MOLECULAR HETEROGENEITY OF PAF IN NORMAL HUMAN MIXED SALIVA - QUANTITATIVE MASS-SPECTRAL ANALYSIS AFTER DIRECT DERIVATIZATION OF PAF WITH PENTAFLUOROBENZOIC ANHYDRIDE

Platelet-activating factor (PAF), a family of phospholipid autacoids w ith potent pro-inflammatory activities, is present in saliva. The curr ent study has quantitated various species of PAF isolated from normal human mixed saliva. Choline-containing, sn-2 acetylated phospholipids with sn-1 ether- or ester-linked fatty alcohol/acid moieties (alkyl-PA F or acyl-PAF, respectively) were evaluated after direct derivatizatio n with pentafluorobenzoic (PFB) anhydride. Individual species of PFB-d erivatized PAF were separated by gas chromatography prior to mass spec tral analysis; quantitative estimates of six different species of PAF in saliva were made by comparison to corresponding authentic, syntheti c PAF standards. In each saliva sample, all six species of PAF were re adily detected by this facile procedure. The predominant PAF was 1-O-h exadecyl-2-acetyl-sn-glycero-3-phosphocholine or 16:0-alkyl-PAF (0.75 +/- 0.09 pmol/ml saliva; mean +/- S.E.; n = 5) which represented only 30.4 +/- 1.5% of the total PAF. Substantial amounts of 18:1- and 18:0- alkyl-PAF and 16:0-acyl-PAF were also identified (0.52 +/- 0.07, 0.35 +/- 0.06, and 0.35 +/- 0.02 pmol/ml saliva, respectively). In summary, mass spectrometric analysis of PAF after direct derivatization with P FB anhydride has revealed that at least six different species of PAF a re present in normal human mixed saliva. This structural diversity may represent an important aspect of homeostasis in the healthy oral cavi ty.