Gastroprotective and Curative Effects of the Aqueous Extract of Stem Bark of Pittosporum Mannii Hook F. (Pittosporaceae) on Some Models of Gastric Ulcer in Rats

Purpose: This work assesses the antiulcerogenic and antiulcer properties of the aqueous extract of Pittosporum mannii and shows at what dosage this plant would not be of any danger to the patient. Methodology: The aqueous extract of its bark, orally administered at the doses of 35, 75, 150 and 300mg/kg, has been experimented on acute (HCl/EtOH (150mM HCl in 60% ethanol); ligature of the pylorus) and chronic ulcers (acetic acid; 0.05 ml of 30% acetic acid) induced on rats. Findings: The results from these experiments show that: the aqueous extract of the barks of Pittosporum mannii possesses antiulcerogenic properties. At 300mg/kg dose, the extract completely inhibited (100%) the ulcer induced by the mixture HCl/EtOH. For the three patterns of gastric ulcers induction used, the mucus weight did not vary significantly (p>0.05) on the treated animals as compared to the negative control groups. In the group that underwent pylorus ligature, the extract did not induce any significant variation in both the gastric acidity and the gastric volume. However these results do not bring out the exact mechanism of action of the plant extract. Furthermore, the extract neither acts in reinforcing the protection barrier of the gastric mucus membrane nor its antisecretory properties. The nitric oxide proportion of the gastric mucous membrane presents a significant variation (p<0.05) at the dose of 300mg/kg. With regards to these results, we realized that this extract increases the nitric oxide rate of the gastric mucosa which intervenes in the healing process. The aqueous extract of the stem bark of Pittosporum mannii provokes the death of all animals of the groups from a dose of 3g/kg (LD100) whereas half of the population of the experimental rats succumbed at the dose of 2.66g/kg (LD50). After two weeks of treatment, the rats that received the extract at the doses of 75, 150 and 300mg/kg presented no significant variation of the hepatic and plasmatic protein levels. The levels of plasma transaminases (AST; 300mg/kg), hepatic ALT (300mg/kg) and plasmatic ALT (150mg/kg) present a significant drop. The stem bark of Pittosporum mannii possess gastroprotective and ulcer-healing effect although at this time it is difficult to explain the exact mechanism involved in these two processes. Unique contribution to theory, policy and practice: According to the results obtained, it would be important to realise a histological test of the detoxification organs such as the liver, the heart and the kidneys. Moreover, the cytotoxicity test has to be done to determine the effect of the extract at the cellular level before any therapeutic use