It is well established that Parkinson's disease patients have a short chain fatty acid deficiency:
Short chain fatty acids and gut microbiota differ between patients with Parkinson's disease and age-matched controls.
ncbi.nlm.nih.gov/pubmed/275...
Sodium butyrate/butyric acid is a short chain fatty acid and, in every model of PD, has been shown to be effective in the lab dish and animal models.
Sodium butyrate improves locomotor impairment and early mortality in a rotenone-induced Drosophila model of Parkinson's disease.
europepmc.org/articles/PMC3...
Sodium butyrate rescues dopaminergic cells from alpha-synuclein-induced transcriptional deregulation and DNA damage.
medscape.com/medline/abstra...
Constipation is a known problem for PwP and Sodium Butyrate has been shown to improve symptoms in IBS patients with constipation:
Butyric acid in functional constipation
"They observed a statistically significant reduction in pain during defecation in patients who received microencapsulated sodium butyrate at a dose of 2 × 150 mg per day for 12 weeks compared with those who received placebo. After 4 weeks, a significant decrease in pain during defecation was reported by the study group, which was maintained for 12 weeks. In the 12th week, statistically significant changes in stool consistency and a reduction in the incidence of constipation were observed."
europepmc.org/articles/PMC4...
Sodium butyrate is not a prescription drug and can be purchased online:
amazon.com/sodium-butyrate/...
Phenylbutyrate is a sodium salt of an aromatic fatty acid, made up of an aromatic ring and butyric acid. Wikipedia.
It is a prescription drug currently not prescribed for PD.
Neuroprotective effects of phenylbutyrate against MPTP neurotoxicity.
ncbi.nlm.nih.gov/pubmed/156...
Phenylbutyrate Up-regulates the DJ-1 Protein and Protects Neurons in Cell Culture and in Animal Models of Parkinson Disease
jbc.org/content/286/17/1494...
Neuroprotective effects of phenylbutyrate against MPTP neurotoxicity.
jbc.org/content/286/17/1494...
Sodium Phenylbutyrate Controls Neuroinflammatory and Antioxidant Activities and Protects Dopaminergic Neurons in Mouse Models of Parkinson’s Disease
journals.plos.org/plosone/a...
Additionally, sodium phenylbuterate is being tested by the MJF Foundation:
Phenylbutyrate for Alpha-synuclein Clearance from the Brain
"We found that the drug increased the level of alpha-synclein in the bloodstream of all 40 people, strongly suggesting that the drug can stop alpha-synuclein from damaging dopamine neurons."
michaeljfox.org/foundation/...
Phase I Trial of Phenylbutyrate to Prevent Progression of Parkinson's Disease
michaeljfox.org/foundation/...
Researchers find drug that stops progression of Parkinson's disease in mice
phys.org/news/2011-03-drug-...
So either sodium butyrate or phenylbutyrate have great potential to treat constipation or potentially the elimination of alpha synuclein from PwP.