Effects of natural phenolic acids on the skeletal system of ovariectomized rats

Recent reports indicate the possibility of antiresorptive and/or bone formation increasing activity of natural phenolic acids, commonly present in plants which are normally consumed in the diet. The effects of 4 natural phenolic acids (ferulic, caffeic, P-coumaric or chlorogenic, 10 mg/kg P. O. daily for 4 weeks) on the skeletal system of ovariectomized (estrogen-deficient) rats were investigated. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. Phenolic acids differentially affected the skeletal system of rats with osteoporotic changes induced by the ovariectomy. Caffeic acid decreased bone mass, whereas P-coumaric acid increased the bone mass/body mass ratio and bone mineral mass/body mass ratio in the long bones, in comparison with the ovariectomized control rats. The phenolic acids improved some bone histomorphometric parameters, impaired by estrogen deficiency. However, they did not increase the ratio of bone mineral mass to bone mass, decreased by estrogen deficiency, and did not significantly affect bone mechanical properties. In conclusion, different natural phenolic acids exert differential effects on the skeletal system of ovariectomized rats, both favourable and deleterious.