Interrelationships between the gastric secretory responses, prostaglandin E2 inhibition and serum level of immunoreactive gastrin in pylorus-ligated and antrectomized rats

Baccharis dracunculifolia, the main botanical source of Brazilian green propolis, displays antiulcer activity

Baccharis dracunculifolia is the most important botanical source of Southeastern Brazilian propolis, known as green propolis for its colour. In a previous study, we described the gastric protective effect of the hydroalcoholic extract of Brazilian green propolis. We therefore wanted to investigate the possibility of using B. dracunculifolia extract for antiulcer treatment. This study was undertaken to evaluate the anti-ulcerogenic property of hydroalcoholic extract of B. dracunculifolia aerial parts. The HPLC analysis of the chemical composition of B. dracunculifolia extract used in this study revealed the presence mainly of cinnamic acid derivates and flavonoids. Doses of 50, 250 and 500 mg/kg of B. dracunculifolia crude extract and positive controls (omeprazole or cimetidine) significantly diminished the lesion index, the total lesion area and the percentage of lesion compared with negative control groups. The percentage of ulcer inhibition was significantly higher in groups treated with B. dracunculifolia, cimetidine or omeprazole, with all protocols used, compared with negative control groups. Regarding the model of gastric secretion, reductions in the volume of gastric juice and total acidity were observed, as well as an increase in the gastric pH. These results were similar to results from studies carried out with green propolis extract. Although more investigations are required, our results suggest that B. dracunculifolia has potential to be used as a phytotherapic preparation for the treatment of gastric ulcer.

Evaluation of antiulcer activity of the main phenolic acids found in Brazilian Green Propolis

AIM OF THE STUDY

In a previous study, our group described the gastric protective effect of the hydroalcoholic extract of Brazilian green propolis. The main compounds found in Brazilian green propolis include phenolic acids, such as: caffeic, ferulic, p-coumaric and cinnamic acids. This study was therefore carried out to evaluate the antiulcerogenic property of the main phenolic acids found in Brazilian Green Propolis.

MATERIAL AND METHODS

The anti-ulcer assays were performed using the following protocols: nonsteroidal-antiinflammatory drug (NSAID)-induced ulcer, ethanol-induced ulcer, and stress-induced ulcer. The effects of the phenolic acids on gastric content volume, pH and total acidity, using the pylorus ligated model, were also evaluated.

RESULTS

It was observed that treatment using doses of 50 and 250 mg/kg of caffeic, ferulic, p-coumaric and cinnamic acids and positive controls (omeprazol or cimetidine) significantly diminished the lesion index, the total area of the lesion and the percentage of lesion in comparison with the negative control groups. In addition, the percentage of ulcer inhibition was significantly higher in the groups treated with the different phenolic acids, cimetidine or omeprazol, in all the protocols used, compared with the negative control groups. In the model to determine gastric secretion, using ligated pylorus, treatment with phenolic acids and cimetidine reduced the volume of gastric juice and total acidity and significantly increased the gastric pH (p<0.05), compared with the control group, with the exception of the group treated with 50mg/kg of p-coumaric acid, in which no significant difference was observed, compared with the control. In relation to the acute toxicity, none sign of toxicity was observed when phenolic acids, used in this study, were administered for rats in dose of 2,000 mg/kg.

CONCLUSIONS

In conclusion, the results of this study show that caffeic, ferulic, p-coumaric and cinnamic acids display antiulcer activity.

Gastroprotective effects of a crude extract of Baccharis illinita DC in rats

Baccharis illinita DC (Compositae) is used in folk medicine to treat gastric disorders. The crude hydroalcoholic extract of leaves and stems tested on mice at doses from 1.0 to 6.0 g/kg, PO, did not produce signs of toxicity. Only the aqueous extract of leaves (0.1 g/kg, PO) increased intestinal motility in mice. The crude hydroalcoholic extract of stems and leaves (HESL) protected rats against lesions induced by ethanol or restraint-in-cold. The crude aqueous extract of roots protected against ulcers induced by ethanol, indomethacin or restraint-in-cold, and the crude aqueous extract of flowers only protected against lesions induced by ethanol. When injected into the duodenal lumen, the aqueous root extract inhibited basal acid secretion in pylorus-ligated rats. The results obtained in the present pharmacological assays indicate that this plant has a protective action against gastric lesions of the mucosa involving the maintenance of protective factors such as mucus, bicarbonate and blood flow, besides the reduction of gastric acid secretion.

Gastric acid response to pylorus ligation in rats: is gastrin or histamine involved?

1. Pylorus ligation stimulated the acid output in vagally intact rats. The serum gastrin concentration and the gastric mucosal histamine content were not affected. The gastric histidine decarboxylase activity was initially slightly elevated and then greatly reduced (12-20 hr after ligation).2. Pylorus ligation stimulated the acid output in chronically, but not in acutely, vagotomized rats. Chronic vagotomy raises the serum gastrin concentration, the gastric histamine content and histidine decarboxylase activity. The serum gastrin concentration was further raised by pylorus ligation. The histamine content was initially lowered but returned to preligation values after 20 hr. The histidine decarboxylase activity first decreased, but increased to very high levels 5-6 hr after ligation. Twelve hours after ligation it was lower than before ligation.3. Following pylorus ligation pentagastrin and histamine stimulated the acid output in vagally intact and in acutely vagotomized but not in chronically vagotomized rats. By contrast, pentagastrin raised the histidine decarboxylase activity in vagally intact and in chronically vagotomized, but not in acutely vagotomized rats.4. The two major populations of endocrine cells of the oxyntic gland area (ECL cells and A-like cells) are argyrophil, store histamine and are capable of taking up exogenous DOPA and of decarboxylating it to dopamine which is retained in the cytoplasm for several hours. As evidenced by light and fluorescence microscopy pylorus ligation did not affect their argyrophilia or their ability to produce and store dopamine.5. Pylorus ligation caused ultrastructural changes in the gastrin cells of the pyloric gland area and in the histamine-storing ECL and A-like cells of the oxyntic gland area. The two endocrine cell types in the oxyntic gland area were enlarged by pylorus ligation, more so after 16 hr than after 4 hr. The size of the gastrin cells seemed unaffected. In all three cell types pylorus ligation reduced the number of cytoplasmic granules. There was no increase in the Golgi area or in the endoplasmic reticulum in any of the endocrine cell types of the oxyntic gland area. It appears unlikely that the ultrastructural changes of the ECL and A-like cells reflect an increased rate of histamine mobilization.6. The acid response to pylorus ligation probably reflects neuronal reflex mechanisms exclusively. There is no evidence that gastrin or histamine released from gastric endocrine cells mediate the response.