Fourteen triterpenes, lup-20(29)-ene-3β,6β-diol (1), betulin (2), lupeol caffeate (3), 3β-caffeoyloxylup-20(29)-en-6α-ol (4), betulin-3β-yl-caffeate (5), 3β-trans-feruloylbetulin (6), betulinaldehyde 3-caffeate (7), 3-O-trans-caffeoylbetulinic acid (8), dammarenediol II 3-caffeate (9), 12-oleanene-3β,6α-diol (10), 11α-hydroxy-3β-amyrin (11), nivadiol (12), 29-hydroxyfriedelin (13), and celastrusin A (14) were isolated from Celastrus orbiculatus Thunb. and evaluated for their activity on receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages (BMMs). Compounds betulin (2), betulin-3β-yl-caffeate (5), 3β-trans-feruloylbetulin (6), and 3-O-trans-caffeoylbetulinic acid (8) significantly inhibited osteoclast formation in a dose-dependent manner. Among these, betulin-3β-yl-caffeate (5) exhibited the most potent inhibitory activity. We demonstrated that betulin-3β-yl-caffeate (5) suppressed F-actin-ring formation and bone resorption activity. At the molecular level, betulin-3β-yl-caffeate (5) inhibited RANK-induced expression of c-Fos and the induction of nuclear factor of activated T cells 1 (NFATc1), a key transcription factor for osteoclast formation, and it also downregulated mRNA expression of osteogenesis-associated marker genes including tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and matrix metalloprotein (MMP). These results indicate that betulin-3β-yl-caffeate (5) may be a promising candidate for the treatment of osteoclast-related diseases such as osteoporosis.

14个三萜，lup-20（29）-ene-3β，6β-二醇（1），betulin（2），lupeol caffeate（3），3β-caffeoyloxylup-20（29）-en-6α-ol（4），桦木醇-3β基-咖啡酸酯（5），3β-反-feruloylbetulin（6），betulinaldehyde 3-咖啡酸酯（7），3- ø -反式-caffeoylbetulinic酸（8），dammarenediol II 3-咖啡酸酯（9），12 -烯烃3β，6α-二醇（10），11α-羟基-3β-淀粉糊精（11），硝酚（12），29-羟基弗里德林（13）和Celastrusin A（14）从Celastrus orbiculatus Thunb分离。并评估了它们对核因子κB配体（RANKL）诱导的骨髓巨噬细胞（BMM）破骨细胞分化的受体激活剂的活性。化合物桦木素（2），桦木素-3β-基-咖啡酸酯（5），3β-反式-阿魏酰贝特林酸（6）和3- O-反式-咖啡酰贝特林酸（8）以剂量依赖的方式显着抑制破骨细胞的形成。其中，桦木素3β-基-咖啡酸酯（5）表现出最强的抑制活性。我们证明了betulin-3β-yl-caffeate（5）抑制F-肌动蛋白环的形成和骨吸收活性。在分子水平上，betulin-3β-yl-caffeate（5）抑制RANK诱导的c-Fos表达和抑制活化T细胞1（NFATc1）的核因子的活化，该因子是破骨细胞形成的关键转录因子，并且下调与成骨相关的标志物基因的mRNA表达，这些标志物包括酒石酸盐抗性酸性磷酸酶（TRAP），树突状细胞特异性跨膜蛋白（DC-STAMP）和基质金属蛋白（MMP）。这些结果表明，betulin-3β-yl-caffeate（5）可能是治疗破骨细胞相关疾病（例如骨质疏松症）的有前途的候选药物。