Profiling of Peak Intensity and Standard Deviation of Metabolites in Industrially Important Red Seaweed Gracilaria dura (Rhodophyta) by 1H NMR Spectra for Benchmarking

Abstract

Mapping of regulatory components of cellular functioning by 1H NMR metabolomics has recently paved the way to study biochemical pathways in plants. Despite the enormous complexity and heterogeneity of the metabolites, the estimation of molar concentration allows for their direct quantification without calibration for individual compounds. 1H NMR spectra of near-native extracts were recorded for a large number (55 each) of wild and cultured samples of the industrially important red seaweed Gracilaria dura to obtain quantitative data of all the metabolites. Average and standard deviation of the respective classes were calculated from 1H NMR spectra wherein significant differences between wild and cultured groups were observed in the 1.56–3.50 ppm region. A significant region in the wild samples having a low average (0–0.98) and standard deviation (0.2–0.81) was 1.56–2.96 ppm representing nitrogen-containing compounds. The same region was found to have a much higher standard deviation (0.13–1.73) with average (0–2.03) in cultured samples. In comparison, sugar metabolites (triethanolamine, galactose, lactate, threonine) have a high average peak intensity and similar standard deviation across both groups of samples. This observation reveals that sugar compounds are critical in central metabolic pathways while nitrogen compounds change due to the environment. PCA analysis revealed an interpretable overview of main information enclosed in a multidimensional data set; the differences were correlated to environmental determinants, developmental, and growth states. A signature metabolite profile is presented with minor standard deviation differences between significant parts of the 1H NMR spectra, confirming its use as a rapid chemo-taxonomic tool supplementary to the conventional approach.