British Journal of Nutrition

Full Papers

Nutritional Endocrinology

Drynaria fortunei-derived total flavonoid fraction and isolated compounds exert oestrogen-like protective effects in bone

Ka-Chun Wonga1, Wai-Yin Panga1, Xin-Lun Wanga2a3, Sao-Keng Moka1, Wan-Ping Laia1, Hung-Kay Chowa4, Ping-Chung Leunga5, Xin-Sheng Yaoa3a6 c1 and Man-Sau Wonga1a7 c1

a1 Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China

a2 Translational Medicine Research and Development Center, Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China

a3 College of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, People's Republic of China

a4 Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, People's Republic of China

a5 Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, People's Republic of China

a6 Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, People's Republic of China

a7 State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), Shenzhen, People's Republic of China

Abstract

Drynaria fortunei (Kunze) J. Sm. (DF), a Chinese herb commonly used for the treatment of bone fracture, was previously shown to exert anabolic effects on bone. However, its active ingredients as well as the mechanisms of action are far from clear. The present study aimed to characterise the bone anabolic effects of DF flavonoid fraction (DFTF) in ovariectomised (OVX) mice and to determine if DFTF and its isolated compounds exert oestrogen-like effects in rat osteoblast-like UMR-106 cells. Young OVX C57/BL6J mice were treated orally with DFTF (0·087, 0·173 or 0·346 mg/g per d), 17β-oestradiol (2 μg/g per d) or its vehicle for 6 weeks. Serum and urine samples were collected for biochemical marker analysis. Bones were collected for computed tomography analysis. UMR-106 cells were treated with DFTF and isolated compounds naringin, (2S)-5,7,3′,5′-tetrahydroxy-flavonone 7-O-neohesperidoside (compound 1) and 5,7-dihydroxychromone 7-O-neohesperidoside (compound 2). DFTF exerted dose-dependent effects in improving bone mineral densities as well as bone strength at the femur, tibia and lumbar spine L1 in OVX mice. DFTF and the three isolated compounds stimulated osteoblastic cell proliferation and alkaline phosphatase activities in a dose-dependent manner. In addition, they stimulated the ratio of osteoprotegrin and receptor-activator NF-κB ligand mRNA expression, suggesting their involvement in inhibiting osteoclastogenesis. These stimulatory effects on osteoblastic functions were abolished in the presence of oestrogen receptor (ER) antagonist, ICI 182780. The present results suggested that DFTF is effective in protecting against OVX-induced bone loss in mice, and its actions in regulating osteoblastic activities appear to be mediated by ER.

(Received June 29 2012)

(Revised November 02 2012)

(Accepted November 02 2012)

(Online publication January 10 2013)

Key Words:

  • Drynaria fortunei ;
  • Total flavonoids;
  • Naringin;
  • Bone properties;
  • Osteoblasts;
  • Oestrogen receptors

Correspondence

c1 Corresponding authors: Dr M.-S. Wong, fax +852 23649932, email bcmswong@polyu.edu.hk; X.-S. Yao, email tyaoxs@jun.edu.cn

Footnotes

  Abbreviations: ALP, alkaline phosphatase; BMD, bone mineral density; C, control group; compound 1, (2S)-5,7,3′,5′-tetrahydroxy-flavonone 7-O-neohesperidoside; compound 2, 5,7-dihydroxychromone 7-O-neohesperidoside; Cr, creatinine; DF, Drynaria fortunei; DFTF, Drynaria fortunei total flavonoids; Dpd, deoxy-pyridinoline; E2, 17β-oestradiol; ER, oestrogen receptor; MTS, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy phenyl)-2-(4-sulphophenyl)-2H tetrazolium; OPG, osteoprotegerin; OVX, ovariectomised; RANKL, receptor activator of NF-κB ligand; SSI, stress–strain index

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