Effect of an Aqueous Extract of <i>Entandrophragma utile</i> Bark on Gastric Acid Secretion in Rat and Isolated Ileum Contractility in Guinea pig

Abstract

Adjunct therapy is needed for patients with compromised gastrointestinal mucosa due to necessary aspirin usage against cardiovascular disorders. We tested the Nigerian bark extract of Entandrophragma utile on gastric acid secretion (GA) and peptic activity (PA). Rats were ligated at the pylorus for collection of gastric juice which was measured for PA spectrophotometrically using bovine serum albumin as substrate and for titratable GA using phenol red indicator. The extract was compared with ranitidine (histamine H₂-receptor antagonist). The extracted was tested on isolated guinea-pig ileum preparations for histaminergic responses and was compared with mepyramine (histamine H₁-antagonist). E. utile reduced GA to 1.33 + 0.6 uEq g^-1 from 2.82 + 0.7 uEq g^-1 in controls using 6h ligations. For 4h ligations, control PA (mg/dL BSA digested) was 38.75 + 4.05 which was lowered to 14.8 + 4.67 (p<0.01) by the extract and to 3.4 + 0.72 (p<0.001) by ranitidine. Chronic administration of E. utile decreased GA in 4h collections. E.utile, 10 -160 x 10^-3 g, antagonized 10 μg histamine-induced contractions by 28-62% dose-dependently. Mepyramine gave a parallel shift of the histamine dose-response graph to the right typical of a competitive antagonism. E. utile extract gave a non-parallel shift to the right with a lowering of maximal response typical of a non-competitive antagonism. The two properties of the E. utile extract on acid and pepsin may be valuable for patients on aspirin with compromised mucosa therefore the extract could be developed as adjunct therapy to minimize aggravation of mucosal damage by acid-peptic autodigestion.

Keyword: Entandrophragma utile, peptic ulcer, stomach acid, peptic activity, antisecretory, Shay rat