Ionization biologically-active anions

The ionization as anions of many commonly used anti-inflammatory agents is positively correlated with their biological action provided that ionization is not complete and that they are sufficiently lipophilic to reach their prostaglandin-inhibiting site of action. Examples include indomethacin 4.5) and the salicylates (Whitehouse and Dean, 1965). In the phenylindanedione 9.39) series, observation of the effect of varying the (on the anti-inflammatory action) pointed to a need for more accurate determinations of in the or Ao-substituted aryl derivatives, which are by far the most biologically active (van der B vgetaL, 1975). 

Many other eicosanoids, such as thromboxanes, lipoxins, 0x0 eicosanoids, hydroperoxy eicosanoids, hydroxyeicosatetraenoic acids, epoxyeicosatetraenoic acids, and isoprostanes, are also biologically active molecules. ESI has emerged as an efficient ionization method for these classes of eicosanoids. An abundant carboxylate anion is produced in the negative-ion ESI mode [59]. Low-energy CID of the ESI-produced [M — H] ions of these molecular species produces structurally distinct ions for these disparate molecular species. 

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