Polysaccharides isolated from lotus leaves (LLEP) exert anti-osteoporotic effects by inhibiting osteoclastogenesis

Abstract

Nelumbo nucifera, more commonly known as the Indian lotus, is an important plant that has been incorporated into traditional herbal remedies along the years. Even today, lotus leaves are considered reservoirs for bioactive compounds that can be used as nutritional supplements to treat various human diseases. However, despite the wide ranging biological activities of lotus polysaccharides, limited information is available regarding the anti-osteoporotic effects of these substances. The aim of this study was to investigate the beneficial effects of pectinase-assisted extractable polysaccharides from lotus leaves (LLEP) on estrogen deficiency-induced bone loss and osteoclast differentiation in bone marrow-derived macrophages. We found that LLEP markedly inhibited receptor activator of the nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation in a dose-dependent manner. It also revoked RANKL-induced activation of osteoclastogenic signals such as the expression of key transcription factors (i.e., c-Fos and nuclear factor of activated T cells cytoplasmic 1), resulting in a decrement in osteoclast-specific marker gene expressions. Microcomputed tomography and morphometric analysis revealed that a four-week oral administration of LLEP notably decreased trabecular bone loss. Taken together, our results suggest that LLEP can mitigate estrogen deficiency-induced bone loss by suppressing osteoclastogenesis, which makes it an excellent candidate for combating osteoporosis.