Spectrofluorometric determination of L-tryptophan in canary (Canarium indicum L.) seed protein hydrolysate

Ilma Nugrahani 1*, Ismail Miftah Abotbina 1, Cynthia Nurul Apsari 1,2, Tutus Gusdinar Kartawinata 1, Sukrasno 1, Rozana Oktaviary 1

1School of Pharmacy, Bandung Institute of Technology, Indonesia

2 Faculty of Pharmacy, Gadjah Mada University, Indonesia

*corresponding author e-mail address: ilma_nugrahani@fa.itb.ac.id | Scopus ID 24335737400

Biointerface Research in Applied Chemistry, Volume 10, Issue 1, 2020, 4780 – 4785, https://doi.org/10.33263/BRIAC101.780785


Canary (Canarium indicum L.) is an indigenous plant of Indonesia, which mainly grows in the eastern part of Indonesia, especially in the Maluku, North Sulawesi, and Seram islands. We believe that no scientific reports have been conducted about L-tryptophan   content in Canarium indicum. Therefore, this study was conducted to determine the presence and quantitate the aromatic amino acid (L-tryptophan) in the canary protein hydrolysate by the spectrofluorometric method. The protein hydrolysate was prepared by two hydrolysis methods, enzymatic and alkaline hydrolysis. L-tryptophan   can be differentiated from tyrosine directly without using any reagent by excitation of the sample at 295 nm in order to avoid tyrosine emission. The equation of calibration curve correlation using standard in the range 0.5-5 ppm was y = 6632.3x – 845.42 and correlation coefficient of 0.9997, while the coefficient of variance in linear regression was 1.29%. The detection limit and quantification limit obtained were 0.116 ppm and 0.35 ppm respectively. The recoveries of the accuracy test were obtained in the range of 95-96%. The relative standard deviation of intra-assay precision tests were obtained in the range of 0.5-1.8%, while the intermediate precision in the range of 2.18-3.74%. L-tryptophan   was detected in all samples (papain, pepsin, and alkaline hydrolysate), with concentrations 5.6, 5 and 1.53 mg/100mg of protein respectively. The used fluorometric method complied with the validation requirements and can be used to analyze L-tryptophan   in samples containing tyrosine without overlapping of spectra and without the use of any specific reagent.

Keywords: Canarium indicum; analysis; L-tryptophan; spectrofluorometric.