Marine algae extract attenuated osteoporosis in OVX mice, enhanced osteogenesis on human mesenchymal stem cells and promoted OPG expression

•Marine algae extract (MAE) contained calcium and multiple mineral elements.•MAE enhanced osteogenesis but inhibited adipogenesis on human MSCs.•MAE increased transcriptional levels of OPG on human MSCs.•MAE attenuated osteoporosis and the elevated body weights in OVX mice.•MAE increased the levels of OPG/RANKL and osteocalcin in OVX mice serum. Osteoporosis is an aging disease that weakens bones and increases risks of sudden and unexpected fractures. Effects of Marine Algae Extract (MAE) on bone formation and resorption remain unknown. We investigated whether MAE could enhance anti-osteoporosis and induce bone formation by using ovariectomized (OVX) mouse model and cultured human bone marrow derived mesenchymal stem cells (MSCs). With calcium content and other mineral elements, MAE attenuated osteoporosis by increasing secretions of osteocalcin and osteoprotegerin (OPG) in serum in OVX mice and resulted in the increasing level of the ratio of OPG to RANKL (P