The Gastroprotective Effects of Eugenia dysenterica (Myrtaceae) Leaf Extract: The Possible Role of Condensed Tannins

• Published in: Biological & pharmaceutical bulletin Vol. 37; no. 5; pp. 722 - 730
• Main Authors: Ligia Carolina da Silva Prado, Silva, Denise Brentan, Oliveira-Silva, Grasielle Lopes de, Hiraki, Karen Renata Nakamura, Canabrava, Hudson Armando Nunes, Bispo-da-Silva, Luiz Borges
• Format: Journal Article
• Language: English
• Published: Japan The Pharmaceutical Society of Japan 2014; Pharmaceutical Society of Japan
• Subjects: Animals; Anti-Ulcer Agents - chemistry; Anti-Ulcer Agents - therapeutic use; Carbenoxolone - therapeutic use; condensed tannin; Ethanol; Eugenia dysenterica; Free Radical Scavengers - pharmacology; Free Radical Scavengers - therapeutic use; Gastric Mucosa - drug effects; Gastric Mucosa - metabolism; gastroprotection; Hydrochloric Acid - metabolism; Male; matrix assisted laser desorption/ionization (MALDI); Mice; Myrtaceae; Nitric Oxide - antagonists & inhibitors; Phytotherapy; Plant Extracts - chemistry; Plant Extracts - pharmacology; Plant Extracts - therapeutic use; Plant Leaves - chemistry; Stomach Ulcer - chemically induced; Stomach Ulcer - drug therapy; Sulfhydryl Reagents - pharmacology; Syzygium - chemistry; Tannins - analysis
• ISSN: 0918-6158; 1347-5215
• DOI: 10.1248/bpb.b13-00514

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.