# Spatial mapping of PUFA incorporation into phospholipids with bisallylic deuteration

## TL;DR

This study introduces a new method to track how specific fatty acids are incorporated into phospholipids in mouse lung tissue using mass spectrometry imaging.

## Contribution

The novel bisallylic deuteration method enables precise tracking of DGLA metabolism and its phospholipid derivatives in vivo.

## Key findings

- Bisallylic deuteration allows clear m/z selection for phospholipids with deuterated DGLA and arachidonic acid.
- D-DGLA and D-arachidonic acid phospholipids were visualized in lung tissue with distinct localization.
- The method reduces background noise and spectral interferences in MS imaging.

## Abstract

MS imaging using stable isotope-labeled fatty acids provides a groundbreaking approach to precisely localizing exogenous fatty acids and their metabolites in vivo. However, challenges persist, particularly with fatty acids labeled with fixed isotopic numbers, which can lead to spectral interferences and limit the number of metabolites that can be detected. In this study, we employed a bisallylic deuteration method to synthesize dihomo-γ-linolenic acid (DGLA) isotopes with m/z values ranging from +4 to +8 Da relative to endogenous DGLA, which allowed us to meticulously dissect DGLA metabolism in mice using LC-quadrupole TOF-MS and MS imaging. Our strategy enabled the clear selection of m/z values for phospholipids enriched with deuterated DGLA (D-DGLA) and deuterated arachidonic acid derived from D-DGLA, all while maintaining low background noise. This precision facilitated the successful visualization of D-DGLA and D-arachidonic acid-containing phospholipids in lung tissue, revealing their distinct localization compared with endogenous phospholipids. Our findings highlight bisallylic deuteration as a powerful tool for elucidating the in vivo dynamics of exogenous PUFAs through MS imaging techniques.