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Review

Flavonoids with Gastroprotective Activity

1
Laboratório de Tecnologia Farmacêutica Prof. Delby Fernandes de Medeiros – LTF, Universidade Federal da Paraíba - UFPB, Cx. Postal 5009, 58051-970, João Pessoa, PB, Brazil
2
Laboratório de Produtos Naturais, Universidade Estadual de Campinas - UNICAMP, Cx. Postal 6109, 13083-970, Campinas, SP, Brazil
3
Departamento de Fisiologia, Instituto de Biosciência, São Paulo, Universidade Estadual de São Paulo UNESP, c.p. 510, Zip Code: 18618-000, Botucatu, SP, Brazil
*
Author to whom correspondence should be addressed.
Molecules 2009, 14(3), 979-1012; https://doi.org/10.3390/molecules14030979
Received: 30 November 2008 / Revised: 7 January 2009 / Accepted: 6 February 2009 / Published: 3 March 2009

Abstract

Peptic ulcers are a common disorder of the entire gastrointestinal tract that occurs mainly in the stomach and the proximal duodenum. This disease is multifactorial and its treatment faces great difficulties due to the limited effectiveness and severe side effects of the currently available drugs. The use of natural products for the prevention and treatment of different pathologies is continuously expanding throughout the world. This is particularly true with regards to flavonoids, which represent a highly diverse class of secondary metabolites with potentially beneficial human health effects that is widely distributed in the plant kingdom and currently consumed in large amounts in the diet. They display several pharmacological properties in the gastroprotective area, acting as anti-secretory, cytoprotective and antioxidant agents. Besides their action as gastroprotectives, flavonoids also act in healing of gastric ulcers and additionally these polyphenolic compounds can be new alternatives for suppression or modulation of peptic ulcers associated with H. pylori. In this review, we have summarized the literature on ninety-five flavonoids with varying degrees of antiulcerogenic activity, confirming that flavonoids have a therapeutic potential for the more effective treatment of peptic ulcers.
Keywords: Flavonoids; Gastroprotective activity; Peptic ulcers; Natural products Flavonoids; Gastroprotective activity; Peptic ulcers; Natural products

Introduction

Peptic ulcers are a common disorder of the entire gastrointestinal tract [1]. They occur mainly in the stomach and the proximal duodenum. They can also occur in the esophagus, jejunum and gastric anastamotic site [2]. A peptic ulcer results from an imbalance between some endogenous aggressive factor(s) [hydrochloric acid, pepsin, refluxed bile, leukotrienes, reactive oxygen species (ROS)] and cytoprotective factors, which include the function of the mucus-bicarbonate barrier, surface active phospholipids, prostaglandins (PGs), mucosal blood flow, cell renewal and migration, nonenzymatic and enzymatic antioxidants and some growth factors [3,4,5,6]. The pathogenesis of gastric ulcers remains widespread, it is multifactorial disease where diverse factors such as a stressful lifestyle, alcohol consumption, use of steroidal and nonsteroidal antiinflammatory drugs (NSAIDs) and drugs which stimulate gastric acid and pepsin secretion, Helicobacter pylori infections, smoking, lower socio-economic status and family history all represent significant risk factors that may contribute to increasing gastric damage [3]. The prevention or cure of peptic ulcers is one of the most important challenges confronting medicine nowadays, as it is certainly a major human illness affecting nearly 8 to 10 % of the global population [7], and of these 5% suffer from gastric ulcers [3]. The prevalence of this disease is higher in men than in women [8].
Although recent advances in our understanding have highlighted the multifactorial pathogenesis of peptic ulcers, secretion of gastric acid is still recognized as a central component of this disease, therefore the main therapeutic target is the control of this secretion using antacids, H2 receptor blockers like ranitidine, famotidine, anticholinergics like pirenzepin, telezipine or proton pump blockers like omeprazole, lansoprazole, etc. [9]. However, gastric ulcer therapy faces nowadays a major drawback because most of the drugs currently available in the market show limited efficacy against gastric diseases and are often associated with severe side effects [10,11].
In this context, the use of medicinal plants is in continuous expansion all over the world for the prevention and treatment of different pathologies, and natural products are recovering space and importance in the pharmaceutical industry as inspiring sources of new potentially bioactive molecules [12]. Clinical research has confirmed the efficacy of several plants for the treatment of gastroduodenal diseases [13,14]. The medicinal properties of many plants are attributed mainly to the presence of flavonoids, but they may be also influenced by other organic and inorganic compounds such as coumarins, alkaloids, terpenoids, tannins, phenolic acids and antioxidant micronutrients, e.g., Cu, Mn, Zn [15,16].
Flavonoids represent a highly diverse class of secondary metabolites comprising about 9,000 structures that have been identified to date. They constitute the largest and most important group of polyphenolic compounds in plants. These compounds are found in all vascular plants as well as in some mosses [17,18]. The term flavonoid is used to describe plant pigments, mostly derived from benzo-γ-pyrone, which is synonymous with chromone (rings A and C in Figure 1) [19,20].
Figure 1. Basic flavonoid structure.
Figure 1. Basic flavonoid structure.
Molecules 14 00979 g001
All flavonoids derive their 15-carbon skeletons (C6–C3–C6) from two basic metabolites, malonyl-CoA and p-coumaroyl-CoA. Their crucial biosynthetic reaction is the condensation of three molecules of malonyl-CoA with one molecule of p-coumaroyl-CoA to give a chalcone intermediate [21]. Chalcones act as the precursors for the vast range of flavonoid derivatives found throughout the plant kingdom. Most contain a six-membered heterocyclic ring, formed by Michael-type nucleophilic attack of a phenol group on to the unsaturated ketone giving a flavanone [22]. The first committed step of the flavonoid pathway is catalyzed by chalcone synthase (CHS; see Scheme 1). Chalcones can then be converted into aurones, a subclass of flavonoids found in certain plant species. Beyond CHS, the next step shared by most of the flavonoid biosynthesis pathways is catalyzed by chalcone isomerase (CHI), which catalyzes a stereospecific ring closure isomerization step to form the 2S-flavanones. The flavanones may represent the most important branching point in flavonoid metabolism, because isomerization of these compounds yields the others class of flavonoids [23]. However, the chemical synthesis is carried out mostly by cyclization and condensation of hydroxyacetophenone.
Taking into account the chemical nature of the molecule, and the positions of substituents on rings A, B, and C, the flavonoids are divided into 14 different groups [24]. Seven of these groups – the flavones, flavonols, flavanones, isoflavones, flavanols (catechins), flavanolols, and anthocyanidines – are particularly well known [24,25,26,27].
Flavonoids belong to the recently popular phytochemicals, chemicals derived from plant material with potentially beneficial effects on human health. The therapeutic effects of many traditional medicines may be related in many cases to the presence of these polyphenols [28]. For example, a wide variety of pharmacological activities have been reported for these substances, including antiviral [29], antiallergic [30], antiplatelet [31], antiestrogenic, anticancerogenic, anti-inflammatory, antiproliferative, antiangiogenic, and antioxidant properties, and their ingestion typically produces no or very little toxicity [24]. Flavonoids were also reported to act in the gastrointestinal tract, having antispasmodic [32], anti-secretory, antidiarrhoeal [33] and anti­ulcer properties [34]. Considering the important role of flavonoids in the prevention or reduction of gastric lesions induced by different ulcerogenic agents, this aim of this study was to review the literature on flavonoids with gastroprotective activity. The search was carried out on Pubmed, Schifinder School, Sciency Direct and NAPRALERT (Acronym for Natural Products ALERT) the data bank of The University of Illinois in Chicago, updated to December 2007, using “anti-ulcer flavonoids” as the search term. The references found in the search were later consulted for details on the models or mechanism based bioassays used for testing flavonoids against peptic ulcers.
Scheme 1. A schematic presentation of the flavonoid biosynthetic pathway showing the enzymatic steps leading to the major classes of end products. Enzymes are indicated with standard abbreviations.
Scheme 1. A schematic presentation of the flavonoid biosynthetic pathway showing the enzymatic steps leading to the major classes of end products. Enzymes are indicated with standard abbreviations.
Molecules 14 00979 g002
Abbreviations: ANR, anthocyanidin reductase; ANS, anthocyanidin synthase (also known as leucoanthocyanidin dioxygenase); CHI, chalcone isomerase; CHR, chalcone reductase; CHS, chalcone synthase; DFR, dihydroflavonol 4-reductase; FNSI and FNSII, flavone synthase I and II; IFR, isoflavone reductase; IFS, isoflavone synthase; LAR, leucoanthocyanidin reductase; GTs, glucosyl transferases [21].

Flavonoids studied in models that investigate anti-ulcer activity

In this literature review, it was possible to identify ninety-five flavonoids, whose gastroprotective activities cover a full range from inactive through weak activity to active and even strong activity. Of the flavonoids found in this study, forty-two were reportedly inactive; however, this inactivity could vary widely according to the experimental model, animal, route of administration and the dose. For example, flavonols like kaempferol, robinin and dactailin showed no gastroprotective effect in experimental models of reserpine [35,36] and restraint stress-induced ulcers in mouse [35], but kaempferol at doses of 50 and 100 mg/kg showed gastroprotective activity, and when the dose was increased to 250 mg/kg, it showed no activity [37]. Similar results were found for nobeletin, a flavone, where doses of 8 and 25 mg/kg protect the gastric mucosa of the rats from injuries induced by ethanol and HCl/ethanol, respectively, but it was only weakly active at a dose of 50 mg/kg in model of aspirin-induced ulcers [38]. Although many of the pharmacological and biochemical actions of flavonoids are attributed to their activities as antioxidants [39], this observed inactivity in high doses may be related to the capacity of flavonoids to act as pro-oxidants. Thus, flavonoids like quercetin, myricetin and kaempferol induce a concentration-dependent decrease of both the nuclear glutathione (GSH) content and glutathione S-transferase (GST) activity in a model system of isolated rat liver nuclei, which could lead to oxidative DNA damage [40], which in turn may be responsible for their mutagenicity and carcinogenicity; this effect may be explained by the pro-oxidant effects of this compounds [40, 41]. Nevertheless, the structural features that might determine the pro-oxidant activity of these compounds are not well established.
Chalcones belong to flavonoid class with the largest number of compounds with gastroprotective activity. In this review were found thirty-eight, among which we can mention sophoradin, an isoprenyl chalcone, which is present in a Chinese crude drug (the root of Sophora subprostrata) and protects the gastric mucosa from lesions induced by pylorus-ligation and water-immersion stress [42,43]. Thirty sophoradin analogs have shown anti-ulcer effects in the same ulcer induction models. Several chalcones, all having more than one isoprenyloxyl group, exhibited high inhibitory ratios. In particular, 2’,4’-dihydroxy-3’-(3-methyl-2-butenyl)-4-(3-methyl-2-butenyloxy) chalcone, 2’-hydroxy-4,4’-bis(3-methyl-2-butenyloxy) chalcone and 2’-carboxymethoxy-4,4’-bis(3-methyl-2-butenyloxy) chalcone (sofalcone), showed strong activity at a dose of 100 mg/kg, with a high percentage of inhibition of lesions (70-100%), when compared to other chalcones at the same dose and were as potent as sophoradin [42]. Sofalcone is one of these analogs that in addition to its gastroprotective effects also accelerates ulcer healing [44]. The mechanisms of action involved in gastric protection are increased gastric blood flow, stimulated synthesis of mucosubstances of the gastric mucosa [45] and increasing effects on gastric tissue PGs contents [46]. Besides its cytoprotective effects, sofalcone has a direct bactericidal effect on H. pylori, with a minimum inhibitory concentration of 55-222 µmol/L, anti-urease activity and it reduces the adhesion of this organism to gastric epithelial cells [47,48]. When outpatients with peptic ulcers and H. pylori infections were medicated for 7 d with sofalcone (100 mg thrice daily) plus the triple therapy with rabeprazole (10 mg twice daily), clarithromycin (200 mg twice daily) and amoxicillin (750 mg twice daily), sofalcone significantly increased the cure rate of H. pylori infections [49]. Therefore flavonoids can be utilized as alternative or additive agents to the current therapy in treatment of peptic ulcer induced by H. pylori infection.
Another flavonoid that appears to exert anti-ulcer activity is monomeric leucocyanidin, a natural flavonoid and the major component present in unripe plantain banana (Musa sapientum L. var. paradisiaca). It and its synthetic analogues hydroxyethylated leucocyanidin and tetrallylleucocyanidin showed protective effects against aspirin-induced gastric erosions in a prophylactic animal model, as shown by the absence of mucosal damage and a significant reduction in the ulcer index, when added to the diet at 5 mg and 15 mg per day [50,51]. The authors concluded that these compounds may be responsible for the displayed anti-ulcer properties and they suggested that the mechanism by which the active agent present in plantain banana and its synthetic analogues protects the mucosa is mediated, at least in part, by an increase in mucus thickness [51].
Another polyphenolic compound with relevant activities is garcinol, a polyisoprenylated benzophenone derivative from Garcinia indica, which shows potent free radical scavenging activity in three kinds of free radical generating systems. In the hypoxanthine/xanthine oxidase system, emulsified garcinol suppressed superoxide anion to almost the same extent as dl-α-tocopherol by weight and also suppressed hydroxyl radical more strongly than dl-α-tocopherol in the Fenton reaction system. In the H2O2/NaOH/DMSO system, this compound suppressed superoxide anion, hydroxyl radical, and methyl radical. Orally administered garcinol prevented acute ulceration in rats induced by indomethacin (40-200 mg/kg) and water immersion stress (200 mg/kg) caused by radical formation. These results suggested that garcinol might have potential as a free radical scavenger and clinical applications as an anti-ulcer drug. Although the mechanism of its anti-ulcer activity is not yet understood, garcinol may scavenge reactive oxygen species on the surface of gastric mucosa, thus protecting cells from injury [52].
A flavonoid that has been studied in some detail is rutin (quercetin-3-rhamnosylglucoside), a natural flavone derivative. It has been reported to prevent gastric mucosal ulceration in animal models including reserpine [35], acidified ethanol [37] and absolute and 50% ethanol [34,37]. The cytoprotective effect of this flavonoid does not appear to be mediated by endogenous prostaglandins [53], but its protective effects may be mediated by endogenous platelet-activating factor (PAF), since it inhibited dose-dependently the mucosal content of PAF [37]. Another possible mechanism involves the antioxidant properties of rutin, which at a dose of 200 mg/kg has a protective effect against lesions induced by 50 % ethanol, probably by reducing the levels of lipoperoxides and increasing the activity of the antioxidant enzyme glutathione peroxidase (GSH-Px). However, no significant modifications were observed in the gastric non-protein sulfhydryl (SH) content or in the ethanol-induced leukocyte infiltrate [34].
One of the most studied flavonoids is quercetin (3,3’,4’,5,7-pentahydroxyflavone). It protects the gastrointestinal mucosa from acute lesions induced by various experiemental models and against different necrotic agents, including restraint stress [37,54,55] pylorus-ligation [56], reserpine [35,36,55,57], aspirin [54], indomethacin [58], acid-ethanol [37] and ethanol-induced gastric ulcers [54,59,60]. Its gastroprotective action mechanism involves endogenous PAF [37], an increase in mucus production [58], antihistaminic properties, which decrease histamine levels and reduction of the number of ethanol-induced mast cells. It also inhibits H. pylori growth, the formation of acid by parietal cells in response to stimulation by histamine and dibutyryl cyclic AMP, as well as the gastric H+/K+ proton pump (data not shown in Table 1) [61]. The main mechanism of action for the gastroprotective effects of this flavonol are its antioxidant properties, since oral pretreatment with quercetin (200 mg/kg) had protective effects in that it significantly reduced the severity of ethanol-induced ulcers by inhibition of lipid peroxidation, enhancement in the levels of mucosal non-protein SH compounds (important antioxidant agents) [59,60] in GSH-Px [59] and superoxide dismutase activities, as well as reduction of protein carbonyl compounds [60]. At a dose of 100 mg/kg twice daily for 5 days it also decreases lipid peroxidation and plasmatic corticosterone in a restraint stress model. This flavonoid, in addition to protecting the gastric mucosa in acute models of ulcer induction, when administered chronically both quercetin and naringenin also promote healing of gastric ulcers induced by acetic acid, a chronic model of ulcer [62]. The antioxidant mechanism of action of flavonoids, especially garcinol, rutin and quercetin, is due mainly the presence in their structures of an o-dihydroxy in the B ring (catechol), and additionally a 2,3 double bond in conjugation with a 4-oxo function, as well as the presence of hydroxyl groups in positions 3, 5 and 7 [24,63,64]
Finally, nowadays it is known that NSAIDs, such as piroxicam or aspirin have several adverse effects on the gastrointestinal tract and increase the risk of myocardial infarction. However, several flavonoids have demonstrated anti-inflammatory properties, without showing any ulcerogenic action as a side effect, and thus showing a great advantage in the treatment of peptic ulcers.
Table 1. Flavonoids with gastroprotective activity.
Table 1. Flavonoids with gastroprotective activity.
SubstanceExperimental assay/Administration routeAnimal testedDoseActivity
Chalcones
Butein
Molecules 14 00979 i001
HCl/ethanol-induced ulcers/intragastricRat10 mg/kg Active [65]
NaOH-induced ulcers/intragastricRat50.0 mg/kg Inactive [65]
2',3,4,4',6'-pentahydroxychalcone
Molecules 14 00979 i002
HCl/ethanol-induced ulcers/intragastricRat 10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastricRat 10.0 mg/kg Active [65]
2',3,4-trihydroxychalcone
Molecules 14 00979 i003
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
2',4',6'-trihydroxychalcone
Molecules 14 00979 i004
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastricRat 10.0 mg/kg Active [65]
2',4'-dihydroxy-3',5'-diprenyl-4-O-prenyl- chalcone
Molecules 14 00979 i005
Stress-induced ulcers (water-immersion)/i.p.Rat 100.0 mg/kg Active [42]
2',4'-dihydroxy-3'-methoxychalcone
Molecules 14 00979 i006
Ethanol-induced ulcers/intragastricMouse * Weak Active [66]
Ethanol-induced ulcers/intragastricRat 100.0 mg/kg Active [67]
Ethanol-induced ulcers/intragastricRat * Active [66]
2',4'-dihydroxy-5'-prenyl-4-O-prenyl- chalcone
Molecules 14 00979 i007
Pylorus ligation-induced ulcers/i.p.Rat 100.0 mg/kg Active [42]
Stress-induced ulcers (water-immersion)/i.p.Rat 100.0 mg/kg Active [42]
2',4'-dihydroxychalcone
Molecules 14 00979 i008
Stress-induced ulcers (water-immersion)/intragastric Rat10.0 mg/kg Active [65]
Acetic acid-induced ulcers/intragastric Rat10.0 mg/kg Active [65]
HCl/ethanol-induced ulcers/intragastric Rat10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastric
Ethanol-induced ulcers/intragastric Rat10.0 mg/kg Active [65]
Ethanol-induced ulcers/intragastric Mouse* Active [66]
Ethanol-induced ulcers/intragastric Rat100 mg/kgActive [67]
Rat* Active [66]
2',4,4',6'-tetrahydroxychalcone
Molecules 14 00979 i009
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Inactive [65]
NaOH-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
2',4,4'-trihydroxy-3,3',5'-tris-(3-methyl-but-2-enyl) chalcone
Molecules 14 00979 i010
*/* Rat * Active [68]
2',4,4'-trihydroxy-3,3',5,5'-tetrakis-(3-methyl-but-2-enyl)-4,4'-bis-(O-3-methyl-but-2-enyl) chalcone
Molecules 14 00979 i011
*/* Rat * Active [69]
2',4,4'-trihydroxy-3,3',5,5'-tetrakis-3-methyl-but-2-enyl) chalcone
Molecules 14 00979 i012
*/* Rat * Active [68]
2',4,4'-trihydroxy-3,3',5-tris-(3-methyl-but-2-enyl)-4-4'-di-O-allyl chalcone
Molecules 14 00979 i013
*/* Rat * Active [69]
2',4,4'-trihydroxy-3,3'-bis-(3-methylbut-2-enyl) chalcone
Molecules 14 00979 i014
*/* Rat * Active [68]
2',4,4'-trihydroxy-3,3'-diprenylchalcone
Molecules 14 00979 i015
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kg Active [42]
2',4,4'-trihydroxy-3,5,5'-tris-(3-methyl-but-2-enyl)-4'-O-(3-methylbut-2-enyl) chalcone
Molecules 14 00979 i016
*/* Rat * Active [69]
2',4,4'-trihydroxychalcone
Molecules 14 00979 i017
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
2',4-dihydroxy-3-prenyl-4'-O-prenyl- chalcone
Molecules 14 00979 i018
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kg Active [42]
2',4-dihydroxy-4'-methoxy-3-5-bis-(3-methyl-but-2-enyl) chalcone
Molecules 14 00979 i019
*/* Rat * Active [42]
2'-carbomethoxy-4,4'-bis-(3-methyl-2-butenyl-oxy) chalcone (sofalcone)
Molecules 14 00979 i020
Histamine-induced ulcers/i.p. Rat 100.0 mg/kg Active [45]
Acetic acid-induced ulcers/gastric intubation Rat 20-50 mg/kg Active [45]
Histamine-induced ulcers/gastric intubation Guinea pig 100.0 mg/kg Active [45]
Pylorus ligation-induced ulcers/i.p. Rat 50.0 mg/kg Active [45]
Stress-induced ulcers (water-immersion)/i.p. Rat 50.0 mg/kg Active [45]
Phenylbutazone-induced ulcers/gastric ntubation Rat 300.0 mg/kg Active [45]
Acetic acid-induced ulcers/gastric intubationRat 50.0 mg/kg Active [44]
HCl induced gastric lesions/i.p. Rat 100.0 mg/kg Active [46]
HCl induced gastric lesions/gastric intubation Rat 100.0 mg/kg Active [46]
Pretreatment with indomethacin vs HCl induced gastric lesions/gastric intubation Rat 300.0 mg/kg Active [46]
Pretreatment with indomethacin vs HCl induced gastric lesions/i.p. Rat 100.0 mg/kg Active [46]
H. pylori induced ulcer/p.o.Human adult 100.0 mg/kg Active [49]
2'-hydroxy-4,4'-di-O-prenylchalcone
Molecules 14 00979 i021
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kg Strong activity [42]
Stress-induced ulcers (water-immersion)/i.p.Rat 100.0 mg/kg Strong activity [42]
2,4'-di-O-prenylchalcone
Molecules 14 00979 i022
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kg Active [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kg Weak activity [42]
2,4,4'-trihydroxy-3,3',5'-tris-(3-methyl-but-2-enyl)-4-O-allyl-4-O-propargyl-chalcone
Molecules 14 00979 i023
*/* Rat * Active [69]
3',5'-dihydroxy-4'-prenyl-5-O-prenyl- chalcone
Molecules 14 00979 i024
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kg Strong activity [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kg Strong activity [42]
3,3',4-trihydroxychalcone
Molecules 14 00979 i025
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
NaOH-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
3,4,4'-trihydroxychalcone
Molecules 14 00979 i026
HCl/ethanol-induced ulcers/intragastric Rat 10.0 mg/kg Inactive [65]
NaOH-induced ulcers/intragastric Rat 10.0 mg/kg Active [65]
4'-hydroxy-3'-prenyl-4-O-prenylchalcone
Molecules 14 00979 i027
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kg Active [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kg Strong activity [42]
4,4'-di-O-geranyl chalcone
Molecules 14 00979 i028
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kg Weak activity [42]
Stress-induced ulcers (water-immersion)/i.p.Rat 100.0 mg/kg Weak activity [42]
4,4'-di-O-prenylchalcone
Molecules 14 00979 i029
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kgActive [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgStrong activity [42]
4,4'-dihydroxy-3,3'-diprenylchalcone
Molecules 14 00979 i030
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgActive [42]
4,4'-dimethoxy-3,3'-diprenylchalcone
Molecules 14 00979 i031
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kgWeak activity [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgActive [42]
4-hydroxy-3-prenyl-4'-O-prenylchalcone
Molecules 14 00979 i032
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kgActive [42]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgWeak activity [42]
2',4-bis-(carbomethoxy)-4'-(3-carboxy-2-butenyl-oxy) dihydrochalcone
Molecules 14 00979 i033
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kgWeak activity [70]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgWeak activity [70]
Histamine-induced ulcers/i.p. Rat 100.0 mg/kgWeak activity [70]
2',4-bis-(carboxymethoxy)-4'-(3-methyl-2-butenyl-oxy) dihydrochalcone
Molecules 14 00979 i034
Pylorus ligation-induced ulcers/i.p. Rat 100.0 mg/kgActive [70]
Stress-induced ulcers (water-immersion)/i.p. Rat 100.0 mg/kgWeak activity [70]
Histamine-induced ulcers/i.p. Rat 100.0 mg/kgActive [70]
2'-carboxymethoxy-4-4'-bis-(3-methyl-2-butenyl-oxy) dihydro-chalcone
Molecules 14 00979 i035
Pylorus ligation-induced ulcers/i.p.Rat 100.0 mg/kg Active [70]
Stress-induced ulcers (water-immersion)/i.p.Rat 100.0 mg/kg Active [70]
Histamine-induced ulcers/i.p.Rat 100.0 mg/kg Active [70]
Garcinol
Molecules 14 00979 i036
Stress-induced (restraint) ulcers/intragastricRat 200.0 mg/kgActive [52]
Indomethacin-induced ulcers/intragastricRat 200.0 mg/kgActive [52]
Sophoradin
Molecules 14 00979 i037
Pylorus ligation-induced ulcers/p.o.Rat * Active [43]
Stress-induced ulcers/p.o.Rat * Active [43]
Pylorus ligation-induced ulcers/p.o.Rat 100.0 mg/kg Strong activity [42]
Stress-induced ulcers/p.o.Rat 100.0 mg/kg Strong activity [42]
Xanthoangelol E
Molecules 14 00979 i038
Stress-induced (restraint) ulcers/intragastricRat 100.0 mg/kg Active [71]
Flavanones
3',4',5,7-tetrahydroxy-3-methoxy- flavanone
Molecules 14 00979 i039
stress-induced (restraint) ulcers/* Rat * Active [72]
2',4',7-trihydroxy-5-methoxy-8-(5-hydroxy-5-methyl-2-iso-propenyl-hexyl) flavanone
Molecules 14 00979 i040
*/p.o. Human adult * Active [73]
Hesperidin
Molecules 14 00979 i041
Cold stress-induced ulcers/intragastric Rat100.0 mg/kg Active [74]
Ethanol-induced ulcers/intragastric Rat100.0 mg/kg Inactive [74]
Naringenin
Molecules 14 00979 i042
Acetic acid-induced ulcers/intragastric Rat100.0 mg/kg Active [62]
Stress-induced ulcers (water-immersion)/intragastric Rat100.0 mg/kg Weak active [56]
Pylorus ligation-induced ulcers/intragastric Rat100.0 mg/kg Active [56]
Pylorus ligation-induced ulcers /intragastric Rat100.0 mg/kg Active [56]
Pylorus ligation-induced ulcers/gastric intubation RatED50 132 mg/kg Active [75]
Stress-induced (restraint) ulcers/gastric intubation RatED50 42.0 mg/kg Active [75]
Aspirin-induced ulcers/gastric intubation Rat* Active [75]
Phenylbutazone-induced ulcers/gastric intubation Rat* Active [75]
Reserpine-induced ulcers/gastric intubationRat* Active [75]
Naringin
Molecules 14 00979 i043
Aspirin-induced ulcers/intragastricRat 200.0 mg/kg Active [76]
Acid-ethanol-induced ulcers/i.p.Rat 100.0 mg/kg Inactive [37]
Acid-ethanol-induced ulcers/i.p. Rat 200.0 mg/kg Active [37]
Acid-ethanol-induced ulcers/i.p.Rat 400.0 mg/kg Active [37]
Ethanol-induced gastric injury/intragastric Rat 400.0 mg/kg Active [37]
Sigmoidin A
Molecules 14 00979 i044
Stress-induced ulcers (water-immersion)/gastric intubationRat 50.0 mg/kg Active [78]
Stress-induced (restraint) ulcers/gastric intubation Rat 50.0 mg/kg Active [78]
Sigmoidin B
Molecules 14 00979 i045
Stress-induced ulcers (water-immersion)/gastric intubationRat 50.0 mg/kg Active [78]
Stress-induced (restraint) ulcers/gastric intubation Rat 50.0 mg/kgActive [78]
Sophoranone
Molecules 14 00979 i046
Pylorus ligation-induced ulcers/p.o.Rat * Active [43]
Stress-induced ulcers/p.o.Rat * Active [43]
Flavane and Flavanols
(+) catechin
Molecules 14 00979 i047
HCl/ethanol-induced stomach ulcers/intragastric Rat * Inactive [79]
*/pathway oral (p.o.) Rat 100.0 mg/kg Active [80]
Reserpine-induced ulcers/gastric intubationMouse 49.7 mg/kg Equivocal [57]
Reserpine-induced ulcers/gastric intubationMouse 72.5 mg/kg Inactive [57]
Stress-induced ulcers (water-immersion)/gastric intubationMouse 500.0 mg/kg Weak Active [81]
(dl) catechin
Molecules 14 00979 i048
Stress-induced (restraint) ulcers/subcutaneous (s.c.)Mouse300.0 mg/kg Active [82]
Stress-induced (restraint) ulcers/intragastricMouse300.0 mg/kg Active [82]
Stress-induced ulcers (water-immersion)/s.c.Mouse300.0 μmol/kgActive [82]
Stress-induced ulcers (water-immersion)/intragastricMouse300.0 mg/kg Active [82]
3-O-methyl: (+) catechin
Molecules 14 00979 i049
Pylorus ligation-induced ulcers/s.c.RatED50 60.0 mg/kg Active [83]
Stress-induced (restraint) ulcers/s.c.RatED50 13.2 mg/kg Active [83]
*/s.c.Rat*Active [83]
Phenylbutazone-induced ulcers/s.c.Rat*Active [83]
Reserpine-induced ulcers/s.c.Rat*Active [83]
*/***Active [84]
(-) Epicatechin
Molecules 14 00979 i050
Stress-induced ulcers (water-immersion)/gastric intubationMouse500.0 mg/kg Weak Active [81]
(+) Cyanidan-3-beta- ol
Molecules 14 00979 i051
Pylorus ligation-induced ulcers/s.c. RatED50 62 mg/kg Active [85]
Restraint-induced ulcers/s.c. RatED50 18 mg/kg Active [85]
Aspirin-induced ulcers/gastric intubation Rat100.0 mg/kg Active [85]
Phenylbutazone-induced ulcers/gastric intubation Rat100.0 mg/kg Active [85]
Ibuprofen-induced ulcers/gastric intubation Rat100.0 mg/kg Active [85]
Reserpine-induced ulcers/gastric intubationRat100.0 mg/kg Active [85]
Leucocyanidin
Molecules 14 00979 i052
Aspirin-induced ulcers/*Rat 5.0 mg/dayActive [50]
*/intragastricRat * Active [51]
Flavanolols
Taxifolin
Molecules 14 00979 i053
Ethanol induced gastric ulcers/intragastric Rat 50.0 mg/kg Active [86]
Taxifolin,(dl)
Molecules 14 00979 i054
HCl /ethanol-induced stomach ulcers/intragastric Rat * mg/kg Inactive [79]
Anthocyanidines
Benzopyrylium chloride,1: 3,5,7- trihydroxy-2-(3-4-dihydroxyphenyl)
Molecules 14 00979 i055
Pylorus ligation-induced ulcers/intragastricRat 12.5 mg/kg Active [87]
Stress-induced (restraint) ulcers/intragastricRat 100.0 mg/kg Active [87]
Phenylbutazone-induced ulcers/intragastricRat 22.0 mg/kg Active [87]
Indomethacin-induced ulcers/intragastricRat 100.0 mg/kg Active [87]
Reserpine-induced ulcers/intragastricRat 100.0 mg/kg Active [87]
Ethanol induced lesion/intragastricRat 200.0 mg/kg Active [87]
Histamine-induced ulcers/intragastricRat 24.0 mg/kg Active [87]
Cysteamine-induced ulcers/intragastricRat 200.0 mg/kgActive [87]
Cysteamine-induced ulcers/intraperitoneal (i.p.)Rat 50.0 mg/kg Active [87]
Acetic acid-induced ulcers/intragastricRat 50.0 mg/kg Active [87]
Flavones
Acacetin
Molecules 14 00979 i056
Reserpine-induced ulcers/gastric intubation Mouse 0.05 mL/g Inactive [36]
Apigenin
Molecules 14 00979 i057
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Cynaroside
Molecules 14 00979 i058
*/intragastric Rat ** [88]
Dactylin
Molecules 14 00979 i059
Reserpine-induced ulcers/gastric intubationMouse*Inactive [35]
Stress-induced (restraint) ulcers/gastric intubation Mouse*Inactive [35]
Eupatilin
Molecules 14 00979 i060
*/ Intragastric Rat *Active [89]
Gnaphaloside A
Molecules 14 00979 i061
Reserpine-induced ulcers/gastric intubation Mouse 0.05 mL/g Active [36]
Gossypin
Molecules 14 00979 i062
*/oral Rat 100.0 mg/kg Active [80]
Hyperoside
Molecules 14 00979 i063
Reserpine-induced ulcers/gastric intubation Mouse* Weak activity [35]
Stress-induced (restraint) ulcers/gastric intubation Mouse* Weak activity [35]
Hypolaetin-8-O-beta-d-glucoside
Molecules 14 00979 i064
Cold stress-induced ulcers/i.p. RatED50 573mg/kg Active [90]
Cold stress-induced ulcers/* *ED50 57.3mg/kg Active [91]
Ethanol-induced gastric lesions/s.c. Rat ED50 68.0mg/kg Active [92]
Kaempferol rhamnoside
Molecules 14 00979 i065
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Active [36]
Linarin
Molecules 14 00979 i066
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Luteolin
Molecules 14 00979 i067
*/intragastric Rat* Active [88]
Reserpine-induced ulcers/gastric intubation Mouse 47.4 mg/kg Active [57]
Reserpine-induced ulcers/gastric intubationMouse474 mg/kg Active [57]
Myricetin rhamnoside
Molecules 14 00979 i068
Reserpine-induced ulcers/gastric intubation Mouse 0.05 mL/g Active [36]
Nobiletin
Molecules 14 00979 i069
Ethanol-induced gastric ulcer/intragastric Rat ED50 8.0 mg/kg Active [38]
Ethanol-induced ulcers/intragastricRat ED50 8.0 mg/kg Active [93]
Aspirin-induced ulcers/intragastricRat 50.0 mg/kg Weak active [93]
HCl/ethanol-induced gastric ulcers/intragastricRat 25.0 mg/kg Active [97]
Pectolinarigenin
Molecules 14 00979 i070
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Pectolinarin
Molecules 14 00979 i071
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Acetyl pectolinarin
Molecules 14 00979 i072
Reserpine-iduced ulcers/gastric itubation Mouse0.05 mL/g Inactive [36]
Quercetin rhamnoside
Molecules 14 00979 i073
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Active [36]
Quercitrin
Molecules 14 00979 i074
Reserpine-induced ulcers/gastric intubation Mouse50.0 mg/g Active [57]
Robinin
Molecules 14 00979 i075
Reserpine-induced ulcers/gastric intubationMouse*Inactive [36]
Stress-induced (restraint) ulcers/gastric intubationMouse*Inactive [36]
Rutin
Molecules 14 00979 i076
Acid-ethanol-induced ulcers/i.p.Mouse 12.5 mg/kg Inactive [37]
Acid-ethanol-induced ulcers/i.p.Rat 25.0 mg/kg Active [37]
Acid-ethanol-induced ulcers/i.p.Rat 50.0 mg/kg Active [37]
Pretreatment with indomethalin vs ethanol induced-ulcers/intragastricRat 25.0 mg/kg Weak activity [53]
Ethanol-induced ulcers/intragastricRat 50.0 mg/kg Active [53]
Ethanol-induced ulcers/ intragastricRat 200.0 mg/kgActive [34]
*/intragastricMouse 7.0 mg/kg Active [95]
*/intragastricMouse *Active [96]
Reserpine-induced ulcers/gastric intubationMouse * Weak activity [35]
Stress-induced (restraint) ulcers/gastric intubation Mouse * Weak activity [35]
Salvigenin
Molecules 14 00979 i077
Pylorus ligation-induced ulcers/i.p. Rat100.0 mg/kg Inactive [97]
Scoparin
Molecules 14 00979 i078
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Ternatin
Molecules 14 00979 i079
Cold stress-induced ulcers/i.p. Rat 25.0 mg/kg Inactive [98]
Ethanol-induced ulcers/i.p. Rat25.0 mg/kg Inactive [98]
Indomethacin-induced ulcers/i.p. Rat25.0 mg/kg Inactive [98]
Vexibinol
Molecules 14 00979 i080
HCl-ethanol induced ulcers/intragastric Rat10.0 mg/kg Active [99]
Stress-induced ulcers (water-immersion)/intragastric Rat10.0 mg/kg Active [99]
Pylorus ligation-induced ulcers/intragastricRat100.0 mg/kg Active [99]
Indomethacin-induced ulcers/intragastric Rat100.0 mg/kg Active [99]
Histamine-induced ulcers/intragastricRat100.0 mg/kg Inactive [99]
5-Ht-induced ulcers/intragastricRat300.0 mg/kg Inactive [99]
Phenylbutazone induced ulcers/intragastricRat300.0 mg/kg Active [99]
Isoflavones
Genistin
Molecules 14 00979 i081
*/intragastric Rat* Active [88]
Flavonols
Kaempferol
Molecules 14 00979 i082
Acid-ethanol-induced ulcers/i.p.Rat 250.0 mg/kg Inactive [37]
Acid-ethanol-induced ulcers/i.p.Rat 50.0 mg/kg Active [37]
Acid-ethanol-induced ulcers/i.p.Rat 100.0 mg/kg Active [37]
Ethanol-induced ulcers/i.p.Rat 100.0 mg/kg Active [100]
Cold stress-induced ulcers/i.p.Rat 200.0 mg/kg Active [100]
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Pylorus ligation-induced ulcers/i.p. Rat 200.0 mg/kg Active [101]
Stress-induced (restraint) ulcers/i.p.Rat 200.0 mg/kg Active [101]
Reserpine-induced ulcers/gastric intubation Mouse* Inactive [35]
Stress-induced (restraint) ulcers/gastricMouse* Inactive [35]
Myricetin
Molecules 14 00979 i083
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Active [36]
Reserpine-induced ulcers/gastric intubation Mouse* Active [55]
Stress-induced (restraint) ulcers/gastric intubation Mouse* Active [55]
Reserpine-induced ulcers/gastric intubation Mouse* Active [35]
Stress-induced (restraint) ulcers/gastric intubationMouse* Active [35]
Patuletin
Molecules 14 00979 i084
Reserpine-induced ulcers/gastric intubationMouse0.05 mL/g Inactive [36]
Patulitrin
Molecules 14 00979 i085
Reserpine-induced ulcers/gastric intubationMouse0.05 mL/g Weak active [36]
Phellavin
Molecules 14 00979 i086
Reserpine-induced ulcers/gastric intubation Mouse0.05 mL/g Inactive [36]
Quercetin
Molecules 14 00979 i087
Ethanol-induced gastric lesions/intragastric Rat 200.0 mg/kg Active [59]
Acetic acid-induced ulcers/intragastricRat 100.0 mg/kg Active [62]
Stress-induced ulcers (water-immersion)/intragastricRat 100.0 mg/kg Active [56]
Pylorus ligation-induced ulcers/intragastricRat 100.0 mg/kg Active [56]
Pylorus ligation-induced ulcers/intragastricRat 100.0 mg/kg Active [56]
*/intragastricRat 200.0 mg/kg Active [58]
Acid-ethanol-induced ulcers/i.p.Rat 12.5 mg/kg Inactive [37]
Acid-ethanol-induced ulcers/i.p.Rat 25.0 mg/kg Active [37]
Acid-ethanol-induced ulcers/i.p.Rat 50.0 mg/kg Active [37]
Ethanol-induced gastric ulcers/i.p. Rat 12.5 mg/kg Active [104]
*/ intragastricMouse* Active [96]
Ethanol-induced ulcers/intragastricRat 100.0 mg/kg Active [54]
Stress-induced (restraint) ulcers/intragastricRat 100.0 mg/kg Active [54]
Ethanol-induced ulcers/intragastricRat 200.0 mg/kg Active [60]
Reserpine-induced ulcers/gastric intubationMouse 0.05 mL/gm Inactive [36]
Reserpine-induced ulcers/gastric intubationMouse 50.0 mg/kg * [57]
Reserpine-induced ulcers/gastric intubationMouse *Active [55]
Stress-induced (restraint) ulcers/gastricMouse *Active [55]
Reserpine-induced ulcers/gastric intubationMouse *Active [35]
Stress-induced (restraint) ulcers/gastric intubationMouse *Active [35]
Quercetin-3'-o-beta-d-glucoside
Molecules 14 00979 i088
Reserpine-induced ulcers/gastric intubation Mouse 0.05 mL/g Inactive [36]
Biflavonoids
Cinnamtannin B-1
Molecules 14 00979 i089
Stress-induced ulcers (water-immersion)/gastric intubation Mouse500.0 mg/kg Inactive [81]
Cinnamtannin D-1
Molecules 14 00979 i090
Stress-induced ulcers (water-immersion)/gastric intubation Mouse 500.0 mg/kg Inactive [81]
Procyanidin B-1
Molecules 14 00979 i091
Stress-induced ulcers (water-immersion)/gastric intubation Mouse500.0 mg/kg Weak activity [81]
Procyanidin B-2
Molecules 14 00979 i092
Stress-induced ulcers (water-immersion)/gastric intubation Mouse200.0 mg/kg Active [81]
Procyanidin B-3
Molecules 14 00979 i093
HCl/ethanol-induced stomach ulcers/intragastric Rat 200.0 mg/kg Inactive [79]
Procyanidin B-4
Molecules 14 00979 i094
Stress-induced ulcers (water-immersion)/gastric intubation Mouse500.0 mg/kg Active [81]
* Dates weren’t provided

Conclusions

Flavonoids represent a highly diverse class of secondary metabolites with potentially beneficial effects on human health. These compounds protect the gastrointestinal mucosa from lesions produced by various experimental ulcer models and against different necrotic agents. Several mechanisms of action may be involved in this protective effect. Quercetin has an anti-secretory mechanism of action. This flavonol has antihistaminic properties, thus, decreases histamine levels, as well as preventing the release of histamine from gastric mast cells and inhibiting the gastric H+/K+ proton pump, diminishing acid gastric secretion. On the other hand chalcones, in particular those with more than one isoprenyloxyl group, possess cytoprotective effects, which increase the mucosal blood flow, stimulate the synthesis of mucosubstances in the gastric mucosa and increase PGs levels. However, the most important mechanism of action responsible for the anti-ulcer activity of flavonoids is their antioxidant properties, seen in garcinol, rutin and quercetin, which involves free radical scavenging, transition metal ions chelation, inhibition of oxidizing enzymes, increase of proteic and nonproteic antioxidants and reduction of lipid peroxidation. These effects are correlated with presence in the structures of an o-dihydroxy in the ring B (catechol), and additionally a 2,3 double bond in conjugation with a 4-oxo function, as well as the presence hydroxyl groups in positions 3, 5 and 7. Besides the gastroprotective activity, sofalcone (a chalcone), quercetin and naringenin (flavanones) accelerate the healing of gastric ulcers. In addition, the two first polyphenolic compounds have anti-H. pylori activity and may be utilized as an alternative or additive agent to the current therapy. Therefore flavonoids could have an ideal more effective and less toxic therapeutic potential for the treatment of gastrointestinal diseases, particularly for peptic ulcers.

Acknowledgements

The authors would like to express their sincere thanks to Ms. Gabriela G. Barbosa for the revision of the English grammar and to College of Pharmacy, the University of Illinois at Chicago, U.S.A., for helping with the computer in the database NAPRALERT.

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