# Mechanisms Underlying the Biological Effects of Molecular Hydrogen.
> 分子状水素の生物学的作用を支える機序に関する考察


## Abstract

Oxidative damage accumulation and dysregulated redox reactions contribute to diverse pathological conditions and aging processes. While antioxidants have been explored as countermeasures, effective options remain scarce. Molecular hydrogen (H2) has attracted attention as a selective scavenger of hydroxyl radicals and peroxynitrite, leaving functionally essential reactive oxygen species such as hydrogen peroxide and nitric oxide unaffected. Evidence from clinical studies, animal models, and cell culture experiments supports its beneficial properties. However, direct radical scavenging alone cannot fully account for the observed effects, particularly given that H2 operates at very low concentrations insufficient to neutralize continuously produced ROS. This review examines the possibility that H2 functions as a signaling molecule capable of activating cellular defense pathways. Both positive and negative aspects of endogenous H2 are analyzed, redox-sensitive pathway components are identified, and the potential regulatory role of H2 in cellular redox homeostasis is discussed.

### Mechanism

H2 selectively neutralizes hydroxyl radicals and peroxynitrite while sparing functionally important ROS. At low concentrations insufficient for continuous scavenging, H2 may act as a signaling molecule that activates redox-sensitive defense pathways within cells.

## Bibliographic

- **Authors**: Radyuk SN
- **Journal**: Curr Pharm Des
- **Year**: 2021
- **PMID**: [33308112](https://pubmed.ncbi.nlm.nih.gov/33308112/)
- **DOI**: [10.2174/1381612826666201211112846](https://doi.org/10.2174/1381612826666201211112846)
- **Study type**: review
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 33308112. https://h2-papers.org/en/papers/33308112
> **Source**: PubMed PMID [33308112](https://pubmed.ncbi.nlm.nih.gov/33308112/)