Effects of caffeic and chlorogenic acids on the rat skeletal system

682 Abstract. - OBJECTIVE: Caffeic acid, pre - dominantly as esters linked to quinic acid (chlorogenic acids), is a phenolic acid present at high levels in coffee.The aim of the study was to investigate effects of caffeic and chlorogenic acids on the skeletal system of female rats with normal estrogen levels and estrogen-deficient. MATERIALS AND METHODS: Caffeic acid (5 and 50 mg/kg p.o. daily) and chlorogenic acid (100 mg/kg p.o. daily) were administered for 4 weeks to non-ovariectomized and bilaterally ovariectomized mature Wistar rats, and their ef - fects were compared with appropriate controls. Moreover, estradiol (0.2 mg/kg p.o. daily) was ad - ministered to ovariectomized rats. Bone turnover markers, mass, mineralization and mechanical properties were examined. RESULTS: Although caffeic acid at a low dose exerted some unfavorable effects on the skele - tal system, at high doses, caffeic and chloro - genic acids slightly increased mineralization in the tibia and improved mechanical properties of the femoral diaphysis (compact bone). Unlike estradiol, they did not counteract the worsen - ing of the tibial metaphysis bone strength (can - cellous bone) and increases in osteocalcin con - centration induced by estrogen deficiency. CONCLUSIONS: High doses of the phenolic acids slightly favorably affected the rat skeletal system independently of the estrogen status.