Abstract
The present study was designed to characterize the bone protective effects of (−)-epiafzelechin (EAF), a flavan-3-ol, in mature ovariectomized mice model and its ability to stimulate osteoblastic activity and inhibit osteoclastic activity. Mature C57BL/6 mice (three to four months old) were either ovariectomised (OVX) or sham-operated and subjected to treatment (vehicle, 17β-oestradiol (E2, 200 μg/kg/day) or EAF (500 μg/kg/day) orally for six weeks. EAF and E2 significantly reduced urinary calcium (Ca) excretion, serum osteocalcin (OCN), and urinary deoxy-pyridinoline (DPD); increased bone mineral density (BMD); and improved micro-architectural properties in OVX mice. EAF significantly increased cell viability, alkaline phosphatise (ALP) activity, and collagen content, as well as runt-related transcriptional factor 2 (Runx2) mRNA expression in murine osteoblastic MC3T3-E1 cells. In addition, EAF significantly reduced the viability of osteoclast precursor murine leukemia monocyte RAW 264.7 cells and tartrate-resistant acid phosphatase (TRAP) activities in mature osteoclastic RAW 264.7 cells. EAF is a bioactive flavan-3-ol that protects estrogen deficiency-induced bone loss in OVX mice and exerts direct modulating effects in bone cells in vitro.
Highlights
Recent epidemiological studies have reported the association between flavonoid intakes and markers of bone health [1,2,3,4] in different female populations, including Scottish peri-menopausal women [1], TwinsUK Cohort [2], postmenopausal Chinese women [3], and elderly Australian women [4]
The present study clearly demonstrated that oral administration of EAF, a flavan-3-ol, could protect against ovariectomy-induced bone loss in mice without inducing uterotrophic responses
EAF could suppress the increase in weight gain, urinary Ca excretion, and bone turnover markers induced by OVX in mice in a way similar to the actions of E2
Summary
Recent epidemiological studies have reported the association between flavonoid (the most common group of plant polyphenols) intakes and markers of bone health [1,2,3,4] in different female populations, including Scottish peri-menopausal women [1], TwinsUK Cohort (population of women aged 18–79 years) [2], postmenopausal Chinese women (aged 56–63 years) [3], and elderly Australian women (aged ≥ 75 years) [4]. In vitro studies suggest that epigallocatechin gallate (EGCG), the in most abundant catechin gene via interaction with estrogen response elements (EREs) the promoters of target flavan-3-ol green tea extract,have might exert bone protective viaunintended its anti-oxidative andof antigenes [12]. EAFThe [24]present as wellstudy as a bioanalytical method for detecting itseffects levelsofinEAF mice its the effects of EAF on bone anddevelopments bone resorption in vitro.It is oursufficient hope thatmaterial the study bioavailability in vivo [25].formation These latest enable us to have forwill the provide evidence for its use as a drug candidate for the prevention and management of evaluation of its in vivo efficacy. The present study aimed toevaluate the bone protective effects of EAF in vivoand to characterize the effects of EAF on bone formation and bone resorption in vitro.It is our hope that the study will provide evidence for its use as a drug candidate for the prevention and management of postmenopausal osteoporosis
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