Analysis of human oral mucosa ex vivo for fatty acid compositions using Fourier-transform infrared spectroscopy.

The purpose of this research was to develop an infrared spectroscopic technique (Fourier transform infrared spectroscopy with attenuated total reflectance system; FTIR-ATR) for non-invasive measurement of saturated and unsaturated fatty acid compositions in human oral mucosa obtained from three nationalities; Iranian, Vietnamese, and Indonesian. The histogram patterns of fatty acid compositions for three nationalities suggest that the pattern of unsaturated fatty acids were quite different, although the distribution profiles of fatty acid to lipid ratios in FTIR-ATR has a similar normal pattern with small difference in skewness and mode. The second derivative infrared spectra of the mucosal tissues in the wavenumber regions from 1,600 to 1,760 cm(-1) and 2,800 to 3,050 cm(-1) were analyzed with partial least squares (PLS) multivariate regression analysis method. With this analysis method we compared predicted values with the measured values of ten categorized fatty acid compositions, i.e., a(saturated C17 or lower), b(C16:1 + C17:1), c(C18:0), d(C18:1), e(C18:2), f(saturated C20 or longer), g(C20:3 + C20:4), h(C22:1 + C24:1), i(C22:6), j(gammaC18:3). Almost all fatty acid compositions of oral mucosa were well predicted with differences between predicted and measured values within +/-5% of total, however, errors were relatively larger in minor components such as C22:6 than major components.