Graduate Thesis Or Dissertation
 

The quantification of malonaldehyde in marine lipids with para-aminobenzoic acid

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/mc87pt491

Descriptions

Attribute NameValues
Creator
Abstract
  • Malonaldehyde, a very reactive member of the homologous series of dialdehydes, is associated with the autoxidative deterioration of lipids. Its measurement, in autoxidized lipid systems is an expression of the extent of oxidation, in lipids. Malonaldehyde lends itself well to such determinations because of the sensitivity and specificity of its quantification in complex lipid systems. Complete knowledge of the formation of malonaldehyde in autoxidized lipids. is lacking. Such knowledge would undoubtedly promote a better understanding of lipid autoxidation mechanisms. In this investigation, a method for detecting malonaldehyde through the use of its reaction with p-aminobenzoic acid was developed. This was adapted for use in measuring malonaldehyde in lipids and in tissue samples. The reaction between p-aminobenzoic acid and malonaldehyde was partially characterized, and a mechanism for the formation of the reaction product was postulated. The quantification of malonaldehyde in lipid systems by the use of p-aminobenzoic acid involves the use of a mild reducing agent such as stannous chloride to prevent interference from hyd roperoxides present in the system. The p-aminobenzoic acid reaction is highly specific for malonaldehyde and proceeds smoothly and rapidly at room temperature in a non-aqueous chloroform-methanol solvent system to yield a highly colored compound having a maximum absorbance at 406 mμ. and with a molar absorptivity of 73,500. The absorbance value may be converted directly to parts-per-million malonaldehyde through the use of a conversion factor in a simple equation. The limits of detectability of themethod are on the order of one ppm malonaldehyde. The measurement of malonaldehyde in the lipid fraction of tissue samples involves the prior extraction of the lipid with a non-aqueous chloroform-methanol solvent, by an extraction method which was developed for this purpose. The reaction of malonaldehyde with p-aminobenzoic acid involves the condensation of two molecules of p-aminobenzoic acid with one molecule of malonaldehyde. The reaction exhibits a rate maximum at a hydrogen ion concentrations of about 0.1 molar, and also exhibits rate dependencies upon the concentrations of both malonaldehyde and p-aminobenzoic acid. This strongly suggests that the reaction proceeds according to an S [subscript N] 2 mechanism. A postulated mechanism involves nucleophilic 1,4-addition of the amino nitrogen of p-aminobenzoic acid to the enol of malonaldehyde followed by-loss of water to form the enamine. The reaction with a second molecule of p-aminobenzoic acid involves nucleophilic substitution of the amino nitrogen at the carbonyl function of malonaldehyde followed by loss of water to form an imine linkage.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Scamax Scan+ V.1.0.32.10766 on a Scanmax 412CD by InoTec inPDF format. LuraDocument PDF Compressor V.5.8.71.50 used for pdf compression and textual OCR.
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details FOLLETTMARK1968.pdf 2017-08-15 Public Download