Fructus Ligustri Lucidi (FLL) ethanol extract increases bone mineral density and improves bone properties in growing female rats

Osteoporosis is a chronic disease affecting millions of people worldwide. It is generally accepted that acquisition of a high peak bone mass (PBM) early in life can reduce the risk of osteoporosis later in life. The aims of this study were to investigate the effects of Fructus Ligustri Lucidi (FLL) ethanol extract on bone mineral density and its mechanical properties in growing female rats and to explore the underlying mechanisms. The rats were given different doses of FLL extract mixed with AIN-93G formula (0.40, 0.65 and 0.90 %), and a group given AIN-93G diet treatment only was used as control. The intervention lasted for 16 weeks until the animals were about 5 months old, the time when the animals almost reach their PBM. Our results showed that FLL treatment increased bone mineral density and improved bone mechanical properties in the growing female rats in a dose-dependent manner. In addition, FLL treatment significantly decreased the serum bone-resorbing marker, CTX-I, while significantly increasing serum 25(OH)D₃ and thereby increasing Ca absorption and Ca retention. Intriguingly, both in vivo and in vitro results demonstrated that FLL treatment could reduce the RANKL/OPG ratio. In conclusion, FLL ethanol extract exerted beneficial effects on peak bone mass acquisition and the improvement of bone mechanical properties by favoring Ca metabolism and decreasing the RANKL/OPG ratio.