Ulcer healing and mechanism(s) of action involved in the gastroprotective activity of fractions obtained from Syngonanthus arthrotrichus and Syngonanthus bisulcatus.

BACKGROUND: Syngonanthus arthrotrichus and Syngonanthus bisulcatus, currently known for Comanthera aciphylla (Bong.) L.R.Parra & Giul. and Comanthera bisulcata (Koern.) L.R. Parra & Giul, popularly known in Brazil as "sempre-vivas," are plants from the family Eriocaulaceae. They are found in the states of Minas Gerais and Bahia. The species are known to be rich in flavonoids to which their gastroprotective activity has been attributed. In this research, experimental protocols were performed to elucidate the associated mechanisms of action. METHODS: The activity was evaluated using induced gastric ulcer models (acetic acid and ethanol-induced gastric lesions in NEM or L-NAME pre-treated mice, and by ischemia/reperfusion). Antioxidant enzymes, serum somatostatin, and gastrin were also evaluated. RESULTS: In chronic gastric ulcers, a single daily oral dose of Sa-FRF or Sb-FRF (100 mg/kg body wt.) for 14 consecutive days accelerated ulcer healing to an extent similar to that seen with an equal dose of cimetidine. The pre-treatment of mice with NEM (N-ethylmaleimide) or L-NAME (N-nitro-L-arginine) abolished the protective activity of Sa-FRF, Sa-FDF, Sb-FDF and Sb-FRF or Sa-FRF and Sb-FRF, respectively, which indicates that antioxidant compounds and nitric oxide synthase activity are involved in the gastroprotective. Sa-FRF and Sb-FRF (100 mg/kg p.o) protected the gastric mucosa against ulceration that was induced by ischemia/reperfusion (72 and 76 %, respectively). It also decreased lipid peroxidation and restored total thiols in the gastric wall of mice that had been treated with ethanol. When administered to rats submitted to ethanol-induced gastric lesions, Sa-FRF and Sb-FRF (100 mg/kg, p.o.) increased the somatostatin serum levels, while the gastrin serum levels were proportionally decreased. CONCLUSIONS: The results indicate significant healing effects and gastroprotective activity for the Sa-FRF and Sb-FRF, which probably involves the participation of SH groups, nitric oxide (NO), the antioxidant system, somatostatin, and gastrin. All are integral parts of the gastrointestinal mucosa's cytoprotective mechanisms against aggressive factors.

Gastroprotective effects (in rodents) of a flavonoid rich fraction obtained from Syngonanthus macrolepsis.

OBJECTIVES: Syngonanthus macrolepis, popularly known in Brazil as 'sempre-vivas', is a plant from the family Eriocaulaceae, it is found in the states of Minas Gerais and Bahia. The species contains a variety of constituents, including flavonoids with gastroprotective effect. In this work, a flavonoid-rich fraction (Sm-FRF) obtained from scapes of S. macrolepis was investigated for preventing gastric ulceration in mice and rats. METHODS: The activity was evaluated in models of induced gastric ulcer (absolute ethanol, stress, non-steroidal anti-inflammatory drugs and pylorus ligation). The cytoprotective mechanisms of the Sm-FRF in relation to sulfhydryl (SH) groups, nitric oxide (NO) and antioxidant enzymes were also evaluated. KEY FINDINGS: The Sm-FRF (100 mg/kg, p.o.) significantly reduced gastric injury in all models, and did not alter gastric juice parameters after pylorus ligation. CONCLUSIONS: The results indicate significant gastroprotective activity for the Sm-FRF, which probably involves the participation of both SH groups and the antioxidant system. Both are integral parts of the gastrointestinal mucosa's cytoprotective mechanisms against aggressive factors.

Anti-inflammatory intestinal activity of Arctium lappa L. (Asteraceae) in TNBS colitis model.

ETHNOPHARMACOLOGICAL RELEVANCE: In Brazilian traditional medicine, Arctium lappa (Asteraceae), has been reported to relieve gastrointestinal symptoms. AIM OF THE STUDY: In the present study, we investigated the effects of the lactone sesquiterpene onopordopicrin enriched fraction (ONP fraction) from Arctium lappa in an experimental colitis model induced by 2,4,6 trinitrobenzene sulfonic acid and performed experiments to elucidate the underlying action mechanisms involved in that effect. MATERIALS AND METHODS: ONP fraction (25 and 50 mg/kg/day) was orally administered 48, 24 and 1 h prior to the induction of colitis and 24 h after. The inflammatory response was assessed by gross appearance, myeloperoxidase (MPO) activity, tumor necrosis factor alpha (TNF-α) levels and a histological study of the lesions. We determined cyclooxygenase (COX)-1 and -2 protein expressions by western blotting and immunohistochemistry assays. RESULTS: TNBS group was characterized by increased colonic wall thickness, edema, diffuse inflammatory cell infiltration, increased MPO activity and TNF-α levels. On the contrary, ONP fraction (25 and 50 mg/kg) treatment significantly reduced the macroscopic inflammation scores (p<0.05 and p<0.01, respectively) and morphological alterations associated with an increase in the mucus secretion. Similarly, the degree of neutrophil infiltration and the cytokine levels were significantly ameliorated. Moreover, COX-2 expression was up regulated in TNBS-treated rats. In contrast, ONP fraction (50 mg/kg) administration reduced COX-2 overexpression. CONCLUSIONS: We have shown that the ONP fraction obtained from Arctium lappa exert marked protective effects in acute experimental colitis, confirming and justifying, at least in part, the popular use of this plant to treat gastrointestinal diseases.

Anti-ulcerogenic mechanisms of the sesquiterpene lactone onopordopicrin-enriched fraction from Arctium lappa L. (Asteraceae): role of somatostatin, gastrin, and endogenous sulfhydryls and nitric oxide.

Arctium lappa L. has been used in folk medicine as a diuretic, depurative, and digestive stimulant and in dermatological conditions. The mechanisms involved in the anti-ulcerogenic activity of the sesquiterpene onopordopicrin (ONP)-enriched fraction (termed the ONP fraction), obtained from A. lappa leaves, were studied. The gastroprotective mechanism of the ONP fraction was evaluated in experimental in vivo models in rodents, mimicking this disease in humans. ONP fraction (50 mg/kg, p.o.) significantly inhibited the mucosal injury induced by ethanol/HCl solution (75%), indomethacin/bethanecol (68.9%), and stress (58.3%). When the ONP fraction was investigated in pylorus ligature, it did not induce alteration in the gastric volume but did modify the pH and total acid concentration of gastric juice. ONP fraction significantly increased serum somatostatin levels (82.1±4.1 vs. control group 12.7±4 pmol/L) and decreased serum gastrin levels (62.6±6.04 vs. control group 361.5±8.2 µU/mL). Mucus production was not significantly altered by the ONP fraction. Gastroprotection by the ONP fraction was completely inhibited by N-ethylmaleimide treatment and did not modify the effect in the animals pretreated with l-N(G)-nitroarginine methyl ester. These results suggest an antisecretory mechanism involved with the antiulcerogenic effect of the ONP fraction. However, only endogenous sulfhydryls play an important role in gastroprotection of the ONP fraction.

Indigofera suffruticosa Mill as new source of healing agent: involvement of prostaglandin and mucus and heat shock proteins.

ETHNOPHARMACOLOGICAL RELEVANCE: Indigofera suffruticosa is specie typical of the "Cerrado" or Brazilian savannah; it is a member of the Fabaceae family - in folkmedicine is used for gastric disorders, infection and inflammation. AIM OF THE STUDY: Ethyl acetate fraction (AcF) and aqueous fraction (AqF) of the methanolic extract of I. suffruticosa leaves were evaluated against acute gastric ulcer. The AcF fraction was selected to assess its activity in ulcer healing and its gastroprotective effects via mucus and gastric secretion. MATERIALS AND METHODS: The gastroprotective action of AcF and AqF fractions were evaluated in a rodent experimental model. The action mechanisms, involvements of the antisecretory action, mucus and prostaglandin production, toxicological and healing activity of the AcF (100mg/kg, p.o.) were evaluated. We also used histological analysis (HE and PAS) and immunohistochemical (PCNA and HSP-70) assays to evaluate the effects of I. suffruticosa. RESULTS: AcF significantly inhibited the gastric mucosal damage caused by ethanol. This effect was statistically significant in 100mg/kg group compared vehicle. AcF did not interfered with gastric secretion, significantly increased the PGE(2) and mucus production (validated in PAS technique). The gastroprotection was attenuated by pretreatment with N-ethylmaleimide, but not L-NAME. In acid-acetic-induced ulcer model AcF accelerated ulcer healing. Immunohistochemistry analysis showed induction of proliferating cell (PCNA) and heat shock protein (HSP 70). CONCLUSIONS: These results showed that AcF acted as gastroprotective agent stimulating prostaglandin, mucus and HSP70.

Antiulcerogenic action of ethanolic extract of the resin from Virola surinamensis Warb. (Myristicaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Virola surinamensis (Myristicaceae), popularly known as "mucuíba", "ucuuba" or "ucuúba do igapó" is a large tree that grows abundantly in "Várzea" forest and on river banks in the Brazilian states of Amazonas and Tocantins. The resin obtained by cuts on the stem bark is a reputed folk remedy in its natural form for the treatment of ulcer, gastritis, inflammation and cancer. AIM OF THE STUDY: The present work evaluated the pharmacological activity of the resin obtained from bark of V. surinamensis as antiulcerogenic in experimental in vivo model in order to observe whether its traditional use is justified. MATERIALS AND METHODS: The preventive action of ethanolic extract of V. surinamensis was evaluated in experimental in vivo models in rodents that simulated this disease in human gastric mucosa. RESULTS: Oral administration of acidified ethanol solution produced severe hemorrhagic lesions in glandular mucosa with ulcerative lesion of 50+/-11.5mm. In animals pretreated with V. surinamensis (500 mg/kg, p.o.) a significant inhibition of mucosal injury of 2.40+/-0.56 mm (95% inhibition) was detected. The V. surinamensis, at the same dose, also reduced significantly (p<0.05) the formation of gastric lesions induced by indomethacin (39%), stress (45%) and by pylorus ligature in mice (31%) when compared to animals treated with vehicle. The extract from V. surinamensis exerts gastroprotective action only when this extract contacts gastric mucosa (oral route) with increased pH values and reduced H+ concentration of gastric contents. The ethanolic extract of V. surinamensis resin was analyzed by TLC and spectrometric methods (NMR and ES-MS) and the main constituent of this extract was epicatechin. CONCLUSIONS: We suggest that the epicatechin present in V. surinamensis resin may be among active principles responsible for the antiulcer activity shown by the tested resin but their used suggest carefulness because toxicological symptoms mentioned by population.

Gastric antiulcer activity of Syngonanthus arthrotrichus SILVEIRA.

Syngonanthus arthrotrichus SILVEIRA, popularly known as "sempre-vivas mini-saia," is found in mountains of the Espinhaço range in the Brazilian states of Bahia and Minas Gerais. Extracts of this species contain several constituents, including flavonoids which may have antiulcerogenic activity. An ethanolic extract (EEOH), and flavonoid-rich (FRF) and flavonoid-deficient (FDF) fractions obtained from the scapes of S. arthrotrichus were investigated for their ability to prevent ulceration of the gastric mucosa in mice and rats. In the ethanol/HCl-induced ulcer model, lansoprazole (30 mg/kg), EEOH (50, 100, 250 mg/kg) given orally protected the gastric mucosal against injury in mice by 79%, 78%, 73%, and 64% respectively. In the ethanol-induced gastric ulcer model in rats, the lansoprazole (30 mg/kg), FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of rats by 65%, 38% and 25% respectively when compared with the negative control group. In indomethacin/bethanechol-induced gastric ulcers, cimetidine (100 mg/kg) and the EEOH (100, 250 mg/kg) inhibited gastric ulcer formation by 73%, 55% and 32% respectively. In this exactly model other treatments as cimetidine, FRF and FDF (100 mg/kg) each caused 54%, 36% and 45% inhibition, respectively. In the stress-induced gastric ulcer model, cimetidine (100 mg/kg) and the EEOH (50, 100, 250 mg/kg), inhibited gastric ulcer formation by 63%, 73%, 68% and 69% respectively. In the same model, cimetidine, FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of the mice by 60%, 51% and 47% when compared to the control group. In pylorus-ligated mice, cimetidine (positive control) and FRF significantly decreased gastric acid secretion, increased gastric pH and reduced the acid output when compared to the negative control. FDF had no significant effect on these parameters. The protection provided by FRF probably involved an antisecretory mechanism mediated by flavonoids which were absent in FDF. The amount of adherent mucous in the stomach contents was also evaluated with the treatments carbenoxolone (200 mg/kg), FRF and FDF (100 mg/kg) treatment. Each treatments significantly increased the amount of adherent mucous in the gastric juice (8.67+/-1.73, 3.35+/-1.59, 2.1+/-0.41 mg/g of wet tissue, respectively) compared to the control group, indicating a cytoprotective action on the gastric mucosa. Treatment with FRF plus indomethacin and FDF plus indomethacin reduced the prostaglandin biosyntesis (13.6+/-6.5, 27+/-5.5 pg/well) by the mucosa, indicating that the cytoprotective action on the gastric mucosa was not related to the level of prostaglandins. Only FDF (38+/-17 pg/well) maintained the level of prostaglandins and guaranteed the integrity of the mucosa. The results indicate that the EEOH, FRF and FDF have antisecretory and cytoprotective actions, that may be related to the presence of luteoline in the extract and active fractions.

Natural trans-crotonin: the antiulcerogenic effect of another diterpene isolated from the bark of Croton cajucara Benth.

The nor-clerodane diterpene trans-crotonin isolated from the bark of Croton cajucara BENTH. was investigated for its ability to prevent the formation of gastric-mucosa ulceration in different experimental models in mice. The results obtained from crotonin were compared with those obtained with another diterpene, DHC (trans-dehydrocrotonin) in the same models. When previously administered (p.o.) at the dose of 100 mg/kg, crotonin, as well as DHC, significantly reduced (p<0.05) gastric injury induced by stress (72, 67%), indomethacin/bethanechol (78, 29%) and pylorus ligature (35, 30%). In the HCl/ethanol-induced gastric ulcer model, at oral doses of 100 and 250 mg/kg, crotonin significantly prevented (p<0.05) the formation of gastric lesions by 51 and 56%, respectively, when compared to the control group. Gastric injury was also of significantly less magnitude in the DHC treatment group (p<0.05). In the pylorus-ligature model, crotonin (p.o.), like cimetidine, increased the volume of gastric juice when compared to the control group (p<0.05). No significant modifications where found in gastric parameters such as pH or total acid content after oral crotonin treatment. However, systemic alterations were observed when crotonin (100 mg/kg) was previously administered intraduodenally to mice. We observed significant changes (p<0.001) in gastric-juice parameters such as an increase in volume and a decrease in gastric acidity. Those pre-treated with crotonin as well as with DHC did not increase free mucus production (p>0.05). The results suggest that crotonin presents a significant anti-ulcer effect when assessed in these ulcer-induced models. As with DHC, the antiulcerogenic effects of crotonin are probably related to anti-secretory or/and gastroprotective properties of this substance. In light of results obtained with DHC and natural trans-crotonin in the present study, we concluded that the A-ring of both diterpenes is not directly involved in the antiulcerogenic activity.