The gastroprotective effects of Eugenia dysenterica (Myrtaceae) leaf extract: the possible role of condensed tannins.
We applied a taxonomic approach to select the Eugenia dysenterica (Myrtaceae) leaf extract, known in Brazil as "cagaita," and evaluated its gastroprotective effect. The ability of the extract or carbenoxolone to protect the gastric mucosa from ethanol/HCl-induced lesions was evaluated in mice. The contributions of nitric oxide (NO), endogenous sulfhydryl (SH) groups and alterations in HCl production to the extract's gastroprotective effect were investigated. We also determined the antioxidant activity of the extract and the possible contribution of tannins to the cytoprotective effect. The extract and carbenoxolone protected the gastric mucosa from ethanol/HCl-induced ulcers, and the former also decreased HCl production. The blockage of SH groups but not the inhibition of NO synthesis abolished the gastroprotective action of the extract. Tannins are present in the extract, which was analyzed by matrix assisted laser desorption/ionization (MALDI); the tannins identified by fragmentation pattern (MS/MS) were condensed type-B, coupled up to eleven flavan-3-ol units and were predominantly procyanidin and prodelphinidin units. Partial removal of tannins from the extract abolished the cytoprotective actions of the extract. The extract exhibits free-radical-scavenging activity in vitro, and the extract/FeCl3 sequence stained gastric surface epithelial cells dark-gray. Therefore, E. dysenterica leaf extract has gastroprotective effects that appear to be linked to the inhibition of HCl production, the antioxidant activity and the endogenous SH-containing compounds. These pleiotropic actions appear to be dependent on the condensed tannins contained in the extract, which bind to mucins in the gastric mucosa forming a protective coating against damaging agents. Our study highlights the biopharmaceutical potential of E. dysenterica.
Laboratory of Pharmacology, Institute of Biomedical Sciences, Federal University of Uberlândia.
Ligia Carolina da Silva
LC
Prado
Denise Brentan
DB
Silva
Grasielle Lopes
GL
de Oliveira-Silva
Karen Renata Nakamura
KR
Hiraki
Hudson Armando Nunes
HA
Canabrava
Luiz Borges
LB
Bispo-da-Silva
D000818:Animals; D000897:Anti-Ulcer Agents / Q000737:chemistry / Q000627:therapeutic use*; D002229:Carbenoxolone / Q000627:therapeutic use; D000431:Ethanol; D016166:Free Radical Scavengers / Q000494:pharmacology / Q000627:therapeutic use; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism; D006851:Hydrochloric Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D008517:Phytotherapy; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D018515:Plant Leaves / Q000737:chemistry*; D013276:Stomach Ulcer / Q000139:chemically induced / Q000188:drug therapy*; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D027842:Syzygium / Q000737:chemistry*; D013634:Tannins / Q000032:analysis
D000897:Anti-Ulcer Agents; D016166:Free Radical Scavengers; D010936:Plant Extracts; D013439:Sulfhydryl Reagents; D013634:Tannins; D009569:Nitric Oxide; D000431:Ethanol; D002229:Carbenoxolone; D006851:Hydrochloric Acid