In vivo and in vitro evaluation of the osteogenic potential of Davallia mariesii T. Moore ex Baker

Ethnopharmacological relevance: Postmenopausal osteoporosis is a major bone health issue worldwide. There is an unmet medical need for osteoporosis treatments, a disease which disproportionately impacts women. Exploring botanicals to prevent or treat osteoporosis is currently an interest of investigations. Rhizomes of Davallia mariesii T. Moore ex Baker (Davalliacea) are used an indigenous herbal medicine in Asia for injuries due to fractures, contusions, and strains. Aim of the study: In the present study, we investigated the osteogenic effect of the water extract of rhizomes of D. mariesii (DMH) on bone loss induced by an ovariectomy (OVX) in mice and also its impact on osteogenesis in primary human osteoblasts (HObs). Additionally, we performed a quantitative analysis of compounds in the DMH extract. Materials and methods: OVX C57BL/6J mice were orally administrated DMH extract for 12 weeks, and microarchitecture parameters were examined by microcomputed tomography. DMH extract was fractionated in a bio-guided manner, and fractions were isolated to obtain active compounds using HObs. Cell viability was evaluated by an MTT assay. Characteristics of early and late osteogenesis were analyzed by alkaline phosphatase activity and a mineralization assay. Molecular mechanisms were explored by a real-time quantitative PCR. Compounds in the DMH extract were identified and quantified using liquid chromatography tandem mass spectroscopy (LC-MS/MS). Results: DMH improved bone mineral densities of vertebrae and the femur. Through microarchitectural observations, DMH significantly decreased the bone surface/volume ratio and trabecular separation, and also increased the connectivity density in the OVX group. Additionally, DMH inhibited osteoclast differentiation in receptor activator of nuclear factor-κB ligand-induced osteoclasts and increased bone formation in HObs. After bio-guided fractionation and isolation, we found that eriodictyol-7-O-β-D-glucuronide (2) significantly increased alkaline phosphatase activity, and 5-O-β-D-(6-O-vanilloylglucopyranosyl)gentisic acid (3) substantially enhanced mineral deposition. In HObs, compound 3 was more potent in upregulating expressions of bone morphogenetic protein-2, bone sialoprotein, osteopontin, osterix, and estrogen receptor-α. The amount of bioactive compound 3 in DMH was 5.68 ± 0.64 mg/g of dry weight according to LC-MS/MS. Conclusion: For the first time we report that D. mariesii and its isolated compounds demonstrated potent osteogenic activities. Quantitative results of D. mariesii could be a reference for phytochemical analyses.