Sex-Driven Variation in Polar Metabolites and Lipid Motifs of Paracentrotus lividus Gonads Profiled by 1H NMR

Sea urchin gonads (“roe”) are a valuable seafood product and a chemically complex matrix whose composition varies with physiology and environment. We present a biphasic extraction and ¹H NMR workflow to build a reusable reference inventory of polar metabolites and apolar lipid features in Paracentrotus lividus. Gonads from 37 adults (23 males, 14 females) collected at two sites (Alicante and Jávea–Dénia, Spain; October 2024) were lyophilized, extracted with methanol/chloroform/water, and analysed by 400 MHz ¹H NMR in buffered aqueous solution (polar) and CDCl₃ (apolar). Polar metabolite identification combined 1D patterns with database matching and ¹H–¹³C HSQC confirmation on representative samples, yielding 71 annotated resonances corresponding to 37 metabolites spanning amino acids, osmolytes/quaternary amines, carbohydrates/aminosugars, and nucleoside/purine-related compounds. Polar fingerprints enabled supervised modelling: PLS-LDA separated sexes with low cross-validated error, and SPA/COSS ranking highlighted glycine, alanine, creatine and osmolyte-associated signals as key discriminants; pathway mapping supported enrichment of amino-acid and one-carbon/purine networks. Apolar spectra were annotated at motif level and used for lipid-index estimation, indicating substantial unsaturation but low DHA and modest sex effects. The curated peak lists and reporting framework facilitate reproducible NMR annotation and future comparative studies of P. lividus gonads.