naphthoquinones and Bone-Diseases

β-lapachone (β-L) is a substrate of reduced nicotinamide adenine dinucleotide (NADH): quinone oxidoreductase 1 (NQO1). NQO1 reduces quinones to hydroquinones using NADH as an electron donor and consequently increases the intracellular NAD+/NADH ratio. The activation of NQO1 by β-L has beneficial effects on several metabolic syndromes, such as obesity, hypertension, and renal injury. However, the effect of β-L on bone metabolism remains unclear. Here, we show that β-L might be a potent inhibitor of receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. β-L inhibited osteoclast formation in a dose-dependent manner and also reduced the expression of osteoclast differentiation marker genes, such as tartrate-resistant acid phosphatase (Acp5 or TRAP), cathepsin K (CtsK), the d2 isoform of vacuolar ATPase V0 domain (Atp6v0d2), osteoclast-associated receptor (Oscar), and dendritic cell-specific transmembrane protein (Dc-stamp). β-L treatment of RANKL-induced osteoclastogenesis significantly increased the cellular NAD+/NADH ratio and resulted in the activation of 5' AMP-activated protein kinase (AMPK), a negative regulator of osteoclast differentiation. In addition, β-L treatment led to significant suppression of the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and peroxisome proliferator-activated receptor gamma coactivator 1β (PGC1β), which can stimulate osteoclastogenesis. β-L treatment downregulated c-Fos and nuclear factor of activated T-cells 1 (NFATc1), which are master transcription factors for osteoclastogenesis. Taken together, the results demonstrated that β-L inhibits RANKL-induced osteoclastogenesis and could be considered a potent inhibitor of RANKL-mediated bone diseases, such as postmenopausal osteoporosis, rheumatoid arthritis, and periodontitis.

Topics: AMP-Activated Protein Kinases; Animals; Bone Diseases; Cell Differentiation; Cell Survival; Gene Expression Profiling; Mice; Mice, Inbred C57BL; NAD; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; NFATC Transcription Factors; Osteoclasts; Osteogenesis; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Proto-Oncogene Proteins c-fos; RANK Ligand; Real-Time Polymerase Chain Reaction

Although various drugs for the treatment of rheumatoid arthritis (RA) have been used in clinics, RA is not completely curable to date. Thus, to seek new drugs for the treatment of RA has been a hotspot. Hydroxynaphthoquinones are the major anti-inflammatory active constituents in Arnebia euchroma (Royle) Johnst. The present study aims to evaluate the anti-arthritic activity of a hydroxynaphthoquinone mixture (HM) of A. euchroma (Royle) Johnst, including its anti-inflammatory and analgesic effects. The anti-arthritic efficacy of HM was examined using complete Freund's adjuvant- and bovine type II collagen-induced arthritic models. The paw edema, polyarthritis index and histopathological change were evaluated. The analgesic effect was assessed using the chemical and thermal models of nociception. Results found that HM administered prophylactically and curatively showed marked anti-arthritic activity by suppressing the paw swelling and development of inflammation, lowering the levels of TNF-α and IL-1β and protecting cartilage and bone from damage. The protection of HM was superior to that of reference drugs such as prednisone acetate or etanercept, and showed no direct deleterious effect. Similarly, HM showed significant analgesic effects. In summary, HM possessed potent anti-arthritic activity. It could relieve inflammatory symptoms and protect against joint destruction. These findings indicate that HM would be a potential therapeutic agent for arthritic disease, which provide pharmacological evidence for its clinical application.

Topics: Analgesics; Animals; Anti-Inflammatory Agents; Antirheumatic Agents; Arthritis, Experimental; Arthritis, Rheumatoid; Bone Diseases; Boraginaceae; Cartilage Diseases; Cattle; Collagen Type II; Edema; Etanercept; Freund's Adjuvant; Hot Temperature; Immunoglobulin G; Inflammation; Interleukin-1beta; Joint Diseases; Male; Naphthoquinones; Phytotherapy; Plant Extracts; Prednisone; Rats; Rats, Sprague-Dawley; Receptors, Tumor Necrosis Factor; Tumor Necrosis Factor-alpha