Greek flora as a source for the detection of natural compounds potentially effective in preventing post-menopausal osteoporosis

Osteoporosis is the most common metabolic bone disorder and remains an increasingly significant problem affecting post-menopausal women. It results from an imbalance between the processes of bone formation and resorption leading to decreased bone mass and increased risk of fracture. Treatments against osteoporosis include hormone replacement therapy (HRT) with estrogens, that unfortunately is combined to an increased hormone-dependant cancer risk, and selective estrogen receptor modulators (SERMs). Nowadays, numerous women use plant derived supplements to prevent postmenopausal diseases including osteoporosis. Despite Greece constituting one of the richest floral diversity regions, there are scarcely any reports connecting Greek flora herbs with prevention of osteoporosis. Therefore, the aim of this work is to identify and characterize plant extracts deriving from Greek flora, and isolated compounds that display significant SERM activity. Considering our research experience on natural products with estrogenic activities and traditional medicine sources, 44 plant species were selected and 91 extracts were prepared using conventional (maceration) and modern-green techniques (ASE, MAE and SFE). Preliminary phytochemical and biological screening revealed Rhamnus sp, Lupinus album, Psoralea bituminosa, Ceratonia siliqua and Cytisus villosus between the most capable extracts of inducing MC3T3-E1 differentiation to osteoblasts. Consequently, we proceeded to the isolation of the major compounds, which were structurally elucidated using NMR spectroscopy, and in vitro evaluated using a cell-based screening, concerning the differentiation of MC3T3-E1 cells to osteoblasts and their estrogenic-antiestrogenic properties. The obtained results, revealed derivatives of genistein, kaempferol and its glycosides, as the most promising agents for the potential prevention and treating of post-menopausal osteoporosis.