Chlorogenic acid is a component of the coffee bean. There are favorable studies of its effect on Parkinson's in animal models. No interventional clinical studies that I know of.
Over a month ago I embarked on a personal trial of chlorogenic acid, 200 mg daily, taken in the morning. Over the ensuing weeks I noticed a gradual worsening of my motor impairment, objectively measurable as reduced hiking and rock scrambling ability. I was reluctant to attribute this to the chlorogenic acid, as I believed it ought to be helping. The last straw came 30 days in, when I felt obliged to take 4 doses of C/L 25/100 ER over the course of a day, instead of my usual 2 and 1/2 doses. In the 10 days since quitting I have experienced a gradual improvement, which confirms to me chlorogenic acid was the cause.
We are all different. What is true for me is not necessarily true for others. That said, I certainly will not be recommending this idea.
Chlorogenic acid was discussed here: