**2. Peptic ulcer**

#### **2.1 Animal models of gastric ulcer**

Rats are commonly used animals to induce ulcers that resemble the human condition by various noxious chemical agents. NSAIDs (eg. Indomethacin and Aspirin) cause gastrointestinal ulceration, due to their ability to suppress cytoprotective prostaglandin synthesis (Wallace, 2001). The NSAIDS-induced ulcer model is important to identify mechanisms of action of plants that maintain the gastric mucosa integrity by balancing the toxic effects of NSAIDs. The widely used ethanol-induced gastric ulcer model is suitable to study gastric protective and free radical scavenging properties of plants. Stress induced gastric lesions in rats are useful to study gastric mucosal barrier strengthening properties (eg. increased mucus production) of potential plant extracts and their actives. Pylorus ligation in rats helps to screen plants for their antisecretory properties.

#### **2.2 Plants used in the treatment of peptic ulcer**


drug interactions, the common assumption that 'herbal products are natural, they are safe' is no longer valid. Safety and quality data of herbal medicines should be made available to medical practitioners and other healthcare professionals to avoid these unwanted effects.

Several plants have been used by traditional healers around the world to treat various gastrointestinal tract diseases. Centuries ago the reliance on nature to cure human ailments was developed by great efforts of dedicated professionals by keen observation and trial and error method. This important knowledge is updated constantly and passed from generations to generations. Today traditional healing systems play important roles in several parts of the world, especially where modern pharmaceuticals are less accessible. Modern scientific research methods are invaluable to support traditional claims and also to develop traditional remedies as a viable alternative to mainstream pharmaceuticals. In recent years, a number of research papers have been published on herbal medicines to provide the experimental evidence for their traditional claims. Given the multitude of these research publications, it is not possible to cover all of them. In this chapter, we only attempted to provide the experimental (animal and human studies) evidence for the plants that have been traditionally used to treat most notable gastrointestinal diseases, namely,

Rats are commonly used animals to induce ulcers that resemble the human condition by various noxious chemical agents. NSAIDs (eg. Indomethacin and Aspirin) cause gastrointestinal ulceration, due to their ability to suppress cytoprotective prostaglandin synthesis (Wallace, 2001). The NSAIDS-induced ulcer model is important to identify mechanisms of action of plants that maintain the gastric mucosa integrity by balancing the toxic effects of NSAIDs. The widely used ethanol-induced gastric ulcer model is suitable to study gastric protective and free radical scavenging properties of plants. Stress induced gastric lesions in rats are useful to study gastric mucosal barrier strengthening properties (eg. increased mucus production) of potential plant extracts and their actives. Pylorus

 *Diodia sarmentosa* (Rubiaceae), *Cassia nigricans* (Celsapinaceae), *Ficus exasperate*  (Moraceae) and *Synclisia scabrida* (Menispermaceae) are the most popularly used antiulcer recipes in Nigeria. In vivo studies in mice and rats revealed their anti-ulcer activities by decreasing the ulcer index in aspirin-induced ulcerogenesis, delayed intestinal transit, increased pH, and decreased volume and acidity of gastric secretion

 *Eruca sativa,* commonly known as Rocket, *is* a commonly used leaf vegetable in Unani, Ayurveda and Arab traditional medicine systems. Rocket is shown to possess significant anti-secretory, anti-ulcer and cytoprotective properties in rats (Alqasoumi et al., 2009). Pretreatment with ethanolic extract of Rocket attenuated gastric ulceration induced by ethanol, indomethacin and hypothermic stress. In pylorus ligated rats, Rocket dose-dependently reduced gastric acid secretion. In addition, the extract

peptic ulcer, diarrhoea and inflammatory bowel syndrome.

ligation in rats helps to screen plants for their antisecretory properties.

**2.2 Plants used in the treatment of peptic ulcer** 

(Akah et al., 1998).

**2. Peptic ulcer** 

**2.1 Animal models of gastric ulcer** 

significantly replenished gut wall mucous and reduced malondialdehyde (an indicator of lipid peroxidation) levels in ethanol treated rats. Gastroprotective effects of Rocket are attributed to the presence of flavonoids, sterols and triterpines.


Pharmacology of Traditional Herbal Medicines and Their Active Principles

**3. Diarrhoea** 

**3.1 Experimental models** 

Used in the Treatment of Peptic Ulcer, Diarrhoea and Inflammatory Bowel Disease 301

Rodents are commonly used to induce experimental diarrhea and to study mechanisms of action of plants and their active principles. Castor oil, Prostaglandin E2 (PG-E2) and heat-labile enterotoxin are commonly used agents to induce diarrhea in animals. The diarrhoeal effect of castor oil is mediated through ricinoleic acid which causes irritation and inflammation of intestinal mucosa, and consequesntly leads to the stimulation of intestinal motility and increased secretion of fluid and electrolytes. This model is ideal to study the antisecretory and antimotility potential of medicinal plants. Prostaglandin E2 causes enteropooling by stimulating fluid secretion and increasing propulsive activity in the colon (Pierre et al., 1991). Heat-labile enterotoxin (LT) is the virulent factor of *Escherichia coli* and diarrhea by accumulation of salt and water in the intestinal lumen (Spangler., 1992). Therefore, the LTinduced diarroheal model is suitable to study inhibitory effects of plant extracts on bacterial toxins. In addition, the charcoal meal test and charcoal-gum acacia-induced hyperperistalsis in animals are helpful to identity the effect of potential medicinal plants on intestinal motility.

**3.2 Plants tested for antidiarrheal activity in animal models of diarrhoea** 

motility in charcoal meal tests in rats (Mukherjee et al., 1997).

avoid toxic effects (Clazada et al., 2009).

mice (Hajhashemi et al., 1999).

rats (Chittrakarn et al., 2008).

 *Ficus bengalensis*, *Eugenia jambolana*, *Ficus racemosa* and *Leucas lavandulaefolia* are commonly used folk medicine to treat diarrhoea by the people who live in Khatra region of West Bengal, India. Ethanolic exracts of *Ficus bengalensis* (hanging roots), *Eugenia jambolana* (bark), *Ficus racemosa* (bark) and *Leucas lavandulaefolia* (aerial parts) significantly inhibited castor oil induced diarrhoea and PGE2 induced enteropooling in rats. In addition, these extracts also showed a significant reduction in gastrointestinal

 *Geranium mexicanum* plant is a commonly used medicinal plant in Traditional Mexican Medicine for the treatment of diarrhoea. Methanolic extract of *Geranium mexicanum* (roots) remarkably inhibited charcoal–gum acacia-induced hyperperistalsis in rats. However the authors suggested that this medicinal plant should be used with care to

 *Galla chinensis and Chaenomeles speciosa* have been traditionally used in China to treat gastrointestinal disorders. These plant extracts significantly inhibited heat-labile

 *Thespesia populnea*, a large tree found in tropical regions and coastal forests of India, is traditionally used in India to treat several disorders including diarrhea and dysentery. Residue fraction of aqueous extract of *T. populnea* significantly inhibited castor oil and prostaglandin E2 (PGE2)-induced diarrhea induced diarrhea in rats. In addition, it also

inhibited intestinal motility in the charcoal meal test (Viswanatha et al., 2011). *Mitragyna speciosa* is an indigenous tree to Thailand, where it is commonly called kratom. In folk medicine, it is often used to treat diarrhea. Methanolic extract of *M. speciosa* dose dependently inhibited castor oil-induced diarrhea and intestinal transit in

enterotoxin-induced diarrhoea in the mouse (Chen et al., 2006, Chen et al., 2007). *Satureja hortensis* is an annual herb that is traditionally used in Iran for treating stomach and intestinal disorders. Essential oil isolated from *S. hortensis* exhibited antispasmodic activity in isolated rat ileum. In addition, it also inhibited castor oil-induced diarrhea in

leaves of Solanum torvum produced significant anti-ulcer activity in HCl/ethanol, indomethacin, pylorus ligation and cold-restraint stress induced gastric ulcers in rats. The authors proposed that the cytoprotective activity of extracts could be due to strengthening of the mucosal barrier through the increase of mucus production (Nguelefack et al., 2008).



Table 1. Plants and their active constituents with anti-ulcer activity
