Isolation and Identification of Novel Taste-Modulating N2-Guanosine 5'-Monophosphate Derivatives Generated by Maillard-Type Reactions

Abstract

Several compounds with taste-modulating properties have been investigated, improving the taste impression without having a pronounced intrinsic taste. The best-known representatives of umami taste-modulating compounds are ribonucleotides and their derivatives. Especially the thio derivatives showed high taste-modulating potential in structure-activity relationship investigations. Therefore, this study focuses on the formation of guanosine 5'-monophosphate derivatives consisting of Maillard-type generated compounds like the aroma-active thiols (2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-furfurylthiol) and formaldehyde to gain insights into the potential of combinations of taste and aroma-active compounds. One literature-known (N²-(furfurylthiomethyl)-guanosine 5'-monophosphate) and three new derivatives (N²-(2-methyl-1-furylthiomethyl)-guanosine 5'-monophosphate, N²-((5-hydroxymethyl)-2-methyl-1-furylthiomethyl)-guanosine 5'-monophosphate, N²-((2-pentanon-1-yl)thiomethyl)-guanosine 5'-monophosphate) were successfully produced using green natural deep eutectic solvents and isolated, and their structures were completely elucidated. Besides the intrinsic taste properties, the kokumi and umami taste-modulating effects of the four derivatives were evaluated via psychophysical investigations, ranging from 19 to 22 μmol/L.

Keywords: 2-methyl-3-furanthiol; Maillard-type model reactions; guanosine 5′-monophosphate derivatives; taste modulating; umami.

Figure 1

ESI⁺-UHPLC-ToF-MS^E spectra (HDMS) of the compounds 1–4 (1: model reaction of FFT, formaldehyde, GMP fraction five out of eight; 2: MFT, formaldehyde, GMP fraction six out of eight; 3: MFT, formaldehyde, GMP fraction five out of eight; 4: MP, formaldehyde, GMP fraction six out of seven) using 20–60 eV ramp voltage (relative intensity [%]; mass-to-charge ratio (m/z) [Da]).

Figure 2

Excerpt of the H,C HMBC spectrum (500 MHz, 125 MHz, methanol-d₄, 298 K) of compound 3 with significant correlations.

Figure 3

Formation pathway of the Maillard-type reaction of formaldehyde, the aroma-active thiols (FFT, MFT, MP), and GMP for forming N²-Alkyl- and N²-arylthiomethylated GMP derivatives (adapted from Suess et al.).