Medicinal Plants Classification Biosynthesis and ... - Index of

In: Medicinal Plants: Classification, Biosynthesis... ISBN: 978-1-60876-027-5
Editor: Alejandro Varela and Jasiah Ibañez © 2009 Nova Science Publishers, Inc.
Gastroprotective Triterpenoids:
Pharmacological Mechanism
Chapter 3
Aracely E. Chávez-Piña and Andrés Navarrete
Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de
México, Ciudad Universitaria Coyoacán 04510, México D.F., México
Abstract
Gastric and duodenal ulcers affect a considerable amount of people in the world.
Ulcer occurs when there is a disturbance of the normal equilibrium caused by either
enhanced aggression or diminished mucosal resistance of gastrointestinal tract. Mucosa
defends gastrointestinal tract of acid, pepsin, bile, leukocyte infiltration and external
substances such as alcohol, caffeine, chilli or certain drugs such as NSAIDs. The defense
mechanisms of the gastrointestinal mucosa mainly consist of functional, humoral and
neuronal factors. Mucus alkaline secretion, mucosal microcirculation and motility act as
functional factors, while prostaglandins and nitric oxide (NO) act as humoral factors, and
capsaicin-sensitive sensory neurons (CPSN) act as neuronal factors. Several plants
containing triterpenoids have been shown to possess anti-ulcer activity. The
gastroprotective effects of triterpenoids have been studied on ethanol or NSAIDsinduced
gastric injury models. These models induced impairment in the mucosal defense
process with the consequent gastric damage. The principal mechanism of
gastroprotection of triterpenoids has been reported by the activations of mucous
membrane secretion instead of the inhibition of gastric acid secretion. Chemically, this
gastroprotective effect has been referred to the presence of a hydroxyl group free or
derivative at position C-3 for sterols and triterpenoids. Some pharmacological
gastroprotective mechanisms for this kind of natural products has been attributed to the
role of prostaglandins, nitric oxide (NO), sulfhydryl groups (-SH), and capsaicinsensitive
afferent neurons. Besides, recently leukocyte adherence, TNF-α and hydrogen
sulfide has been implicated on mucosal defense mechanism, however it is unknown on
triterpenoids gastroprotection.