Cytotoxic and genotoxic potential of geraniol in peripheral blood mononuclear cells and human hepatoma cell line (HepG2).

Geraniol is an acyclic monoterpene alcohol present in the essential oil of many aromatic plants and is one of the most frequently used molecules by the flavor and fragrance industries. The literature also reports its therapeutic potential, highlighting itself especially as a likely molecule for the development of drugs against cancer. In view of these considerations, this study was designed to evaluate the cytotoxic and genotoxic potential of geraniol, in an in vitro protocol, using two types of human cells: one without the ability to metabolize (peripheral blood mononuclear cells - PBMC), and the other with this capability (human hepatoma cell line - HepG2) through the comet assay and the micronucleus test. Four concentrations (10, 25, 50, and 100 µg/mL) were selected for the genotoxic assessment for PBMC and three (1.25, 2.5, and 5 µg/mL) for HepG2 cells based on cytotoxicity tests (MTT assay). Results showed that geraniol did not present genotoxic or clastogenic/aneugenic effects on both cell types under the conditions studied. However, caution is advised in the use of this substance by humans, since a significant reduction in viability of HepG2 and a marked decrease in cell viability on normal PBMC were verified.

Effect of menthol in experimentally induced ulcers: pathways of gastroprotection.

Based on ethnopharmacological indications that Mentha species may be used in the treatment of gastrointestinal diseases, this study aimed to characterize the gastroprotective mechanisms of menthol (ME), the major compound of the essential oil from species of the genus Mentha. The gastroprotective action of ME was analyzed in gastric ulcers that were induced by ethanol or indomethacin in Wistar male rats. The mechanisms responsible for the gastroprotective effect were assessed by analyzing the amount of mucus secreted, involvement of non-protein sulfhydryl (NP-SH) compounds, involvement of calcium ion channels and NO/cGMP/K(+)ATP pathway, gastric antisecretory activity and the prostaglandin E2 (PGE2) production. The anti-diarrheal activity and acute toxicity of ME were also evaluated. Oral treatment with ME (50mg/kg) offered 88.62% and 72.62% of gastroprotection against ethanol and indomethacin, respectively. There was an increased amount of mucus and PGE2 production. The gastroprotective activity of ME involved NP-SH compounds and the stimulation of K(+)ATP channels, but not the activation of calcium ion channels or the production of NO. The oral administration of ME induced an antisecretory effect as it decreased the H(+) concentration in gastric juice. ME displayed anti-diarrheal and antiperistaltic activity. There were no signs of toxicity in the biochemical analyses performed in the rats' serum. These results demonstrated that ME provides gastroprotective and anti-diarrheal activities with no toxicity in rats.

Gastric Ulcers in Middle-Aged Rats: The Healing Effect of Essential Oil from Citrus aurantium L. (Rutaceae).

The elderly population has experienced increased life expectancy as well as the increased incidence of gastric ulcers. The peels of fruits from Citrus aurantium L., popularly known in Brazil as orange bitter, are commonly used asatea form for the treatment of gastrointestinal tract disorders, such as ulcer and gastritis. We evaluated the healing effects of essential oil from the peels of Citrus aurantium fruits (OEC) on gastric ulcers in middle-aged rats. We examined the effects of a 14-day chronic OEC treatment on gastric mucosa in middle-aged male Wistar rats that were given acetic-acid-induced gastric lesions by morphometric and immunohistological analyses. Oral OEC treatment significantly reduced the lesion area (76%) within the gastric mucosa and significantly increased (P < .05) the height of regenerated mucosa (59%) when compared to the negative control group. Immunohistochemical analysis of the molecular markers such as COX-2, HSP-70, VEGF, and PCNA in the gastric mucosa confirmed that OEC treatment induced healing effects by increasing the number of new blood vessels and by augmenting gastric mucus in the mucosa glands. These results suggest that the oil from Citrus aurantium effectively heals gastric ulcers in middle-aged animals; however, safe use of OEC demands special care and precautions.

Morphologic and pharmacological investigations in the epicatechin gastroprotective effect.

Previous studies of the gastroprotective activity of plants have highlighted the importance of the polyphenolic compound epicatechin (EC) in the treatment of gastric ulcers. This paper aimed to evaluate and characterize the gastroprotective mechanism of action of EC using male rats. The gastroprotective action of EC was analyzed in gastric ulcers induced by ethanol or indomethacin. The involvement of sulfhydryl (SH) groups, K(+) (ATP) channels, α(2) adrenoceptors, gastric antisecretory activity, and the amount of mucus in the development of gastric ulcers were investigated. The lowest effective dose of EC providing gastroprotective effects was 50 mg/kg in the ethanol-induced gastric ulcers and 25 mg/kg in the indomethacin-induced gastric ulcers. The gastroprotection seen upon treatment with EC was significantly decreased in rats pretreated with a SH compound reagent or an α(2)-receptor antagonist, but not with a K(+) (ATP) channel blocker. Furthermore, oral treatment with EC increased mucus production and decreased H(+) secretion. Immunohistochemistry demonstrated the involvement of superoxide dismutase (SOD), nitric oxide (NO), and heat shock protein-70 (HSP-70) in the gastroprotection. These results demonstrate that EC provides gastroprotection through reinforcement of the mucus barrier and neutralization of gastric juice and this protection occurs through the involvement of SH compounds, α(2)-adrenoceptors, NO, SOD, and HSP-70.

Effect of Mouriri pusa tannins and flavonoids on prevention and treatment against experimental gastric ulcer.

AIM OF THE STUDY: Mouriri pusa, popularly known as "manapuçá" or "jaboticaba do mato", is a plant from Brazilian cerrado that has been found to be commonly used in the treatment of gastrointestinal disturbs in its native region. The present work was carried out to investigate the effect of tannins (TF) and flavonoids (FF) fractions from Mouriri pusa leaves methanolic extract on the prevention and cicatrisation process of gastric ulcers, and also evaluate possible toxic effects. MATERIALS AND METHODS: The following protocols were taken in rats: acute assay, in which ulcers were induced by oral ethanol after pre-treatment with the fractions; and 14 days treatment assay, in which ulcers were treated for 14 days after induction by local injection of acetic acid. RESULTS: In the acute model, treatment with either, TF (25mg/kg) or FF (50mg/kg), was able to reduce lesion area, showing gastroprotective effect. In addition, FF proved itself anti-inflammatory by reducing COX-2 levels. In acetic acid model, both fractions exhibited larger ulcers' regenerative mucosa, indicating cicatrisation enhancement. FF group also showed augmented cell proliferation, anti-inflammatory action and enhanced angiogenesis as well as increased mucus secretion. Moreover, concerning the toxicity parameters analyzed, no alteration in the fractions groups was observed. CONCLUSIONS: Tannins and flavonoids from Mouriri pusa provide beneficial effects against gastric ulcers with relative safety.

Brazilian medicinal plant acts on prostaglandin level and Helicobacter pylori.

Among the current treatment strategies for the peptic ulcer patient with Helicobacter pylori infection, the method of choice is triple therapy based on the concurrent use of proton inhibitors and two antibiotics. Alchornea triplinervia is a medicinal plant commonly used by people living in the Cerrado region of Brazil to treat gastrointestinal ulcers. In the present work we proposed therapy based on this medicinal plant that presents effective gastroprotective action with antibiotic effects. Oral pretreatment with methanolic extract (ME) of A. triplinervia in rats and mice decreased the gastric injuries induced by ethanol and HCl/ethanol. Increasing the dose reduced the gastroprotective effects of ME on the gastric lesions induced by nonsteroidal anti-inflammatory drug. After pylorus ligature of mice, oral administration of ME induced a decrease not only in total acid but also in the ulcer index. We also observed that ME displayed antibacterial activity against H. pylori. Liquid-liquid separation of ME indicated that active constituents responsible for the gastroprotective action are concentrated in the ethyl acetate fraction (EAF) (50% protection) rather than in the aqueous fraction, which did not induce significant gastroprotection at the same dose (100 mg/kg). EAF induced an increase of gastric mucosa prostaglandin (PG) E(2) levels, which remained high even after previous administration of indomethacin. The phytochemical profile of ME revealed that EAF contains mainly flavonoids. In conclusion, all these results suggest that ME did not show acute toxicity, but exhibited an antisecretory property, anti-H. pylori effect, and gastroprotective action. The observed effect did not involve the participation of nitric oxide or endogenous sulfhydryl groups. However, EAF showed a more efficient gastroprotective effect than ME at a lower dose and protected the gastric mucosa by increasing PGE(2).

Antimicrobial activity of some medicinal plants of the Cerrado, Brazil.

In order to determine the potential of Cerrado plants as sources of antimicrobial activity, the phytochemical screening of ethanol extracts from Virola surinamensis, Qualea grandiflora, Alchornea castaneifolia, Hancornia speciosa and Curatella americana traditionally used in folk medicine are reported.

Differences in gastroprotective and mutagenic actions between polar and apolar extracts of Ananas ananassoides.

Several plants are used in folk medicine to treat gastrointestinal disorders. Ananas ananassoides (Baker) L.B. Smith (Family Bromeliaceae) is a medicinal plant commonly used in the central region of Brazil against gastric pain. We evaluated two extracts (methanol [MeOH] and dichloromethane [DCM]) obtained from the leaves of A. ananassoides for their ability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3 M HCl/60% ethanol, absolute ethanol, non-steroidal anti-inflammatory drugs, and pylorus ligation) in mice and rats. The best results were obtained after pretreatment with the DCM extract, whereas the MeOH extract did not show any significant anti-ulcerogenic activity but presented mutagenic action. The mechanism of action of the DCM extract suggested the effective participation of endogenous sulfhydryl group in the gastroprotective action. The data, taken together with the absence of acute toxicity and mutagenicity, indicate the apolar extract, instead of the polar, extract of A. ananassoides as a safe and potential new anti-ulcerogenic drug.

Studies of gastric mucosa regeneration and safety promoted by Mouriri pusa treatment in acetic acid ulcer model.

ETHNOPHARMACOLOGICAL RELEVANCE: Mouriri pusa Gardn. (Melastomataceae) is a medicinal plant commonly used by people living in the Cerrado to treat gastrointestinal disturbances. This medicinal plant has shown intense gastroprotective action in rodent gastric lesion, but still there are no data about its healing effect on gastric mucosa. AIM OF THE STUDY: To evaluate the methanolic extract (MeOH) obtained from Mouriri pusa leaves for its effect on the cicatrisation process of gastric ulcer. MATERIALS AND METHODS: The healing effects on gastric ulcers inducted by subserosal injection of acetic acid were evaluated by macroscopic and microscopic measures, immunohistochemistry and cell counting in rats treated with MeOH extract of Mouriri pusa (250 mg/kg, p.o./daily) for 14 or 30 days. The toxicity of Mouriri pusa was also evaluated by body and organ weight measure and clinical biochemical parameters. RESULTS: Mouriri pusa treatments lasting 14 and 30 days showed elevated mucus secretion (PAS) and thicker regenerative gastric mucosa, denoting increased cell proliferation, which was confirmed by PCNA immunohistochemical analysis. Moreover, there was important cell recruitment (neutrophils and mast cells) to the site of the ulcer, which is an important factor in ulcer healing. No toxic effect was observed in all parameters evaluated. Phenolic compounds present in the MeOH extract like tannins, flavonoids and epicatechin are the probable agents involved in the healing effects of this medicinal plant. CONCLUSIONS: These findings showed a potential effect of Mouriri pusa in increasing regeneration of damaged gastric mucosa with safety for human use.

The gastroprotective effect of the essential oil of Croton cajucara is different in normal rats than in malnourished rats.

It has been shown previously that malnourished rats are resistant to acute gastric lesions but not to subchronic gastric ulceration. It also has been demonstrated that the essential oil obtained from the bark of Croton cajucara (Sacaca) has antiulcer properties. In the present study, the ability of this essential oil to prevent the formation of gastric ulcers in rats fed a diet with 17% protein (normoproteic rats) or 6% protein (malnourished rats) was investigated. At a dose of 100 mg/kg body weight, orally, the essential oil significantly reduced the gastric injury caused by indomethacin (25% after 2 h and 70% after 4 h) only in normoproteic rats. In the pylorus ligature model, the essential oil increased the pH and gastric volume, but decreased the total acid concentration in both groups when compared to the respective control group. The essential oil significantly increased prostaglandin E2 production in glandular cells by 50% compared to the controls in both groups of rats. In addition, the amount of gastric mucus was two-fold higher in malnourished rats than in normoproteic rats. The present results show that the enhanced protective effect of essential oil in malnourished rats involved an increase in prostaglandin E2 production and mucus secretion, which are both factors that protect the gastric mucosa against damage. In agreement with this, malnourished rats always had a lower number of acute gastric ulcers.

Can the aqueous decoction of mango flowers be used as an antiulcer agent?

This study was designed to determine the effect of Mangifera indica flowers decoction, on the acute and subacute models of induced ulcer in mice and rats. A single oral administration of the aqueous decoction (AD) from M. indica up to a dose of 5 g/kg, p.o. did not produce any signs or symptom of toxicity in the treated animals. The oral pre-treatment with AD (250, 500 and 1000 mg/kg) in rats with gastric lesions induced by ethanol, decreased the gastric lesions from 89.0+/-6.71 (control group) to 9.25+/-2.75, 4.50+/-3.30 and 0, respectively. Pretreatment with AD (250, 500 and 1000 mg/kg) to mice with HCl/ethanol- or stress-induced gastric lesions resulted in a dose-dependent significant decrease of lesion index. In the piroxicam-induced gastric lesions, the gastroprotective effect of AD was reducing with the increase of the AD dose. In the pylorus-ligature, AD (p.o.) significantly decreased the acid output indicating the antisecretory property involved in the gastroprotective effect of M. indica. Treatment with AD during 14 consecutive days significantly accelerated the healing process in subacute gastric ulcer induced by acetic acid in rats. Pretreatment with N-nitro-l-arginine methyl ester (l-NAME), an inhibitor of NO-synthase, did not abolish the gastroprotective effects (99% with saline versus 80% with l-NAME) of AD against ethanol-induced gastric lesions. Pretreatment with N-ethylmaleimide (NEM), a blocker of endogenous sulphydryl group, significantly abolished the protective effects of AD against ethanol-induced gastric ulcers (95% with saline versus 47% with NEM). Phytochemical screening showed the presence of steroids, triterpenes, phenolic compounds and flavonoids. Estimation of the global polyphenol content in the AD was performed by Folin-Ciocalteu method and showed approximately 53% of total phenolic on this extract. These findings indicate the potential gastroprotective and ulcer-healing properties of aqueous decoction of M. indica flowers and further support its popular use in gastrointestinal disorders in Caribbean.

Qualea grandiflora, a Brazilian "Cerrado" medicinal plant presents an important antiulcer activity.

Qualea grandiflora is one of the species widely used in folk medicine to treat gastric ulcers in Cerrado of the central region of Brazil. The hydroalcoholic extract of bark (HE) of Qualea grandiflora was investigated for their ability to prevent and heal lesions in the gastric mucosa. The oral administration of HE exhibited antiulcer activity decreasing the ulcerative index induced by HCl/ethanol solution, indomethacin/bethanechol and stress. In the Shay model, results showed that HE (p.o.) only reduced the severity of gastric lesions without effects on pH, gastric acidity or volume. When given by intraduodenal route, HE changed the pH, but did not modify the other parameters of the gastric juice. These data were in accordance with those obtained when HE was administered orally for 14 days after gastric ulcers were induced by acetic acid in rats. HE presented healing process in subacute gastric ulcer induced by acetic acid in rats. Moreover, histological examinations showed the simple columnar epithelium, lamina propria with simple branched tubular glandules with dilated lumen and large amounts of mucus secretion. Phytochemical investigation of HE led to the detection of terpenes, steroids, saponins, phenolic compounds and tannins in this extract, which may be involved in the observed activity.

Strychnos L. da América do Sul e Central / Strychnos L. of South America and Central

Uma revisão do perfil químico e farmacológico é apresentada de espécies de Strychnos (Loganiaceae) ocorrentes na América do Sul e Central, incluindo o uso popular, as substâncias isoladas e suas atividades biológicas.

A review of the chemical and pharmacological profile of Strychnos species (Loganiaceae) found in South and in Central America is presented. It includes the folk uses, the isolated compounds as well as the pharmacological activities as reported in the literature.

Preliminary studies of Mammea americana L. (Guttiferae) bark/latex extract point to an effective antiulcer effect on gastric ulcer models in mice.

Plant extracts are some of the most attractive sources of new drugs and have shown promising results for the treatment of gastric ulcers. Several folk medicinal plants and herbs have been used to treat gastrointestinal disorders, including gastric ulcers. Mammea americana L. (Guttiferae) fruit is very common in the diet of the population of northern South America. Our research interest in this plant arose because of its potential medicinal value as a tonic and against stomachache, as used in folk medicine. In this paper we evaluated three different extracts (ethanolic/EtOH, methanolic/MeOH and dichloromethane/DCM) obtained from M. americana L., for their ability to protect the gastric mucosa against injuries caused by necrotizing agents (0.3 M HCl/60% EtOH), hypothermic restraint stress, nonsteroidal anti-inflammatory drugs (NSAID, indomethacin) and pylorus ligation. In the HCl/EtOH-induced gastric-ulcer model, EtOH and DCM extracts demonstrated significant inhibition of the ulcerative lesion index by 54% (12.0 +/- 2.6 mm) and 86% (3.7 +/- 1.8 mm), respectively, in relation to the control value (26.0 +/- 1.4 mm) (p<0.0001). In the NSAID/cholinomimetic-induced lesion model, both EtOH and DCM extracts showed antiulcerogenic effects with significant reduction in the damage to these gastric lesions of 36% (8.3 +/- 2.0 mm) and 42% (7.5 +/- 1.4 mm), respectively, as compared to the control group (13.0 +/- 0.9 mm) (p<0.0001). In the gastric ulcer induced by hypothermic-restraint stress, both extracts also showed significant activity, and inhibited the gastric lesion index by 58% and 75%, respectively. The EtOH and DCM extracts also changed gastric juice parameters as well as those of cimetidine, decreased gastric acid secretion significantly (p<0.0001), increased pH values and promoted reduced acid output (p<0.0001). In all gastric-ulcer-induced models, MeOH extract did not show any significant antiulcerogenic activity, nor did it change gastric-juice parameters (p>0.05). The results suggest that EtOH and DCM extracts obtained from M. americana possess excellent antisecretory and/or gastrotective effect in all gastric ulcer models. These results suggest that the antiulcerogenic compound(s) present in M. americana may be clustered in the apolar fraction, which will be investigated by our group for the probable mechanisms of action.

Flavonoids and antiulcerogenic activity from Byrsonima crassa leaves extracts.

Byrsonima crassa Niedenzu (IK) (Malpighiaceae) is used in Brazilian folk medicine for the treatment of diseases related mainly to gastric ulcers. In this study, we evaluated the potential antiulcerogenic effect of three different extracts obtained from the leaves of Byrsonima crassa namely hydromethanolic (80% MeOH), methanolic (MeOH) and chloroformic extracts (CHCl(3)). The oral administration (250, 500 and 1000 mg/kg) of all the extracts reduced the formation of lesions associated with HCl/ethanol administration in mice. The 80% MeOH extract significantly reduced the incidence of gastric lesions by 74, 78 and 92% at doses of 250, 500 and 1000 mg/kg, respectively (P<0.01). The MeOH extract reduced the ulceration by 93 and 99% only at the doses of 500 and 1000 mg/kg (P<0.01). The lower gastroprotective action (69%) was observed when animals were treated with CHCl(3) extract at the dose of 1000 mg/kg (P<0.01). Phytochemical investigation of Byrsonima crassa afforded five known substances: quercetin-3-O-beta-d-galactopyranoside, quercetin-3-O-alpha-l-arabinopyranoside, the biflavonoid amentoflavone, (+)-catechin and (-)-epicatechin. The presence of these phenolic compounds may probably explain the antiulcerogenic effect of the extracts of Byrsonima crassa leaves.

Byrsonima crassa Niedenzu (IK): antimicrobial activity and chemical study

The methanolic extract of leaves from Byrsonima crassa, a Brazilian medicinal plant, was analyzed by CC and HPLC. Four constituents were isolated and identified as quercetin, methyl gallate, (-)-epigallocatechin gallate and quercetin-3-O-(2-galloyl)-a-L-arabinopyranoside. The methanolic and hydromethanolic extract, as well as fractions, were evaluated regarding their possible antimicrobial activity using in vitro methods. Results showed that both extracts and fractions exhibited significant antimicrobial activity against all tested strains

Evaluation of the analgesic and antiedematogenic activities of Quassia amara bark extract.

We evaluated the possible antiedematogenic, antinociceptive and/or sedative effects of four different extracts obtained from the bark of Quassia amara namely, 70% ethanol (70EtOH), 100% ethanol (100EtOH), dichloromethane (DCM) and hexane extracts (HEX). The oral administration (100, 250 and 500 mg/kg) of these extracts did not show significant effects in any experiment. However, when administered intraperitoneally, the HEX extract decreased the paw edema induced by carrageenan, showed antinociceptive effects on the hot-plate test and on acetic acid-induced writhing, and showed sedative effects on pentobarbital-induced sleep. Naloxone did not reverse the antinociceptive effect of this extract. In conclusion, although the mechanisms are uncertain, the results demonstrated that these effects are apparently related to sedative and muscle relaxant or psychomimetic activities of the HEX extract of the plant.

Effect of essential oil obtained from Croton cajucara Benth. on gastric ulcer healing and protective factors of the gastric mucosa.

The bark of Croton cajucara Benth. (Euphorbiaceae) is used widely in Amazonian folk medicine for the treatment of a wide range of gastrointestinal symptoms. Infusions of C. cajucara bark contain dehydrocrotonin (DHC), the furan diterpene, and an essential oil, a rich mixture of sesquiterpenes. Although the antiulcerogenic activity of the essential oil has been studied in different gastric ulcer models in mice and rats, its mechanism remains unclear. In this work, we examined the ability of this essential oil to increase PGE2 release from mucus cells, as well as its effects on the amount of gastric mucus and on the healing of acetic acid-induced gastric ulcers. The essential oil (100 mg/kg body wt., p.o), significantly increased PGE2 production by glandular cells (by 102% as compared to control) and the amount of Alcian blue binding to the gastric mucus. In chronic gastric ulcers, a single daily oral dose of essential oil (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. Thus, the protective and healing actions of the essential oil from C. cajucara bark on gastric lesions resulted mainly from an increase in PGE2 release and gastric mucus formation which would protect the gastric mucosa.

Gastroprotective effect of aparisthman, a diterpene isolated from Aparisthmium cordatum, on experimental gastric ulcer models in rats and mice.

Aparisthmium cordatum (Juss.) Bail. (Euphorbiaceae), known in the State of Pará, Brazil as "ariquena queimosa", is a medium-sized tree which is native to the North Brazilian coastal region. Previous phytochemical studies of the bark of A. cordatum yielded a furan diterpenoid with a clerodane skeleton, called aparisthman. Recently, we reported the antiulcerogenic activity of trans-dehydrocrotonin (DHC), a furan diterpene isolated from Croton cajucara bark, in different ulcerogenic models in mice and rats. The aim of the present study was to assess the possible antiulcerogenic activity of aparisthman. When previously administered (p.o.) at the dose of 100 mg/kg(-1), aparisthman reduced significantly (p < 0.01) gastric injury induced by the indomethacin/bethanechol (71%), ethanol (71%), pylorus ligature, (59%) and hypothermic restraint-stress models (50%), in mice and rats. In the HCl/ethanol-induced gastric ulcer model in mice, at oral doses of 100 and 250 mg/kg(-1), aparisthman from A. cordatum reduced significantly (p < 0.001) the formation of gastric lesions by 59% and 66%, respectively, as compared with control. In the pylorus-ligature model, aparisthman (p.o.) decreased the volume of gastric juice as compared with control (p < 0.001). When aparisthman (100 mg/kg(-1)) was administered intraduodenally to mice, significant modifications were found, such as a decrease in gastric acidity as compared with control. In the animals pre-treated with aparisthman, free mucus production increased by 19% in the gastric mucosa (p < 0.05). The results suggest that aparisthman from A. cordatum presents a significant anti-ulcer effect when assessed in these induced ulcer models. Although the mechanism underlying this antiulcerogenic effect remains unknown, it seems to be related to an increase of the defensive mechanisms of the stomach such as prostaglandin synthesis and mucus production. The good yield of aparisthman obtained from A. cordatum, as well as its antiulcerogenic activity, suggest that this compound should be submitted to pharmacological research as a potential new antiulcerogenic drug.

Antiulcerogenic effect of a hydroalcoholic extract and its organic fractions of Neurolaena lobata (L.) R.BR.

Neurolaena lobata is a species used widely in Caribbean folk medicine to treat gastric pain and ulcers. The hexane (HxF), chloroform (ClF) and aqueous (H2OF) fractions of a hydroalcoholic extract (HE) of N. lobata aerial parts were investigated for their ability to prevent ulceration of the gastric mucosa. In the stress-induced gastric model the HE, HxF and ClF fractions produced a significant reduction of gastric lesion formation by 48, 70 and 52%, respectively. HE, HxF and ClF fractions (41, 57 and 51%, respectively) also reduced significantly the gastric lesions induced by the combination of indomethacin and bethanechol, and the ulcers induced by HCl/ethanol solution by 77, 86 and 83%, respectively (P < 0.05). The pylorus-ligature experiment demonstrated that the HE, HxF and ClF fractions changed significantly the gastric juice parameters, such as pH values (increases to 5.4, 4.9 and 4.8, respectively) and acid output (decreased by 4.6, 5.8 and 6.2 mEq mL(-1) 4h respectively) and gastric content (increased by 400, 410 and 390 mg, respectively) in animals. In the animals pre-treated orally with the HxF fraction, prostaglandin synthesis was increased significantly, by 104%, and free mucus production was increased by 54 % in the gastric mucosa (P < 0.001). The H2OF did not exhibit activity in any of the experimental models assayed. The data suggest that the HE and mainly the HxF of fractions from N. lobata present a significant anti-ulcer effect when assessed in these ulcer-induced models. Although the mechanism underlying this antiulcerogenic effect remains unknown, it seems to be related to an increased activity of the defensive mechanisms of the stomach, such as prostaglandin synthesis and mucus production.