Preparation and immunological cross-reactions of penicilloic and penilloic acids.

Methods are described for the preparation of pure crystalline samples of the penicilloic and penilloic acids of penicillin G, carbenicillin, cloxacillin, floxacillin, methicillin, penicillin V, and ticarcillin and the penicilloic acids of amoxicillin, ampicillin, phenethicillin, and propicillin. The interaction between the compounds and rabbit antibenzylpenicilloyl antibodies was evaluated by hemagglutination inhibition measurements. A significant correlation was found in this system between the reactivity of penicilloic acids and the corresponding penilloic acids; on average, the penicilloic acids were more reactive on a molar basis by a factor of 11. The results are discussed in terms of the general immunochemistry and side-chain structure of the parent penicillins.