Gastroprotections of escins Ia, Ib, IIa, and IIb on ethanol-induced gastric mucosal lesions in rats

New biofunctional effects of oleanane-type triterpene saponins

In the current review, we describe the novel biofunctional effects of oleanane-type triterpene saponins, including elatosides, momordins, senegasaponins, camelliasaponins, and escins, obtained from Aralia elata (bark, root cortex, young shoot), Kochia scoparia (fruit), Polygala senega var. latifolia (roots), Camellia japonica (seeds), and Aesculus hippocastanum (seeds), considering the following biofunctional activities: (1) inhibitory effects on elevated levels of blood alcohol and glucose in alcohol and glucose-loaded rats, respectively, (2) inhibitory effects on gastric emptying in rats and mice, (3) accelerative effects on gastrointestinal transit in mice, and (4) protective effects against gastric mucosal lesions in rats. In addition, we describe (5) suppressive effects of the extract and chakasaponins from Camellia sinensis (flower buds) on obesity based on inhibition of food intake in mice. The active saponins were classified into the following three types: (1) olean-12-en-28-oic acid 3-O-monodesmoside, (2) olean-12-ene 3,28-O-acylated bisdesmoside, and (3) acylated polyhydroxyolean-12-ene 3-O-monodesmoside. Furthermore, common modes of action, such as involvements of capsaicin-sensitive nerves, endogenous NO and PGs, and possibly sympathetic nerves, as well as common structural requirements, were observed. Based on our findings, a common mechanism of action might mediate the pharmacological effects of active saponins. It should be noted that the gastrointestinal tract is an important action site of saponins, and the role of the saponins in the gastrointestinal tract should be carefully considered.

Anti-Inflammatory and Gastroprotective Effects of Escin

Escin is a triterpenoid saponin extracted from the fruit of Aesculus wilsonii Rehd. and Aesculus hippocastanum (Hippocastanaceae). Clinically, it is widely used in the treatment of edema induced by either trauma or surgery, as well as treating chronic venous insufficiency. The anti-inflammatory and antiedema effects of escin have been extensively investigated. This article systematically reviews the effects of escin on inflammation and gastrointestinal diseases, including its role in inflammation, as an antioxidant, and in inhibiting gastric acid secretion and promoting gastrointestinal movement, especially, the molecular mechanism. The advantages and potential uses of escin have also been discussed.

Effects of intracerebroventricularly injected glucagon-like peptide-2 on ethanol-induced gastric mucosal damage in rats

PURPOSE

The present study aims to investigate the effects of intracerebroventricularly (i.c.v.)-injected glucagon-like peptide-2 (GLP-2) on ethanol-induced gastric mucosal damage and to reveal the mechanisms involved in this effect.

MATERIALS AND METHODS

Rats received absolute ethanol orally via an orogastric tube 30 minutes after GLP-2 (1-200 ng/10 µl; i.c.v.) or saline (10 µl) injections. They were decapitated 1 hour later, their stomachs were removed, and the gastric mucosal damage was scored.

RESULTS

A total of 100 ng GLP-2 inhibited the gastric mucosal damage by 67%. This effect was abolished by the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP-(8-37) (10 µg/kg; s.c.), but was not affected by either the nitric oxide (NO) synthase inhibitor L-NAME (30 mg/kg; s.c.) or the cyclooxygenase inhibitor indomethacin (5 mg/kg; i.p.). The most effective gastroprotective dose of GLP-2 (100 ng/10 µl; i.c.v.), but not the higher doses (150 or 200 ng/10 µl; i.c.v.) prevented the decrease in gastric mucosal blood flow caused by ethanol. In conclusion, i.c.v. GLP-2 protects against ethanol-induced gastric mucosal damage and this effect is mediated by CGRP receptor activation and gastric mucosal blood flow, but not by NO or prostaglandins.

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.

Pharmacokinetics of escin Ia in rats after intravenous administration

ETHNOPHARMACOLOGICAL RELEVANCE

Escin, a natural mixture of triterpene saponins, is commonly utilized for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema. Escin Ia is the chief active ingredient in escin and plays key role in mediating its pharmacological effects. Adequate pharmacokinetic data are essential for proper application of escin agent in clinical practice. However, pharmacokinetic properties of escin Ia are still poorly understood and this conflicts with the growing use of escin agent over the years. The goal of this study is to investigate the pharmacokinetic behavior of escin Ia in rats after low, medium and high-dose intravenous administration.

MATERIALS AND METHODS

Wistar rats were divided into 3 groups (n=6 per group) and escin Ia was administered via the caudal vein at doses of 0.5, 1.0 and 2.0 mg/kg, respectively. Subsequently, the concentrations of escin Ia and its metabolite isoescin Ia, a positional isomer of escin Ia, in rats׳ plasma were measured by an established liquid chromatography tandem mass spectrometry (LC-MS/MS) method at various time points following the administration of the drug. Main pharmacokinetic parameters were calculated by non-compartmental analysis using the TopFit 2.0 software package (Thomae GmbH, Germany).

RESULTS

After intravenous administration, the Cmax and AUC of escin Ia increased in a dose-proportional manner at the dose of 0.5 mg/kg and 1.0 mg/kg, while increased in a more than dose-proportional manner at the doses of 1.0 mg/kg and 2.0 mg/kg. The t₁/₂ was significantly longer with increased intravenous doses, while other parameters such as CL and Vd also exhibit disagreement among three doses. Taken together, our data showed dose-dependent pharmacokinetic profile of escin Ia in rats after intravenous administration at the doses of 0.5-2.0 mg/kg. After intravenous administration, escin Ia was rapidly and extensively converted to isoescin Ia.

CONCLUSIONS

The results suggested dose-dependent pharmacokinetics of escin Ia at the doses of 0.5-2.0 mg/kg after intravenous administration. Escin Ia is isomerized to isoescin Ia rapidly and extensively regardless of the doses.

Comparative pharmacokinetics and the bioavailability of escin Ib and isoescin Ib following the administration of escin, pure escin Ib and isoescin Ib in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Adequate pharmacokinetic data of escin, a natural mixture of triterpene saponins used for the treatment of chronic venous insufficiency, hemorrhoids, inflammation and edema, is of special interest in view of the growing use of escin agent in clinical medicine. However, pharmacokinetic data are inadequate to support their clinical indication. Escin Ib and isoescin Ib are the chief active ingredients in escin, pharmacokinetics study of them would be helpful for improving the practice of escin application. The goals of this study are to determine the plasma concentration of escin Ib and isoescin Ib using an established liquid chromatography tandem mass spectrometry (LC-MS/MS) method and to compare the pharmacokinetics and bioavailability of these compounds in rats when administered as pure isomers or as sodium escinate.

MATERIALS AND METHODS

Five groups of Wistar rats (n=6 per group) were treated with either an intravenous (IV) dose (2.78mg/kg) of sodium escinate (corresponding to 0.5mg/kg of escin Ib and 0.5mg/kg of isoescin Ib), an IV dose (0.5mg/kg) and an oral dose (4mg/kg) of pure escin Ib or isoescin Ib. The concentrations of escin Ib and isoescin Ib in rat plasma were determined by LC-MS/MS at various times following the administration of the drugs. The pharmacokinetic parameters were estimated by a non-compartmental analysis and then subjected to statistical analysis.

RESULTS

The administration of sodium escinate, which contains the two isomers, gave rise to higher terminal phase half-life (t1/2) and mean residence time (MRT) values for both escin Ib and isoescin Ib compared to the corresponding compounds administered alone. The absorption of escin Ib and isoescin Ib was very poor, with the oral bioavailability (F) values of <2% observed for both compounds. The two compounds were found to isomerize in vivo, wherein the conversion of escin Ib to isoescin Ib was much easier than that of isoescin Ib to escin Ib.

CONCLUSIONS

A comparison of the pharmacokinetics of escin Ib and isoescin Ib administered alone and together in rats suggests that the administration of herbal preparations of escin in a clinical setting may result in a longer duration of action than the administration of each isomer alone. The interconversion of escin Ib and isoescin Ib when administered alone indicates that the administration of one isomer results in exposure to the other isomer.

The effect of a minor constituent of essential oil from Citrus aurantium: the role of β-myrcene in preventing peptic ulcer disease

The monoterpene β-myrcene has been widely used in cosmetics, food and beverages, and it is normally found in essential oil from citrus fruit. The aim of this study was to investigate the anti-ulcer effects of β-myrcene on experimental models of ulcers that are induced by ethanol, NSAIDs (non-steroidal anti-inflammatory drugs), stress, Helicobacter pylori, ischaemia-reperfusion injury (I/R) and cysteamine in order to compare with the essential oil of Citrus aurantium and its major compound limonene. The results indicate that the oral administration of β-myrcene at a dose of 7.50mg/kg has important anti-ulcer activity with significantly decreased gastric and duodenal lesions as well as increased gastric mucus production. The results showed treatment with β-myrcene caused a significant increase in mucosal malondialdehyde level (MDA), an important index of oxidative tissue damage. The β-myrcene was also endowed with marked enhancement of antioxidant enzyme activity from GR system as evidenced by the decreased activity of superoxide dismutase (SOD) and increased levels of glutathione peroxidase (GPx), glutathione reductase (GR), and total glutathione in gastric tissue. Our results also shown that treatment with β-myrcene is not involved with thioredoxin reductase (TrxR) activity. Our results reveal, for the first time, the importance of β-myrcene as an inhibitor of gastric and duodenal ulcers and demonstrate that an increase in the levels of gastric mucosa defence factors is involved in the anti-ulcer activity of β-myrcene.

Hymenaea stigonocarpa Mart. ex Hayne: a Brazilian medicinal plant with gastric and duodenal anti-ulcer and antidiarrheal effects in experimental rodent models

ETHNOPHARMACOLOGICAL RELEVANCE

Hymenaea stigonocarpa Mart. ex Hayne (Fabaceae) is a medicinal species commonly found in the Brazilian savannah. The stem bark of this medicinal plant, popularly known as "jatobá-do-cerrado", is widely used in tea form to treat gastric pain, ulcers, diarrhoea and inflammation, whereas its fruits pulp is edible.

AIM OF THE STUDY

The aim of this study was to investigate the antidiarrheal and anti-ulcer effects of a methanolic extract derived from the stem bark (MHs) and diet with fruit pulp of H. stigonocarpa.

MATERIALS AND METHODS

The antidiarrheal action of MHs was measured against the intestinal motility and diarrhoea induced by castor oil in mice. The preventive action of MHs (50, 100, 150 and 200mg/Kg, by oral route (p.o.)) against peptic ulcers was evaluated in experimental rodent models challenged with absolute ethanol, non-steroidal anti-inflammatory drugs (NSAIDs), ischemia-reperfusion (I/R) (200mg/Kg, p.o.) and cysteamine (200mg/Kg, p.o.). The main anti-ulcer mechanisms of action of MHs were analysed as follows: evaluation of the gastric juice parameters, assessment of mucus adherence to the gastric wall, determination of the role of nitric oxide (NO) and sulfhydryl compounds (SH), glutathione (GSH) levels and myeloperoxidase (MPO) activity. The healing effects from MHs (200mg/Kg) and diet with fruit pulp (10%) against gastric and duodenal ulcers induced by acetic acid were also evaluated by treating rats over 7 or 14 consecutive days of treatment.

RESULTS

The phytochemical profile of MHs and fruit pulp indicated the presence of phenolic compounds (mainly flavonoids and condensed tannins). MHs (200mg/Kg, p.o.) displayed an antidiarrheal effect and were able to protect gastric mucosa against absolute ethanol (68% protection) and also against the injurious effect of NSAIDs (86% protection) when compared to the group treated with vehicle. These results were accompanied by the prevention of GSH depletion and an inhibition of MPO activity when compared to animals treated with vehicle (P<0.05). MHs markedly protected duodenal mucosa against injuries caused by cysteamine (98%) and also against I/R induced gastric ulceration (80%) when compared to the group treated with vehicle. Furthermore, MHs also prevented the GSH depletion of gastric mucosa relative to the control group treated with vehicle. NO appeared to be involved in this gastroprotective effect. MHs and diet with fruit pulp clearly demonstrated gastric healing actions after treatment for 7 (MHs - 53% inhibition) or 14 days (MHs - 60% inhibition and fruit pulp - 61% inhibition). Treatment with diet with fruit pulp for 7 days demonstrates a significant duodenal healing effect (71% inhibition) without any signs of toxicity.

CONCLUSIONS

MHs clearly demonstrate antidiarrheal, gastroprotective and cicatrising effects in experimental gastric and duodenal ulcers, and the diet with fruit pulp displays duodenal healing effects. The observed effects may be associated with the antioxidant effect, which may be due the presence of condensed tannins and flavonoids in the bark and fruit of H. stigonocarpa.

Byrsonima intermedia A. Juss.: gastric and duodenal anti-ulcer, antimicrobial and antidiarrheal effects in experimental rodent models

ETHNOPHARMACOLOGICAL RELEVANCE

An ethnopharmacological survey indicated that the leaves of Byrsonima intermedia A. Juss. (Malpighiaceae), a medicinal species commonly found in the Brazilian Cerrado, can be used against gastroduodenal disorders, such as gastric ulcers and diarrhea.

AIM OF THE STUDY

The objective of this study was to evaluate the effects of a methanolic extract of Byrsonima intermedia (MBI) leaves on gastric and duodenal ulcers and to assess the antimicrobial and antidiarrheal effects of this extract.

MATERIAL AND METHODS

The anti-ulcerogenic effect of MBI was investigated with different ulcerogenic agents in rodents (mice and rats), including non-steroidal anti-inflammatory drug (NSAID), HCl/ethanol, pyloric ligature, absolute ethanol, cysteamine and ischemia-reperfusion. The gastroprotective effect of MBI was assessed by analysing the volume of gastric juice, pH, total acidity, mucus, NO, sulfhydryl compound, vanilloid receptor, glutathione (GSH) levels, and myeloperoxidase (MPO) activity in the gastric and duodenal mucosa. The gastric and duodenal healing effects of MBI were also evaluated during 7 or 14 days of treatment. The antidiarrheal action (measured by intestinal motility and diarrhea induced by castor oil) and anti-bacterial action of MBI against Staphylococcus aureus, Escherichia coli and Helicobacter pylori were also evaluated by microdilution methods.

RESULTS

The phytochemical profile from MBI indicated the presence of phenolic acids, flavan-3-ols, oligomeric proanthocyanidins, and flavonoids. MBI (500mg/kg, p.o.) significantly inhibited totally gastric and duodenal lesions (69%) and healed gastric (49% on 14 days) and duodenal lesions (45% on 7 and 14 days). The MBI exert gastroprotective action by participation of endogenous sulfhydryl compounds, vanilloid receptors and increase in GSH level to effective gastric and duodenal protection. MBI also displayed curative (42%) and preventive (49%) antidiarrheal effects by involvement of opiate receptors and also antimicrobial effects in vitro.

CONCLUSIONS

Byrsonima intermedia leaves present gastroprotective, healing and antidiarrheal activities, supporting previous claims that its traditional use can treat gastrointestinal disorders.

Protective effect of aescin from the seeds of Aesculus hippocastanum on liver injury induced by endotoxin in mice

To investigate the effect and underlying mechanism of aescin on acute liver injury induced by endotoxin, liver injury was established by injecting lipopolysaccharide (LPS) in mice. Animals were assigned to seven groups: the control group and groups treated with LPS (40 mg/kg), aescin (3.6 mg/kg), LPS plus dexamethasone (4 mg/kg) and LPS plus aescin (0.9, 1.8 or 3.6 mg/kg). Hepatic histopathological changes were examined under a light microscope. Activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were determined. Levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), nitric oxide (NO) and antioxidative parameters in liver homogenate were measured. Glucocorticoid receptor (GR), 11 beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and 11 beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2) expressions in liver were determined by western blotting. Treatment with escin could inhibit immigration of inflammatory cells, alleviate the degree of necrosis, and decrease serum ALT and AST activities. Aescin also down-regulated levels of inflammation mediators (TNF-α, IL-1β and NO) and 11β-HSD2 expression in liver, up-regulated GR expression, enhanced endogenous antioxidative capacity, but have no obvious effect on 11β-HSD1 expression in liver. The findings suggest aescin has protective effects on endotoxin-induced liver injury, and the underlying mechanisms were associated with its anti-inflammatory effects, up-regulating GR expression, down-regulating 11β-HSD2 experssion, and antixoidation.

Evaluation of the antiulcerogenic activity profile of a flavonol diglucoside from Equisetum palustre L

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial parts of Equisetum palustre L. are used to treat peptic ulcer disease in Turkey. In a previous study, a flavonol diglucoside i.e., kaempferol 3-O-1''-beta-D-glucopyranosyl-3-O-1'''-beta-D-glucopyranoside (KGG) was isolated as the major antiulcerogenic constituent from the plant.

AIM OF THE STUDY

The present study was undertaken to evaluate the antiulcer activity profile of KGG using various in vivo experimental ulcer models as well as by assessing gastric biochemical parameters.

MATERIAL AND METHODS

KGG was obtained from the ethanol extract of the aerial parts of the plant by successive chromatographical methods. The activity profile of the compound was investigated using several ulcerogenesis models such as indomethacin-, indomethacin plus HCl/EtOH-, cysteamine-, serotonin-, N(G)-nitro-L-arginine methyl ester plus EtOH-, diethyldithiocarbamate-, N-ethylmaleimide plus EtOH-, water immersion and restraint stress-, pyloric ligation-induced ulcers. In addition, effects of KGG on the biochemical parameters of gastric juice; i.e., inhibition of titratable gastric acidity, acid output, gastric pH, gastric secretion volume and peptic activity were studied.

RESULTS

KGG exerted statistically significant gastroprotective activity against indomethacin-, indomethacin plus HCl/EtOH- and N-ethylmaleimide plus EtOH-induced ulcerogenesis. Moreover, KGG demonstrated weak activity against N(G)-nitro-L-arginine methyl ester plus EtOH, water immersion and immobilization-induced stress, pyloric ligation-induced and diethyldithiocarbamate-induced gastric ulcer models, and also it was ineffective in the prevention of ulcers induced by serotonin and cysteamine. On the other hand, among the gastric biochemical parameters studied, KGG was only found to increase the gastric acid pH from 2.03 to 3.35.

CONCLUSION

Results of this investigation have clearly demonstrated that KGG was found to improve the cytoprotective mechanisms of the gastric mucosa. On the other hand, a weak activity profile was observed on the parameters affecting the gastric acidity (water immersion and restraint-induced-, pyloric ligation-induced-ulcerogenesis and titratable acidity).

Escin, a pentacyclic triterpene, chemosensitizes human tumor cells through inhibition of nuclear factor-kappaB signaling pathway

Agents that can enhance tumor cell apoptosis and inhibit invasion have potential for the treatment of cancer. Here, we report the identification of escin, a pentacyclic triterpenoid from horse chestnut that exhibits antitumor potential against leukemia and multiple myeloma. Whether examined by esterase staining, phosphatidyl-serine staining, DNA breakage, or caspase-mediated poly(ADP-ribose) polymerase cleavage, escin potentiated tumor necrosis factor (TNF)-induced apoptosis but inhibited tumor cell invasion. This correlated with the down-regulation of bcl-2, cellular inhibitor of apoptosis protein-2, cyclin D1, cyclooxygenase-2, intercellular adhesion molecule-1, matrix metalloproteinase-9, and vascular endothelial growth factor, which are all regulated by the activation of the transcription factor NF-kappaB. When examined by electrophoretic mobility shift assay, the triterpenoid suppressed nuclear factor-kappaB (NF-kappaB) activation induced by TNF and other inflammatory agents, and this correlated with the inhibition of IkappaBalpha phosphorylation and degradation, inhibition of IkappaB kinase complex (IKK) activation, suppression of p65 phosphorylation and nuclear translocation, and abrogation of NF-kappaB-dependent reporter activity. Overall, our results demonstrate that escin inhibits activation of NF-kappaB through inhibition of IKK, leading to down-regulation of NF-kappaB-regulated cell survival and metastatic gene products and thus resulting in sensitization of cells to cytokines and chemotherapeutic agents.

Medicinal flowers. XVI. New dammarane-type triterpene tetraglycosides and gastroprotective principles from flower buds of Panax ginseng

The oligoglycoside fraction from the flower buds of Panax ginseng C. A. MEYER (Araliaceae) was found to show protective effects on ethanol-induced gastric mucosal lesions in rats. From the oligoglycoside fraction, new dammarane-type triterpene tetraglycosides, floralginsenosides M, N, O, and P, were isolated together with the major oligoglycosides ginsenoside Rd and Re. The structures of the new floralginsenosides were elucidated on the basis of chemical and physicochemical evidence. Ginsenoside Rd (protopanaxadiol 3,20-O-bisdesmoside) exhibited inhibitory effects on ethanol- and indomethacin-induced gastric mucosal lesions in rats.

Evaluation of the anti-ulcerogenic effect of sesquiterpene lactones from Centaurea solstitialis L. ssp. solstitialis by using various in vivo and biochemical techniques

The guaianolide type sesquiterpene lactones chlorojanerin, 13-acetyl solstitialin A and solstitialin A were identified as the anti-ulcerogenic components of the chloroform extract of the aerial parts of Centaurea solstitialis ssp. solstitialis (Asteraceae). In this study, these compounds were investigated by using various in vivo ulcer models in rats and mice. Chlorojanerin was shown to be significantly effective in preventing the induction of lesions by ethanol- (EtOH-) (both oral and subcutaneous administration), indomethacin-, indomethacin plus HCl/EtOH-, N(G)-nitro-l-arginine methyl ester plus EtOH-, N-ethylmaleimide plus EtOH-, water immersion and restraint stress, and serotonin, as well as inhibiting titratable gastric acidity and acid output, and increasing gastric pH, but was ineffective in the prevention of ulcers induced by pyloric ligation, diethyldithiocarbamate, and cysteamine, and had no effect on gastric secretion volume or peptic activity. A mixture of 13-acetyl solstitialin A (95%) and solstitialin A (5%) was found to be significantly effective against EtOH-induced lesions on oral administration but was ineffective when administered subcutaneously. This mixture was also found to be effective in preventing lesions induced by EtOH, indomethacin, indomethacin plus HCl/EtOH, N(G)-nitro-l-arginine methyl ester plus EtOH, N-ethylmaleimide plus EtOH, water immersion and restraint stress, serotonin and cysteamine, as well as inhibiting titratable gastric acidity and titratable acid output, and gastric pH, but was found ineffective against the pyloric ligation-induced and diethyldithiocarbamate-induced ulcerogenesis models, as well as gastric secretion volume and peptic activity. On the other hand, active compounds did not show any toxic effect on acute toxicity (3 days administration) evaluation tests in mice.

Effects of allyl isothiocyanate from horseradish on several experimental gastric lesions in rats

Allyl isothiocyanate is well known to be a principal pungent constituent of horseradish and an agonist for transient receptor potential (TRP) A1. Ally isothiocyanate markedly inhibited the formation of gastric lesions induced by ethanol (1.5 ml/rat, p.o.), 0.6 M HCl (1.5 ml/rat, p.o.), 1% ammonia (1.5 ml/rat, p.o.), and aspirin (150 mg/kg, p.o.) (ED(50)=1.6, 2.2, 1.7, ca. 6.5 mg/kg, p.o.). It also significantly inhibited the formation of gastric lesions induced by indomethacin (20 mg/kg, p.o.), though the inhibition was ca. 60% at a high dose (40 mg/kg, p.o.). Furthermore, several synthetic isothiocyanate compounds also significantly inhibited ethanol and indomethacin-induced gastric lesions. Whereas, TRPV1 agonists, capsaicin and piperine, inhibited gastric lesions induced by ethanol, 1% ammonia, and aspirin, but had less of an effect on 0.6 M HCl-induced gastric lesions. With regard to mode of action, the protective effects of ally isothiocyanate on ethanol-induced gastric lesions were attenuated by pretreatment with indomethacin, but not with N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME), or ruthenium red. Pretreatment with indomethacin reduced the protective effects of piperine, and L-NAME reduced the effects of capsaicin and omeprazole. Furthermore, ruthenium red reduced the effects of capsaicin, piperine, and omeprazole. These findings suggest that endogenous prostaglandins play an important role in the protective effect of allyl isothiocyanate in ethanol-induced gastric lesions different from capsaicin, piperine, and omeprazole.

Capsaicin and gastric ulcers

In recent years, infection of the stomach with the organism Helicobacter Pylori has been found to be the main cause of gastric ulcers, one of the common ailments afflicting humans. Excessive acid secretion in the stomach, reduction in gastric mucosal blood flow, constant intake of non-steroid anti-inflammatory drugs (NSAIDS), ethanol, smoking, stress etc. are also considered responsible for ulcer formation. The prevalent notion among sections of population in this country and perhaps in others is that "red pepper" popularly known as "Chilli," a common spice consumed in excessive amounts leads to "gastric ulcers" in view of its irritant and likely acid secreting nature. Persons with ulcers are advised either to limit or avoid its use. However, investigations carried out in recent years have revealed that chilli or its active principle "capsaicin" is not the cause for ulcer formation but a "benefactor." Capsaicin does not stimulate but inhibits acid secretion, stimulates alkali, mucus secretions and particularly gastric mucosal blood flow which help in prevention and healing of ulcers. Capsaicin acts by stimulating afferent neurons in the stomach and signals for protection against injury causing agents. Epidemiologic surveys in Singapore have shown that gastric ulcers are three times more common in the "Chinese" than among Malaysians and Indians who are in the habit of consuming more chillis. Ulcers are common among people who are in the habit of taking NSAIDS and are infected with the organism "Helicobacter Pylori," responsible for excessive acid secretion and erosion of the mucosal layer. Eradication of the bacteria by antibiotic treatment and avoiding the NSAIDS eliminates ulcers and restores normal acid secretion.

Triterpene saponins with gastroprotective effects from tea seed (the seeds of Camellia sinensis)

Six new triterpene saponins, theasaponins A(1) (1), A(2) (2), A(3) (3), F(1) (4), F(2) (5), and F(3) (6), were isolated from the saponin fraction of the seeds of Camellia sinensis. The stereostructures of 1-6 were elucidated on the basis of chemical and physicochemical evidence. Theasaponin A(2) (2) showed an inhibitory effect on ethanol-induced gastric mucosal lesions in rats at a dose of 5.0 mg/kg, p.o., and its activity was more potent than that of omeplazole. Structure-activity relationships for theasaponins on ethanol-induced gastroprotective activities may be suggested as follows: (1) the 28-acetyl moiety enhances activity; (2) theasaponins having a 23-aldehyde group exhibit more potent activities than those with a 23-hydroxymethyl group or a 23-methoxycarbonyl group.

Investigation of the mechanisms involved in the central effects of glucagon-like peptide-1 on ethanol-induced gastric mucosal lesions

The aim of this study was to investigate the effects of intracerebroventricularly injected glucagon-like peptide-1 (GLP-1) on ethanol-induced gastric mucosal damage and to elucidate the mechanisms involved. Absolute ethanol was administered through an orogastric cannula 5 min before GLP-1 (1 microg/10 microl) injection. One hour later, the rats were decapitated, their stomachs were removed and scored for mucosal damage. GLP-1 inhibited the ethanol-induced gastric mucosal damage by 92%. Centrally injected atropine sulphate, a muscarinic receptor antagonist (5 microg/10 microl), prevented the gastroprotective effect of GLP-1, while mecamylamine, a nicotinic receptor antagonist (25 microg/10 microl), was ineffective. Peripherally injected atropine methyl nitrate (1 mg/kg) did not change the effect of GLP-1, but mecamylamine (5 mg/kg) blocked it. Cysteamine, a somatostatin depletor (280 mg/kg, s.c.), did not affect the protective activity of GLP-1, while inhibition of nitric oxide (NO) synthesis by L-NAME (3 mg/kg, i.v.) significantly abolished the protective effect of GLP-1 on ethanol-induced gastric mucosal lesions. We conclude that central muscarinic and peripheral nicotinic cholinergic receptors and NO, but not somatostatin, contribute to the protective effect of intracerebroventricularly injected GLP-1 on ethanol-induced gastric mucosal damage.

Bioactive Saponins and Glycosides. XXIII. Triterpene Saponins with Gastroprotective Effect from the Seeds of Camellia sinensis-Theasaponins E3, E4, E5, E6, and E7-

The saponin fraction from the seeds of the tea plant [Camellia sinensis (L.) O. KUNTZE (Theaceae)] was found to exhibit potent protective effects on ethanol- and indomethacin-induced gastric mucosal lesions in rats. Five new triterpene saponins, theasaponins E3 (1), E4 (2), E5 (3), E6 (4), and E7 (5), were isolated together with 11 known saponins from the saponin fraction. The chemical structures of 1-5 were elucidated on the basis of chemical and physicochemical evidence. Among the isolated saponins, theasaponins E1 (6), E2 (7), and E5 (3) and assamsaponin C (10) showed an inhibitory effect on ethanol-induced gastric mucosal lesions at a dose of 5.0 mg/kg, p.o. and their activities were stronger than that of omeplazole. With regard to the structure-activity relationships of theasaponins, the following structural requirements for a protective effect on ethanol-induced gastric lesions were suggested; 1) the 21- and/or 22-acyl groups are essential for the activity, 2) acetylation of the 16-hydroxyl group reduce the activity.

Effects of centrally injected GLP-1 in various experimental models of gastric mucosal damage

Glucagon-like peptide-1 (GLP-1) is accepted to be a peptide involved in the central regulation of gastrointestinal function, but its potential gastroprotective effect is not clear. The aim of this study was to investigate whether intracerebroventricularly injected GLP-1 has protective effects on gastric mucosal lesions induced by several models, and if yes, whether these effects are due to the gastric antisecretory effect of the peptide. GLP-1 which was injected in three different doses (1, 10, 100 ng/10 microl; i.c.v.) to conscious rats prevented the mucosal lesions induced by reserpine and ethanol, but did not prevent the gastric mucosal lesions induced by pyloric ligation. In addition, 1 ng/10 microl dose of centrally injected GLP-1 inhibited gastric acid secretion in pylorus-ligated rats. As a result, we conclude that intracerebroventricularly injected GLP-1 may play a role in the prevention of gastric mucosal lesions induced by certain experimental models and this gastroprotective effect may be independent from its antisecretory effect.

Gastroprotective effects of phenylpropanoids from the rhizomes of Alpinia galanga in rats: structural requirements and mode of action

The effects of 1'S-1'-acetoxychavicol acetate and related phenylpropanoids isolated from the rhizomes of Alpinia galanga on ethanol-induced gastric lesions in rats were examined. Among them, 1'S-1'-acetoxychavicol acetate and 1'S-1'-acetoxyeugenol acetate markedly inhibited the ethanol-induced gastric mucosal lesions (ED(50)=0.61 and ca. 0.90 mg/kg). In addition, 1'S-1'-acetoxychavicol acetate inhibited the lesions induced by 0.6 M HCl (ED(50)=0.73 mg/kg) and aspirin (ED(50)=0.69 mg/kg) but it did not show a significant effect on indomethacin-induced gastric lesions and acid output in pylorus-ligated rats at doses of 0.5-5.0 mg/kg. From the gastroprotective effects of various related compounds, the 1'-acetoxyl group of 1'S-1'-acetoxychavicol acetate and 1'S-1'-acetoxyeugenol acetate was found to be essential for their strong activity. With regard to the mode of action, the gastroprotective effects of 1'S-1'-acetoxychavicol acetate were attenuated by pretreatment with indomethacin and N-ethylmaleimide, and 1'S-1'-acetoxychavicol acetate significantly increased the glutathione levels of gastric mucosa in rats. These findings suggest that endogenous prostaglandins and sulfhydryl compounds are involved in the protective effect of 1'S-1'-acetoxychavicol acetate.

Protective effects of steroid saponins from Paris polyphylla var. yunnanensis on ethanol- or indomethacin-induced gastric mucosal lesions in rats: structural requirement for activity and mode of action

The methanolic extract from the rhizomes of Paris polyphylla SM. var. yunnanensis (FR.) H-M. was found to potently inhibit ethanol-induced gastric lesions in rats. Through bioassay-guided separation, four known spirostanol-type steroid saponins, pennogenin 3-O-alpha-L-rhamnopyranosyl(1-->2)-[alpha-L-arabinofuranosyl(1-->4)]-beta-D-glucopyranoside (1), pennogenin 3-O-alpha-L-rhamnopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->4)-[alpha-L-rhamnopyranosyl(1-->2)]-beta-D-glucopyranoside (2), diosgenin 3-O-alpha-L-rhamnopyranosyl(1-->2)-[alpha-L-arabinofuranosyl(1-->4)]-beta-D-glucopyranoside (3), and diosgenin 3-O-alpha-L-rhamnopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->4)-[alpha-L-rhamnopyranosyl(1-->2)]-beta-D-glucopyranoside (4), and a new furostanol-type steroid saponin, parisaponin I (5), together with two known furostanol-type steroid saponins, trigofoenoside A (6) and protogracillin (7), were isolated from the active fraction. Compounds 1-4 (1.25-10 mg/kg, po) strongly inhibited gastric lesions induced by ethanol and indomethacin. With regard to structural requirement of steroid saponins, the 3-O-glycoside moiety and spirostanol structure were found to be essential for the activity and the 17-hydroxyl group in the aglycon part enhanced the protective effects against ethanol-induced gastric lesions. The protective effects of 1 and 3 against ethanol-induced gastric lesions were attenuated by pretreatment with indomethacin and N-ethylmaleimide. Compounds 1 and 3 weakly inhibited acid secretions in pylorus-ligated rats. These findings suggested that endogenous prostaglandins and sulfhydryl compounds were involved in the protective activity.

Pharmacokinetics and bioavailability of herbal medicinal products

The use of herbs for treating various ailments dates back several centuries. Usually, herbal medicine has relied on tradition that may or may not be supported by empirical data. The belief that natural medicines are much safer than synthetic drugs has gained popularity in recent years and led to tremendous growth of phytopharmaceutical usage. Market driven information on natural products is widespread and has further fostered their use in daily life. In most countries there is no universal regulatory system that insures the safety and activity of phytopharmaceuticals. Evidence-based verification of the efficacy of HMPs (herbal medicinal products, botanicals) is still frequently lacking. However, in recent years, data on evaluation of the therapeutic and toxic activity of herbal medicinal products became available. The advances in analytical technology have led to discovery of many new active constituents and an ever-increasing list of putatively active constituents. Establishing the pharmacological basis for efficacy of HMPs is a constant challenge. Of particular interest is the question of bioavailability to assess to what degree and how fast compounds are absorbed after administration of HMPs. Of further interest is the elucidation of metabolic pathways (yielding potentially new active compounds), and the assessment of elimination routes and their kinetics. These data become an important issue to link data from pharmacological assays and clinical effects. Of interest are currently also interactions of herbal medicinal products with synthetically derived drug products. A better understanding of the pharmacokinetics and bioavailability of phytopharmaceuticals can also help in designing rational dosage regimens. In this review, pharmacokinetic and bioavailability studies that have been conducted for some of the more important or widely used phytopharmaceuticals are critically evaluated. Furthermore, various drug interactions are discussed which show that caution should be exercised when combining phytopharmaceuticals with chemically derived active pharmaceutical ingredients.

Medicinal flowers. III. Marigold. (1): hypoglycemic, gastric emptying inhibitory, and gastroprotective principles and new oleanane-type triterpene oligoglycosides, calendasaponins A, B, C, and D, from Egyptian Calendula officinalis

The methanolic extract and its 1-butanol-soluble fraction from the flowers of Calendula officinalis were found to show a hypoglycemic effect, inhibitory activity of gastric emptying, and gastroprotective effect. From the 1-butanol-soluble fraction, four new triterpene oligoglycosides, calendasaponins A, B, C, and D, were isolated, together with eight known saponins, seven known flavonol glycosides, and a known sesquiterpene glucoside. Their structures were elucidated on the basis of chemical and physicochemical evidence. The principal saponin constituents, glycosides A, B, C, D, and F, exhibited potent inhibitory effects on an increase in serum glucose levels in glucose-loaded rats, gastric emptying in mice, and ethanol- and indomethacin-induced gastric lesions in rats. Some structure-activity relationships are discussed.

Medicinal foodstuffs. XXII. Structures of oleanane-type triterpene oligoglycosides, pisumsaponins I and II, and kaurane-type diterpene oligoglycosides, pisumosides A and B, from green peas, the immature seeds of Pisum sativum L

Two new oleanane-type triterpene oligoglycosides, pisumsaponins I and II, and two new kaurane-type diterpene oligoglycosides, pisumosides A and B, were isolated from the immature seeds (green peas) of Pisum sativum L. together with soyasaponin I, bersimoside I, dehydrosoyasaponin I, and their 6'-methyl esters. The structures of pisumsaponins and pisumosides were determined on the basis of chemical and physicochemical evidence as 22-O-malonylsoyasapogenol B 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D-glucopyranosiduronic acid (22-O-malonylsoyasaponin I), sandosapogenol 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D-glucopyranosiduronic acid, 17-O-beta-D-glucopyranosyl-6beta,7beta,13gamma,17-tetrahydroxy-19-kauranoic acid 19-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranoside, and 6beta,7beta,13beta,17-tetrahydroxy-19-kauranoic acid 19-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranoside, respectively.

Medicinal foodstuffs. XXI. Structures of new cucurbitane-type triterpene glycosides, goyaglycosides-a, -b, -c, -d, -e, -f, -g, and -h, and new oleanane-type triterpene saponins, goyasaponins I, II, and III, from the fresh fruit of Japanese Momordica charantia L

Eight cucurbitane-type triterpene glycosides called goyaglycosides-a, -b, -c, -d, -e, -f, -g, and -h and three oleanane-type triterpene saponins termed goyasaponins I, II, and III were isolated from the fresh fruit of Japanese Momordica charantia L. (Cucurbitaceae) together with five known cucurbitane-type triterpene glycosides momordicosides A, C, F1, I, and K. The structures of goyaglycosides and goyasaponins were elucidated on the basis of chemical and physicochemical evidence.

Possible involvement of 5-HT and 5-HT2 receptors in acceleration of gastrointestinal transit by escin Ib in mice

We have reported previously that escin Ib accelerated gastrointestinal transit (GIT) in mice, and that its effect may be mediated by the release of endogenous prostaglandins (PGs) and nitric oxide (NO). In this study, the possible involvement of 5-HT and 5-HT receptors in the GIT acceleration of escin Ib was investigated in mice. The acceleration of GIT by escin Ib (25 or 50 mg/kg, p.o.) was attenuated by pretreatment with ritanserin (0.5-5 mg/kg, s.c., a 5-HT(2A/2C/2B) receptor antagonist), but not with MDL 72222 (1 and 5 mg/kg, s.c.) and metoclopramide (10 mg/kg, s.c.) (5-HT3 receptor antagonists) or tropisetron (1 and 10 mg/kg, s.c., a 5-HT(3/4) receptor antagonist). Furthermore, pretreatment with ketanserin (0.05-5 mg/kg, s.c.), haloperidol (1-5 mg/kg, s.c.) and spiperone (0.5-5 mg/kg, s.c.) (5-HT2A receptor antagonists), as well as a bolus of dl-p-chlorophenylalanine methyl ester (PCPA, 1000 mg/kg, p.o., 1, 6 or 24 h before administration of the sample) (an inhibitor of 5-HT synthesizing enzyme tryptophan hydroxylase) and reserpine (5 mg/kg, p.o.) (a 5-HT depletor), but not 6-hydroxydopamine (80 mg/kg, i.p., a dopamine depletor) or repeated PCPA (300 mg/kg x2, p.o., 72 and 48 h before administration of the sample), also attenuated the effects of escin Ib. It is postulated that escin Ib accelerates GIT, at least in part, by stimulating the synthesis of 5-HT to act through 5-HT2, possibly 5-HT2A receptors, which in turn causes the release of NO and PGs.

Enhancement by escins Ib and IIb of Mg(2+) absorption from digestive tract in mice: role of nitric oxide

The effects of escins Ib and IIb isolated from horse chestnuts on Mg(2+) absorption from the digestive tract and the role of endogenous nitric oxide (NO) were investigated in mice. Test samples were given orally to fasted mice 30, 120, 180, 240 and 300 min before administration of 0.5 M MgSO(4) (10 ml/kg, p.o.). The serum Mg(2+) levels were determined 30, 60, 120 and 180 min after administration of MgSO(4). Escins Ib and IIb (12.5 and 25 mg/kg) significantly increased the serum Mg(2+) by 10.0-27.3%, 30, 120 and 180 min after administration of the samples, and 30, 60, 120 and 180 min after administration of MgSO(4). Escins Ib and IIb (12.5 mg/kg) significantly decreased the Mg(2+) content in the small intestinal fluid in MgSO(4)-loaded mice, but did not increase the serum Mg(2+) levels in normal mice. The effects of escins Ib and IIb (12.5 mg/kg) on serum Mg(2+) levels were attenuated in a dose-related manner by the pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 3-20 mg/kg, i.p., an inhibitor of constitutive and inducible NO synthase), but not with D-NAME (10 mg/kg, i.p., the inactive enantiomer of L-NAME) or dexamethasone (0.05 and 0.5 mg/kg, s.c., an inhibitor of inducible NO synthase). The effect of L-NAME was reversed by L-arginine (600 mg/kg, i.p., a substrate of NO synthase), but not by D-arginine (900 mg/kg, i.p., the enantiomer of L-arginine). These results suggest that escins Ib and IIb enhance Mg(2+) absorption from the digestive tract in mice, in which the constitutive, but not the inducible, NO synthase plays an important role.