Chrysin

Chrysin is a natural compound, a type of flavonoid, found in honey, propolis and passionflower, and it is studied for how it interacts with enzymes involved in hormone balance. People mostly look at it for low testosterone, but the research is thin: the one small study found no clear difference in testosterone, and the evidence is very limited. That study followed just 20 men and measured urinary testosterone, so it says little about longer use or other groups.

Sources: PMID 14977449