Esculetin affects the microarchitecture of long bones in vivo and the alkaline phosphatase activity and bone nodule formation in vitro

Abstract

Osteoporosis is a condition of deterioration of bone quality and quantity, making it susceptible to fractures. The current therapy, with its associated risks and also approval for only short period  makes the search for better molecules on priority imperative for effective treatment. Esculetin, a phytoconstituent, known to inhibit osteoclast differentiation in vitro and increase bone density in vivo, could serve to cure osteoporosis. Here, we studied the effect of esculetin on the microarchitecture of long bones in the ovariectomized rat model. The cellular cause for in vivo effect was sought by studying its effect on the pre-osteoblastic cell line. Osteopenia was induced by bilateral ovariectomy. Esculetin @1.0 or 10 mg/kg was administered for three months to osteopenic rats. Micro-CT of tibias and femurs was performed. The effect of esculetin on pre-osteoblastic MC3T3-E1 cells was studied. Cell viability in the presence of esculetin was determined by MTT assay. Alkaline phosphatase activity was determined using p-nitrophenol as a substrate. Bone nodules were stained with Alizarin Red S. Esculetin treated groups showed a significant worsening of microarchitecture parameters in the trabecular and cortical regions of the femur and tibia. This deterioration was more evident in the trabecular region than the cortical region. Esculetin augmented bone loss in estrogen-deficient rats without affecting the cell viability of MC3T3-E1 cells up to a concentration of 10 µg/mL. However, it affected the alkaline phosphatase activity and mineralization effect in preosteoblastic cells in addition to its in vivo effect in ovariectomized rats.