**5. Conclusions**

The present study demonstrated, in GSH-depleted SaOS-2 cells, that TSPs, together with other phytocompounds contained in BJ, are able to prevent early oxidative stress-induced inhibition of osteogenic di fferentiation and the mineralization process. This can occur in vivo in estrogen deficiency, as well as in aging and inflammatory diseases in which the loss of antioxidants leads to accelerated bone loss and, thus, to osteoporosis or osteopenia. It was also shown that the e ffect of BJ is not only due to its protective antioxidant activity, but also due to its ability to modulate signals that upregulate the expression and activity of osteogenic factors which are related to bone remodeling and bone formation. In fact, the increased expression of SIRT1 seems to be related to the osteogenic action of BJ, and these findings confirm that this enzyme may be considered a possible target for anti-resorptive drugs and for anabolic treatments for osteoporosis [58,59]. Finally, qualitative and quantitative analysis of the BJ soluble polyphenolic component showed the prevalence and high presence of anthocyanins. Overall, the results of this study, together with those previously obtained on osteocytes, may contribute to explain, at a cellular and molecular level, the beneficial e ffects of BBs on bone metabolism. In particular, they sugges<sup>t</sup> that BJ e ffects are mainly related to TSP; in fact, polyphenols activate osteoblast function and inhibit osteoclast di fferentiation, thereby promoting bone growth [18–20,26,54,62]. Indeed, data obtained in animal studies showed the anabolic e ffects of BB in bone, and they suggested BB as a useful supplement for the prevention and/or managemen<sup>t</sup> of osteoporosis and osteopenia [18,19,26,30,62]. In fact, anti-resorption drugs are e ffective in reducing bone mass loss and osteoclast activity, while they are also associated with limitations and side e ffects [28,65], as they do not restore a normal bone remodeling process [1,28]. Therefore, there is a growing demand for natural substances that can support medical therapy to reduce bone loss and restore normal bone metabolism. Future researches in vivo and in vitro are needed to better elucidate the molecular mechanisms underlying the action of a complex mixture of BB polyphenols on bone repair and formation processes in osteoporosis or bone inflammatory diseases related to oxidative stress.

**Author Contributions:** Conceptualization, M.T.V., T.I., and M.L.B.; methodology, V.D., G.M., and I.F.; validation, V.D. and G.M.; investigation, V.D., G.M., I.F., and A.R.B.; resources, V.D., G.M., and A.R.B.; writing—original draft preparation, M.T.V. and T.I.; writing—review and editing, M.L.B., M.T.V., T.I., and V.D.; funding acquisition, M.L.B. and T.I. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by grants from Fondazione Cassa di Risparmio di Pistoia e Pescia (IANTCRPP15) and Ministero dell'Istruzione, dell'Università e della Ricerca (RICATEN18) to T.I. and M.L.B.

**Conflicts of Interest:** The authors declare no conflict of interest.
