Anti-ulcer effect of the hot water extract of black tea (Camellia sinensis)

Gastroprotective Effect of Microencapsulated Myrtus communis Essential Oil against Ethanol/HCl-Induced Acute Gastric Lesions

Myrtus communis L. essential oil (EO), mainly composed of myrtenyl acetate (30.6%), linalool (14.9%), α-pinene (11.10%) and 1,8-cineole or eucalyptol (9.9%), was microencapsulated with maltodextrin by emulsification and spray-drying, reaching a yield and efficiency of 43.7 and 48.7%, respectively. The microencapsulated myrtle EO (MMEO) was then evaluated regarding its gastroprotective activity in a model of ethanol/HCl-induced acute gastric ulcer in Wistar rats. Pretreatment with MMEO induced a remarkable inhibition of gastric lesions and acidity, correlated to high healing and protection percentages. Moreover, it exerted a potent anti-inflammatory effect on the gastric mucosa, counteracting EtOH-induced gastric lipoperoxidation and preventing the depletion of the antioxidant enzyme activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Taken together, the gastroprotective action of encapsulated MMEO may be multi-factorial, and ascribable, at least in parts, to its anti-inflammatory and antioxidant properties.

Potential Antiulcer Agents From Plants: A Comprehensive Review

Background:

Peptic ulcer is a deep gastrointestinal erosion disorder that involves the entire mucosal thickness and can even penetrate the muscular mucosa. Nowadays, several plants and compounds derived from it have been screened for their antiulcer activity. In the last few years, there has been an exponential growth in the field of herbal medicine. This field has gained popularity in both developing and developed countries because of their natural origin and less side effects.

Objective:

This review aims to provide a comprehensive summary of currently available knowledge of medicinal plants and phytoconstituents reported for their anti-ulcer properties.

Methods:

The worldwide accepted database like SCOPUS, PUBMED, SCIELO, NISCAIR, ScienceDirect, Springerlink, Web of Science, Wiley, SciFinder and Google Scholar were used to retrieve available published literature.

Results:

A comprehensive review of the present paper is an attempt to list the plants with antiulcer activity. The review narrates the dire need to explore potential chemical moieties that exert an antiulcer effect, from unexploited traditional plants. Furthermore, the present study reveals the intense requirement to exploit the exact mechanism through which either the plant extracts or their active constituents exhibit their antiulcer properties.

Conclusion:

This article is the compilation of the plants and its constituents reported for the treatment of peptic ulcers. The Comprehensive data will surely attract the number of investigators to initiate further research that might lead to the drugs for the treatment of ulcers. As sufficient scientific data is not available on plants, most of the herbals cannot be recommended for the treatment of diseases. This can be achieved by research on pure chemical structures derived from plants or to prepare new lead compounds with proven beneficial preclinical in vitro and in vivo effects. However, a lot remains to be done in further investigations for the better status of medicinal plants.

The role of tea and coffee in the development of gastroesophageal reflux disease

Objective

The incidence of gastroesophageal reflux disease (GERD) is increasing, and the disease has a close association with dietary habits. This study aims to investigate the role of tea and coffee drinking in the development of GERD.

Materials and Methods

This study prospectively enrolled individuals who underwent an upper gastrointestinal endoscopy during a health checkup. Each participant completed the reflux disease questionnaire (RDQ). Coffee or tea drinking was defined as drinking the beverage at least 4 days/week for 3 months. Heavy coffee or tea consumption was defined as drinking at least two cups every day.

Results

A total of 1837 participants (970 men; age 51.57 ± 10.21 years), who had data on clinical characteristics and consumption of coffee and tea with or without additives such as milk or sugar were included for final analysis. Among them, 467 (25.4%) were diagnosed as having symptomatic GERD based on the RDQ score, and 427 (23.2%) had erosive esophagitis (EE) on endoscopy. Drinking coffee or tea was not associated with reflux symptoms or EE in univariate and multivariate analyses. In contrast, drinking coffee with milk was associated with reflux symptoms and drinking "tea and coffee" was associated with EE in univariate analysis. However, these associations became insignificant after multivariate analysis.

Conclusion

Drinking coffee or tea and adding milk or sugar was not associated with reflux symptoms or EE.

Gastroprotective effect of carob (Ceratonia siliqua L.) against ethanol-induced oxidative stress in rat

BACKGROUND

We aimed in the present study, at investigating the gastroprotective effect of carob pods aqueous extract (CPAE) against ethanol-induced oxidative stress in rats as well as the mechanism implicated.

METHODS

Adult male wistar rats were used and divided into six groups of ten each: control, EtOH (80% v/v, 4 g/kg b.w.), EtOH 80% + various doses of CPAE (500, 1000 and 2000 mg/kg, b.w.) and EtOH + Famotidine (10 mg/kg, p.o.) Animals were perorally (p.o.) pre-treated with CPAE during 15 days and intoxicated with a single oral administration of EtOH (4 g/kg b.w.) for two hours.

RESULTS

The colorimetric analysis demonstrated that the CPAE exhibited an importance in vitro antioxidant activity against ABTS and DPPH radicals. We found that CPAE pretreatment in vivo, protected against EtOH-induced macroscopic and histological changes induced in stomach mucosa. Carob extract administration also protected against alcohol-induced volume gastric juice decrease. More importantly, We showed that CPAE counteracted EtOH-induced gastric lipoperoxidation, reversed the decrease of sulfhydryl groups (-SH) an hydrogen peroxide (H2O2) levels, and prevented the depletion of antioxidant enzyme activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx).

CONCLUSIONS

These findings suggest that CPAE exerted a potential gastro-protective effect against EtOH-induced oxidative stress in rats, due in part, to its antioxidants properties.

Efficient extraction strategies of tea (Camellia sinensis) biomolecules

Tea is a popular daily beverage worldwide. Modulation and modifications of its basic components like catechins, alkaloids, proteins and carbohydrate during fermentation or extraction process changes organoleptic, gustatory and medicinal properties of tea. Through these processes increase or decrease in yield of desired components are evident. Considering the varied impacts of parameters in tea production, storage and processes that affect the yield, extraction of tea biomolecules at optimized condition is thought to be challenging. Implementation of technological advancements in green chemistry approaches can minimize the deviation retaining maximum qualitative properties in environment friendly way. Existed extraction processes with optimization parameters of tea have been discussed in this paper including its prospects and limitations. This exhaustive review of various extraction parameters, decaffeination process of tea and large scale cost effective isolation of tea components with aid of modern technology can assist people to choose extraction condition of tea according to necessity.

Antioxidant-mediated preventative effect of Dragon-pearl tea crude polyphenol extract on reserpine-induced gastric ulcers

Dragon-pearl tea is a type of green tea commonly consumed in Southwest China. In the present study, the antioxidative and anti-gastric ulcer effects of Dragon-pearl tea crude polyphenols (DTCP) were determined in vitro and in vivo. Treatment with 25, 50 or 100 µg/ml DTCP resulted in notable antioxidant effects in vitro, which manifested as 2,2-diphenyl-1-picrylhydrazyl and OH radical-scavenging activity. Furthermore, using an in vivo mouse model, DTCP was shown to reduce the gastric ulcer area in the stomach, in which the 200 mg/kg DTCP dose exhibited the most marked effect, with a gastric ulcer index inhibitory rate of 72.63%. In addition, DTCP was demonstrated to improve stomach acidity conditions in vivo by increasing the pH and reducing the level of gastric juice, as compared with the reserpine-induced gastric ulcer control mice. Furthermore, DTCP altered the serum levels of a number of oxidation-related biomolecules, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), lipid peroxidation (LPO) and catalase (CAT), to subsequently exert an anti-gastric ulcer effect. Treatment with 50, 100 and 200 mg/kg DTCP increased the SOD, GSH-Px and CAT levels and reduced the MDA and LPO levels in the mouse model of gastric ulcers. These serum level alterations resulted in the modified serum levels of prostaglandin E2 (PGE2) and nitric oxide (NO), which are associated with gastric mucosal protection. A reverse transcription-quantitative polymerase chain reaction (RT-PCR) assay is a molecular biology experiment which could determine the changes of mRNA in tissues. Using the RT-PCR assay, DTCP was observed to increase the mRNA expression levels of certain genes associated with gastric ulcers: Epidermal growth factor, epidermal growth factor receptor, vascular endothelial growth factor and vascular endothelial growth factor receptor 1, while reducing gastrin expression levels. Therefore, the results indicated that DTCP induced a marked preventative effect on reserpine-induced gastric ulcers in vivo, as a result of its antioxidative capacity.

Gastroprotective bio-guiding fractionation of hydro-alcoholic extracts from green- and black-teas (Camellia sinensis)

Hydro-alcoholic extracts from leaves of Camellia sinensis (green- and black-tea leaves) were submitted to a fractionation, promoting the compound separation according to their polarity, and analyzed by ultra-high performance liquid chromatography-mass spectrometry. A wide range of compounds could be identified, such as catechins and their gallate (esters) or oxidation derivatives (theaflavins), glycosylated flavonoids and other phenolics, as well as lipids, saponins and alkaloids. Also have been developed, via bio-guided examination, the gastroprotective property of the compounds identified. The samples were assayed using the model of acute gastric lesions induced in rats by ethanol. Hydro-alcoholic extracts of green-tea and black-tea protected the gastric mucosa with ED₅₀=3.6 and 10.2mg/kg, respectively, with participation of gastric mucus and reduced glutathione (GSH). The ethyl acetate fraction from green-tea and aqueous fraction from black-tea were, respectively, 6 and 10 times more effectiveness than the initial extracts. Moreover, the epigallocatechin gallate (EGCG, 0.204mg/kg), a main component of ethyl acetate fraction from green tea, reduced the gastric lesion by 56% and restored the mucus levels, however the rutin (0.0133mg/kg), a flavonoid found in the most active fraction of black-tea, was less significant at the natural concentrations. These results have confirmed that the different compounds present in green- and black-tea hydro-alcoholic extracts and partitioned fractions produce relevant gastroprotection mainly via maintenance of the protective factors, mucus and GSH.

L-Theanine healed NSAID-induced gastric ulcer by modulating pro/antioxidant balance in gastric ulcer margin

L-Theanine is a unique non-protein-forming amino acid present in tea [Camellia sinensis (L.) O. Kuntze]. In the present work, we evaluated the healing effect of L-theanine on NSAID (indomethacin)-induced gastric ulcer. Histology of the stomach tissues revealed maximum ulceration on the third day after indomethacin administration (18 mg/kg, single dose p.o.) which was accompanied by increased lipid peroxidation; protein carbonylation; Th1 cytokine synthesis, and depletion of thiol, mucin, prostaglandin (PG) E, Th2 cytokine synthesis; and total antioxidant status in mice. L-Theanine healed gastric ulcer at a dose of 10 mg/kg b.w. but aggravated the ulcerated condition at a higher dose of 40 mg/kg b.w. At 10 mg/kg b.w., L-theanine significantly alleviated the adverse oxidative effect of indomethacin through enhanced synthesis of PGE2 by modulation of cyclo-oxygenase-1 and 2 [COX-1 and COX-2] expression, Th1/Th2 cytokine balance, and restoration of cellular antioxidant status at the gastric ulcer margin. The present study revealed for the first time the dose-dependent biphasic effect of a natural neuroprotective agent, L-theanine, on gastric ulcer disease.

Herbal Remedy: An Alternate Therapy of Nonsteroidal Anti-Inflammatory Drug Induced Gastric Ulcer Healing

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most commonly used therapeutic drug groups used worldwide for curing an array of health problems like pain, inflammation, cardiovascular complications, and many other diseases, but they may cause different side effects including gastroduodenal disorders. So, there is a growing interest and need to search for nontoxic, antiulcer formulations from medicinal plants to treat NSAIDs induced gastric ulcer. Extensive research has reported on many natural plants like Camellia sinensis, Phyllanthus emblica, Myristica malabarica, Piper betle, Picrorhiza kurroa, and so forth, and their active constituents reduced NSAIDs induced gastric ulcer via their antioxidative as well as immunomodulatory activity. Therefore, use of herbal formulations in daily life may prevent NSAIDs induced gastric ulceration and other side effects.

Inhibition of endogenous CO by ZnPP protects against stress-induced gastric lesion in adult male albino rats

Carbon monoxide (CO) has been found to be produced in every living cell in a biochemical reaction catalyzed by heme-oxygenase (HO) enzyme which degrades heme into biliverdin, CO, and iron. Endogenous CO is not a waste product, but acts as a chemical messenger mediating and modulating many intracellular biochemical reactions that regulate physiological functions. This study was designed to investigate the effect of inhibition of endogenous CO production by zinc protoporphyrin (ZnPP), an HO inhibitor, on the gastric secretion and ulceration induced by cold-restraint stress (CRS) in adult male albino rats. Rats were pylorically ligated and divided randomly into the following groups (six rats each): control, ZnPP treated (50 μmol/kg/day, s.c. for 10 days), CRS, and stressed ZnPP treated groups. Blood samples were collected from the retro-orbital sinus of anesthetized rats for determination of CO concentration. We found that ZnPP pretreatment significantly decreased HO-1 level, CO level, and volume of gastric juice as compared to the control non-stressed rats. In the present study, ZnPP pretreatment proved to be protective against development of ulcerative lesions in CRS model as evidenced by reduction of the ulcer index, and this could be mediated through reduction of free and total acidity of gastric secretion and decreased lipid peroxidation but with significantly decreased gastric protective nitric oxide and prostaglandin E(2) levels. In conclusion and according to our results, the protective effect of ZnPP on CRS-induced gastric ulcers despite of inhibition of endogenous CO could be attributed to the presence of zinc which is known to have a protective anti-ulcer effect.

Protective effect of polysaccharide from Hizikia fusiformis against ethanol-induced toxicity

Polysaccharide extracted from Hizikia fusiformis (Hf-PS-1) exhibited protective effects against ethanol-induced peptic injury. In in vivo assay, the ethanol group exhibited decrease of total glutathione (GSH) and increase of jun N-terminal kinase (JNK) phosphorylation relative to the control group, whereas levels were significantly increased and decreased, respectively, in the Hf-PS-1 group. Hf-PS-1 reduced ethanol-induced gastric injury. In in vitro assay, ethanol induced IEC-6 cells' death in a dose-dependent manner. Ethanol decreased the phosphorylation of Shc and the binding of Grb2 to Shc, and Hf-PS-1 pretreatment increased them. Ethanol also induced the phosphorylation of JNK and extracellular signal-regulated kinase (ERK), whereas Hf-PS-1 pretreatment decreased JNK activation but not ERK. Co-treatment with JNK inhibitor and ethanol decreased GSH levels, indicating that JNK phosphorylation is a critical factor during ethanol-induced injury. Therefore, Hf-PS-1 may be useful to protect against ethanol-induced gastrointestinal injury.

Black tea and theaflavins assist healing of indomethacin-induced gastric ulceration in mice by antioxidative action

The healing activities of black tea (BT) and the theaflavins (TF) against the indomethacin-induced stomach ulceration were studied in a mouse model. Indomethacin (18 mg/kg, p.o.) administration induced maximum ulceration in the glandular portion of the gastric mucosa on the 3rd day, accompanied by increased lipid peroxidation and protein oxidation, depletion of thiol-defense and mucin, as well as reduced expressions of cyclooxygenases (COX) and prostaglandin (PG) E synthesis in the gastric tissues, and plasma total antioxidant status of mice. Treatment with BT (40 mg/kg), TF (1 mg/kg), and omeprazole (3 mg/kg) produced similar (74%-76%) ulcer healing, as revealed from the histopathological studies. Treatment with all the above samples reversed the adverse oxidative effects of indomethacin significantly. BT and TF also enhanced the PGE synthesis by augmenting the expressions of COX 1 and 2, but did not modulate acid secretion.

Protective effect of a polysaccharide from Hizikia fusiformis against ethanol-induced cytotoxicity in IEC-6 cells

In the present study, we examined the signaling pathways related to the ethanol-protective effect of Hf-PS-1 in IEC-6 cells. Ethanol induced the death of IEC-6 cells in a dose-dependent manner, and pretreatment with Hf-PS-1 abrogated the ethanol toxicity. When we examined whether the effect of Hf-PS-1 on ethanol cytotoxicity was associated with insulin growth factor-I receptor signaling pathways, involving mitogen-activated protein kinase (MAPK), we found that ethanol treatment decreased the phosphorylation of Shc and the binding of Grb2 to Shc, and Hf-PS-1 pretreatment increased them. Ethanol treatment also induced the phosphorylation of JNK and ERK, whereas Hf-PS-1 pretreatment decreased JNK activation but not ERK activation. Using a JNK inhibitor (SP600125), we examined GSH levels to determine whether Hf-PS-1 pretreatment mi20 ght protect against ethanol-induced gastric intestinal damage by down-regulating JNK. Co-treatment with SP600125 and ethanol decreased GSH levels, indicating that JNK phosphorylation is a critical factor during ethanol-induced injury and that the effect of Hf-PS-1 occurs via JNK down-regulation. We have thus demonstrated the protective effect of Hf-PS-1 against ethanol-induced cellular damage. Therefore, Hf-PS-1 may be useful as a bio-functional food source to protect against ethanol-induced gastrointestinal injury.

A thought on the biological activities of black tea

Tea is the most widely used ancient beverage in the world and black tea possesses many biological effects on the organisms. It acts as an effective antioxidant because of its free radical-scavenging and metal-chelating ability. Due to this, it is active against inflammation, clastogenesis, and several types of cancer. Tea reduces DNA damage and mutagenesis due to oxidative stress or the presence of pro-mutagens through antioxidant function, blocking activation pathways of mutagens, suppressing transcription of enzymes involved etc. Inhibition of low-density lipoprotein (LDL) peroxidation, suppression of fatty acid synthase etc., suggest that tea may have a role in preventing cardiovascular diseases. Some epidemiological studies support the protective role of black tea against cardiovascular diseases but some do not. Besides, black tea has beneficial effects on the gastrointestinal tract; it affects motility, absorption, microflora etc., by influencing the hormonal balance and antioxidant function black tea improves bone mineral density. It is also antiviral due to its enzyme-inhibiting and receptor-blocking properties. Although its role in cancers of the gastrointestinal tract, liver, and prostate is confirmed, its effect against urinary tract cancer is uncertain and further studies are required. Apart from these, excess consumption may lead to the formation of a stained pellicle layer on teeth, which is difficult to eliminate, inhibits trypsin, influences mineral absorption, causes convulsions etc. Excess caffeine intake may have adverse effects on selected organs as reported in studies on some organisms. These reports indicate that there is a wide scope of further research for the efficient use of black tea active conserves/isolates to reap health benefits.

Protective effects of a polysaccharide from Hizikia fusiformis against ethanol toxicity in rats

Hizikia fusiformis is an edible brown alga that is widely consumed in Korea, Japan, and China and possesses a number of potentially beneficial compounds, including antioxidants and anticoagulants. No reports have investigated potential H. fusiformis protectants against ethanol-induced peptic injury. We extracted a polysaccharide from H. fusiformis (Hf-PS-1) that exhibited protective effects against ethanol-induced peptic injury and related mechanisms in rats. Experimental animals were divided into three groups: control, ethanol-only, and ethanol+Hf-PS-1. The ethanol-only group exhibited decreased levels of total glutathione (GSH) and increased levels of jun N-terminal kinase (JNK) phosphorylation relative to the control group, whereas levels were significantly increased and decreased, respectively, in the ethanol+Hf-PS-1 group. The ethanol-only group also exhibited increased levels of extracellular signal-regulated kinase 1/2 (ERK 1/2) phosphorylation relative to the control group; these levels were not significantly different in the ethanol+Hf-PS-1 group. Hf-PS-1 appeared to reduce ethanol-induced gastric injury. Therefore, we suggest that Hf-PS-1 could protect against ethanol-induced peptic ulcers primarily through a mechanism associated with the inhibition of JNK activation.

The effect of polysaccharide extracted from the marine alga Capsosiphon fulvescens on ethanol administration

Seaweed extracts have recently been found to have antioxidant and antitumor activities. Capsosiphon fulvescens (Cf) is a green alga and nutrient-dense food source. In a previous study, we extracted polysaccharide from Cf (Cf-PS) and demonstrated its antitumor effect in gastric cancer cells. In this report, we describe the protective effect of Cf-PS against alcohol-induced gastric injury in rats and adenocarcinoma (AGS) cells. In vivo assay revealed stomach damage in rats treated with alcohol alone; however, the stomach condition of rats co-treated with Cf-PS and alcohol matched that of the control group. Cf-PS also inhibited alcohol-induced cell death in AGS cells. Compared with alcohol treatment alone, Cf-PS and alcohol co-treatment increased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt but inhibited poly-ADP-ribose polymerase (PARP) cleavage. Thus, ERK1/2 and Akt activation are instrumental in the protective effect of Cf-PS against alcohol-induced cell death in AGS cells. Moreover, Cf-PS treatment reduced the expressions of cyclooxygenase-2 (COX-2) and the inducible form of nitric oxide (iNOS), proteins related to ulcers. These results suggest that Cf-PS could help protect against alcohol-induced peptic ulcers.

Studies of the Antioxidative Effects of Green and Black Tea (Camellia sinensis) Extracts in Rats

This paper reports a comparative study of the antioxidative effects of black and green tea extracts in sodium oxalate-challenged rats. A dose of 10 mg/kg of body weight of sodium oxalate was used to induce lipid peroxidation in vivo. Rats treated with sodium oxalate had 42.06 +/- 3.10 nM/hour, 45.39 +/- 9.75 mg/100 mL, 10.95 +/- 1.52%, 15.95 +/- 3.19 mg/dL, 112.25 +/- 5.15 mg/dL, 59.21 +/- 2.95 IU, 39.55 +/- 2.51 IU, and 150.62 +/- 9.62 KA/unit for serum levels of malondialdehyde, reduced ascorbic acid, catalase, cholesterol, phospholipid, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP), respectively. These values are significantly (P < .05) different from values obtained from normal rats. Rats pretreated with 100 mg/kg of body weight of green tea had 27.59 +/- 3.56 nM/hour, 79.11 +/- 5.13 mg/100 mL, 4.23 +/- 0.36%, 50.09 +/- 5.24 mg/dL, 97.58 +/- 4.73 mg/dL, 23.10 +/- 1.59 IU, 31.14 +/- 1.26 IU, and 96.48 +/- 2.36 KA/unit for serum levels of malondialdehyde, reduced ascorbic acid, catalase, cholesterol, phospholipid, AST, ALT, and ALP, respectively, compared with 37.28 +/- 2.07 nM/hour, 72.62 +/- 2.10 mg/100 mL, 6.23 +/- 1.52%, 37.25 +/- 2.84 mg/dL, 78.05 +/- 2.36 mg/dL, 36.08 +/- 1.80 IU, 29.00 +/- 3.02 IU, and 109.23 +/- 6.32 KA/unit recorded for the same parameters in rats treated with black tea. The cholesterol to phospholipid ratio was increased from 0.14 +/- 0.04 in control rats to 0.47 +/- 0.02 and 0.51 +/- 0.01 by black and green tea extracts, respectively. These results suggest that tea extracts have antioxidant properties and that green tea extract is more potent.

The theaflavin fraction is responsible for the facilitatory effect of black tea at the skeletal myoneural junction

The effect of various fractions of black tea [(Camellia Sinensis) (L) O. Kuntze (Theaceae)] on the function of mammalian skeletomotor apparatus was studied. The theaflavin fraction (Tfs) produced a concentration- dependent facilitation of indirect twitch responses of the rat phrenic nerve diaphragm preparation and the facilitation was dependent on the amount of calcium present in the bathing fluid. Nifedipine reduced the facilitatory effect of Tfs as a function of its concentration. Tfs failed to produce facilitation when the twitch height was reduced to about 50% of the control value in presence of magnesium chloride. Tfs completely antagonized the submaximal paralytic effect of d- tubocurarine and decamethonium bromide. Tfs did not have any effect on direct twitch responses or on acetylcholine (Ach) and potassium chloride (KCl) induced contractures of denervated diaphragm. The results revealed that the site of action of Tfs is on the contractile mechanism of the voluntary muscle and point to a critical role of calcium in the mechanism of action of Tfs. N omega-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, antagonized both the facilitatory and inhibitory effects on indirect twitch responses of rat diaphragm induced by L-arginine and Tfs when the phrenic nerve was stimulated at 5 Hz and 50 Hz respectively. The thearubigin (Trs) fraction of black tea and the aqueous part which is completely devoid of Tfs, did not potentiate the twitch responses. The findings suggest that Tfs have a potentiating effect on the contractile mechanism of skeletal muscle and that calcium and nitric oxide may modulate this action of Tfs.

Role of reduced glutathione and nitric oxide in the black tea extract-mediated protection against ulcerogen-induced changes in motility and gastric emptying in rats

The aim of the present study was to investigate the underlying mechanism of the role of hot water extract of black tea [Camellia sinensis (L). O. Kuntze Theaceae] in normalizing the changes in intestinal transit and gastric emptying induced by various ulcerogenic agents in experimental rats. Intestinal transit as well as gastric emptying were significantly reduced in rats treated with glutathione (GSH) depleting agents, diethyl maleate (DEM), indoacetamide (IDA) and N-ethyl maleimide (NEM). Prior oral administration of black tea extract (BTE) at 20 ml/kg of a 10% solution, i.g. once a day for 7 days significantly increased the intestinal transit and gastric emptying with restoration of serum GSH level. Singular administration of succimer (60 mg/kg, i.g.), the standard sulfhydryl containing antiulcer agent used as a reference drug, was also effective. Increase in intestinal transit caused by BTE was reversed both by N-omega-nitro-L-arginine methyl ester (L-NAME) (25 mg/kg, i.p.) and N-omega-monomethyl-L-arginine (L-NMMA) (25 mg/kg, i.p.), but not with N-omega-nitro-D-arginine methyl ester (D-NAME) (25 mg/kg, i.p.). Furthermore, restoration of intestinal nitric oxide synthase (NOS) activity was found to be associated with BTE treatment. These results provide evidence that nitric oxide may play a role in BTE-mediated improvement of intestinal motility changes and gastric emptying induced by DEM, IDA and NEM.

The plant kingdom as a source of anti-ulcer remedies

Phytogenic agents have traditionally been used by herbalists and indigenous healers for the prevention and treatment of peptic ulcer. This article reviews the anti-acid/anti-peptic, gastro-protective and/or anti-ulcer properties of the most commonly employed herbal medicines and their identified active constituents. Botanical compounds with anti-ulcer activity include flavonoids (i.e. quercetin, naringin, silymarin, anthocyanosides, sophoradin derivatives) saponins (i.e. from Panax japonicus and Kochia scoparia), tannins (i.e. from Linderae umbellatae), gums and mucilages (i.e. gum guar and myrrh). Among herbal drugs, liquorice, aloe gel and capsicum (chilli) have been used extensively and their clinical efficacy documented. Also, ethnomedical systems employ several plant extracts for the treatment of peptic ulcer. Despite progress in conventional chemistry and pharmacology in producing effective drugs, the plant kingdom might provide a useful source of new anti-ulcer compounds for development as pharmaceutical entities or, alternatively, as simple dietary adjuncts to existing therapies.

Prokinetic effect of black tea on gastrointestinal motility

The gastrokinetic effects of hot water extract of black tea [Camellia sinensis, (L) O. Kuntze (Theaceae)] on gastrointestinal motility were studied both in vivo and in vitro. The extract significantly accelerated the gastrointestinal transit (GIT) in vivo in mice. These facilitatory effect was reduced after pretreatment with atropine, hemicholinium-3, morphine, indomethacin, McN-A-343 and L-arginine. In guinea pig ileum, the extract facilitated the peristaltic reflex in response to pressures in normal preparation. The black tea extract and L-NMMA (nitric oxide synthase inhibitor) significantly reduced the electrical field stimulated nonadrenergic, noncholinergic (NANC) relaxation of isolated rat fundal strips. The extract markedly enhanced the tonic ('hump') responses to transmural stimulation in longitudinal muscle of guinea pig ileum which was unaltered in the presence of atropine. These findings suggest a cholinergic involvement and a partial role of prostaglandin and nitric oxide in the mechanism of action of black tea extract on gastrointestinal motility. To determine the effective constituents in black tea responsible for this activity, the effect of black tea polyphenols on GIT were also studied. Thearubigin fraction (but not theaflavin) accelerated GIT significantly which suggests its involvement in the prokinetic effect of black tea.

Proconvulsive effect of tea (Camellia sinensis) in mice

Investigations were carried out to evaluate the effect of acute and chronic administration of both black and green tea on three models of experimentally induced convulsions in mice. Tea extract (both black and green) significantly accelerated the onset of convulsion, increased the duration of convulsion and mortality in mice. Since both the extracts failed to alter the GABA level in brain, based on the earlier report that both black and green tea might act on Ca(2+) channels, it can be suggested that the observed proconvulsive effect of tea is not mediated through GABA but through Ca(2+) channels.

Role of glutathione in the antiulcer effect of hot water extract of black tea (Camellia sinensis)

The role of a hot water extract of black tea (Camellia sinensis (L). O. Kuntze Theaceae) in the gastric cytoprotective mechanisms was studied using gastric mucosal lesions produced by various ulcerogens in rats as an experimental model. Prior oral administration of black tea extract (BTE) at 20 ml/kg, i.g. once a day for 7 days significantly reduced the incidence of gastric erosions and severity induced by ethanol, diethyldithiocarbamate (DDC) and diethylmaleate (DEM). This treatment also favorably altered the changes in acid and peptic activity of gastric juice in these ulcerogen-treated animals. Singular administration of succimer (60 mg/kg, i.g.), the standard sulfhydryl containing antiulcer drug used as a reference drug, was also effective. The levels of glutathione and glutathione peroxidase were significantly decreased after treatment with ethanol, DDC and DEM, and this decrease was prevented by BTE pretreatment in the aforesaid manner. Other major features of BTE-induced reversal of ulcerogenic agents include a significant decrease in the protein content and a marked increase in hexosamine and sialic acid content. These results suggest a major role for glutathione, an endogenous antioxidant, in the cytoprotection against ulceration afforded by BTE.

Effects of Anchusa strigosa root aqueous extract on gastric ethanol-induced ulcer in laboratory animals

Anchusa strigosa Banks et Sol (Boraginaceae) root extracts (ASRE) were prepared by soaking the dry material in boiling water. The clear soluble extract was dried and found to be 0.238 g/g dry roots. A gastric ulcer was induced in fastened animals by oral ingestion of ethanol. Administration of 0.080 g of ASRE prior to ethanol ingestion protected the stomach of the rat from ulcer formation. The ulcer index values, expressed as a percentage of total stomach surface area affected by the ulcer, were lowered from 34.0+/-4.0 to 6.0+/-0.7 and 32.5+/-9.4 to 2.2+/-1.4 by the morphometric and the planimetric methods, respectively. Treatment of the induced ulcer in guinea pigs was achieved by oral administration of ASRE at the therapeutic dose of extract of 0.286 g/kg body weight/day for 24 days. The intraperitoneal LD50 of ASRE in mice was 0.080 g extract/kg body weight. Replacing water intake by ASRE at 75 ml of variable extract concentrations of 2.865, 3.57 and 4.284 g/l per animal per day for 90 days showed no histopathological changes in all organs of the rat. However, a clear depression effect on the central nervous system and anemia were observed particularly with extract of 3.57 g/l or more.