A preclinical pharmacological screening for antiulcer activity was performed in Raghavendra Institute of Pharmaceutical Education and Research (RIPER), Anantapur, from November 2015 to January 2016. The protocol of this study was approved by IAEC with an approval number: 878/ac/05/CPCSEA/004/2015.

The leaves of Peltophorum pterocarpum were collected from the Anantapur regions, Andhra Pradesh, India. The plant material was authenticated and identified by Dr. J. Raveendra Reddy, JNTUA, Anantapur, where the voucher specimen was deposited for further reference. The leaves were dried in shade and powdered in a blender. The powder was extracted with methanol by soxhalation [2,12].

Albino rats of both sexes, strain Wistar, weighing 160-180 g were procured from the Raghavendra enterprises, Bangalore, Karnataka, India. The animals were housed in polypropylene cages with free access to food and water at 24±2°C, relative humidity of 40-45% and in a 12:12 hour light and dark cycle [13]. The rats were divided into four groups of six animals each, and acclimatised to laboratory atmosphere for a minimum of seven days prior to the study and were used only once throughout the experiment.

Acute toxicity test was performed on another set of albino rats and healthy male albino rats were divided into four groups of six rats in each group. The rats were fastened overnight prior to the experiment. Each group was treated orally with different doses of methanolic extract of Peltophorum pterocarpum (5 mg/kg, 50 mg/ kg, 300 mg/kg, 2000 mg/kg). The rats were observed for any gross behavioural changes and mortality as per OECD (Organization for Economic Cooperation and Development) Guidelines 425 [14]. The leaf extract of P. pterocarpum was found to be nontoxic up to the maximum dose of 2000 mg/kg body weight.

Albino rats weighing 160-180 g. were selected and divided into four groups of six animals each. Animals were abstained for 24 hours before the study, but had free access to water. Group I treated as control, received only distilled water; Group II and III treated as treatment groups, received with MEPP at the dose of 100 mg/ kg and 200 mg/kg respectively, and Group IV as standard group, received misoprostol 100 mcg/kg.

Gastric lesions were induced to all groups of rats by oral administration of Indomethacin (20 mg/kg suspension in 1% CMC) for three successive days followed by pylorus ligation under pentobarbitone (45 mg/kg i.p.) anaesthesia on 4^th day [15,16]. The standard drug misoprostol (100 mcg/kg i.p.) was administered immediately after oral indomethacin administration for three successive days. In the same manner, test compounds (MEPP dose 100 mg/kg and 200 mg/kg i.p.) were administered after oral indomethacin administration for three successive days [17].

The rats were sacrificed after four hours of pylorus ligation; abdomen was opened by making an incision. Gastric contents were collected for the determination of total acid output and the stomach was washed with water. Ulcer index was calculated with the help of a ulcer score scale.

Normal stomach without any red colouration=0

Red colouration=0.5

1 Ulcer spot=1

Haemorrhagic streaks=1.5

3-5 ulcer spots=2

More than 5 ulcer spots=3

Mean ulcer score for each group was calculated and recorded as Ulcer index [18,19].

Gastric contents of all groups of rats were collected and centrifuged at 2000 rpm for five minutes. Supernatant clear fluid was pipetted out. A 1 ml of this fluid was mixed with 9 ml of distilled water and titrated with 0.01 N sodium hydroxide, phenolphthalein being used as an indicator. Titre value was recorded at the end point (Pink to orange colour) which was expressed as free acid. Titration was continued till the reappearance of pink colour and the titre value was recorded again which was expressed as total acid [16].

The stomachs of all groups of rats were preserved in a 10% buffered formalin solution and processed for subsequent embedment. The tissue samples were cut into sections of 2.5 µm. Two slides were prepared and stained with Haematoxylin–Eosin (HE) and Periodic Acid-Schiff (PAS) [20]. The slides were appraised by light microscopy (10X).

The results were expressed as the mean±SEM. Statistical differences were evaluated using a one-way analysis of variance (ANOVA) followed by Dunnett’s t-test. Results were considered to be statistically significant at p<0.05.

The animals treated with MEPP 100 mg/kg and 200 mg/kg showed significant as well as dose dependent inhibition (p<0.01) of ulcer index when compared with control group [Table/Fig-1]. Moreover, free acidity and total acidity also significantly decreased (p<0.01) in the animals treated with MEPP 100 mg/kg and 200 mg/kg when compared with control group [Table/Fig-2]. Additionally, histological analysis also supported that the treatment with MEPP showed gastroprotection with both doses against indomethacin induced gastric damage when compared with control group [Table/Fig-3].

[Table/Fig-3]:

Histopathological analysis (10X): (Haematoxylin–Eosin and Periodic Acid-Schiff).

Greater beneficial effects have been reported for natural products in folk medicine. Studies on medicinal plants, have shown them to be alternative source for new compounds with potential pharmacological activity [6]. Gastroprotective effect of MEPP was evaluated against indomethacin induced ulcers in rat model. NSAIDs were known to cause ulcer by inhibiting prostaglandin synthesis. Prostaglandin synthesis is inhibited by Cyclooxygenase (COX) enzyme inhibitors like indomethacin and induces gastric damage [20,21].

The results of this study revealed that the MEPP was beneficial to treat gastric ulcers by preventing oxidative stress. The mechanism of gastro protection of Peltophorum pterocarpum by antioxidant effect may be mediated by stimulation of prostaglandin biosynthesis [6,20,21]. Prostaglandin synthesis protects the stomach from the irritation and injuries by stimulating the secretion of protective substance mucus and bicarbonates [22]. The MEPP reduces mucosal damage compared to control. The ability of the extract to reduce gastric mucosal damage further supports cytoprotective effect and suggests the possible involvement of prostaglandins in the antiulcer effect of the extract [22]. Acute toxicity studies showed no toxic symptoms at 2000 mg/kg, which indicates that MEPP was safe. However subacute and carcinogenic studies have to be performed before clinical studies.

Further detailed study on the isolation and characterisation of the compounds responsible for the antiulcer activity in methanolic extract of Peltophorum pterocarpum needs to be carried out.

The results obtained in this study showed that the methanolic extract of Peltophorum pterocarpum possesses antiulcer activity and showed the dose dependent gastroprotective effect against indomethacin induced and pylorus ligation ulcers.