Oestrogen modulation in the management of uterine fibroids: a potential role for herbal medicine

摘要

It is common to utilise herbal extracts such as Silybum marianum and Rosmarinus officinalis in naturopathic practice to support hepatic function and improve oestrogen clearance, but what pharmacodynamic evidence is there to support this hypothesis? This article explores the potential use of these two traditional hepatic herbs for the potential treatment of uterine fibroids via and their action on specific CYP450 enzymes. Uterine fibroids are benign smooth muscle overgrowths which occur in various locations in the myometrium and develop from an unknown cause. There is however a wide diversity of known promoters involved in the pathogenesis including steroid hormones, such as oestrogen. Excessive oestrogen synthesis from aromatase P450 can lead to an overexpression of alpha (ER-a) and beta (ER-β) oestrogen receptors, which through binding activity, causes a cascade of growth factors contributing to fibroid development. Considering this increased oestrogen activity has been implicated in stimulating uterine tissue, a novel approach to treating uterine fibroids is by inducing CYP1A1 and inhibiting CYP3A4 to improve the ratio between 2:16 hydroxy catechol oestrogens. Silybum marianum has shown potential in inhibiting CYP3A4 activity in vitro, but evidence from two small clinical trials did not support this. Rosmarinus officinalis shows promise by improving 2:16 hydroxy catechol oestrogen ratio equilibrium in vivo by inducing CYP1A1 and inhibiting CYP3A4 activity. Rosmarinus officinalis may have a role in altering these pathways and therefore may help to reduce the excessive uterotropic action of oestrogen and its metabolites by shifting the metabolism of oestrogen to a less proliferative pathway, but further clinical research is required.