**5. Conclusions**

This study is the first to demonstrate that *G. littoralis* extracts can enhance osteoblast cell formation. The data produced at the molecular level suggest that *G. littoralis* extracts effectively induced osteoblast cell ALP production and mineralization. However, further research is required to establish the detailed mechanism involved in *G. littoralis*'s antiosteoporotic potential by identifying the active components present in *G. littoralis* extracts. This study suggests that *G. littoralis* extracts have phytoestrogenic properties that may enable the development of therapeutic agents to prevent osteoporosis.

**Supplementary Materials:** The following supporting information can be downloaded at: https: //www.mdpi.com/article/10.3390/pr11051491/s1. Table S1. Pearson's correlation coefficient among antioxidant activities, total phenolic contents, and total flavonoid contents.

**Author Contributions:** C.J.K. and B.K.G. contributed by doing experiments and writing the manuscript. C.Y.Y. supervised the experiments. S.K.C. and J.G.L. contributed by analyzing phenolic compounds and editing the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by funding from Hwajin Bio Cosmetic, Chuncheon 24232, Korea. Also, this work was supported by funding from the KU research professor program.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

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