arginyl-glycyl-aspartyl-phenylalanine and Osteoporosis

To enhance the potency, reduce the side effects and improve oral property of estradiol in estrogen replacement therapy (ERT), 6 novel estradiol-RGD octapeptide conjugates have been prepared. In an ovariectomized mouse osteoporotic model, at an oral dosage of 110.3 nmol/kg per day, their anti-osteoporosis activity was significantly higher than that of estradiol and estradiol-RGD tetrapeptide conjugates, and their risks of thrombogenesis and endometrial hyperplasia were significantly lower than that of estradiol and estradiol-RGD tetrapeptide conjugates. Using QSAR module of Cerius2, the 3D QSAR was performed for both femur weights and femur ash weights of estradiol-RGD peptide conjugates receiving mice. The r(2) of the 3D QSAR equations up to 0.995 and 0.988 indicates that they are capable of predicting a comparatively exact anti-osteoporosis activity for a conjugate.

Topics: Administration, Oral; Alkaline Phosphatase; Animals; Blood Coagulation; Calcium; Endometrial Hyperplasia; Estradiol; Female; Femur; Mice; Mice, Inbred ICR; Minerals; Models, Molecular; Molecular Conformation; Oligopeptides; Organ Size; Osteoporosis; Phosphorus; Quantitative Structure-Activity Relationship; Reference Standards; Thromboembolism; Uterus

To improve the specificity and potency of estrogen replacement therapy therapeutics while also minimizing the side effects such as bone resorption and thickening of the uterine wall, a series of novel estrogen-derived conjugates estradiol-3-RGD, estradiol-17-RGD, and estrone-3-RGD peptides have been prepared. In a mouse model, intraperitoneal (i.p.) administration of these estrogen-RGD peptide conjugates resulted in decreased serum concentrations of calcium and alkaline phosphatase, as well as increased levels of calcium, phosphorus, and minerals in the mouse femur. Furthermore, the anti-osteoporosis action of these conjugates followed a dose-dependent manner and was accompanied with no observable effects on endometrial cell hyperplasia. In addition to all of these compounds exhibiting biological activity when administered by the i.p. route, we were particularly pleased to note that the estradiol-3-RGD and estradiol-17-RGD conjugates were both orally active.

Topics: Alkaline Phosphatase; Animals; Calcium; Endometrium; Estrogen Replacement Therapy; Estrogens; Female; Hyperplasia; Mice; Oligopeptides; Organ Size; Osteoporosis; Ovariectomy