ABSTRACT

Background: Peptide derived from natural sources as candidate of new active pharmaceutical compound has been explored. Canarium nut (Canarium indicum), grown and consumed as traditional food mainly in Eastern Indonesia, was found to contain peptide which potentially holds pharmacological activity. While the determination of peptide content in natural sources has been conducted using various instruments, FTIR remains underutilized. It has been used in qualitative analysis of peptide but has not been applied yet on quantitative.  Objective: This study aimed to determine peptide content of Canarium nut and its hydrolysates using FTIR.  Materials and Methods: Hydrolysates were obtained by enzymatic (with papain and pepsin) and chemical hydrolysis (with alkaline reagent). Bovine Serum Albumin (BSA) as standard and Canarium nut were scanned from 4000-400 cm^-1 to determine a characteristic wavenumber. BSA spectra from a series of concentrations were derivatised and peak area of previously selected wavenumber were used to construct callibration curve. Peptide concentration in Canarium nut and its hydrolysates were determined. Results: The AUC calculated from 1724.05-1619.91 cm^-1, corresponds to C=O stretching in peptide bond, shows decent linearity profile with correlation coefficient (r) of 0,9977. The LOD and LOQ of this method are 0.12% w/w and 0.35% w/w. Compared to BSA, Canarium nut contains 5.08 times more peptide while papain hydrolysate, pepsin hydrolysate and alkaline hydrolysate contains 1.94, 1.71 and 1.45. Peptide content decreased by 38.24%, 33.67% and 28.53% in after hydrolysis using papain, pepsin and alkaline, respectively. Conclusion: Based on these results, the method is useful for determining peptide content in natural sources and could indicate the occurrence of hydrolysis as well as estimate its resulting fractions.

Key words: Canarium nut, peptide, hydrolysate, quantitative, FTIR, alkaline, enzymatic