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

## TL;DR

The study identifies sex-based differences in the chemical profiles of sea urchin gonads using NMR, providing a reference for future research.

## Contribution

A curated polar metabolite annotation and NMR workflow for sea urchin gonads, enabling reproducible metabolomics studies.

## Key findings

- Polar metabolite fingerprints distinguish male and female sea urchin gonads with low cross-validated error.
- Key discriminant metabolites include glycine, alanine, creatine, and osmolyte-associated signals.
- Apolar lipid analysis shows high unsaturation but low DHA and modest sex differences.

## Abstract

What are the main findings?
Paracentrotus lividus gonads show clear sex-linked 1H NMR fingerprints when polar and apolar fractions are profiled together.A curated polar metabolite annotation is provided (37 metabolites; 71 assigned resonances), supported by 1D NMR and HSQC confirmation.

Paracentrotus lividus gonads show clear sex-linked 1H NMR fingerprints when polar and apolar fractions are profiled together.

A curated polar metabolite annotation is provided (37 metabolites; 71 assigned resonances), supported by 1D NMR and HSQC confirmation.

What are the implications of the main findings?
The curated peak list and reporting workflow offer a reusable reference framework for reproducible NMR metabolomics in sea urchin gonads and related matrices.Sex-linked markers and lipid-motif readouts can be cited as a baseline for comparative studies (season, diet, site, aquaculture conditions) and for future authentication/quality investigations.

The curated peak list and reporting workflow offer a reusable reference framework for reproducible NMR metabolomics in sea urchin gonads and related matrices.

Sex-linked markers and lipid-motif readouts can be cited as a baseline for comparative studies (season, diet, site, aquaculture conditions) and for future authentication/quality investigations.

Background/Objectives: 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. Methods: 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 analyzed 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. Results: 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 the enrichment of amino-acid and one-carbon/purine networks. Apolar spectra were annotated at the motif level and used for lipid-index estimation, indicating substantial unsaturation but low docosahexaenoic acid (DHA) and modest sex effects. Conclusions: The curated peak lists and reporting framework facilitate reproducible NMR annotation and future comparative studies of P. lividus gonads.