H₂S-Releasing Compounds Therapy

H₂S-Releasing Compounds Therapy

Overview

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">H₂S-Releasing Compounds Therapy</th>
</tr>
<tr>
<td class="label">Compound</td>
<td>Release Kinetics</td>
</tr>
<tr>
<td class="label">GYY4137</td>
<td>Slow, sustained</td>
</tr>
<tr>
<td class="label">NaHS</td>
<td>Rapid release</td>
</tr>
<tr>
<td class="label">AP39</td>
<td>Mitochondria-targeted</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Compound</td>
<td>Indication</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Heart failure</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Pulmonary hypertension</td>
</tr>
<tr>
<td class="label">GYY4137</td>
<td>Preclinical only</td>
</tr>
<tr>
<td class="label">NaHS</td>
<td>Preclinical only</td>
</tr>
<tr>
<td class="label">AP39</td>
<td>Preclinical only</td>
</tr>
</table>

H₂S-Releasing Compounds Therapy

Overview

<table class="infobox infobox-therapeutic">
<tr>
<th class="infobox-header" colspan="2">H₂S-Releasing Compounds Therapy</th>
</tr>
<tr>
<td class="label">Compound</td>
<td>Release Kinetics</td>
</tr>
<tr>
<td class="label">GYY4137</td>
<td>Slow, sustained</td>
</tr>
<tr>
<td class="label">NaHS</td>
<td>Rapid release</td>
</tr>
<tr>
<td class="label">AP39</td>
<td>Mitochondria-targeted</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Compound</td>
<td>Indication</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Heart failure</td>
</tr>
<tr>
<td class="label">SG1002</td>
<td>Pulmonary hypertension</td>
</tr>
<tr>
<td class="label">GYY4137</td>
<td>Preclinical only</td>
</tr>
<tr>
<td class="label">NaHS</td>
<td>Preclinical only</td>
</tr>
<tr>
<td class="label">AP39</td>
<td>Preclinical only</td>
</tr>
</table>

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](https://pubmed.ncbi.nlm.nih.gov/34758326/). 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. [@zhang2021]

The therapeutic potential of H₂S donors stems from H₂S's multifaceted neuroprotective properties, including antioxidant, anti-inflammatory, anti-apoptotic, and mitochondrial protective effects [2](https://pubmed.ncbi.nlm.nih.gov/32977345/). This therapy aims to augment deficient endogenous H₂S signaling in neurodegenerative conditions while avoiding the challenges associated with direct H₂S administration. [@liu2020]

Mechanism of Action

H₂S Release Kinetics

H₂S-releasing compounds differ in their release profiles, which critically influences their therapeutic applications: [@cao2022]

Enzyme Modulation

H₂S-releasing compounds modulate the activity of key H₂S-producing enzymes: [@zhou2019]

Cystathionine β-Synthase (CBS)

CBS is the primary H₂S-producing enzyme in the central nervous system. H₂S donors can: [@liu2020a]

• Upregulate CBS expression through transcriptional activation [3](https://pubmed.ncbi.nlm.nih.gov/36278901/)
• Enhance CBS activity via post-translational modifications
• Modulate CBS coupling status to increase H₂S production from L-cysteine

Cystathionine γ-Lyase (CSE)

CSE plays a complementary role in H₂S production, particularly in peripheral tissues: [@tao2019]

• H₂S donors can enhance CSE activity [4](https://pubmed.ncbi.nlm.nih.gov/34125678/)
• CSE-derived H₂S contributes to vascular protection and anti-inflammatory effects

3-Mercaptopyruvate Sulfurtransferase (3-MST)

3-MST operates primarily in mitochondria: [@lu2018]

• AP39 and similar mitochondria-targeted donors enhance 3-MST function [5](https://pubmed.ncbi.nlm.nih.gov/32890123/)
• Mitochondrial H₂S production supports electron transport chain function

Molecular Targets

H₂S released from donors activates multiple downstream targets: [@giorgi2017]

Classes of H₂S Donors

Slow-Release Donors

GYY4137

GYY4137 (morpholin-4-yl 1-morpholoino carboniodithioate) is a prototype slow-releasing H₂S donor: [@polito2016]

• Releases H₂S slowly over 24-48 hours
• Has been extensively studied in preclinical models [6](https://pubmed.ncbi.nlm.nih.gov/31594412/)
• Shows neuroprotective effects in both acute and chronic neurodegeneration models
• Oral and intraperitoneal administration effective

ACS Series

The ACS series (ACS1-16) represents next-generation H₂S donors with improved: [@cao2018]

• Tissue specificity
• Release kinetics
• Drug-like properties

Mitochondria-Targeted Donors

AP39

AP39 ((10-oxo-10-(pyridin-2-yl)decyl)triphenylphosphonium) is a mitochondria-targeted H₂S donor: [@yang2020]

• Specifically accumulates in mitochondria due to triphenylphosphonium moiety [7](https://pubmed.ncbi.nlm.nih.gov/29229467/)
• Protects against mitochondrial dysfunction in neurodegenerative models
• Shows promise in reducing oxidative stress in [neurons](/entities/neurons)

AP123

AP123 is an improved mitochondria-targeted donor with:

• Enhanced cellular uptake
• Controlled H₂S release
• Reduced off-target effects

Thiol-Activated Donors

SG1002

SG1002 is a thio-activated H₂S donor:

• Activated by endogenous thiols (cysteine, glutathione)
• Provides physiologically relevant H₂S concentrations
• Currently in clinical development for cardiovascular applications [8](https://pubmed.ncbi.nlm.nih.gov/35618654/)

Classic H₂S Donors

Sodium Hydrosulfide (NaHS)

NaHS is a classic H₂S donor that rapidly releases H₂S:

• Used extensively in research
• Provides immediate but short-lived H₂S exposure
• Limited therapeutic utility due to rapid release kinetics

Preclinical Evidence

Alzheimer's Disease Models

Amyloid-Beta Toxicity

H₂S-releasing compounds demonstrate significant protection against [amyloid-beta](/proteins/amyloid-beta) (Aβ)-induced neurotoxicity:

• GYY4137 reduces Aβ-induced neuronal death in hippocampal cultures [9](https://pubmed.ncbi.nlm.nih.gov/30879456/)
• NaHS attenuates Aβ-induced oxidative stress and inflammation
• AP39 protects against mitochondrial dysfunction induced by Aβ

Tau Pathology

• H₂S donors reduce [tau](/proteins/tau) phosphorylation through modulation of [GSK-3β](/entities/gsk3-beta) activity [10](https://pubmed.ncbi.nlm.nih.gov/31789234/)
• Improve synaptic plasticity in AD models

Cognitive Deficits

• GYY4137 improves memory and learning in [APP](/entities/app-protein)/PS1 transgenic mice [11](https://pubmed.ncbi.nlm.nih.gov/32456234/)
• Restores hippocampal [long-term potentiation](/mechanisms/long-term-potentiation) (LTP)

Parkinson's Disease Models

MPTP/6-OHDA Models

• GYY4137 protects dopaminergic neurons in MPTP models [12](https://pubmed.ncbi.nlm.nih.gov/29154892/)
• Reduces striatal dopamine depletion
• Improves motor function

Alpha-Synuclein Models

• H₂S donors reduce [alpha-synuclein](/proteins/alpha-synuclein) aggregation [13](https://pubmed.ncbi.nlm.nih.gov/30368567/)
• Protect against alpha-synuclein-induced cytotoxicity
• Modulate [autophagy](/entities/autophagy) pathways

Mitochondrial Protection

• AP39 specifically protects mitochondrial function in dopaminergic neurons [14](https://pubmed.ncbi.nlm.nih.gov/28645328/)
• Reduces oxidative stress in substantia nigra

Amyotrophic Lateral Sclerosis (ALS) Models

SOD1 Models

• H₂S donors extend survival in SOD1-G93A mouse models [15](https://pubmed.ncbi.nlm.nih.gov/27568938/)
• Reduce motor neuron loss
• Attenuate gliosis

Excitotoxicity

• Modulate glutamate transport to reduce excitotoxicity
• Protect against oxidative stress in motor neurons

Stroke and Acute Brain Injury

• H₂S donors reduce infarct size in stroke models [16](https://pubmed.ncbi.nlm.nih.gov/30478291/)
• Provide neuroprotection through anti-apoptotic mechanisms
• Improve functional recovery

Clinical Trial Status

Completed and Ongoing Trials

Clinical Development Challenges

Future Directions

• Phase I trials for neurodegenerative indications anticipated
• Novel donors with enhanced brain penetration in development
• Combination therapies with existing treatments being explored

Safety Profile

General Toxicity

H₂S-releasing compounds generally show favorable safety profiles:

• GYY4137: Well-tolerated in animal studies up to 200 mg/kg [17](https://pubmed.ncbi.nlm.nih.gov/30638021/)
• AP39: No significant toxicity at therapeutic doses
• NaHS: Safe at low concentrations; high doses can cause respiratory depression

Adverse Effects

Potential adverse effects include:

Contraindications and Cautions

• Use cautiously in patients with compromised respiratory function
• Avoid in severe hepatic impairment (altered H₂S metabolism)
• Potential interactions with other gasotransmitter therapies

Cross-Links

• [Hydrogen Sulfide Signaling Pathway in Neurodegeneration](/mechanisms/hydrogen-sulfide-signaling-neurodegeneration) - Background on endogenous H₂S biology
• [Cystathionine Beta Synthase (CBS)](/cystathionine-beta-synthase-))))))))))))))) - Key enzyme in H₂S production
• [Cystathionine Gamma Lyase (CSE)](/genes/cse) - H₂S-producing enzyme
• [3-Mercaptopyruvate Sulfurtransferase (3-MST)](/proteins/3-mst-protein) - Mitochondrial H₂S production
• [Alzheimer's Disease](/diseases/alzheimers-disease) - Primary indication
• [Parkinson's Disease](/diseases/parkinsons-disease) - Primary indication
• [Amyotrophic Lateral Sclerosis (ALS)](/diseases/amyotrophic-lateral-sclerosis) - Target indication
• [Mitochondrial Dysfunction](/mechanisms/mitochondrial-dysfunction-neurodegeneration) - Key mechanism
• [Neuroinflammation](/mechanisms/neuroinflammation) - Therapeutic target
• [Oxidative Stress](/mechanisms/oxidative-stress-neurodegeneration) - Key pathological mechanism

See Also

• [Hydrogen Sulfide Signaling Pathway in Neurodegeneration](/mechanisms/hydrogen-sulfide-signaling-neurodegeneration)
• [Cystathionine Beta Synthase (CBS)](/cystathionine-beta-synthase-)))))))))))))))
• [Cystathionine Gamma Lyase (CSE)](/genes/cse)
• [3-Mercaptopyruvate Sulfurtransferase (3-MST)](/proteins/3-mst-protein)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Amyotrophic Lateral Sclerosis (ALS)](/diseases/amyotrophic-lateral-sclerosis)
• [Mitochondrial Dysfunction](/mechanisms/mitochondrial-dysfunction-neurodegeneration)
• [Neuroinflammation](/mechanisms/neuroinflammation)
• [Oxidative Stress](/mechanisms/oxidative-stress-neurodegeneration)

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/)
• [KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

References

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From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

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