IDENTIFICATION AND QUANTIFICATION OF AMINO ACIDS FROM PSORIATIC AND NORMAL EPIDERMIS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Abstract

In this study, a modified fluorescence technique high performance liquid chromatography (HPLC) was adapted to separate the amino acids from the hydrolyzed keratin samples. These samples obtained from the epidermal layer of the normal and psoriatic human subjects. The keratin extracts were quantified in gram percentage of the dried skin and the amino acids concentrations were measured in μg/g, mean retention time (tR), slope value and the coefficient of determination (r2) of each eluted amino acid was calculated. The coefficients of variation for amino acid standards ranged from 0.12% to 0.28%, mean, standard deviation of peak area and coefficients of variation of peak area were calculated. From the normal hydrolyzed keratin protein fraction, 12 amino acids were determined and identified as aspartic acid, glutamic acid, asparagines, serine, glutamine, glycine, histidine, citrulline, arginine, β-alanine, tyrosine and valine. These amino acids were also determined in psoriatic samples while standard deviations (SD), standard error mean (SEM) and coefficient variation (CV%) of normal and psoriatic samples were also calculated. The higher concentration of amino acids in normal samples against psoriatic samples determined as glutamic acid 92.76±16.83/50.87±9.88, glutamine 198.05±18.74/19.74±3.74 while higher concentrations of amino acids was determined in psoriatic samples against normal samples such s asparagines 81.06±10.62/29.98±3.64/, arginine 164.42±35/46.14±8.46, tyrosine 214.38±29.61/59.64±8.82 and valine 169.7± 19.35/128.06±15.14. It is concluded that the absolute concentration of amino acids in psoriatic skin indicated a number of variations as compared to normal skin samples.