Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Short communication First-principles identification of C-methyl-scyllo-inositol (mytilitol) – A new species-specific metabolite indicator of geographic origin for marine bivalve molluscs (Mytilus and Ruditapes spp.) Violetta Aru a, ⁎ , Mohammed Saddik Motawie b , Bekzod Khakimov a , Klavs Martin Sørensen a , Birger Lindberg Møller b , Søren Balling Engelsen a a Chemometrics & Analytical Technology, Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark b Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark ARTICLE INFO Keywords: NMR spectroscopy Metabolomics Foodome Seafood Bivalve molluscs Mytilitol C-methyl-scyllo-inositol Seven-carbon (7-C) sugar alcohols ABSTRACT This study presents a level-1 identification of the seven carbon (7-C) sugar C-methyl-scyllo-inositol (mytilitol) in mussels and clams (Mytilus and Ruditapes spp., respectively) purchased in Denmark and Italy. For each sample, the hydrophilic extract of the soft tissue was analyzed by proton nuclear magnetic resonance ( 1 H NMR) spec- troscopy using a 600 MHz NMR spectrometer. A first tentative identification of mytilitol was carried out by computing a statistical total correlation spectroscopy (STOCY) analysis of the 1 H NMR spectra, followed by a level-1 identification based on first-principles methods including chemical synthesis, structure elucidation and standard-addition experiments. Mytilitol was quantified in the 1 H NMR spectra and its average relative con- centration turned out to be significantly lower in clams than in mussels (p-value < 0.001), with Danish mussels having the highest mytilitol concentration. Principal component analysis (PCA) of the NMR dataset brought further evidence to a species-specific and geographic-dependent content of mytilitol in mussels and clams. 1. Introduction A great variety of seafood products, from tunicates to microalgae, are important sources of natural compounds highly appreciated for their nutritional value and beneficial properties (Hamed, Özogul, Özogul, & Regenstein, 2015). These compounds include poly- unsaturated fatty acids (PUFA), polysaccharides, essential minerals and vitamins, antioxidants, enzymes and bioactive peptides (Aru, Khakimov, Sørensen, & Engelsen, 2018). In the marine environment, suspension feeders, such as bivalve molluscs (i.e. mussels and clams), are considered the best reservoirs of functional compounds (Odeleye, White, & Lu, 2019), which are accumulated as a result of the feeding process. Over the last decade, marine molluscs, including bivalves, have received significant attention in the search for novel biologically active compounds for use in the nutritional, clinical and cosmeceutical fields (Ahmad, Liu, Kotiw, & Benkendorff, 2018; Benkendorff, 2010; Hamed et al., 2015; Odeleye et al., 2019). Due to the anti-inflammatory properties and positive impact on cardiovascular diseases, ω-3 PUFA are amongst the most studied beneficial compounds (Demaison, Leger, Vergely, Rochette, & Azarnoush, 2019; Grienke, Silke, & Tasdemir, 2014). Bioactive molecules are also amino acids and peptides with antioxidant activity, and several carbohydrates, the main energy sub- strates for all animal species (Grienke et al., 2014). Much less well studied are seven-carbon (7-C) sugars and sugar alcohols, which are commonly found in plants and algae (Cowan, 2016). Their physiolo- gical functions mainly involve metal ion chelation, translocation and remobilization to fulfil the nutrient demand, which in turn suggests a role in the organism’s growth and development (Cowan, 2016). In the aquatic environment, the biosynthesis of 7-C sugars and sugar alcohols is mainly confined to the Phaeophyta, Rhodophyta and Chlorophyta divisions. While a wealth of information can be retrieved on their dis- tribution in plants and algae, very little is known about the metabolism, occurrence and distribution of 7-C sugars and sugar alcohols in marine animals, including bivalve molluscs. In the recent years, metabolomics and foodomics have proven to be effective approaches for analyzing the chemical components of food, and for measuring and monitoring the interactions of food with the human body (Cifuentes, 2012a; Wishart, 2008). Through the compre- hensive and high-throughput analysis of the foodome – defined as the “collection of all compounds (chemical substances) present in an https://doi.org/10.1016/j.foodchem.2020.126959 Received 23 October 2019; Received in revised form 29 April 2020; Accepted 29 April 2020 ⁎ Corresponding author. E-mail addresses: violetta@food.ku.dk (V. Aru), mosm@plen.ku.dk (M.S. Motawie), bzo@food.ku.dk (B. Khakimov), kms@food.ku.dk (K.M. Sørensen), blm@plen.ku.dk (B.L. Møller), se@food.ku.dk (S.B. Engelsen). Food Chemistry 328 (2020) 126959 Available online 30 April 2020 0308-8146/ © 2020 Elsevier Ltd. All rights reserved. T