EFFECTS OF SUCRALFATE, CIMETIDINE AND RABEPRAZOLE ON MUCOSAL HYDROXYPROLINE CONTENT IN HEALING OF ETHANOL-HCL-INDUCED GASTRIC LESIONS

[THE INFLUENCE OF MELANIN ON THE GASTRIC MUCOSA AND HYPOTHALAMIC-PITUITARY-ADRENOCORTICAL AXIS UNDER ACUTE STRESS CONDITIONS]

We studied the influence of melanin from yeast-like fungi Nadsoniella nigra strain X1 on the changes of the levels of adrenocorticotropic hormone (ACTH) and cortisol in blood serum of rats, adrenal glands weight ratio and lesions of the gastric mucosa (GM) caused by neuromuscular tension by Selye. Melanin administration restored functioning of the hypothalamic-pituitary-adrenal axis that was evident by an increase of ACTH concentration by 42% and a decrease of cortisol concentration by 19% compared to the rats injected with water (group 2). In rats treated with melanin, the adrenal glands weight ratio, didn't differ from intact control group of the rats. Melanin decreased ulcers area by 64% and reduced the content of free hydroxyproline by 29%, the free fucose by 16% and the free hexuronic acids by 24% in the GM compared to the group 2 of the rats. It is established that the mechanism of melanin stress-protective properties are based on its regulation of the glucocorticoids secretion and prevention of GM collagen and extracellular matrix substances depolymerization. Melanin possesses gastroprotective properties and is a perspective agent for preventing and treatment of consequences of the stress influence on the organism.

Campomanesia lineatifolia Ruiz & Pav. as a gastroprotective agent

ETHNOPHARMACOLOGICAL RELEVANCE

Campomanesia lineatifolia Ruiz and Pav. (Myrtaceae) is a native edible species found in the Amazon Rainforest, commonly known as gabiroba. In Brazil, Campomanesia species are frequently used in traditional medicine for gastrointestinal disorders.

MATERIALS AND METHODS

The present study performed phytochemical analyses and determined both the in vitro antioxidant activity of the ethanolic extract of Campomanesia lineatifolia leaves (EEC) as well as its ethyl acetate fraction (EAFC). In this analysis, quercetin was used as a positive control. Gastroprotective activity was also investigated at different oral doses in two experimental models in rats - gastric lesion induced by ethanol and gastric lesion induced by indomethacin. In this analysis, cimetidine and sucralfate were used as positive controls. The area of gastric lesion underwent macroscopic and histomorphometric evaluations, while the mucus content was estimated by applying the periodic acid-Schiff stain. Oral acute toxicity was also assessed.

RESULTS

Phytochemical studies revealed the presence of flavonoids and tannins. Catechin and quercitrin were isolated by bioguided chromatographic fractionation of EAFC. EEC and EAFC presented in vitro antioxidant activity. The oral administration of EEC and EAFC at doses 100-400 mg/kg (ethanol model) and at doses of 400-1200 mg/kg (indomethacin model) proved to be effective in preventing gastric ulcerations in rats. Pretreatment with EAFC (400mg/kg) significantly increased the gastric mucus content in the ethanol model. No animals died during the acute oral toxicology test.

CONCLUSIONS

Results confirm the Brazilian ethnopharmacological use of Campomanesia lineatifolia as a gastroprotective agent and indicate that the anti-ulcer effect is most likely mediated by scavenging free radicals due to the polyphenol content and, at least in part, by increasing the mucus secretion and the mucosal defense. In addition, EEC and EAFC were found to be safe when applied to a 2000 mg/kg single oral dose.

Mechanisms of the gastric antiulcerogenic activity of Anacardium humile St. Hil on ethanol-induced acute gastric mucosal injury in rats

Leaves and bark infusions Anacardium humile St. Hil. (Anacardiaceae), known as in Brazil as "cajuzinho do cerrado", have been used in folk medicine as an alternative treatment for ulcers and gastritis. This study evaluated the gastroprotective activity of an ethyl acetate extract of the leaves of A. humile (AcF) and the mechanism involved in this gastroprotection. Pretreatment concentrations (50, 100, 200 mg x kg⁻¹) were administered by gavage. Following a 60 min. period, all the rats were orally administered 1 mL of absolute ethanol. One hour after the administration of ethanol, all groups were sacrificed, and the gastric ulcer index was calculated. Prostaglandin PGE₂ concentration, gastric adherent mucous, and the participation of nitric oxide (NO) and sulfhydryl compounds in the gastroprotection process were also analyzed using the most effective tested dose (50 mg x kg⁻¹). A histological study of the glandular stomach for the evaluation of the epithelial damage and mucus content was also performed. AcF significantly reduced the gastric damage produced by ethanol. This effect was statistically significant for the 50 mg x kg⁻¹ group compared to control. Also, it significantly increased the PGE₂ (by 10-fold) and mucous production, while pretreatment with NG-nitro-L-arginine methyl ester (L-NAME) or N-ethylmaleimide (NEM) completely abolished the gastroprotection. AcF has a protective effect against ethanol, and this effect, might be due to the augmentation of the protective mechanisms of mucosa.

Gastroprotective effect of Cissus sicyoides (Vitaceae): involvement of microcirculation, endogenous sulfhydryls and nitric oxide

AIM OF THE STUDY

Cissus sicyoides L. is a medicinal plant popularly known in Brazil against various diseases and the research interest in this plant is justifiable because of its potential medicinal value in stomachache and gastric ulcer.

MATERIALS AND METHODS

The methanolic extract obtained from the leaves of Cissus sicyoides (Cc) was evaluated for the ability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3 M HCl/60% EtOH, absolute ethanol, piroxicam and pylorus ligature) in rodents. We also evaluated microcirculation, antioxidant action and participation of NO (nitric oxide) and sulfhydryls (SH) groups in the Cc gastroprotective action.

RESULTS

Administration of Cc significantly reduced gastric lesions induced by different ulcerogenic agents in rodents. This extract administered by oral route significantly increased gastric volume without exerting antisecretory effect. The Cc effect involved an increase of the defense mechanism of the gastrointestinal mucosa such as NO and SH groups that prevent and attenuate the ulcer process. The Cc also has antioxidant property against oxidative stress but does not modify microcirculation response in gastric mucosa.

CONCLUSIONS

These results confirmed the traditional use of Cissus sicyoides for the treatment of gastric ulcer.