Medicinal Plants Classification Biosynthesis and ... - Index of

Gastroprotective Triterpenoids: Pharmacological Mechanism
More about miscellaneous triterpenes with gastroprotective activities are
Calendasaponins A, B, C and D, triterpene oligoglycosides compounds which have induced
gastric emptying in mice, and decrement in the lesions induced by ethanol- and indomethacin
administration [136].
Theasaponin A2, a triterpene saponin isolated from the saponin fraction of the seeds of
Camellia sinensis showed inhibitory effect on ethanol-induced gastric mucosa lesions in rats.
Furthermore, structure-activity relationships for theasaponins on ethanol-induced
gastroprotective activities may suggest that the 28-acetyl moiety enhances activity and
theasaponins having a 23-aldehyde group exhibit more potent activities [137]. Furthermore,
theasaponin E1, E2 and E5 showed gastroprotective properties and the structure-activity
requirements suggested that 21- and/or 22-acyl groups and acetylation contribute to their
gastroprotective activity [138].
A cycloartane-type triterpene glycoside, Astragaloside IV, is the active constituent of
Astragalus species [139] and has exhibited gastroprotective activity in the experimental
model of ethanol-induce gastric lesions in the rat [140]. Furthermore, 3αhydroxymasticadienonic
acid, 3-epi-oleanolic acid and β-sitosterol are the gastroprotective
compounds of Amphipterygium adstringens; where first and second are triterpenes.
Masticadienonic acid was also isolated form the active fraction, but it was unable to inhibit
ethanol-induced gastric lesions. Interestingly masticadienonic acid does not possess a
hydroxyl group in the position C-3 [141]. Then, triterpenoid compounds isolated from natural
products have shown gastroprotective activity, the study of those compounds may help the
understanding of how natural products exert pharmacological effects.
5.3. Gastroprotective Mechanisms Described for Triterpenoids
It has been described that triterpernoids possess pharmacological activity, being their
gastroprotective effect one of them. The knowledge of how those compounds exert their
protective activity may provide information of their pharmacological mechanism involved.
At this moment it has been elucidated some mechanism of how triterpenoids induce their
gastroprotective activity. Most of the studies have been focus on the role of prostaglandins,
nitric oxide, sulfhydryls and capsaicin-sensitive neurons in the gastroprotective effect of
several kinds of triterpenoids.
The antiulcerogenic effect of carbenoxolone has been attributed to the stimulation of
gastric mucus production [142]; further evidence showed that carbenoxolone increases PGE2
synthesis [143]. More recently it has been found that NO contributes to the gastroprotective
effect of carbenoxolone [144]. Moreover partial participation of sulfhydryl groups has been
implicated on its mechanism [140].
Besides, it was explored the gastroprotective mechanism of Astragaloside IV, where the
NO synthesis is involved on its antiulcerogenic effect, while prostaglandin inhibition or
endogenous sulfhydryls are not involved on its mechanism of gastroprotection [140]. More
evidence shows that Astragaloside IV decreases adhesive molecules such as VCAM and Eselectin;
then decreases leukocyte adherence in a model of LPS-induced inflammation. Due
gastric injury is a consequence of inflammatory process; it should be interesting measure the
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