2. Inflammatory Diseases and Ulcers Inflammation is a natural reaction in the defense of tissues against various injuries caused by physical stress combined with harmful chemicals or microbes. The inflammation tends to be one of the prime causes for the occurrence of various diseases such as cancer, obesity, cardiovascular disease, rheumatoid arthritis, osteoporosis, asthma, IBD, central nervous system (CNS) depression, diabetes, and Parkinson disease. Inflammation can be triggered by many stimuli including pathogens or cytokines (i.e., interleukin-6 or IL-6, tumor necrosis factor-alpha or TNF-α, neutrophils, and monocytes). These stimulating agents can be differentiated into macrophages, which are subsequently attracted to injured tissue sites by chemotaxis and intensify the inflammatory reactions to the damaged areas as well as initiate phagocytosis. Inflammation can be characterized by swelling, joint pain, and redness. Inflammation leads to several chronic diseases including arthritis, autoimmune disease, coeliac disease, colitis, and asthma, which are often associated with the increased risk of development of cardiovascular diseases, diabetes, cancer, and osteoporosis. Phytochemicals derived from medicinal plants can be used in the alleviation of inflammatory reactions by inhibiting different forms of enzymes e.g., lipoxygenase (LOX), cyclooxygenase (COX), phospholipase A2, and proteins (e.g., inhibition of the proinflammatory cytokines). In medical science, Crohn’s disease, and ulcerative colitis (UC) are two types of IBD that cause inflammation in the entire gastrointestinal tract and colonic mucosa, raising the risk of colon cancer as well [27]. An ulcer is the condition of corrosion in the linings of the stomach and the duodenum. Thus, ulcers in the gastrointestinal tract are subdivided into ulcerative colitis (lower) and peptic ulcers (upper) depending on the location of the infection. Peptic ulcers, also known as gastric and duodenal ulcers, can be characterized as submucosal damage of the digestive tract caused by the disruption of the balance between the hostile factors (i.e., gastric acid, Helicobacter pylori, and anti-inflammatory drugs) and protective factors (i.e., mucus, bicarbonate, prostaglandins, and blood flow towards the mucosa). The common symptoms of peptic ulcers include a burning sensation and pain in the middle or upper stomach, bloating, heartburn, nausea or vomiting, and weight loss. Excessive consumption of alcohol, smoking, chewing tobacco, serious illness, and the intake of NSAIDs increase the risk of ulcer development. Gastric ulcers and duodenal ulcers, which are more prevalent in the Eastern and Western countries, cause morbidity and mortality worldwide, and H. pylori are considered as one of the most important factors in the development of this disease.
3. Plant Mediated Treatment of Ulcer and Inflammatory Diseases Medicinal plants are the blessings of nature that humans have been using since prehistoric times as the precursor of most drugs. The treatment of ulcers and IBD is facilitated by the intensive use of many medicinal plants. In addition, in recent years, numerous studies on plant extracts have substantially demonstrated anti-ulcer and anti-inflammatory activities in both in vitro and in vivo models. Drugs derived from medicinal plants are effective against inflammation of the digestive tract primarily in two ways, either by reducing acid and pepsin secretion or by assisting the cytoprotection via mucosal defense factors [36]. The mode of action of these drugs differs according to their function. These medications maintain a balance between several aggressive factors (i.e., pepsin, acid, bile salts, and H. pylori) and defensive factors (i.e., cellular mucus, mucin secretion, mucosal blood flow, bicarbonate secretion, and cell turnover). For instance, the methanol extract of drumstick leaves, and flower buds inhibited aspirin-induced gastric lesion formation in rats. It has been reported that several compounds, such as cavidine, chelerythrine, quercetin, hesperidin, α-pinene, and garcinol, present in medicinal plants were used against ulcer diseases [39]. Additionally, prominent anti-inflammatory compounds such as resveratrol, colchicine, epigallocatechin3-gallate (EGCG) capsaicin, phytosterols, saponins, and curcumin derived from plants were used to treat inflammatory diseases.
In addition to the use of traditional medicines such as NSAIDs, the use of proton pump inhibitors (e.g., pantoprazole, omeprazole, lansoprazole, and rabeprazole), histamine receptor blockers (e.g., famotidine and ranitidine), synthetic prostaglandin E1 (e.g., misoprostol), antacids (e.g., aluminum hydroxide and magnesium trisilicate combination), corticosteroids (e.g., dexamethasone), immune-suppressants, immune-modulators (e.g., azathioprine and 6-mercapto-purine), antibiotics (e.g., clarithromycin and metronidazole), and biologic agents (e.g., TNF-α) for the treatment of inflammatory diseases is in practice on a large scale and has significant adverse and undesirable side effects including gastrointestinal and hepatic toxicity, renal and cardiovascular malfunctions, and hematologic effects such as hemophilia and thrombocytopenia. As a result, the use of natural products such as plants and herbal derivatives is increasingly growing among ulcerated and inflammatory patients having minimal or no side effects as they are the products of nature. Different types of plants that are currently considered to be effective to treat ulcers and inflammatory diseases are discussed.