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INTRODUCTION
Peptic ulcer disease (PUD) is one of the most prevalent gastrointestinal disorders with high annual incidence and significant mortality rates. Unfortunately, the drugs available for the treatment of PUD confer simple to severe side effects like arrhythmias, gynaecomastia, enterochromaffin like hyperplasia and hematopoietic changes like leucopoenia and thrombocytopenia, limiting drug utility and leading the demand of a safe and effective gastroprotective agents especially for the people of non-industrialized countries28. An extensive research is being conducted on herbs to discover and identify remedies and lead compounds for the management of PUD as a consequence of growing interest in natural products and complementary and alternative therapies. In this context, we have also been studying traditional herbs in Ayurveda, Siddha and Unani systems of medicine1,26-28. Leathery Murdah, Terminalia coriacea (Roxb.) Wight & Arn. (Combretaceae) is a traditional herb used in Siddha for the treatment of ulcers. Terminalia coriacea is found in parts of Andhra Pradesh and Tamil Nadu states of India. It is called as “Tani” or “Nalli maddi” by the locals and it is used as cattle feed13,31. Our previous studies reveal that T. coriacea has anti-convulsant, anti-inflammatory, anti-nociceptive, anti-pyretic and wound healing properties8,25,29,48,61. The present study focuses on the assessment of phytochemicals and gastroprotective potential of Terminalia coriacea leaves methanolic extract (TCLME) in view of its traditional use.
METHODS
Plant material and the preparation of extract
The fresh leaves of Leathery Murdah, Terminalia coriacea (Roxb.) Wight & Arn. (Synonyms - T. alata, T. crenulata, T. elliptica, T. tomentosa) belonging to the Combretaceae family were collected from Talakonda forest, Tirumala Hills, Tirupathi, Andhra Pradesh, India. The plant material was authenticated by a plant taxonomist, Dr. P. V. Prasanna (Scientist-E) at the Botanical Survey of India, Deccan Regional Centre, Hyderabad (establishment under the Ministry of Environment & Forests, Government of India). The specimen deposited in the herbarium was assigned a voucher number BSID 882. After collection, the leaves were shade dried and coarsely powdered. The extraction was carried out in six phases; in each phase approximately 110 gm of the powdered leaves were extracted using methanol AR (SD Fine-Chem Limited) in a soxhlet apparatus in 1:4 ratio. The extract was concentrated under reduced pressure and stored in an airtight container in a refrigerator at the temperature below 10°C. The solution of TCLME was prepared using distilled water for the evaluation of the anti-ulcer activity.
Drugs and chemicals
Chloroform AR, diethyl ether LR, methanol AR, phenolphthalein pH indicator solution, and sodium hydroxide pellets were procured from SD Fine-Chem Limited, Mumbai, while pure aspirin was obtained from Divis Laboratories, Hyderabad. Absolute Ethanol was purchased from Changshu Yangyuan Chem, China, Ranitidine (as Rantac 150 mg) from J.B Chemicals and Pharmaceuticals, Mumbai and Misoprostol (as Misoprost-200) from Cipla Ltd., Goa, while surgical spirit was obtained from Kakatiya Pharma, Hyderabad. Topfer’s reagent and distilled water were obtained from Nice Chemicals, China, and Stangen Fine Chemicals, Hyderabad, respectively. All chemicals were used without further purification.
Animals
Adult male Wistar rats weighing 150-200 gm were used for the evaluation of anti-ulcer activity. The animals were maintained under standard laboratory conditions in polypropylene cages under 12 hr light/dark cycle, controlled temperature (24±2°C), fed with commercial pellet diet, and water ad libitum in an animal house approved by the Committee for the Purpose and Supervision of Experiments on Animals (Reg. no. 1534/PO-/a/11/CPCSEA). All the animals were acclimatized to the laboratory environment for 10 days before the initiation of experiments. The protocol (IAEC/AUCP/2011-12/03) was approved by the Institutional Animal Ethical Committee before the commencement of animal experimentation. All measures were taken to ensure that the experiments were conducted in accordance with the instructions of IAEC, Anwarul Uloom College of Pharmacy, New Mallepally, Hyderabad, Andhra Pradesh, India.
Acute toxicity test and selection of test doses
Three test doses (125, 250, and 500 mg/kg) of TCLME were selected based on our earlier report where maximum safe dose was found to be 2000 mg/kg, p.o.25. In order to determine LD50, the method described by Chinedu et al. (2013) was followed with slight modification14. Briefly, the study was carried out in eight stages with three test doses given from second to eighth stages. Doses of 50-5000 mg/kg were given in the first four stages (Stage - 1: 50, 200, 400, 800; Stage - 2: 1000, 1500, 2000; Stage - 3: 3000, 4000, 5000). The method was extended and doses from 6000-20,000 mg/ kg, p.o. were given in later four stages with an incremental dose of 1000 mg/ kg, p.o. to female albino Wistar rats. Each dose was administered to one rat and they were observed for 24 hours for mortality and signs of toxicity. A confirmatory test was performed at the end of each stage by administering the highest dose of each level to one more animal to confirm the lethality. The total number of animals used for acute toxicity study was 33 (inclusive of confirmatory test).
Analytical profile of TCLME
• Confirmatory chemical tests for flavonoids
TCLME was subjected to Alkali reagent, Zinc-Hydrochloric acid and Shinoda tests to reconfirm presence of flavonoids20,30,32.
• High Performance Liquid Chromatographic (HPLC) and Ultra Violet (UV) spectroscopic analysis
HPLC-UV analysis was carried out at Analytical Development Laboratory, Mylan Laboratories Limited, Bollaram, Hyderabad with the method described earlier by Khan et al.27. Briefly, HPLC analysis of TCSBAE was performed by gradient system using Waters 2996 Photo Diode Array HPLC System with Kromasil C18 - (250 X 4.5 mm, 5 μm) column. Two solvents, A (water with 0.1% trifluoroacetic acid) and B (acetonitrile with 0.1% trifluoroacetic acid) were used for elution of constituents. The column was equilibrated in 85% A / 15% B prior to injection of sample and upon injection this composition was then changed to 60% A / 40% B over 30 min utilizing a linear gradient followed by changing to 50% A / 50% B over the next 10 min and then the concentration was returned to 85% A / 15% B over the final 10 min. The flow rate was set to 1 ml/min, injection volume was 10 μL and column temperature was maintained at 30°C. The system was run for 60 minutes. The eluents were monitored at 255 and 350 nm. Further the characteristic A & B band wavelengths in U.V region were recorded, to identify the nature of flavonoids as per the method described by Bohm and Tsimogiannis et al.9,63. The peak numbers, retention times, area, percentage area, A & B bands in U.V region were recorded.
• Liquid Chromatography-Mass Spectral (LC-MS) analysis
LC-MS analysis was also carried out at analytical development laboratory, Mylan Laboratories Limited, Bolarum, Hyderabad. The liquid chromatographic analysis of TCLME was performed by gradient system using Waters 2996 PDA HPLC system with Luna C18 - (250 X 4.5 mm, 5 μm) column. Two solvents, A (water with 0.1% trifluoroacetic acid) and B (acetonitrile with 0.1% trifluoroacetic acid) were used for elution of constituents. The column was equilibrated in 85% A / 15% B prior to injection of sample and upon injection this composition was then changed to 75% A / 25% B from 0-22 min. With linear gradient change 85% A / 15% B from 22-35 min. The flow rate was set to 1 mL/min and column temperature was maintained at 30°C. The injection volume was 10 μL. The system was run for 35 minutes and the eluents were monitored at 254 nm, 300 nm and 366 nm. The mass spectral analysis was done by Electro Spray Ionization using a coupled Agilent Ion-Trap Mass Spectrometer in both positive and negative models in the scan range of 100-2000 m/z.
• Evaluation of anti-ulcer activity by in-vivo assays
Aspirin induced ulcerogenesis in pylorus ligated rats. Aspirin induced ulcerogenesis in pylorus ligated rats model was used for the evaluation of anti-ulcer activity with slight modification. The animals were divided into five groups (n=6). Group I - served as negative control and received only vehicle. Groups II, III & IV received TCLME at 125, 250 and 500 mg/kg respectively per oral at the volume of 10 ml/kg. Group - V served as standard and was treated with standard drug (Ranitidine 50 mg/kg)19. Aspirin suspended in 1% CMC in water was administered orally at a dose of 500 mg/kg in 12 hours fasted rats24. The test extract and standard drug treatment was done 30 min prior the administration of Aspirin. After 30 min, the pyloric ligation surgery was performed as per Shay et al.60. Four hours later, the animals were sacrificed by euthanasia.
• Collection and Measurement of Gastric Juice (GJ)
The stomachs were excised carefully keeping the esophagus closed. The stomachs were opened along the greater curvature, removing the luminal contents. The gastric contents were collected and centrifuged at 1000 rpm for 10 minutes. After centrifugation samples were decanted and the volume of gastric juice was noted and is expressed as mL/100 g body weight. The contents were subjected to analysis for free and total acidities.
• Determination of gastric juice pH (pH)
One mL of supernatant liquid was diluted to 10 mL with distilled water. The pH of the solution was recorded with the help of digital pH meter.
• Estimation of Free and Total Acidities (FA & TA)
The above solution was titrated against 0.01 N NaOH using Topfer’s reagent as indicator. The end point of the titration was when the solution turns orange in colour. The volume of NaOH was noted which corresponds to the free acidity. Further the titration was continued till the solution regained pink colour. The total volume of NaOH was noted, which corresponds to total acidity.
• Determination of Ulcer Index (UI)
Mean ulcer score for each animal is expressed as Ulcer Index. The stomachs were washed with running water to see the ulcers in the glandular portion of the stomach. The number of ulcers per stomach were noted and the severity of the ulcers was scored microscopically with the help of hand lens (10x) and scoring was done as per Kulkarni33. The scoring was based on the following observations and assigned values: 0=Normal Stomach; 0.5=Red Colouration 1=Spot Ulcers; 1.5=Haemorraghic Streaks 2=Ulcers >3 mm but <5 mm; 3=Ulcers >5 mm.
• Determination of Gastric Mucin Content (GMC)
Mucin content was estimated by the method described by Corne et al.16 with some modifications. The glandular segments of the stomachs of rats subjected to the ethanol induced ulcers model were isolated and weighed. Each glandular segment was immediately immersed in 10 mL of 0.1% alcian blue solution (0.16 M sucrose/0.05 M sodium acetate, pH 5.8). After immersion for 2 h, excess dye was removed by two successive rinses with 10 mL of 0.25 M sucrose, first for 15 min and then for 45 min. The stomachs were all sequentially transferred to a 0.5 M magnesium chloride and shaken for 2 h. Four mL of the blue extract was then shaken vigorously with an equal volume of ether. The resulting emulsion was centrifuged at 3600 g-force and the absorbance of the aqueous layer was read at 580 nm. The amount of alcian blue extracted per gram of wet glandular tissue was then calculated.
• Estimation of Catalase (CAT)
Catalase activity in stomach tissue was determined according to the method of Leyck and Parnham36. The stomach tissue was scraped and homogenized in ice cold saline medium with the help of a homogenizer. The solution was centrifuged for 10 minutes at 3000 g-force and collected for the experiment. 100 L of the supernatant was added to a solution of 3 L of H2O2, phosphate buffer mixture (50 mM phosphate buffer, pH 7.0, and 30% H2O2). The change in optical density at 240 nm per unit time was measured.
• Estimation of Superoxide Dismutase (SOD)
Superoxide dismutase activity in stomach tissue was determined according to the method of Fridovich18. The stomach tissue was scrapped and homogenized in ice cold normal saline medium with the help of a homogenizer. Then, the tissue homogenate was centrifuged for 10 minutes at 3000 g force and the supernatant was collected and used for the estimation of SOD activity. 10 mL of the solution was taken in a test tube and mixed with 0.5 mL of 50 mM phosphate buffer (pH 7.8), 0.1 mM of EDTA, 0.05 mM xanthine, and 0.01 mM cytochrome c, and then, 100 mL of 2.5 mM of xanthine oxidase was added to start the reaction, and the absorbance was measured at 550 nm.
• Determination of Malondialdehyde (MDA)
Malondialdehyde, formed from the breakdown of polyunsaturated fatty acids, serves as a convenient index for determining the extent of peroxidation reaction. Malondialdehyde has been identified as the product of lipid peroxidation that reacts with thiobarbituric acid to give a red colour absorbing light maximally at 535 nm. One g of tissue sample with 10 mL of 0.2 M Tris HCl buffer (pH 7.2) was taken in a tissue homogenizer to get a 10% homogenate. 500 μL of supernatant from the homogenate, 1 mL of 10% trichloroacetic acid and 1 mL of 0.67% thiobarbituric acid were taken in a tightly stoppered tube. The tube was heated to boiling temperature for 45 min. After cooling the tube, the contents were centrifuged. The supernatant was read at 532 nm against blank. The concentration of test samples was obtained using molar extinction coefficient of MDA. The amount of MDA is expressed as number of moles of MDA / mg of tissue64.
• Estimation of Total Protein content (TP)
Total protein content was estimated by the method of Lowry et al.39. The dissolved proteins in gastric juice were estimated in the alcoholic precipitate obtained by adding 90% alcohol with gastric juice in a 9:1 ratio, respectively. Then, 0.1 mL of alcoholic precipitate of gastric juice was dissolved in 1 mL of 0.1 N NaOH. From this, 0.05 mL was taken in another test tube and 4mL of alkaline mixture was added and allowed to stand. After 10 min, 0.4 mL of phenol reagent was added and again allowed to stand for 10 min for the development of colour. Reading was taken against a blank prepared with distilled water at 610 nm. The protein content was calculated from the standard curve prepared with bovine albumin and has been expressed in terms of µg/ mL of gastric juice.
• Acute Ethanol induced gastric lesions
All the animals (n=6) in each group were fasted for 36 hours before the administration of ethanol. The standard drug (Misoprostol 100 g/kg, p.o.) or the test extract was administered one hour before ethanol administration. Ethanol (90%) was administered to all animals at a dose of 1 mL/200 gm. After one hour all animals were sacrificed, and stomachs were isolated as per Salim et al.57. Lesion severity was determined by measuring ulcer index.
Histopathological Studies
The isolated stomachs were preserved in 15% formalin solution and were sent to the pathologist for histopathological examination by staining with haematoxylin and eosin. The morphological changes were observed and recorded with 100x lenses1.
Statistical analysis
Data obtained was analyzed by One way ANOVA followed by Dunnett’s multiple comparisons post-hoc test using Graphpad Prism version 5.0, 32 bit for windows, Graphpad software, San Diego, California, USA (http://www.graphpad.com/). The values are expressed as Mean ± standard error of mean (SEM). <0.05 was considered statistically significant.
RESULTS AND DISCUSSION
Results of extraction and acute toxicity testing
The dried mass of crude Terminalia coriacea leaves methanolic extract (TCLME) was found to be 24.54% w/w with respect to the powdered leaves. There were no mortalities or signs of toxicity up to the dose of 20,000 mg/kg, p.o, therefore further dosing was discontinued.
Results of Analytical Profile of TCLME
• Confirmatory chemical tests for flavonoids
All the chemicals tests confirmed the presence of flavonoids.
• Results of HPLC-UV analysis
On HPLC analysis of TCLME, 25 peaks were recorded. Peaks 8, 12, 13, 14, 15, 17, 21, and 22 had noteworthy area and percentage area. The peak numbers and their respective retention times are shown in Table 1 and Figure 1. Further, the UV spectrum plot indicates, that peaks 8-15 gave characteristic band A & B wavelengths demonstrating flavonoidal nature of compounds. The six peaks 8-10 and 13-15 gave typical band A & B wavelengths of flavonols while peaks 11 and 12 were confirmed as flavones. The HPLC-UV spectrum plot results are summarized in Table 1.
TABLE 1 Nature of compounds confirmed by characteristic bands A & B in U.V region with respective retention time and peak numbers on HPLC analysis
| Peak no. | HPLC retention time in min. | Wavelength of bands A & B in UV region in nm | Nature of compound |
|---|---|---|---|
| 8 | 9.653 | 354.0 & 253.7 | Flavonol |
| 9 | 9.890 | 356.1 & 253.7 | Flavonol |
| 10 | 10.679 | 353.7 & 263.1 | Flavonol |
| 11 | 11.162 | 347.7 & 265.5 | Flavone |
| 12 | 11.523 | 338.1 & 269.1 | Flavone |
| 13 | 12.118 | 357.2 & 254.9 | Flavonol |
| 14 | 12.325 | 354.9 & 256.0 | Flavonol |
| 15 | 12.594 | 354.9 & 256.0 | Flavonol |
HPLC: High Performance Liquid Chromatographic.
• Results of LC-MS analysis
The LC-MS analysis of crude TCLME lead to the identification of seven flavonoids by the recorded m/z values of molecular ions and their fragment ions via reported fragmentation patterns. The compounds could mostly be Rutin (Quercetin-3-O-rutinoside), Luteolin-7-O-glucoside, Myricetin hexoside, Apigenin-6-C-glucoside, Quercetin-3-O-glucoside, Isorhamnetin-3-O-rhamnosylglucoside, and Isorhamnetin-3-O-glucoside. An intense peak with m/z 633.1 was recorded between 7.7-7.9 min in positive mode ESI-MS. Rutin is reported to be characterized by the presence of sodium adduct (m/z 633). The molecular ion [MH]+ with m/z 611 is almost absent and presence of aglycone residue [aglycone+H]+ of m/z 302 is rare indicating hindrance in the removal of glucose50. Therefore, the observed peak could be due to Rutin. The retention time 8.1-8.4 min showed molecular ion peaks m/z 449.2 [M+H]+ and 447.0 [M-H]- in both ESI positive and negative modes respectively and the various reported fragments - 413.2, 329.1, and 299.1 of Luteolin-7-O-glucoside in ESI positive mode as described by Colombo et al.15. The retention time 8.9-9.2 min revealed molecular ion m/z of Myricetin hexoside 479.0 [M-H]- & 316 [Aglycone-H]-. The recorded m/z values were in conformance with the plant metabolomics standards of Institute of Food Research, Norwich Research Park, UK52.
During the retention time 10.6-10.8 min, in the positive and negative mode ESI-MS, molecular ion m/z of 433.2 [M+H]+, 431.1 [M-H]- and the standard fragments 397.2, 367.1, 313.2 were observed in + ESI-MS. These facts establish identity of compound as Apigenin-6-C-glucoside as mentioned by Correia et al.17. The same report evidenced the character of next compound as Quercetin-3-O-glucoside that appeared between the retention time 11.1-11.3 min. The observed sodium adduct, molecular ion, and aglycone fragments in +ESI-MS m/z were at 487.1 [M+Na]+, 465.1 [M+H]+, 303.1 [Aglycone+H]+ while deprotonated dimer, glycoside, and aglycone were recorded in -ESI-MS as 927.1 [Dimer-H]-, 463.1 [M-H]-, 301 [Aglycone-H]-. The molecular ions and fragments of Isorhamnetin-3-O-rhamnosylglucoside 663.2 [M+K]+, 647.2 [M+Na]+, 625.2 [M+H]+, and 623.1 [M-H]- and Isorhamnetin-3-O-glucoside 501.1 [M+Na]+, 479.1 [M+H]+, 317.1 [Aglycone+H]+ & 477.1 [M-H]- were observed between 12.5-12.8 and 13.8-14.1 min respectively. The identity of former was established by the plant metabolomics standard MS data by IFR, UK and later compound was recognized with the reports of Makris and Kefalas; Scheiber et al.40,59. Beside these compounds, the spectra also revealed presence of Kaempferol and its fragments. The observed characteristic m/z values and corresponding fragments were 121 [0, 2 B+ ring fragment], 133 [1,3B+ ring fragment], 213 [M+H-H2O-2CO]+, 231 [M+H-2CO]+, 259 [M+H-CO]+, 287 [M+H]+, and 309 [M+Na]+ (data not shown) Tsimogiannis et al.63. The LC-MS analysis results are summarized in the Table 2.
TABLE 2 Identification of flavonoids present in Terminalia coriacea leaf methanolic extract by LC-MS analysis
| LC-MS Retention Time in min. | Identified Compounds & m/z values | ESI +/- Mode Mass Fragments | % Area |
|---|---|---|---|
| 7.7 - 7.9 | Quercetin-3-O-rutinoside [610] | 633.1 [M+Na]+ | 0.7469 |
| 8.1 - 8.4 | Luteolin-7-O-glucoside [448] | 449.2 [M+H]+, 413.2, 329.1, 299.1 447.0 [M-H]- | 1.7445 |
| 8.9 - 9.2 | Myricetin hexoside [480] | 479.0 [M-H]- & 316 [Aglycone-H]- | 4.8938 |
| 10.6 - 10.8 | Apigenin-6-C-glucoside [432] | 433.2 [M+H]+, 397.2, 367.1, 313.2 431.1 [M-H]- | 11.7753 |
| 11.1 - 11.3 | Quercetin-3-O-glucoside [464] | 487.1 [M+Na]+, 465.1 [M+H]+, 303.1 [Aglycone+H]+ 927.1 [Dimer-H]-, 463.1 [M-H]-, 301 [Aglycone-H]- | 15.3687 |
| 12.5 - 12.8 | Isorhamnetin-3-O-rhamnosylglucoside [624] | 663.2 [M+K]+ , 647.2 [M+Na]+ , 625.2 [M+H]+ 623.1 [M-H]- | 2.3087 |
| 13.8 - 14.1 | Isorhamnetin-3-O-glucoside [478] | 501.1 [M+Na]+, 479.1 [M+H]+, 317.1 [Aglycone+H]+ 477.1 [M-H]- | 5.3556 |
• Results of Aspirin induced ulcerogenesis in pylorus ligated rats model
The results are shown in Table 3.
TABLE 3 Results of Aspirin induced ulcerogenesis in pylorus ligated rats model
| Parameters | Negative Control | Standard Drug | Test-I TCLME 125 mg/kg | Test-II TCLME 250 mg/kg | Test-III TCLME 500 mg/kg |
|---|---|---|---|---|---|
| Volume of Gastric Juice (mL / 100 g) | 4.51±0.26 | 1.90±0.27 c | 3.10±0.22 b | 2.81±0.22 c | 1.86±0.22 c |
| pH of Gastric Juice | 2.93±0.24 | 4.46±0.16 c | 3.68±0.13 a | 3.73±0.10 a | 3.70±0.17 a |
| Free Acidity (mEq / L / 100 g) | 39.67±1.20 | 22.00±1.88 c | 41.67±1.62 ns | 32.17±1.10 b | 31.33±0.91 b |
| Total Acidity (mEq / L / 100 g) | 90.50±3.06 | 78.00±0.96 b | 83.33±1.64 ns | 84.17±2.12 ns | 80.17±1.53 a |
| Ulcer Index | 12.75±1.03 | 2.75±0.38 c | 6.16±0.44 c | 4.58±1.04 c | 1.16±0.24 c |
| Mucin Content (µg / g tissue) | 0.49±0.02 | 0.82±0.07 a | 1.02±0.04 c | 1.30±0.05 c | 1.62±0.11 c |
| Catalase (µMol H2O2 utilized / min / mg tissue) | 3.56±0.14 | 8.59±0.14 c | 4.20±0.11 b | 4.32±0.05 b | 6.06±0.12 c |
| Superoxide dismutase (µMol H2O2 utilized / min / mg tissue) | 3.25±0.11 | 5.83±0.27 c | 4.27±0.11 b | 4.55±0.16 c | 4.57±0.21 c |
| Malondialdehyde (no. moles / mg tissue) | 8.01±0.08 | 7.28±0.06 b | 6.99±0.10 c | 6.43±0.16 c | 6.08±0.14 c |
| Total Protein (µg / mL gastric juice) | 341±4.31 | 321.3±4.68 a | 314.8±5.04 b | 312.5±3.0 c | 308.7±3.52 c |
Sample size (n=6) rats per group. Data is expressed as Mean ± Standard Error of Mean. a <0.05, b <0.01, c <0.001 and ns non-significant versus Negative Control (on statistical analysis with ANOVA, followed by Dunnett’s multiple comparison post-hoc test). Ranitidine 50 mg/kg was the standard drug. TCLME stands for Terminalia coriacea leaf methanolic extract.
• Effect of TCLME on Volume of gastric juice
TCLME 250 & 500 mg/kg and standard drug exhibited potent anti-secretory effect. All the above treatments decreased the volume of gastric juice by P<0.001 while the decrease with TCLME 150 mg/kg was found to be P<0.01.
• Effect of TCLME on pH of gastric juice
Ranitidine elevated the pH of gastric juice with P<0.001 while all the doses of test extract raised pH with P<0.05.
• Effect of TCLME on free and total acidities
Ranitidine 50 mg/kg reduced the free and total acidity with P<0.001 and P<0.01 respectively. TCLME 500 mg/kg was the only dose that reduced both free and total acidities (P<0.01 and P<0.05 respectively). TCLME 125 mg/kg did not show any significant reduction in free and total acidities whereas TCLME 250 mg/kg reduced only free acidity by P<0.01.
• Effect of TCLME on ulcer index
All the doses of test extract and the standard drug displayed strong anti-ulcer effect as all the treatments lead to decrease in ulcer index by P<0.001 when compared to the negative control (as shown in Figure 2).
• Effect of TCLME on gastric mucin content
TCLME 125-500 mg/kg enhanced the production of gastric Mucin with P<0.001. Though Ranitidine showed a significant effect (P<0.05) but it not as effective as the test extracts (as shown in Figure 3).
FIGURE 3 Gastric wall mucous content in Aspirin induced ulcerogenesis in pylorus ligated rats model.
• Effect of TCLME on Total Protein (TP)
Although significant inhibition but of varying levels (P<0.01 - P<0.001) was seen with the treatment of TCLME on depletion of proteins from gastric tissue. In all the test extract treated groups the effect was better than the standard that showed P<0.05 (as shown in Table 3).
• Effect of TCLME on Malondialdehyde (MDA)
All the test extracts demonstrated greater degree of inhibition on lipid peroxidation ( P<0.001) while the standard suppressed level of MDA by P<0.01 (as shown in Table 3).
• Effect of TCLME on Catalase (CAT)
Ranitidine 50 mg/kg and TCLME 500 mg/kg increased the levels of Catalase with P<0.001 whereas TCLME 125 & 250 mg/ kg improved the levels by P<0.01 (as shown in Table 3).
• Effect of TCLME on Superoxide dismutase (SOD)
Ranitidine and the higher test dose (250 & 500 mg/kg) of TCLME upgraded the level of Superoxide dismutase by P<0.001. TCLME 125 mg/kg promoted SOD with P<0.01 (as shown in Table 3).
Results of Acute ethanol induced gastric lesions model
• Effect of TCLME on Ulcer Index of acute ethanol induced gastric lesions
The gastroprotective action of TCLME was also evident in ethanol induced gastric lesions model. TCLME at all the test doses diminished the ulcer index like standard with P<0.001 vs. Control Table 4 and Figure 4. The macroscopic images of stomachs of rats subjected to this model are shown in Figure 5.
TABLE 4 Result of Ulcer Index in Ethanol-induced gastric lesions
| Parameters | Negative Control | Standard Drug | Test-I TCLME 125 mg/kg | Test-II TCLME 250 mg/kg | Test-III TCLME 500 mg/kg |
|---|---|---|---|---|---|
| Ulcer Index† | 10.17±0.24 | 8.08±0.30 * | 8.16±0.24 * | 5.91±0.35 * | 4.66±0.16 * |
Sample size (n=6) rats per group. Data is expressed as Mean ± Standard Error of Mean. * <0.001 versus Negative Control (on statistical analysis with ANOVA, followed by Dunnett’s multiple comparison post-hoc test). Misoprostol 100 μg/ kg was the standard drug.
FIGURE 5 Photographs of stomachs subjected to Ethanol induced gastric ulcers. (A) Negative Control; (B) Standard (Misoprostol 100 g/kg); (C) Test-I (TCLME 125 mg/kg); (D) Test-II (TCLME 250 mg/kg) and (E) Test-III (TCLME 500 mg/kg). Where DU - Deep Ulcer, GB - Gastric Bleeding, NS - Normal Stomach, RC - Red Coloration, SU - Spot Ulcer and TCLME - Terminalia coriacea leaf methanolic extract.
• Effect of TCLME on histology of gastric tissues
(A) Negative Control. The stomachs of negative control group showed degenerated epithelial cells, severe haemorrhage, necrosis, vascular congestion and marked inflammatory infiltration.
(B) Standard Misoprostol (100 μg/kg). Grossly, the mucosa of standard group showed intact epithelial lining. The sub-mucosa was found to be mostly normal, however mild haemorrhage was seen in few stomachs.
(C) TCLME (125 mg/kg). The stomachs of rats treated with TCLME 125 mg/kg revealed moderate haemorrhage, mild oedema, and few scattered inflammatory cells.
(D) TCLME (250 mg/kg). Mild inflammatory infiltration and congestion of vascular spaces was noticed in stomachs of group that received TCLME 250 mg/kg.
(E) TCLME (500 mg/kg). The treatment of TCLME 500 mg/ kg prevented gastric ulceration. On examination the stomachs were found to be normal with intact epithelial lining and no signs of injury. Histopathological slides of rat’s stomachs are shown in Figure 6.
FIGURE 6 Histopathological slides of rat’s stomachs subjected to Ethanol induced gastric ulcers. (A) Negative Control; (B) Standard (Misoprostol 100 g/kg); (C) Test-I (TCLME 125 mg/kg); (D) Test-II (TCLME 250 mg/kg) and (E) Test-III (TCLME 500 mg/kg) where I - Inflammatory infiltration, N - Necrosis, NS - Normal Stomach, O - Oedema and TCLME - Terminalia coriacea leaf methanolic extract.
All these flavonoids are reported in the allied species. Quercetin-3-O-glucoside was isolated from aerial parts of T. muelleri55 while Quercetin-3-O-rutinoside (Rutin) is reported in T. catappa38,44. Luteolin-7-O-glucoside (Cynaroside) is reported to be present in T. arjuna49. Isorhamnetin glycosides was isolated from T. chebula leaves whereas Apigenin-6-C-glucoside (Isovitexin), Kaempferol and Quercetin glycosides are reported in T. arjuna, T. catappa2,38,44. Myricetin hexoside is present in T. ferdinandiana45. Flavonoids are being extensively studied for their beneficial effects on human health and literature reveals that they produce no or very little toxicity21,41. Moreover, they are considered to be responsible for the therapeutic effects of many traditional herbs. The gastroprotective role of flavonoids is well documented47,58,62,65. More than 95 flavonoids have been studied for their effectiveness in PUD. About 42 flavonoids were found to be inactive. The inactivity varies broadly with the experimental model, animal used in the study, route of administration and dose46. Flavonoids exhibit anti-secretory10, anti-spasmodic37, anti-ulcer12, and anti-diarrhoeal10 properties. The other actions like anti-inflammatory and anti-platelet effects are the secondary actions or alternative mechanisms that support therapeutic actions of flavonoids on gastrointestinal tract11. The biochemical and pharmacological actions of flavonoids are attributed to their strong antioxidant potential34. The antioxidant mechanism of action of flavonoids, especially rutin and quercetin, is mainly due to the presence of an O-dihydroxy in the B ring (catechol), and additionally a 2, 3 double bond in conjugation with a 4-oxo function, as well as the presence of hydroxyl groups in positions 3, 5 and 7 in their structures21,51,56. These compounds cover a full range of activity from weak to strong. Apigenin is inactive4 while Kaempferol exhibited gastroprotection at doses 50 & 100 mg/kg22. Luteolin-7-O-glucoside (Cynaroside) at 47.4 mg/kg and Myricetin at a dose of 0.05 mL/g were found to be active anti-ulcer compounds in mice and rats on screening with reserpine induced gastric ulcers model4,6,53.
Rutin prevents gastric mucosal ulceration in wide-range of in-vivo models like absolute ethanol, acidified-ethanol, and reserpine induced gastric ulcers3,12,22. The cytoprotective effect is mediated by dose dependent inhibition of mucosal platelet-activating factor (PAF) and anti-oxidant mechanism22. In a study, Rutin at a dose of 200 mg/kg, reduced level of lipid peroxides and increased the activity of anti-oxidant enzymes like glutathione peroxidase. The beneficial effects of Rutin do not involve effects on endogenous prostaglandins and non-protein sulfhydryls12. Quercetin is one of the most studied flavonoids that protects gastrointestinal mucosa from acute lesions induced by various methods like absolute ethanol23,42,54, acidified-ethanol22, aspirin54, indomethacin, pyloric ligation43, reserpine3-6 and restraint stress22 induced gastric ulcers. Quercetin (3, 5, 7, 3’, 4’ - pentahydroxy-flavonol) is also one of the compounds that shows diverse mechanisms of action like increase in mucous production42, enhancement of mucosal sulfhydryl23 and anti-oxidant mechanism (increase in superoxide dismutase)35, anti-histaminic properties like decrease in histamine level, reduction in number of mast cells, PAF22, inhibition of H. pylori growth, lipid peroxidation23,42 and formation of acid by parietal cells7.
CONCLUSION
It is concluded that Leathery Murdah, Terminalia coriacea (Roxb.) Wight & Arn. possesses strong dose-dependent gastroprotective action and it can be mainly attributed to the flavonoids present in it. The identified flavonoids Kaempferol, Luteolin, Myricetin, Quercetin and Rutin possess weak to strong anti-ulcer activity. The present study highlights that TCLME exhibits gastroprotective action predominantly due to its anti-secretory, anti-ulcer, and anti-oxidant effects besides prevention of lipid peroxidation and induction of mucous secretion.
