Effect of flavonoids from Rhizoma Drynariae on osteoporosis rats and osteocytes

In this experimental study, we evaluated the protective effects and the safety of main flavanones derived from Rhizoma Drynariae (Gusuibu) in vitro and in vivo. The MTT assay showed that compared with vehicle treatment, treatment with such flavanones as neoeriocitrin, naringin, and naringenin significantly promoted the viability of osteocyte-like cells. Quantitative real-time PCR showed that neoeriocitrin and naringin significantly attenuated mRNA expressions of RANKL and SOST in osteocyte-like cells. In rats with retinoic acid-induced osteoporosis, total flavonoid of Rhizoma Drynariae (TFRD), naringin, and naringenin significantly increased the number of trabeculae and improved trabecular bone structure compared with no treatment, without affecting liver and renal function. In addition, naringenin and naringin administration significantly increased bone mineral density of femur neck and femur shaft compared with the osteoporotic model rats. Western blot analysis showed that naringenin and naringin significantly attenuated protein expressions of bone resorption-related factors (TRAP, RANKL and RANK), and inhibited sclerostin expression compared with the osteoporotic model rats. On the other hand, naringin markedly increased protein expressions of ALP and PTH1R, and TFRD and naringenin also promoted PTH1R expression compared with the model rats. In conclusion, such flavanones as naringenin and naringin exhibited antiresorptive properties, and naringin particularly showed potential benefits for osteoporosis treatment.