Procyanidin B‐3, isolated from barley and identified as a hair‐growth stimulant, has the potential to counteract inhibitory regulation by TGF‐β1

Abstract: With the aim of identifying natural products, which possess hair‐growing activity, we examined more than 1000 plant extracts with respect to their growth‐promoting effects on hair epithelial cells. We discovered intensive growth‐promoting activity, about 140% relative to controls, in barley extract. Our strategy for identifying active compounds in barley extract involved subjecting it to column chromatography using HP‐20 resin columns, an LH‐20 resin column, and preparative high‐performance liquid chromatography (HPLC) using an ODS column. The 60% (v/v) aqueous methanol eluted fraction from the HP‐20 column and the 75% (v/v) aqueous methanol eluted fraction from the subsequent LH‐20 column showed high hair‐growing activity in vivo. We isolated two major substances from the LH‐20 active fraction using preparative HPLC. By means of mass spectrometry, 1H‐NMR, and 13C‐NMR analyses, one substance was revealed to be procyanidin B‐3 and the other substance was identified as (+)‐catechin. Purified procyanidin B‐3 showed high hair‐growing activity in the form of in vitro hair epithelial cell growth‐promoting activity and in vivo anagen‐inducing activity; however (+)‐catechin showed no hair‐growing activity. For the purpose of examining the hair‐growing mechanisms of procyanidin B‐3, we examined its relationship to the TGF‐β signal pathway, which is known to be a regulator of catagen induction. Addition of TGF‐β1 to hair epithelial cell cultures dose‐dependently decreased the cell growth, and addition of procyanidin B‐3 to the culture neutralized the growth‐inhibiting effect of TGF‐β1. From these results, it is concluded that procyanidin B‐3 can directly promote hair epithelial cell growth in vitro, has the potential to counteract the growth‐inhibiting effect caused by TGF‐β1 in vitro, and has potential to stimulate anagen induction in vivo.