Procyanidin B3Procyanidin B3 is a B type proanthocyanidin. Procyanidin B3 is a catechin dimer.Natural occurrencesIt can be found in red wine, in barley, in beer, in peach or in Jatropha macrantha, the Huanarpo Macho.Health effectsIt has been identified as a hair-growth stimulant.Chemical synthesisMolar equivalents of synthetic -leucocyanidin and -catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-- and -bi- the all-trans-- and -tri-.