Osteoprotective effects of Cimicifuga racemosa and its triterpene-saponins are responsible for reduction of bone marrow fat

Elderly people often develop visceral obesity accompanied by osteoporosis. Visceral adipocytes secrete a number of adipokines and cytokines which augment the development of arteriosclerosis and type 2 diabetes. Bone marrow fat cells also secrete these pro-inflammatory cytokines which stimulate osteoclast and inhibit osteoblast activity. Ovariectomized (ovx) rats also develop general and bone marrow obesity and osteoporosis both of which can be partially prevented by estradiol (E2) and the special extract of Cimicifuga racemosa (CR) BNO 1055. Whether this extract or the thereof isolated triterpene-saponins or polar substances can also prevent bone marrow obesity and thereby the development of osteoporosis was compared with the effects of estradiol (E2). Rats were ovx and fed with food containing either CR BNO 1055 or its triterpene-saponin or polar constituents or with E2 for 4 weeks. Histomorphometry and STRUT analyses were applied to histological preparations to determine the amount of trabecles, hematopoietic and fat tissue in the bone marrow. Ovx rats lost significant amounts of trabecular BMD, surface and nodes while the number of free trabecular ends and fat load in the marrow increased. This was totally prevented by E2 and partially by CR BNO 1055 and the triterpene-saponin but not by the polar fraction. High serum osteocalcin and CrossLaps levels were reduced by E2 and the S-fraction. It is well established that E2 prevents osteoporosis. It is also known that CR BNO 1055 does not contain estrogenic substances. CR BNO 1055 and the triterpene-saponin-fraction reduced the development of osteoporosis most likely by a reduction of the bone marrow fat load and possibly by reducing the secretion of pro-inflammatory cytokines. Hence, the triterpene-saponin-fraction may serve as a basis for a new osteoporosis preventing preparation also in human patients.