Gastroprotective activity of oleanolic acid derivatives on experimentally induced gastric lesions in rats and mice

Antiulcer activity and mechanism of action of the hydroethanolic extract of leaves of Terminalia argentea Mart. In different in vivo and in vitro experimental models

ETHNOPHARMACOLOGICAL RELEVANCE

Terminalia argentea Mart. (Combretaceae) is a deciduous tree commonly found in Brazil, Bolivia, and Paraguay. It occurs in all regions of Brazil and is widespread in the Amazon, Cerrado, Pantanal, Atlantic Rain Forest, and Caatinga Biomes. In the traditional medicine of Brazil, people widely use tea or decoction of its leaf materials for treating gastritis, ulcers, wound healing, and inflammation.

AIM OF THE STUDY

The current study aims to evaluate the gastroprotective and ulcer-healing activities of the hydroethanolic extract of T. argentea leaves (HETa) and investigate the underlying mechanisms of action through in vivo and in vitro experiments.

METHODS

We extracted the leaves of T. argentea with a 70% hydroethanolic solution (HETa) and performed phytochemical analysis using high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MSn). We researched the antiulcer activity using in vivo and in vitro experiments, administering three doses (2, 10, and 50 mg/kg) and different concentrations of 1, 5, and 20 μg/mL, respectively. We verified the acute antiulcer activity using chemical models (acidified ethanol (EtOH/HCl) and indomethacin (IND)) and physiological models (water-immersion stress (WRS)). To induce chronic ulcers, used acetic acid and treated the animals for seven days. To investigate the mechanism of action, conducted assays of antioxidant activity, measured the dosage of inflammatory cytokines, quantified mucus, treated with inhibitors (IND, L-NAME, glibenclamide, and yohimbine), performed histopathological analysis, and measured gastric acid secretion. Furthermore, we performed in vitro experiments on murine macrophage cell lines (RAW 264-7 cells) to quantify nitrite/nitrate and cytokine production and on V79-4 cells to verify cell proliferation/migration.

RESULTS

We conducted HPLC and ESI-MSn analyses to obtain a fingerprint of the chemical composition of the HETa, revealing the presence of phenolics (caffeoyl ellagic acid), flavonoids (rutin, quercetin xyloside, quercetin rhamnoside, quercetin glucoside, quercetin galloyl xyloside, quercetin), and tannins (terminalin), respectively. The three doses of HETa reduced acute and chronic ulcers in different models. The mechanism of action involves increasing mucus production and angiogenesis, and it partially involves prostaglandins, nitric oxide, K+ATP channels, and α2-adrenergic receptors. HETa also exhibited antioxidant potential, reducing myeloperoxidase (MPO) activity, and increasing glutathione (GSH) levels. Moreover, it demonstrated anti-inflammatory action by reducing nitrite/nitrate levels and pro-inflammatory cytokine concentrations in vivo, and it increased in vitro proliferation/migration of fibroblasts.

CONCLUSIONS

The study shows that HETa presents a potent preventive and curative antiulcer effect in different ulcer models, supporting the popular use of homemade preparations of T. argentea leaves. The preventive and gastric healing ulcer activity of HETa involves multiple targets, including increasing the gastric mucus barrier, antioxidant defenses, and anti-inflammatory effects on gastric mucosa repair. Phytochemical analysis identified the presence of phenolic compounds, flavonoids, and tannins in HETa, and the antiulcer activity may be attributable to the combined effect of these constituents.

Oleanolic acid ameliorates intestinal alterations associated with EAE

Background

Multiple sclerosis (MS) is a chronic demyelinating autoimmune disease affecting the CNS. Recent studies have indicated that intestinal alterations play key pathogenic roles in the development of autoimmune diseases, including MS. The triterpene oleanolic acid (OA), due to its anti-inflammatory properties, has shown to beneficially influence the severity of the experimental autoimmune encephalomyelitis (EAE), a preclinical model of MS. We herein investigate EAE-associated gut intestinal dysfunction and the effect of OA treatment.

Methods

Mice with MOG_35–55-induced EAE were treated with OA or vehicle from immunization day and were daily analyzed for clinical deficit. We performed molecular and histological analysis in serum and intestinal tissues to measure oxidative and inflammatory responses. We used Caco-2 and HT29-MTX-E12 cells to elucidate OA in vitro effects.

Results

We found that OA protected from EAE-induced changes in intestinal permeability and preserved the mucin-containing goblet cells along the intestinal tract.

Serum levels of the markers for intestinal barrier damage iFABP and monocyte activation sCD14 were consistently and significantly reduced in OA-treated EAE mice. Beneficial OA effects also included a decrease of pro-inflammatory mediators both in serum and colonic tissue of treated-EAE mice. Moreover, the levels of some immunoregulatory cytokines, the neurotrophic factor GDNF, and the gastrointestinal hormone motilin were preserved in OA-treated EAE mice. Regarding oxidative stress, OA treatment prevented lipid peroxidation and superoxide anion accumulation in intestinal tissue, while inducing the expression of the ROS scavenger Sestrin-3. Furthermore, short-chain fatty acids (SCFA) quantification in the cecal content showed that OA reduced the high iso-valeric acid concentrations detected in EAE-mice. Lastly, using in vitro cell models which mimic the intestinal epithelium, we verified that OA protected against intestinal barrier dysfunction induced by injurious agents produced in both EAE and MS.

Conclusion

These findings reveal that OA ameliorates the gut dysfunction found in EAE mice. OA normalizes the levels of gut mucosal dysfunction markers, as well as the pro- and anti-inflammatory immune bias during EAE, thus reinforcing the idea that OA is a beneficial compound for treating EAE and suggesting that OA may be an interesting candidate to be explored for the treatment of human MS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02042-6.

Tetracyclic and Pentacyclic Triterpenes with High Therapeutic Efficiency in Wound Healing Approaches

Wounds are among the most common skin conditions, displaying a large etiological diversity and being characterized by different degrees of severity. Wound healing is a complex process that involves multiple steps such as inflammation, proliferation and maturation and ends with scar formation. Since ancient times, a widely used option for treating skin wounds are plant- based treatments which currently have become the subject of modern pharmaceutical formulations. Triterpenes with tetracyclic and pentacyclic structure are extensively studied for their implication in wound healing as well as to determine their molecular mechanisms of action. The current review aims to summarize the main results of in vitro, in vivo and clinical studies conducted on lupane, ursane, oleanane, dammarane, lanostane and cycloartane type triterpenes as potential wound healing treatments.

Oleanolic Acid Derived from Plants: Synthesis and Pharmacological Properties of A-ring Modified Derivatives

Background:

Oleanolic Acid (OA) is a ubiquitous product of triterpenoid compounds. Due to its inexpensive availability, unique bioactivities, pharmacological effects and non-toxic properties, OA has attracted tremendous interest in the field of drug design and synthesis. Furthermore, many OA derivatives have been developed for ameliorating the poor water solubility and bioavailability.

Objective:

Over the past few decades, various modifications of the OA framework structure have led to the observation of enhancement in bioactivity. Herein, we focused on the synthesis and medicinal performance of OA derivatives modified on A-ring. Moreover, we clarified the relationship between structures and activities of OA derivatives with different functional groups in A-ring. The future application of OA in the field of drug design and development also was discussed and inferred.

Conclusion:

This review concluded the novel achievements that could add paramount information to the further study of OA-based drugs.

Structural Elucidation and Antimicrobial Characterization of Novel Diterpenoids from Fabiana densa var. ramulosa

Novel diterpenoids were isolated from the extracts of Fabiana densa var. ramulosa and found to display a selective activity against Gram-positive bacterial strains with negligible cytotoxicity toward human keratinocytes. This study highlighted the role played by the acidic group at C18 of the tetracyclic ent-beyerene scaffold for antibacterial effects and how the length and flexibility of the alkyl chain between the two carbonyl groups are crucial factors to increase the antimicrobial activity of the molecules, supporting the development of natural products from F. densa and their derivatives for treatment of microbial infections.

Fabiana imbricata Ruiz et Pav. (Solanaceae), a review of an important Patagonian medicinal plant

ETHNOPHARMACOLOGICAL RELEVANCE

Fabiana imbricata (Solanaceae) is a Patagonian medicinal plant with a long tradition of use. The aim of this review is to provide an integrative overview of the traditional uses, chemistry, bioactivity and chemical profiling of the crude drug.

MATERIALS AND METHODS

The information was collected from scientific databases searching with the keywords Fabiana imbricata, Fabiana species, Fabiana (Solanaceae) and includes local literature and books.

RESULTS

The indications of use reported in literature show little variation from the data published as early as 1889. The chemical studies showed a rich diversity in metabolites including phenolics, coumarins, flavonoids, phenylpropanoids, terpenes, alkaloids and sugars. Bioactivity studies supported the traditional use as diuretic and also the potential of the crude drug as a gastroprotective agent. The plant can be used as a source of compounds with effect on gastric ulcers and shows enzyme inhibitory activity. While the germination rate of the plant is very low, protocols were developed for the rapid in vitro propagation of the species. The toxicity of the crude drug extracts was low and did not show clastogenic effect in human lymphocytes. Further research is needed to disclose the potential of the F. imbricata sesquiterpenes on other relevant biological targets.

Berberis aristata Ameliorates Testicular Toxicity Induced by Combination of First-Line Tuberculosis Drugs (Rifampicin + Isoniazid + Pyrazinamide) in Normal Wistar Rats

First-line antituberculosis drugs, namely, isoniazid (INH), rifampicin (RIF), and pyrazinamide (PZA), contribute to diverse pathological complications. Testicular toxicity is one such complication. Berberis aristata DC is an herb with potentially curative characteristics. The aim of this study was to test whether extract of Berberis aristata DC (Berberidaceae) has curing potential against testicular toxicity. Characterization of extract was done using ultra-performance liquid chromatography along with acute toxicity testing. Antioxidant activity of extract was checked by DPPH inhibition assay and H₂O₂ scavenging assay. Rats were dosed once daily for 28 days in groups: control group (saline), toxicant group (30.85 mg/kg body weight INH + 61.7 mg/kg body weight RIF + 132.65 mg/kg body weight PZA), treatment groups (TB drugs + 150/300 mg/kg body weight extract) and standard group (TB drugs +100 mg/kg body weight silymarin). Spectrophotometric evaluations of lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione-S-transferase (GST), and catalase (CAT) content in testes were done using standard protocols. DNA fragmentation and histopathological studies were performed to check the damage at the cellular level. Acute toxicity studies revealed LD₅₀ > 5 g/Kg body weight of B. aristata extract. IC₅₀ for DPPH free-radical scavenging activity and H₂O₂ scavenging assay were 44.78 µg/mL and 85.28 µg/mL, respectively. Results revealed significant increase in thiobarbituric acid reactive substances, decrease in glutathione and different antioxidants levels, DNA fragmentation pattern, and changes in histology in toxicant group. All the changes were absent in high-dose (300 mg/kg body weight) extract treatment group. This work proved that B. aristata extract has protective efficacy against testicular damage caused by anti-TB drugs.

MAGL inhibition modulates gastric secretion and motility following NSAID exposure in mice

Non-steroidal anti-inflammatory drugs (NSAIDs) are common analgesic drugs that also cause well-known, negative gastrointestinal (GI) side effects. The physiological mechanism(s) of NSAID-induced GI damage are unclear and are likely due to multiple causes. The most studied contributing mechanisms are increased gastric acid secretion and increased gastric motility. The present study was designed to determine which ulcerogenic effects of the NSAID diclofenac sodium are reversed by blocking the endocannabinoid catabolic enzyme monoacylglycerol lipase (MAGL). Both male and female mice were used to identify possible sex differences. We hypothesized that the MAGL inhibitor JZL184 would attenuate diclofenac-induced increases in both gastric acid secretion and gastric motility. Diclofenac dose-dependently induced gastric hemorrhages to a similar extent in both male and female mice. Gastric hemorrhage severity significantly correlated with gastric levels of myeloperoxidase, an objective measure of neutrophil infiltration. Similarly, JZL184 reduced gastric acidity, in controls as well as mice treated with pentagastrin, which stimulates gastric acid release. As hypothesized, JZL184 decreased gastric motility. Surprisingly, diclofenac also slowed gastric emptying, indicating that diclofenac-induced ulcers most likely occur through increased gastric acid secretion, and not increased gastric motility, as measured in the present study. Thus, MAGL inhibition may proffer gastroprotection through modulating the secretory pathway of gastric hemorrhage. These data underscore the importance of sampling multiple time points and using both sexes in research, in addition to multiple mechanistic targets, and contribute to the basic understanding of NSAID-induced gastric inflammation.

Triterpenes for Well-Balanced Scar Formation in Superficial Wounds

Triterpenes are demonstrably effective for accelerating re-epithelialisation of wounds and known to improve scar formation for superficial lesions. Among the variety of triterpenes, betuline is of particular medical interest. Topical betuline gel (TBG) received drug approval in 2016 from the European Commission as the first topical therapeutic agent with the proven clinical benefit of accelerating wound healing. Two self-conducted randomized intra-individual comparison clinical studies with a total of 220 patients involved in TBG treatment of skin graft surgical wounds have been screened for data concerning the aesthetic aspect of wound healing. Three months after surgery wound treatment with TBG resulted in about 30% of cases with more discreet scars, and standard of care in about 10%. Patients themselves appreciate the results of TBG after 3 months even more (about 50%) compared to standard of care (about 10%). One year after surgery, the superiority of TBG counts for about 25% in comparison with about 10%, and from the patients’ point of view, for 25% compared to 4% under standard of care. In the majority of wound treatment cases, there is no difference visible between TBG treatment and standard of care after 1 year of scar formation. However, in comparison, TBG still offers a better chance for discreet scars and therefore happens to be superior in good care of wounds.

Triterpenes with healing activity: A systematic review

The purpose of this review was to systematically evaluate the literature on the efficacy of triterpenes for wound healing. We searched for original studies in the Medline, SCIDIRECT and LILACS databases published from 1910 to 2013. For each study, the title, abstract and full article were evaluated by two reviewers. We identified 2181 studies; however, after application of the inclusion and exclusion criteria, only 12 studies were subjected to further review. In surgical wounds, the triterpenes induced a reduction in time to closure, and this effect was reported in virtually all wound types. Triterpenes also modulate the production of ROS in the wound microenvironment, accelerating the process of tissue repair. Triterpenes may also induce cell migration, cell proliferation and collagen deposition. Although the pharmacological effects of triterpenes are well characterized, little is known about their effects in cells involved in healing, such as keratinocytes and fibroblasts. In addition, the lack of studies on the risks associated with the therapeutic use of triterpenes is worrisome. Our study reveals that triterpenes seem to favor wound healing; however, toxicological studies with these compounds are required. Taken together, these findings show that the triterpenes are a class of molecules with significant promise that leads for the development of new drugs to treat skin injury.

Refractory organic pollutants and toxicity in pulp and paper mill wastewaters

This review describes medium and high molecular weight organic material found in wastewaters from pulp and paper industry. The aim is to review the versatile pollutants and the analysis methods for their determination. Among other pollutants, biocides, extractives, and lignin-derived compounds are major contributors to harmful effects, such as toxicity, of industrial wastewaters. Toxicity of wastewaters from pulp and paper mills is briefly evaluated including the methods for toxicity analyses. Traditionally, wastewater purification includes mechanical treatment followed by chemical and/or biological treatment processes. A variety of methods are available for the purification of industrial wastewaters, including aerobic and anaerobic processes. However, some fractions of organic material, such as lignin and its derivatives, are difficult to degrade. Therefore, novel chemical methods, including electrochemical and oxidation processes, have been developed for separate use or in combination with biological treatment processes.

Gastroprotective effect of alpha-pinene and its correlation with antiulcerogenic activity of essential oils obtained from Hyptis species

Background:

Alpha-pinene (α-pinene) is a monoterpene commonly found in essential oils with gastroprotective activity obtained from diverse medicinal plants, including Hyptis species. The genus Hyptis (lamiaceae) consists of almost 400 species widespread in tropical and temperate regions of America. In the north and northeastern Brazil, some Hyptis species are used in traditional medicine to treat gastrointestinal disturbances.

Objective:

The present study has investigated the gastoprotective effect of purified α-pinene in experimental gastric ulcer induced by ethanol and indomethacin in mice.

Materials and Methods:

Gastric ulcers were induced in male Swiss mice (20-30 g) by oral administration of absolute ethanol or indomethacin 45 min after oral pretreatment with vehicle, standard control drugs or α-pinene (10, 30, and 100 mg/kg). One hour after the ulcerative challenges, the stomach were removed, and gastric lesions areas measured. The effects of α-pinene on the gastric juice acidity were determined by pylorus ligation model. The gastrointestinal motility and mucus depletion were determined by measuring the gastric levels of phenol red and alcian blue, respectively. Hematoxylin and eosin stained sections of gastric mucosa of the experimental groups were used for histology analysis.

Results:

α-pinene pretreatment inhibited ethanol-induced gastric lesions, reduced volume and acidity of the gastric juice and increased gastric wall mucus (P < 0.05). Furthermore, we showed an interesting correlation between concentration of α-pinene and gastroprotective effect of Hyptis species (P Pearson = 0.98).

Conclusion:

Our data showed that the α-pinene exhibited significant antiulcerogenic activity and a great correlation between concentration of α-pinene and gastroprotective effect of Hyptis species was also observed.

Antiulcerogenic activity of the essential oil of Hyptis martiusii Benth. (Lamiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Hyptis martiusii (Lamiaceae), popularly known as "cidreira-do-mato" or "cidreira-brava", grows in abundance in the Northeast region of Brazil, where its leaves are traditionally used in folk medicine in the treatment of intestinal and stomach diseases. The aim of this study was to characterize the chemical constituents and to evaluate the anti-ulcerogenic activity of the essential oil of the leaves of Hyptis martiusii (EOHM) in in vivo models of experimental ulcers in rodents.

MATERIALS AND METHODS

EOHM was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Acute gastric ulcer was induced using absolute ethanol, HCl/ethanol and indomethacin. The volume, pH and total acidity of gastric secretion were determined by the pyloric ligature method and gastrointestinal motility using gastric emptying and intestinal transit.

RESULTS

Chemical analysis revealed the presence of 24 components that account for 92.13% of the essential oil of dried leaves, indicating the occurrence of mono and sesquiterpenes. Oral administration of EOHM (100, 200 and 400mg/kg) inhibited ethanol-, HCl/ethanol- and indomethacin-induced ulcers. In the case of pylorus ligature, the oil reduced the volume of gastric juices and total acidity, and increased gastric pH. The EOHM reduced the rate of gastric emptying with only the highest doses, but did not show any effect on intestinal transit at any of the three doses.

CONCLUSIONS

The results indicate that the essential oil of leaves of Hyptis martiusii has an antiulcerogenic activity, as evidenced by its significant inhibition of the formation of ulcers in various models. This effect could be related to an increase of gastric mucosal defensive factors. Further pharmacological studies are being undertaken in order to provide more precise elucidation of the action mechanism involved in this activity.

Antiulcer and Anti-inflammatory Activity of Aerial Parts Enicostemma littorale Blume

The antiulcer and in vitro anti-inflammatory activities of the aerial parts of Enicostemma littorale against aspirin, ethanol, and pyloric ligation-induced ulcers in rats and bovine serum albumin denaturation were studied. The extract (200 mg/kg and 400 mg/kg po) was administered to the overnight fasted rats, one hour prior to aspirin / alcohol / pyloric ligation challenge. The ulcer index, tissue GSH levels, and lipid peroxidation levels were estimated in all the models of ulcers and the volume of gastric secretion, acidity, and pH, were estimated in the pyloric ligation model of ulcers. Pretreatment with the extract showed a dose-dependent decrease in the ulcer index (Against Aspirin, ethanol challenge, and pyloric ligation. The prior administration of the extract also reduced the total acidity, free acidity, and volume of gastric secretion, and elevated the gastric pH. In addition, it was also observed that the extract inhibited the serum albumin denaturation in a dose-dependent manner. It may be concluded that the methanolic extract possesses antiulcer activity, and the anti-inflammatory activity of the extract may be attributed to the antioxidant potential, as reported earlier.

Gastroprotective activity of a new semi-synthetic solidagenone derivative in mice

The gastroprotective activity of the new semi-synthetic solidagenone derivative 15,16-epoxy-8(9),13(16),14-labdatrien-7β-methoxy-6β-ol (ELMO) has been assessed on the model of HCl/EtOH-induced gastric lesions in mice. Human gastric epithelial cells (AGS) and fibroblasts (MRC-5) were used to determine its mode of action. The effect of ELMO on the prostaglandin E2 content, cellular reduced glutathione (GSH) and protection against damage induced by sodium taurocholate was assessed against AGS cells. The effect of ELMO on the growth of AGS and fibroblast cultures was evaluated. The superoxide anion scavenging capacity of the compound was studied also. The cytotoxicity of ELMO, expressed as cell viability, was assessed using two independent endpoints: neutral red uptake (NRU) and the reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for MRC-5 fibroblasts and NRU for AGS cells. A single oral dose of ELMO (10 and 20 mg kg−1) inhibited the appearance of gastric lesions in mice displaying similar values to lansoprazole at 20 mg kg−1. At 40 μm ELMO increased the prostaglandin E2 content but not GSH in AGS cells. The compound showed no effect on sodium taurocholate-induced damage and was devoid of superoxide anion scavenging activity. Concentrations of 0.5, 1, 2 and 4 μm stimulated fibroblast but not AGS cell proliferation. The compound showed weak cytotoxicity with values (IC50) of 411 (NRU) and 418 μm (MTT) for fibroblasts and 261 μm (NRU) for AGS cells. The results support further pharmacological study of this compound as a potential new anti-ulcerogenic drug.

Chemosensory perception and medicinal plants for digestive ailments in a Mapuche community in NW Patagonia, Argentina

AIM OF THE STUDY

To document the richness of plant species used in gastrointestinal disorders and to investigate about the criteria of aroma and flavor associated with its recognition, classification, selection and use.

MATERIALS AND METHODS

Ethnobotanical fieldwork consisted of interviews to 30 inhabitants living in a Mapuche community of Northwestern Patagonia; data collected was analyzed by means of non-parametric statistics.

RESULTS

This work records 75 ethnospecies, pertaining to 40 botanic families. Lamiaceae, Asteraceae and Chenopodiaceae were the most frequently mentioned and described in terms of smell and taste. Most of species (69%) have notable aroma and/or flavor characteristics. The species presenting highest consensus in the population are positively associated with a higher frequency of organoleptic descriptions. In addition, local people consider these perceptions to be potentially useful in the search for substitutes when species are scarce or disappear from a locality.

CONCLUSIONS

It is possible to establish a preliminary system of classification of medicinal plants based on their organoleptic characteristics and relate this to their effects on health. Moreover the cultural interpretation of smell and taste is of great heuristic importance to ethnopharmacology, in that it indicates which plants are most likely to contain the main active ingredients sought.

Oleanolic acid and related derivatives as medicinally important compounds

Oleanolic acid has been isolated from chloroform extract of Olea ferruginea Royle after removal of organic bases and free acids. The literature survey revealed it to be biologically very important. In this review the biological significance of oleanolic acid and its derivatives has been discussed. The aim of this review is to update current knowledge on oleanolic acid and its natural and semisynthetic analogs, focussing on its cytotoxic, antitumer, antioxidant, anti-inflamatory, anti-HIV, acetyl cholinesterase, alpha-glucosidase, antimicrobial, hepatoprotective, anti-inflammatory, antipruritic, spasmolytic activity, anti-angiogenic, antiallergic, antiviral and immunomodulatory activities. We present in this review, for the first time, a compilation of the most relevant scientific papers and technical reports of the chemical, pre-clinical and clinical research on the properties of oleanolic acid and its derivatives.

A preliminary pharmacokinetic study of betulin, the main pentacyclic triterpene from extract of outer bark of birch (Betulae alba cortex)

During the last two decades triterpenes have attracted attention because of their pharmacological potential. Triterpene extract (TE) from outer bark of birch consisting mainly of betulin is able to form an oleogel which was successfully tested in the treatment of actinic keratosis. Some aspects of TE in vitro pharmacology are already known. Now we show preliminary pharmacokinetics of betulin and results of a subchronic toxicity study of TE in rats and dogs. Because of poor aqueous solubility of the TE-triterpenes (< 0.1 microg/mL respectively), for pharmacokinetic studies it was suspended in sesame oil (rats, i.p.) and PEG 400 / 0.9 % NaCl (dogs, s.c.). I.p. administered, betulin, the main component of TE, shows time dependency over a period of 4 h and reaches a dose-independent serum level of 0.13 microg/mL. Dose dependency was observed with s.c. administration. At 300 mg/kg a maximum plasma concentration of 0.33 microg/mL betulin was detected after 28 daily applications. The subchronic toxicity study showed no toxicity of TE in rats (i.p.) and dogs (s.c.). In conclusion, triterpene extract from birch bark is safe, its betulin is bioavailable and in addition to published triterpene biological activities TE provides high potential for further pharmaceutical and pharmacological research.

Evaluation of gastroprotective activity of Plinia edulis (Vell.) Sobral (Myrtaceae) leaves in rats

Plinia edulis, an arboreous species popularly known as "cambucá", is native to the Brazilian Atlantic Rain Forest. Despite its traditional uses, no reports are available on the safety of this utilization or on the relationship between the antiulcer activity of its extract and its phytochemical compounds. This paper reports on the investigation of the acute toxicity and gastroprotective effect of the aqueous ethanol extract of leaves of Plinia edulis on HCl/ethanol-induced ulcers. In order to correlate the secondary metabolites and the efficacy of the crude drug in traditional medicine, the extract was submitted to chromatographic fractionation after solvent partition. The extract did not show acute toxicity in mice treated with 5 g/kg p.o., but exhibited significant antiulcer activity in rats at doses of 100, 200, and 400mg/kg p.o., more active than the reference drug lansoprazole.The ethyl acetate fraction yielded beta-amyrin, oleanolic acid, ursolic acid, and maslinic acid, which were identified based on spectrometric analyses. Since antiulcerogenic activity is not restricted to one class of compounds in plants, the triterpenoids isolated in the extract can be associated with the observed effect.

Gastroprotective and ulcer-healing activity of oleanolic acid derivatives: In vitro–in vivo relationships

The triterpene oleanolic acid 1 and its semisynthetic derivatives 2-7 were assessed for gastroprotective and ulcer-healing effect using human epithelial gastric cells (AGS) and human lung fibroblasts (MRC-5). The ability of the compounds to protect the AGS cells against the damage induced by sodium taurocholate (NaT), to stimulate the cellular reduced glutathione (GSH) and prostaglandin E(2) content, to enhance AGS and MRC-5 cell proliferation and to scavenge superoxide anion in vitro was studied. The cytotoxicity of the compounds was assessed towards MRC-5 and AGS cells. In addition, the gastroprotective activity of the compounds was assessed in vivo using the HCl/EtOH-induced ulcer model in mice. All the assayed compounds displayed a significant reduction of AGS cells damage after incubation with NaT. None of the studied compounds was active as a superoxide anion scavenger nor stimulated the GSH content in AGS cell cultures. Compounds 1, 2, 4 and 6 were able to increase the prostaglandin content in AGS cell cultures. Concerning the proliferation assays, a significant stimulating effect was observed for compounds 3 and 7 on AGS cells and for 1 and 7 on MRC-5 fibroblasts. Regarding cytotoxicity, derivatives 2, 4, 6 and 7 were less toxic than the parent compound oleanolic acid. Our results strongly support the predictive capacity of the in vitro assessment of gastroprotective activity allowing the reduction of experimental animals.

Traditional medicine and gastroprotective crude drugs

A frequent question when dealing with the search for gastroprotective compounds from natural sources is how far or close are both the plant preparations and extract amounts from the doses recommended in traditional medicine and what should be considered realistic levels for experimental studies. The administration way is oral and therefore extracts and products should be administered by gavage when looking for validation of ethnopharmacological uses. Suggestions of doses for both crude extracts and pure compounds are presented and discussed. For plant extracts prepared from single herbs and herbal mixtures, dose-response studies in the range between 100 and 300 mg/kg are suggested, with more than a single gastric ulcer model either in rats or mice. A suitable reference compound should be used according to the ulcer model and in doses resembling those used for human patients. For pure compounds and structure-activity studies or trends, dose-response results should be provided for at least a parent compound in order to select a reasonable dose for comparison purposes. We suggest an evaluation of the activity of the parent compound in the 50-300 mg/kg range and to look for structural modification leading to derivatives with similar or higher gastroprotective effects than the reference antiulcer compounds.

A Pilot trial evaluating meta050, a proprietary combination of reduced iso-alpha acids, rosemary extract and oleanolic acid in patients with arthritis and fibromyalgia

The aim of this open-label, 8-week observational trial was to investigate the efficacy of Meta050 (a proprietary, standardized combination of reduced iso-alpha-acids from hops, rosemary extract and oleanolic acid) on pain in patients with rheumatic disease. Osteoarthritis, rheumatoid arthritis and fibromyalgia patients were given 440 mg Meta050 three times a day for 4 weeks, which was changed to 880 mg twice a day for the subsequent 4 weeks in the majority of patients. Pain and condition-specific symptoms were assessed using a standard visual analog scale (VAS), an abridged arthritis impact measurement scale (AIMS2) and the fibromyalgia impact questionnaire. Fifty-four subjects with rheumatic disease completed the trial. Following treatment, a statistically significant decrease in pain of 50% and 40% was observed in arthritis subjects using the VAS (p < 0.0001; Wilcoxon-ranked sums) and AIMS2 (p < 0.0001), respectively. Fibromyalgia subject scores did not significantly improve. A decreasing trend of C-reactive protein, a marker for inflammation, was also observed in those subjects who presented with elevated C-reactive protein. No serious side effects were observed. These observations suggest that Meta050 at a dosage of 440 mg three times a day has a beneficial effect on pain in arthritis subjects.

Gastroprotective activity of sesquiterpene derivatives fromFabiana imbricata

An infusion or decoction of the aerial parts of Fabiana imbricata (Solanaceae) is used in traditional medicine in Chile and Argentina as a digestive and diuretic agent. The main sesquiterpene of the plant was identified as 11-hydroxy-4-amorphen-15-oic acid. At doses of 25, 50 and 100 mg/kg, the compound showed a dose-dependent gastroprotective effect in HCl/EtOH-induced gastric lesions in mice reducing the lesions by 68% at 100 mg/kg. Seven derivatives of the terpene were prepared and their gastroprotective effect was assessed in HCl/EtOH-induced gastric lesions in mice. The cytotoxicity of the products was evaluated in fibroblasts and AGS cells. At 100 mg/kg, 11-hydroxy-4-amorphen-15-p-toluidinamide presented the best gastroprotective effect reducing the gastric lesions by 80%, showing a similar effect to lansoprazole at 20 mg/kg. The compound, however, presented higher cytotoxicity than other derivatives with the IC50 ranging between 110 and 145 microm in AGS cells and fibroblasts, respectively. Most compounds proved to be non-toxic showing cytotoxicity values higher than 1000 microm. The spectroscopic data of six 11-hydroxy-4-amorphen-15-oic acid derivatives are presented here for the first time.