Date of Award

1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

William A. Pryor

Abstract

Ozonation of methyl oleate has been shown for the first time to form ozonides in aqueous micelles of sodium dodecyl sulfate (SDS) and in L-$\alpha$-distearoyl-phosphatidylcholine (DSPC) liposomes. The total yield of ozonides in 0.02 M SDS micelles exposed to 26 ppm ozone at pH 7.4 and 22$\sp\circ$C is 11.1%. This 11.1% consists of 7.5% of the normal ozonide (MOO2), ca. 4.2% of trans-isomer and ca. 3.3% of cis-isomer, and the rest 3.6% is accounted for by the cross ozonides (MOO1 and MOO3). Regarding the hydrolytic stability of the ozonides under physiologically relevant conditions (e.g., pH 7.4 and 37$\sp\circ$C), the half-lives of trans-MOO2 and cis-MOO2 in 0.10 M SDS micelles are 22.6 days and 6.1 days respectively. The demonstration of formation and stability of ozonides in such aqueous systems as micelles and liposomes would mean that they may be formed in vivo and may serve as potential marker molecules for ozone reactions in lung surfactant or cell membranes. Additionally, the formation of ozonides in vivo could have potential toxicological significance, since they are shown to initiate the autoxidation of methyl linoleate in 0.10 M SDS micelles at pH 7.4 and 37$\sp\circ$C. Detailed $\sp1$H and $\sp{13}$C 400 MHz NMR data for the ozonide ring protons and carbons in MOO1, MOO2, and MOO3 as well as cis-MOO2 and trans-MOO2 are presented for the first time. Also presented are extensive UV, IR, HPLC and MS data for the ozonides of methyl oleate. Coming to the second portion of the dissertation, the relative antioxidant efficiencies (RAE) of 12 naturally occurring and synthetic antioxidants have been determined in both 0.10 M SDS and 0.10 M hexadecyl trimethylammonium bromide (HDTBr) micelles by following the formation of conjugated dienes (CD) spectrophotometrically at 234 nm in a model system using inhibited autoxidation of linoleic acid. The RAE values in SDS micelles for $\beta$-, $\gamma$- and $\delta$- tocopherols, 2,6-di-tert-butyl-4-methyl-phenol (BHT), ascorbyl palmitate, and ascorbic acid as compared to $\alpha$-tocopherol are in good agreement with the literature values using other methodologies. Micelles of different charge types are shown to have a significant effect on the relative antioxidant efficiency of charged antioxidants such as ascorbic acid and Trolox C.

Pages

196

DOI

10.31390/gradschool_disstheses.5218

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