Objective To explore the effects of Humulus lupulus L. extract (HLE) and xanthohumol (XN) on preventing glucocorticoid-induced osteoporosis (GIOP). Methods The GIOP model was established by intraperitoneal injection of dexamethasone (DEX). Bone microstructure, bone mineral density and serum biochemical indexes were evaluated by Micro-CT and ELISA kits. The levels of cells proliferation and ALP activity, and the expression of bone formation related proteins were assayed with primary osteoblasts injured by DEX. Results HLE and XN significantly alleviated the bone microstructure damage, enhanced the bone mineral density, and improved the trabecular parameters in GIOP mice. In vitro experiments showed that HLE and XN can prevent bone loss not only by improving cell proliferation and ALP activity, but also through increasing the expression of bone γ-glutamic acid-containing proteins (BGP), bone morphogenetic protein 2 (BMP-2) and runt-related transcription factor 2 (Runx-2). Conclusion This study confirmed that HLE and XN had anti-GIOP effects for the first time. It provides a new resource for the development of anti-osteoporosis medications.

Objective To explore the effect and mechanism of Bajitianwan on preventing D-galactose (D-gal)-induced osteoblast bone loss. Methods Osteoblasts isolated from 24 h old Wistar rats were injured by D-gal and intervened with Bajitianwan extract. The osteoblastic proliferation and differentiation were determined by MTT and alkaline phosphatase (ALP), respectively. The cell reactive oxygen species (ROS) levels were detected by DCFH-DA fluorescent probes. The expression of cellular oxidation-related protein nuclear factor erythroid 2-related factor 2 (Nrf2), phosphorylated protein kinase B (p-AKT), protein kinase B (AKT), heme oxygenase-1 (HO-1), and NADPH quinone oxidoreductase 1 (NQO1) were detected by Western blotting. The intranuclear expression of Nrf2 protein was measured by immunofluorescence. Results Bajitianwan extract had significantly increased the osteoblastic proliferation and differentiation, and significantly reduced the intracellular ROS level. Bajitianwan extract had activated the PI3K/AKT pathway via activating the phosphorylation of AKT in osteoblasts, and promoted NQO1 and HO-1 expression. In addition, Bajitianwan had significantly promoted the expression of Nrf2 in the nucleus of osteoblasts, activating Nrf2 signaling pathway, and further promoted bone formation. Conclusion This study confirmed that Bajitianwan could prevent D-gal injured osteoblastic bone loss for the first time. The mechanism might be related to the regulation of oxidative stress associated PI3K/AKT and Nrf2 signaling pathway.