using the pylorus ligation-induced antiulcer model. Ulcers induced by this model are due to accumulation of gastric acid and pepsin which leads to digestion of gastric mucosa [
35]. The formulation reduced ulcer index but did not significantly (
P > 0.05) affect the gastric secretion volume, pH and H
+ concentration. These findings suggest that the gastrointestinal protective action of the formulation may not involve anti gastric acid secretory activity. The major components of the formulation are
Brassica juncea seed and edible oil .
Brassica juncea seeds have been shown to possess antioxidant activity [
11]. Olive oil is an example of edible oil and has been reported to contain high amount of phenolic compounds with antioxidant properties and other potent biological activities including anti-ulcer activity [
8,
36‐
40], that could partially account for the observed effect. However, further studies will be required to identify other biological activities of edible oil and
Brassica juncea seed and to confirm their possible roles in the gastroprotective activities of Mystomate4® as recorded in the present study. Further work will be needed to confirm the adverse effect or otherwise of Mystomate4® on heamatological parameters, the lungs and the heart which are other vital visceral organs of the body.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.