So with this method with THF and potassium permanganate ...
Swim could use the piperine (from black pepper extract <95% pure piperine)
straight as is ?
Or
Convert the piperine to piperic acid (as usual, by reacting it with a hydroxide such as potassium hydroxide, then acidifying the formed piperate salt with hydrochloric acid or another acid.)
And then use the piperic acid with the THF and potassium permanganate method ?