Osteoporosis is one of common bone disorders, affecting millions of people worldwide.
Treatments of osteoporosis consist of pharmacotherapy and non-pharmacological interventions, such
as mineral supplementation, lifestyle changes, and exercise programs. Due to the minimum side effects
and favorable cost-effective therapeutic effects, herbal medicine has been widely applied in
clinical practices for more than 2,000 years in China. Of the many traditional formulas reported for
treating bone diseases, 4 single herbs namely (1) Herba Epimedii, (2) Rhizoma Drynariae, (3) Fructus
Psoraleae, and (4) Cortex Eucommiae, are considered as the featured "Kidney-Yang" tonics, and frequently
and effectively applied for preventing and treating osteoporosis. With the accruing development
of modern chemistry, hundreds of active compounds have been identified and isolated for their
anti-osteoporotic effects. This review would first sketch the phytochemistry of these featured "Kidney-
Yang" tonics and present the pharmacological characteristics of the most abundant and bioactive
compounds derived from the herb Herba Epimedii and Rhizoma Drynariae, including icariin and naringin.
Then, the cellular and molecular underpinnings under anti-osteoporotic effects of icariin and
naringin are discussed. The concerned structure-function relationships of the featured active herbal
compounds would also be reviewed so as to pave the way for future drug design in treating osteoporosis.