# Accelerated dl-Amino Acid Quantification of Deep Sea Water from Toyama Bay and Anti-Aging Activity Investigation Using Caenorhabditis elegans

## TL;DR

This study develops a fast method to measure amino acids in deep seawater and shows it has anti-aging effects in worms.

## Contribution

A novel reagent and method for rapid dl-amino acid quantification in deep seawater is developed.

## Key findings

- Deep seawater from Toyama Bay contains 10–100 nmol/L of dl-amino acids.
- d-Leucine, d-valine, and other d-AAs were found at higher concentrations.
- DSW reduced d-aspartic acid levels and extended worm lifespan.

## Abstract

Deep seawater (DSW),
defined as seawater deeper than 200 m, has
notable applications in various fields such as energy, agriculture,
food, cosmetics, and public health. Several studies have attributed
its utility to mineral effects; however, its organic compounds have
rarely been investigated. To support mechanistic evidence related
to DSW, a sensitive analytical method was developed for the individual
analysis of d- and l-amino acids (AAs) using enantiochemical
tagging–liquid chromatography–tandem mass spectrometry.
A novel reagent, 2,4-dichloro-6-methoxy-1,3,5-triazine-d-leucine,
was developed to enable high-speed analysis of individual dl-AAs, allowing quantification of 19 proteogenic and 2 nonproteogenic dl-AAs within 17 min. Furthermore, this reagent facilitated
rapid tagging of target AAs within 10 min of reaction. A limit of
detection of 10–100 pmol/L (in vial) was achieved, which was
sufficient to characterize the dl-AA profiles in DSW. Three
batches of DSW from Toyama Bay were quantitatively analyzed using
the spiking standard method, revealing dl-AA concentrations
of 10–100 nmol/L. Notably, d-leucine, d-valine, d-alanine, d-serine, d-threonine, and d-glutamic acid were detected at higher concentrations than
other d-AAs. A lifespan assay using the Caenorhabditis
elegans model demonstrated that DSW exhibited a clear
proliferative effect, similar to the positive control. Moreover, dl-AA analysis revealed a reduction in d-aspartic acid,
an established aging marker, in the proliferated groups.