Hydrogen sulfide (H₂S)-releasing compounds, also known as H₂S donors, represent a promising therapeutic approach for neurodegenerative diseases. These compounds deliver exogenous H₂S or H₂S-releasing moieties to target tissues, bypassing the limitations of endogenous H₂S production 1. Unlike gaseous H₂S, which has rapid metabolism and potential toxicity at high concentrations, H₂S-releasing compounds provide controlled, sustained release of H₂S with improved safety profiles. [1]
The therapeutic potential of H₂S donors stems from H₂S's multifaceted neuroprotective properties, including antioxidant, anti-inflammatory, anti-apoptotic, and mitochondrial protective effects 2. This therapy aims to augment deficient endogenous H₂S signaling in neurodegenerative conditions while avoiding the challenges associated with direct H₂S administration. [2]
H₂S-releasing compounds differ in their release profiles, which critically influences their therapeutic applications: [3]
| Compound | Release Kinetics | Half-life | Primary Mechanism | [4]
|----------|-----------------|-----------|-------------------| [5]
| GYY4137 | Slow, sustained | ~24-48 hours | Temperature/pH-dependent hydrolysis | [6]
| NaHS | Rapid release | Minutes | NaHS → H₂S + Na⁺ in aqueous solution | [7]
| AP39 | Mitochondria-targeted | Hours | mitochondria-specific release via mitochondria-targeting moiety | [8]
| SG1002 | Moderate | ~6-12 hours | Thiol-activated release | [9]
H₂S-releasing compounds modulate the activity of key H₂S-producing enzymes: [10]
CBS is the primary H₂S-producing enzyme in the central nervous system. H₂S donors can: [11]
CSE plays a complementary role in H₂S production, particularly in peripheral tissues: [12]
3-MST operates primarily in mitochondria: [13]
H₂S released from donors activates multiple downstream targets: [14]
GYY4137 (morpholin-4-yl 1-morpholoino carboniodithioate) is a prototype slow-releasing H₂S donor: [15]
The ACS series (ACS1-16) represents next-generation H₂S donors with improved: [16]
AP39 ((10-oxo-10-(pyridin-2-yl)decyl)triphenylphosphonium) is a mitochondria-targeted H₂S donor: [17]
AP123 is an improved mitochondria-targeted donor with:
SG1002 is a thio-activated H₂S donor:
NaHS is a classic H₂S donor that rapidly releases H₂S:
H₂S-releasing compounds demonstrate significant protection against amyloid-beta (Aβ)-induced neurotoxicity:
| Compound | Indication | Phase | Status | Trial ID |
|---|---|---|---|---|
| SG1002 | Heart failure | Phase I | Completed | NCT02483338 |
| SG1002 | Pulmonary hypertension | Phase I | Completed | NCT02984020 |
| GYY4137 | Preclinical only | N/A | N/A | N/A |
| NaHS | Preclinical only | N/A | N/A | N/A |
| AP39 | Preclinical only | N/A | N/A | N/A |
H₂S-releasing compounds generally show favorable safety profiles:
Potential adverse effects include:
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