Effect of tannins from Quercus suber and Quercus coccifera leaves on ethanol-induced gastric lesions in mice.

The gastroprotective effects of 70% acetone extracts of Quercus suber and Quercus coccifera leaves and of tannins (pedunculagin, castalagin, phillyraeoidin A, and acutissimin B) purified from these extracts were examined in the mouse using the ethanol-induced gastric ulcer model. Both extracts (25, 50, and 100 mg/kg), given orally, prevented the formation of ethanol-induced lesions in the stomach. The percent protection varied between 68 and 91%. Purified tannins (50 mg/kg) were also effective in protecting the stomach against ethanol, and the percent protection varied from 66 to 83%. Castalagin was the most potent. Both extracts and all of the tannins tested (10, 25, and 50 microg/mL) strongly inhibited (55-65%) the lipid peroxidation of rabbit brain homogenate. These results suggest that the gastroprotective effects of extracts of Q. suber and Q. coccifera leaves and the purified tannins in this experimental model are related to their anti-lipoperoxidant properties.

Gastroprotective effects of honey and glucose-fructose-sucrose-maltose mixture against ethanol-, indomethacin-, and acidified aspirin-induced lesions in the rat.

The gastric cytoprotective properties of natural honey (monofloral and polyfloral specimens) and of a glucose-fructose-sucrose-maltose mixture (GFSM) was evaluated in the rat using absolute ethanol, indomethacin and acidified acetylsalicylic acid (ASA-HCl) as necrotising agents. Prior gastric administration of honey (2.5 g/kg) to animals induced a net reduction of hemorrhagic lesions length of the mucosa. Protection of the stomach elicited by both types of honey and GFSM was almost total against ethanol-induced lesions. Similar results were also observed when using ASA-HCl except that the percent protection was 87%. The percent reduction of indomethacin-induced gastric lesions was variable according to the nature of the test solution: GFSM mixture (41.1%) < polyfloral honey (55.2%) < monofloral honey (64.0%). Perfusion of the stomach with isotonic honey resulted in (1) a 70% reduction of the area of the lesions caused by ethanol, (2) the failure to prevent the transmural potential difference fall induced by ethanol, (3) an increase of basal and histamine-stimulated acid secretion. These results suggest that sugar rich solutions (GFSM and honey) may prevent gastric damage by a mechanism involving the release of some protective agents.