The Preventive Effects Of Pueraria Isoflavone On Osteoporosis And Its Mechanism

Pueraria Lobata is an exterior-resolving herb in traditional Chinese medicine. Pueraria isoflavones have been proven effects of quicken the blood and transform stasis in past 40years. In modern clinical, Pueraria isoflavones are widely used in hypertension and coronary disease. But, both in traditional Chinese medicine and in modem clinical, Pueraria and its isoflavones are never used in osteoporosis and relative symptoms. After 1995, more than ten Chinese drug for osteoporosis come into the market. But all of these are based on traditional Chinese medicine theory, on principle of supplement kidney and supplement spleen. Although the components of activateing blood were considered in the compound descriptions used to osteoporosis hi recently 1 or 2 years, Pueraria was also not found in all of these descriptions.In fact, the chemical structure of mainly components in Pueraria isoflavones are much similar to those in soybean isoflavones which have been proved preventive effects to osteoporosis. Some isoflavones are exist in bom plants. So we theoretically presume that Pueraria isoflavones are effective to osteoporosis. But up to now, there is no report relative to the effects of Pueraria or its isoflavone on bone metabolism hi clinical or experiment hi Chinese and west In Chinese, also mere is no report about the new pharmacological effect or potential application based on its estrogen-like action.So hi present paper, we study the preventive effect of Pueraria isoflavones on osteoporosis and bone metabolism hi whole body and cell levels, and discuss the mechanisms.1 Preventive effects of TIP on osteoporosis in animal models. (1) The Effects of TIP on primary osteoporisis in Ovariectomized RatsFemale SD rats, 10-month-aged, were Ovariectomized bilaterally under anesthesia. 7 days late, animals were orally administrated with TIP 100 and 20 mg/kg/d respectively for 7 months. The total body BMC, BMD, bone biodynamics and other parameter were detected at 4th or 7th month.BMC and BMD hi both TIP groups were significantly greater than those in OVXgroup. Maximum load and structural strength of femur were markedly enhanced by TIP. These parameters in tibia were also markedly improved. The densities of femur and tibia were increased. The contents of Ca, P, Mg and other trance elements in tibia were also partial recovery. Additionally, both me weights of the uterine and adrenal gland were increased with positive interrelationship.These results suggest that TIP can inhibit bone mass loss induced by estrogen-deficiency, increase HMD and improve bone biodynamics strength. The estrogen-like action may be the key role of its mechanism and may also be account for its effect of stimulating adrenal gland cortex. (2) Prevention of TIP on Secondary Osteoporosis Induced by Glococorticoid in Rats4 month aged female SD rats were given dexamethasone intramuscularly with 1.5 rng/kg twice weekly for 6 months. The treated groups were orally given TIP 100, 50 and 25 mg-kg^-d"1. The whole body BMD and BMC were detected at 3 and 6 months. The parameters of femurs and tibias were determined after 6 months.At 3 and 6 month, BMD and BMC in TIP100 and TIP 50 groups were significantly higher than those in control group. The physical parameters of femur and tibia were unproved. The dynamic properties of femur and tibia were increased. However, most parameters in TIP 25 group were not significantly increased.These result showed TIP can partially prevent the bone mass loss induced by glucocorticoids, although the potency is not as strong as that in the OVX model. These results are consistent with the mechamsm(estrogen-like effect).2 Primary investigation of the mechanism of the anti-osteoporosis of TIP (1) TIP and pnerarin accelerate proliferation and differentiation of osteoblastsOsteoblastic cells was isolated from calvarium bone of newborn rats by sequential enzymatic digestion. The cells were cultured in MEM medium containing different concentration of TIP or puerarin for 5d to l...