Pharmacological topics of bone metabolism: antiresorptive microbial compounds that inhibit osteoclast differentiation, function, and survival.

The mass and function of bones depends on the maintenance of a complicated balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Osteoporosis typically reflects an imbalance in skeletal turnover, such that bone resorption exceeds bone formation. Osteoclasts are target cells for anti-osteoporosis therapies. To discover new types of antiresorptive agents, we screened for natural compounds that regulate osteoclast differentiation, function, and survival. As a result, we identified reveromycin A, destruxins, mevastatin, FK506, cyclosporin A, prodigiosins, concanamycins, and symbioimine among microbial natural compounds. In this review, we discuss the mechanisms of action of these compounds on osteoclasts.