> rosmarinic acid
rosemary oil. It is already known to be beneficial. I dont know why you'd go for a much more obscure source when rosemary extract/oils are widely available and dirt cheap. In 2015 Rosemary oil was demonstrated to be more efficacious than minoxidil 2% in a small study on men with Androgenetic Alopecia/male pattern baldness. The results weren't mindblowing or anything (5% vs 1.7% from memory) i always say the bigger takeway from the study is just how poorly effective minoxidil is despite its FDA approval, but since rosemary is dirt cheap and appears to be well tolerated, i dont think anyone has an excuse for not at least trying it out for a year.
rosmarinic is:
anti-androgenic
anti-inflammatory
inhibits fibrosis/scarring
vasodilator (promotes blood flow)
antibacterial
these are all related to hair loss pathology as we know it today, and while i dont expect rosemary to do anything dramatic as a monotherapy, given its dirt cheap supply and widespread availability, I think its silly for anyone to not at least consider adding it to a regimen.