Antiulcer Agents from Higher Plants

Abstract

The gastrointestinal tract has its own conformation, with a large surface area that permits high absorption, and glands that produce digestive juices, thereby enabling digestion and absorption of nutrients, in order to maintain the functioning of the organism. One of the segments of the gastrointestinal tract is the stomach. This organ is formed by several layers of smooth muscle and is lined by a mucous membrane. It is anatomically divided into four regions: cardia, fundus, body, and antrum [1,2].The stomach surface contains mucus-secreting cells, which cover the entire surface; peptic cells, which secrete large amounts of pepsinogen; parietal cells, which secrete hydrochloric acid and intrinsic factor; G cells, which secrete gastrin; and chromaffin cells, which secrete histamine [3,4].The stomach has a series of protective barriers, for its primordial function, digestion of proteins, and protection against self-digestion and injuries. The mucosal layer plays a key role, with four levels of protection. The first level is the factors secreted into the lumen (surface phospholipids, bicarbonate, mucus, and prostaglandins); the second level of protection is the epithelium itself; the third level is related to the joint action of the afferent sensory nerve and the microcirculation mucosa and submucosa; and the fourth level of defense is the mucosal immune system, including mast cells and macrophages [5,6]. Thus, disorders involving the secretory and protector functions may be related to the pathogenesis of peptic ulcer [4].