INHIBITION OF EXPERIMENTAL IMMEDIATE HYPERSENSITIVITY REACTIONS BY A NOVEL XANTHONE, RU 31156

  • 1 January 1978
    • journal article
    • research article
    • Vol. 231  (2) , 328-339
Abstract
RU 31156, the tris-(hydroxymethyl)-aminomethane salt of 7-(S-methylsulfonimidoyl)-5-(n-hexyl)-xanthen-9-one-2-carboxylic acid was a potent inhibitor of experimental immediate hypersensitivity reactions in vivo. In the Ig[immunoglobulin]E-mediated rat PCA [passive cutaneous anaphylaxis] test, RU 31156 had an ED50 of 0.0046 (0.0037-0.0057) mg/kg which compared to a figure of 1.21 (1.04-1.42) mg/kg for disodium cromoglycate (DSCG), both compounds being administered i.v. RU 31156 was also active when administered orally, having an ED50 of 0.19 (0.07-0.30) mg/kg when given 10 min before antigen. RU 31156 partially inhibited an IgG-mediated PCA reaction in the rat. RU 31156 and DSCG inhibited anaphylactic bronchoconstriction in the rat, giving bell-shaped dose-response curves. From the upward part of the curves, approximate ED30 values of 0.02 and 2.0 mg/kg were obtained for RU 31156 and DSCG, respectively. Anaphylactic bronchoconstriction in the guinea pig was not affected by RU 31156 and pinnal anaphylaxis was inhibited at only relatively high doses of 1-10 mg/kg i.v. The effects of histamine and 5-hydroxytryptamine in the mouse pinna were not affected by RU 31156. In PCA experiments, RU 31156 showed self-tachyphylaxis following i.v. and oral administration. It also showed cross-tachyphylaxis with DSCG, indicating that these compounds are likely to share a similar mode of action.

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