Inhibition of experimental gastric lesion and inflammation by Phyllanthus amarus extract

An insight into the potent medicinal plant Phyllanthus amarus Schum. and Thonn

Phyllanthus amarus Schum. and Thonn., a globally distributed herb is known for its several therapeutic potentials. P. amarus has a long history of use in the traditional system of medicine for over 2000 years owing to its wide array of secondary metabolites that confer significant medicinal attributes. Research on various aspects including ethnobotany, phytochemistry to bioactivity, or pharmacological studies has been conducted over the past several decades on this potent herb. P. amarus extracts have shown a broad range of pharmacological activities like hepatoprotective, antioxidant, antiviral, antimicrobial, antidiabetic, anti-inflammatory, anticancer, antimalarial, nephroprotective, diuretic, and several other properties. The present review compiles and covers literature and research of several groups across past decades to date and focuses on how the therapeutic significance of this plant can be further explored for future research either as herbal formulations, alternative medicine, or in the pharmaceutical industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13237-022-00409-z.

Mechanistic Studies of the Antiallergic Activity of Phyllanthus amarus Schum. & Thonn. and Its Compounds

Phyllanthus amarus Schum. & Thonn. (Phyllanthaceae) is a medicinal plant that is commonly used to treat diseases such as asthma, diabetes, and anemia. This study aimed to examine the antiallergic activity of P. amarus extract and its compounds. The antiallergic activity was determined by measuring the concentration of allergy markers release from rat basophilic leukemia (RBL-2H3) cells with ketotifen fumarate as the positive control. As a result, P. amarus did not stabilize mast cell degranulation but exhibited antihistamine activity. The antihistamine activity was evaluated by conducting a competition radioligand binding assay on the histamine 1 receptor (H1R). Four compounds were identified from the high performance liquid chromatography (HPLC) analysis which were phyllanthin (1), hypophyllanthin (2), niranthin (3), and corilagin (4). To gain insights into the binding interactions of the most active compound hypophyllanthin (2), molecular docking was conducted and found that hypophyllanthin (2) exhibited favorable binding in the H1R binding site. In conclusion, P. amarus and hypophyllanthin (2) could potentially exhibit antiallergic activity by preventing the activation of the H1 receptor.

Productive, metabolic and anatomical parameters of menthol mint are influenced by light intensity

The cultivation of aromatic species to obtain essential oils has great economic importance, presenting an increasing demand from different industrial sectors, especially to menthol mint (Mentha arvensis L.) essential oil, rich in menthol (70-80%). Consortium cultivation has been an important practice in agricultural systems whose land use is necessary, consequently promoting strong competition for light in reduced space. Thus, this study aimed verifying if different light intensities might promote chemical, metabolical and anatomical alterations in menthol mint. Plants were grown in greenhouse at different average of light intensities (137, 254, 406 and 543 µmol photons m2 s1). Samples were collected 43 days after germination and submitted to following analyses: Gravimetric test, photosynthetic pigments, soluble fractions, enzymatic activity, N-total, trichome density and histochemistry and chemometric test based on essential oil chemical profile. Fresh mass gain, trichome density, essential oil content and soluble sugars were positively influenced by light intensity increase. On the other hand, total-N, NO3--N and pigments content have decreased influenced by light intensity increase. In the secretion from the trichomes, phenolic substances were reported, as well as lipophilic ones in the peltate ones. The increase of oxygenated monoterpenes was favored by light intensity decrease.

Modulation of cell signaling pathways by Phyllanthus amarus and its major constituents: potential role in the prevention and treatment of inflammation and cancer

The causal and functional connection between inflammation and cancer has become a subject of much research interest. Modulation of cell signaling pathways, such as those involving mitogen activated protein kinases (MAPKs), nuclear factor kappa β (NF-κB), phosphatidylinositol 3-kinase and protein kinase B (PI3K/Akt), and Wnt, and their outcomes play a fundamental role in inflammation and cancer. Activation of these cell signaling pathways can lead to various aspects of cancer-related inflammation. Hence, compounds able to modulate inflammation-related molecular targets are sought after in anticancer drug development programs. In recent years, plant extracts and their metabolites have been documented with potential in the prevention and treatment of cancer and inflammatory ailments. Plants possessing anticancer and anti-inflammatory properties due to their bioactive constituents have been reported to modulate the molecular and cellular pathways which are related to inflammation and cancer. In this review we focus on the flavonoids (astragalin, kaempferol, quercetin, rutin), lignans (phyllanthin, hypophyllanthin, and niranthin), tannins (corilagin, geraniin, ellagic acid, gallic acid), and triterpenes (lupeol, oleanolic acid, ursolic acid) of Phyllanthus amarus, which exert various anticancer and anti-inflammatory activities via perturbation of the NF-κB, MAPKs, PI3K/Akt, and Wnt signaling networks. Understanding the underlying mechanisms involved may help future research to develop drug candidates for prevention and new treatment for cancer and inflammatory diseases.

Protective effects and potential underlying mechanisms of sodium copper chlorophyllin against ethanol-induced gastric ulcer in mice

In study, we aimed to determine the mechanisms underlying the gastroprotective effects of sodium copper chlorophyllin (SCC) against ethanol-induced gastric ulcer injury in mice. First, the gastroprotective effects of SCC against gastric ulcer induced by ethanol were assessed. Then, biochemical, histopathological, immunohistochemistry assays, and western blot analysis were conducted to determine the possible mechanisms of action underlying the effects of SCC. Compared to the effects of omeprazole (OME) in a confirmed mouse model of ethanol-induced gastric ulcer injury, treatment with various doses of SCC resulted in up-regulation of Bcl-2 and down-regulation of the pro-apoptotic protein Bax. Significant decreases in the levels of the malondialdehyde (MDA), myeloperoxidase (MPO), and NO in the gastric tissues were observed. Furthermore, inflammatory cytokine analysis revealed that SCC treatment inhibited the expressions of TNF-α and IL-6, greatly reduced the phosphorylation level of IκB, and repressed the nuclear translocation of NF-κB p65, which demonstrated that SCC inhibited the activation of the NF-κB pathway. The present findings suggest that the protective effects of SCC may be beneficial as a potential preventive and therapeutic agent for gastric ulcer through the NF-κB pathway. Taken together, SCC administration significantly decreased the levels of MPO, NO, and MDA in gastric tissue and exerted a powerful anti-inflammatory activity as demonstrated by reduction in the secretions of proinflammatory mediators such as IL-6 and TNF-α in the serum of mice exposed to ethanol.

Hemostasis and uterine contraction promoting effect of the extract from drugs in the Zi-Yin-Tiao-Jing granule, a traditional Chinese compound preparation

ETHNOPHARMACOLOGICAL RELEVANCE

Zi-Yin-Tiao-Jing granule (ZG) is a traditional Chinese medicine compound preparation for perimenopausal dysfunctional uterine bleeding. It is made from 9 Chinese crude drugs based on a modified traditional Chinese prescription recorded in Fu Qingzhu Nvke as Guben Zhibeng Tang.

AIM OF THE STUDY

This study aimed to investigate the hemostasis and uterine contraction promoting effect of quality controlled ZG extract on animals as a preclinical study.

MATERIALS AND METHODS

ZG extract was quality controlled by determining the contents of asperosaponin Ⅵ and tetrahydroxystilbene glucoside (TSG) with high-performance liquid chromatography (HPLC) and the contents of total tannins, total saponins and total flavonoids with ultraviolet spectrophotometry (UV). Bleeding time, clotting time, prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (FIB) content were assayed to test the hemostasis effect of ZG extract on sixty healthy female Kunming mice. In addition, ten healthy female Sprague-Dawley rats were used to test the effect of ZG extract on uterine contractions in vitro with the BL-420 Biological Function Experiment System.

RESULTS

The ZG extract contained 0.81mgg^-1 asperosaponin Ⅵ, 0.15mgg^-1 TSG, 1.98mgg^-1 total tannins, 1.83mgg^-1 total saponins, and 4.09mgg^-1 total flavonoids. Compared with placebo, the ZG extract shortened the bleeding time at a dosage of 1.2gkg^-1 and 2.4gkg^-1, and shortened the clotting time at 0.6gkg^-1, 1.2gkg^-1 and 2.4gkg^-1 in mice (P < 0.01). It also decurtated the APTT at a dosage of 0.6gkg^-1 (P < 0.05) and raised the content of FIB in the plasma at a dosage of 2.4gkg^-1 (P < 0.05). However, the PT showed no changes after the administration of ZG extract (P > 0.05). In addition, ZG extract at the doses of 1.8mgmL^-1, 3.6mgmL^-1, and 5.4mgmL^-1 increased the amplitude and motoricity of uterine contractions of rats (P < 0.05 or P < 0.01) but maintained the frequency as unchanged.

CONCLUSIONS

The ZG extract was quality controllable by assaying for asperosaponin Ⅵ, TSG, total tannins, total saponins and total flavonoids. It could promote the hemostasis of mice in vivo, as well as the uterine contractions of rats in vitro. Therefore, it may be a promising preparation for clinical treatment of perimenopausal dysfunctional uterine bleeding.

Amelioration of aspirin induced oxidative impairment and apoptotic cell death by a novel antioxidant protein molecule isolated from the herb Phyllanthus niruri

Aspirin has been used for a long time as an analgesic and anti-pyretic drug. Limitations of its use, however, remain for the gastro-intestinal side effects and erosions. Although the role of aspirin on gastro-intestinal injury has been extensively studied, the molecular mechanisms underlying aspirin-induced liver and spleen pathophysiology are poorly defined. The present study has been conducted to investigate whether phyllanthus niruri protein (PNP) possesses any protective role against aspirin mediated liver and spleen tissue toxicity, and if so, what signaling pathways it utilizes to convey its protective action. Aspirin administration in mice enhanced serum marker (ALP) levels, reactive oxygen species (ROS) generation, reduced antioxidant power and altered oxidative stress related biochemical parameters in liver and spleen tissues. Moreover, we observed that aspirin intoxication activated both the extrinsic and intrinsic apoptotic pathways, as well as down regulated NF-κB activation and the phosphorylation of p38 and JNK MAPKs. Histological assessments and TUNEL assay also supported that aspirin induced tissue damages are apoptotic in nature. PNP treatment after aspirin exposure effectively neutralizes all these abnormalities via the activation of survival PI3k/Akt pathways. Combining all results suggest that PNP could be a potential protective agent to protect liver and spleen from the detrimental effects of aspirin.

Anti-quorum sensing activity of the traditional Chinese herb, Phyllanthus amarus

The discovery of quorum sensing in Proteobacteria and its function in regulating virulence determinants makes it an attractive alternative towards attenuation of bacterial pathogens. In this study, crude extracts of Phyllanthus amarus Schumach. & Thonn, a traditional Chinese herb, were screened for their anti-quorum sensing properties through a series of bioassays. Only the methanolic extract of P. amarus exhibited anti-quorum sensing activity, whereby it interrupted the ability of Chromobacterium violaceum CVO26 to response towards exogenously supplied N-hexanoylhomoserine lactone and the extract reduced bioluminescence in E. coli [pSB401] and E. coli [pSB1075]. In addition to this, methanolic extract of P. amarus significantly inhibited selected quorum sensing-regulated virulence determinants of Pseudomonas aeruginosa PA01. Increasing concentrations of the methanolic extracts of P. amarus reduced swarming motility, pyocyanin production and P. aeruginosa PA01 lecA∷lux expression. Our data suggest that P. amarus could be useful for attenuating pathogens and hence, more local traditional herbs should be screened for its anti-quorum sensing properties as their active compounds may serve as promising anti-pathogenic drugs.

A 35 kD Phyllanthus niruri protein modulates iron mediated oxidative impairment to hepatocytes via the inhibition of ERKs, p38 MAPKs and activation of PI3k/Akt pathway

It has been reported that the herb, Phyllanthus niruri, possess antioxidant, anti-infection, anti-asthmatic, anti-diuretic, anti-soresis and many more beneficial activities. The goal of our present study was to evaluate the protective role of a 35 kD protein (PNP) isolated from this herb against iron-induced cytotoxicity in murine hepatocytes. Exposure of hepatocytes to iron (FeSO4) caused elevation of reactive oxygen species (ROS) production, enhanced lipid peroxidation and protein carbonylation, depleted glutathione levels, decreased the antioxidant power (FRAP) of the cells and reduced cell viability. Iron mediated cytotoxicity disrupted mitochondrial membrane potential (Δψm) and thereby caused apoptosis mainly by the intrinsic pathway via the down-regulation of IκBα with a concomitant up-regulation of NF-kB as well as the phosphorylation of ERKs and p38 MAP kinases. In addition, iron-induced cytotoxicity disrupted the normal balance of Bcl-2 family proteins in hepatocytes. Incubation of hepatocytes with PNP, however, protected the cells from apoptosis by stabilizing the mitochondria and arresting the release of cytochrome c. It also suppressed caspase activation and cleavage of PARP. Moreover, this protein has strong free radical scavenging activity and thereby scavenged ROS extensively. Combining all, results suggest that simultaneous treatment with PNP might suppress the iron-induced cytotoxicity in hepatocytes.

Tannins, peptic ulcers and related mechanisms

This review of the current literature aims to study correlations between the chemical structure and gastric anti-ulcer activity of tannins. Tannins are used in medicine primarily because of their astringent properties. These properties are due to the fact that tannins react with the tissue proteins with which they come into contact. In gastric ulcers, this tannin-protein complex layer protects the stomach by promoting greater resistance to chemical and mechanical injury or irritation. Moreover, in several experimental models of gastric ulcer, tannins have been shown to present antioxidant activity, promote tissue repair, exhibit anti Helicobacter pylori effects, and they are involved in gastrointestinal tract anti-inflammatory processes. The presence of tannins explains the anti-ulcer effects of many natural products.

Phyllanthus amarus: ethnomedicinal uses, phytochemistry and pharmacology: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus amarus Schum. & Thonn. belongs to the family Euphorbiaceae is a small herb well known for its medicinal properties and widely used worldwide. P. amarus is an important plant of Indian Ayurvedic system of medicine which is used in the problems of stomach, genitourinary system, liver, kidney and spleen. It is bitter, astringent, stomachic, diuretic, febrifuge and antiseptic. The whole plant is used in gonorrhea, menorrhagia and other genital affections. It is useful in gastropathy, diarrhoea, dysentery, intermittent fevers, ophthalmopathy, scabies, ulcers and wounds.

MATERIALS AND METHODS

The present review covers a literature across from 1980 to 2011. Some information collected from traditional Ayurvedic texts and published literature on ethanomedicinal uses of Phyllanthus amarus in different countries worldwide.

RESULTS

Phytochemical studies have shown the presence of many valuable compounds such as lignans, flavonoids, hydrolysable tannins (ellagitannins), polyphenols, triterpenes, sterols and alkaloids. The extracts and the compounds isolated from P. amarus show a wide spectrum of pharmacological activities including antiviral, antibacterial, antiplasmodial, anti-inflammatory, antimalarial, antimicrobial, anticancer, antidiabetic, hypolipidemic, antioxidant, hepatoprotective nephroprotective and diurectic properties.

CONCLUSION

The present review summarizes information concerning the morphology, ecology, ethnopharmacology, phytochemistry, biological activities, clinical applications and toxicological reports of P. amarus. This review aims at gathering the research work undertaken till date on this plant in order to provide sufficient baseline information for future works and commercial exploitation.

Phytochemical analysis, antioxidant and anti-inflammatory activities of Phyllanthus simplex

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus simplex (Family: Euphorbiacae) is widely used in traditional medicines for treatment of various diseases including inflammation.

MATERIALS AND METHODS

Petroleum ether extract (PSPE) and ethanol extract (PSEE) of the whole plant of Phyllanthus simplex were characterized for their total phenolics, tannins and flavonoids content. These extracts were standardized by HPTLC using phyllanthin and gallic acid respectively as markers. Antioxidant activity of extracts was evaluated by the DPPH, hydroxyl and superoxide radicals scavenging assay. The total antioxidant capacity of extracts was determined. Anti-inflammatory activity was evaluated by their effect on nitric oxide (NO) production in isolated rat peritoneal macrophages; carragennan-induced paw edema and formation of cotton pellet-induced granuloma in rats.

RESULTS

Abundance of phenolics was found in PSEE. Phyllanthin and gallic acid content in PSPE and PSEE were found to be 14.5 and 0.65% (w/w) respectively. PSEE showed concentration dependent significant scavenging of DPPH, hydroxyl and superoxide radicals with IC(50) values 102.219, 171.485 and 24.73 μg/ml respectively. PSEE significantly inhibited NO production in isolated rat peritoneum macrophages. Moreover, it also exhibited significant inhibition of carragennan-induced paw edema (58.48 ± 0.028%, p < 0.001, at 6h, 200 mg/kg oral dose) and cotton pellet-induced granuloma formation (45.671 ± 0.712%, p < 0.001, at 200mg/kg oral dose). Anti-inflammatory activity of PSEE was found to be comparable to diclofenac sodium.

CONCLUSIONS

Significant antioxidant and anti-inflammatory activities were found in PSEE which may be attributed to its high phenolic content.

Radioprotective properties of polyphenols from Phyllanthus amarus Linn

Radioprotective activity of pure compounds isolated from the plant Phyllanthus amarus was studied using rat liver mitochondria and pBR322 plasmid DNA as an in vitro model system. These compounds were ellagitannins namely amariin, 1-galloyl-2,3-dehydrohexahydroxydiphenyl (DHHDP)-glucose, repandusinic acid, geraniin, corilagin, phyllanthusiin D, and flavonoids namely rutin, and quercetin 3-O-glucoside. The activity was then correlated with their hydroxyl and superoxide radical scavenging activity. Both ellagitannins and flavonoids effectively prevented lipid peroxidation and protein oxidation in mitochondria. The compounds also prevented radiation induced single strand breaks in pBR322 plasmid DNA. The radioprotective activity of ellagitannins and flavonoids could be due to their ability to scavenge different radicals more or less efficiently, relieving the oxidative stress. Protection conferred by flavonoids, rutin and quercetin 3-O-glucoside to rat liver mitochondria and plasmid pBR322 DNA from radiation induced damage was due to their strong hydroxyl radical scavenging activity. The inhibitory effect of ellagitannins on lipid peroxidation in liver mitochondria was due to their efficient superoxide radical scavenging ability. This is the first report about the radioprotective activity of pure ellagitannins from Phyllanthus amarus.

An extract of Phyllanthus amarus protects mouse chromosomes and intestine from radiation induced damages

We reported earlier on our preliminary study of the radioprotective effect of Phyllanthus amarus (P.amarus) in mice. P.amarus was found to inhibit the myelosuppression and elevated the levels of antioxidant enzymes in the blood and liver. In the present study we have evaluated the protective effect of P.amarus against radiation-induced changes in the intestine and mouse chromosomal damage. P.amarus at concentrations of 250 & 750 mg/Kg. b. wt were found to elevate the antioxidant enzymes in the intestine and decrease the lipid peroxidation levels. Histopathological evaluations of the intestine revealed decreased damage to intestinal cells, demonstrating that P.amarus protected the intestine. The genotoxic effects of radiation on mouse chromosomes were evaluated by assaying the micronuclei formation and chromosomal aberrations. P.amarus was found to protect the clastogenic effects of radiation as seen from decreased number of micronuclei. The administration of P.amarus was also found to decrease the percentage of chromosomal aberrations. Based on our present and previous reports it could be concluded that P.amarus extract has significant radioprotective activity.

Hepatoprotective activity of Phyllanthus amarus Schum. et. Thonn. extract in ethanol treated rats: in vitro and in vivo studies

The present study was undertaken to investigate the protective effect and possible mechanism of aqueous extract from Phyllanthus amarus Schum. et. Thonn. (PA) on ethanol-induced rat hepatic injury. In the in vitro study, PA (1-4 mg/ml) increased %MTT reduction assay and decreased the release of transaminases (AST and ALT) in rat primary cultured hepatocytes being treated with ethanol. Hepatotoxic parameters studied in vivo included serum transaminases (AST and ALT), serum triglyceride (STG), hepatic triglyceride (HTG), tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1beta), together with histopathological examination. In acute toxicity study, single dose of PA (25, 50 and 75 mg/kg, p.o.) or SL (silymarin, a reference hepatoprotective agent, 5 mg/kg), 24h before ethanol (5 g/kg, p.o.) lowered the ethanol-induced levels of transaminases (AST and/or ALT). The 75 mg/kg PA dose gave the best result similar to SL. Treatment of rats with PA (75 mg/(kg day), p.o.) or SL (5 g/(kg day), p.o.) for 7 days after 21 days with ethanol (4 g/(kg day), p.o.) enhanced liver cell recovery by bringing the levels of AST, ALT, HTG and TNF-alpha back to normal. Histopathological observations confirmed the beneficial roles of PA and SL against ethanol-induced liver injury in rats. Possible mechanism may involve their antioxidant activity.

alpha-Amylase inhibitory activity of some Malaysian plants used to treat diabetes; with particular reference to Phyllanthus amarus

Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of Anacardium occidentale, Lagerstroemia speciosa, Averrhoa bilimbiPithecellobium jiringa and Parkia speciosa were not active when tested without pre-incubation. Extraction and fractionation of Phyllanthus amarus hexane extract led to the isolation of dotriacontanyl docosanoate, triacontanol and a mixture of oleanolic acid and ursolic acid. Dotriacontanyl docosanoate and the mixture of oleanolic acid and ursolic acid are reported from this plant species for the first time. All compounds were tested in the alpha-amylase inhibition assay and the results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-amylase inhibition activity of the extract. Three pure pentacyclic triterpenoids, oleanolic acid, ursolic acid and lupeol were shown to inhibit alpha-amylase.

Antiinflammatory and antiallodynic actions of the lignan niranthin isolated from Phyllanthus amarus

Previous studies have shown that the extracts obtained from Phyllanthus amarus, and some of the lignans isolated from it, exhibit pronounced antiinflammatory properties. In the present study, we have assessed whether the antiinflammatory actions of these lignans can be mediated by interaction with platelet activating factor (PAF) receptor or interference with the action of this lipid. The local administration of nirtetralin, phyltetralin or niranthin (30 nmol/paw), similar to WEB2170 (a PAF receptor antagonist, 30 nmol/paw), significantly inhibited PAF-induced paw oedema formation in mice. The extracts of P. amarus (100 microg/ml) and niranthin (30 microM), but not nirtetralin or phyltetralin (30 microM), decreased the specific binding of [(3)H]-PAF in mouse cerebral cortex membranes. Furthermore, both niranthin and WEB2170 displaced, in a concentration-dependent manner, the [(3)H]-PAF binding sites. The mean IC(50) values from these effects were 6.5 microM and 0.3 microM, respectively. Additionally, both niranthin and WEB2170 (30 nmol/paw) inhibited the increase of myeloperoxidase activity induced by PAF injection in the mouse paw. When assessed the mouse model of pleurisy induced by PAF, pretreatment with niranthin (100 micromol/kg, p.o.) or WEB2170 (1.7 micromol/kg, i.p.) significantly inhibited PAF-induced protein extravasations. Moreover, in the rat model of PAF-induced allodynia, both niranthin (30 nmol/paw) and WEB2170 (30 nmol/paw) treatment significantly inhibited PAF-induced allodynia. In addition, niranthin had a rapid onset and long-lasting antiallodynic action when compared with WEB2170. Collectively, the present findings suggest that niranthin exhibits antiinflammatory and antiallodynic actions which are probably mediated through its direct antagonistic action on the PAF receptor binding sites.

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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.