Stimulatory Effects of the Extract of Arachis Hypogaea (Fabaceae) on the Proliferation of Osteoblastic Cells in Vitro

Extracts of Arachis hypogaea (Fabaceae) have been studied in order to search for their effects on the metabolism of osteoblastic cells. ROS 17/2.8 osteoblastic cells were cultured in plates in standard medium and plant extracts were added in presence or in absence of tamoxifen a partial estrogen-receptor inhibitor. The proliferation rate was assessed by measuring the incorporation of 3H-thymidine in the DNA counted with liquid spectrometry. The measurement of alkaline phosphatase activity by spectrometry using p-nitrophenylphosphate as substrate and protein content by Coomassie brilliant blue method indicates the differentiation rate. The results indicate that hydro-ethanolic extract stimulated the proliferation of the ROS cells but did not have any effect on osteoblastic cells derived from culture of rat diaphysal bone marrows. Hexane-ethylacetate (5/1) extract activate the proliferation of the ROS cells. The induced stimulative effects of hydro-ethanolic extract persist even after the addition of Tamoxifen which is an inhibitor of estrogen activities. But when the Tamoxifen was added to the medium before extract, effects induced by extract persist or disappear either according to the dose of the extract. Hydro-ethanolic and hexane-ethylacetate (5/1) provoked a stimulation of the differentiation of the ROS cells. The effects of hydro-ethanolic extract disappeared in the presence of Tamoxifen when the dose of the plant extract is 10-5 g/ml but persist when this dose is 10-4 g/ml. The extract of Arachis hypogaea stimulated the proliferation and the differentiation of ROS cells. These actions could be assigned to phyto-estrogens notably by isoflavones and/or to non-estrogenic substances. These substances might act through the estrogen receptors but also through mechanisms not involving estrogen receptors.