This is a list of the best compounds with the ability to reach the human brain and have been shown in test tube or animal research to slow or stop the accumulation of misfolding a-Syn. The first 4 have the added evidence that they work in humans by epidemiological studies. Most of the other compounds listed do not have epidemiological evidence because they are not consumed in large enough quantities, not because they are less effective. There is every good reason to believe most of these slow PD in humans.
This is not all the compounds that help PD. There are many others that alleviate symptoms, reduce inflammation, chelate iron, cause neurogenesis, improve mitochondria function, and reduce oxidation. This also does not include basic RDA nutrients that have also been shown to result in less PD in humans (vitamins A, D, B's, magnesium, and zinc).
Most people do not have the time, ability, and/or desire to really go through this list, let alone take more than 3 of them, so isolating what is best is important. My main point is to show PD research is extensive and succeeding. Most of this research in a-syn misfolding for these compounds has occurred in the just the past 3 to 5 years.
Also shown in human epidemiological work
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caffiene
nicotine
Black tea (maybe the gallic acid that may not be present in the extracts)
EGCG (green tea extract)
grape seed extract (gallic acid)
Myricetin (in many plants)
Morin (orange, guava)
apigenin (parsley, celery, chamomile, dandelion)
baicalein (skullcap, a purple flower plant, powerful but appears to not make it to brain)
Nordihydroguaiaretic (a stilbene, may not absorb)
specific citrus compounds: naringin, tangeritin (expensive), HMF, morin, auraptene (VERY expensive)
less likely in one good paper, but still very possible
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Ginkgolide B (ginkgo)
Genistein (ginseng)
olive oil (ellagic acid)
Quercetin (e.g. apples)
Non-plant compounds
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nilotinib (pharmaceutical, primarily by increasing AMPK)
rasagiline (pharmaceutical)
methylene blue (common chemical, not completely safe)
4-phenyl butyrate (BPA)
rapamycin
fisetin (in strawberries, reduces a-syn expression, not exactly its misfolding directly)
myricetin: vegetables, fruits, nuts, berries, tea, and is also found in red wine. Structurally similar to fisetin, luteolin, and quercetin and is reported to have many of the same functions as these other members of the flavonol class of flavonoids
references to FULL text articles:
ncbi.nlm.nih.gov/pubmed/226...
ncbi.nlm.nih.gov/pubmed/182...
ncbi.nlm.nih.gov/pubmed/214...
rasagiline, methylene blue, BPA, baicalein
sciencedirect.com/science/a...
nicotine
ncbi.nlm.nih.gov/pubmed/128... (full)
nicotine and caffeine
ncbi.nlm.nih.gov/pubmed/250...
Grape Seed Extract (gallic acid)
ncbi.nlm.nih.gov/pubmed/241...
ncbi.nlm.nih.gov/pubmed/192... (full)
ncbi.nlm.nih.gov/pubmed/206...
naringin and rutin
ncbi.nlm.nih.gov/pubmed/223...
tangeretin (tangeritin)
ncbi.nlm.nih.gov/pubmed/231...
ginseng
ncbi.nlm.nih.gov/pubmed/243...
ellagic acid
ncbi.nlm.nih.gov/pubmed/252...
heat shock proteins (hot baths and exercise)