Medicarpin, a legume phytoalexin, stimulates osteoblast differentiation and promotes peak bone mass achievement in rats: evidence for estrogen receptor β-mediated osteogenic action of medicarpin. medicarpin (Med); a phytoalexin that is structurally related to isoflavones and is found in dietary legumes. Co-activator interaction studies demonstrated that Med acted as an estrogen receptor (ER) agonist; however, in contrast to 17β-estradiol, Med had no uterine estrogenicity and blocked proliferation of MCF-7 cells. Med increased protein levels of ERβ in osteoblasts. Selective knockdown of ERα and ERβ in osteoblasts established that osteogenic action of Med is ERβ-dependent. Med treatment resulted in increased formation of osteoporgenitor cells in the bone marrow and osteoid formation (mineralization surface, mineral apposition/bone formation rates) compared with vehicle group. In addition, Med increased cortical thickness and bone biomechanical strength.
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