The natural dihydroflavonol (+) taxifolin was investigated for its protective effect on Fenton reagent-treated bone marrow-derived mesenchymal stem cells (bmMSCs). Various antioxidant assays were used to determine the possible mechanism. These included •OH-scavenging, 2-phenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide radical-scavenging (PTIO•-scavenging), 1, 1-diphenyl-2-picryl-hydrazl radical-scavenging (DPPH•-scavenging), 2, 2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) radical-scavenging (ABTS+•-scavenging), Fe3+-reducing, and Cu2+-reducing assays. The Fe2+-binding reaction was also investigated using UV-Vis spectra. The results revealed that cell viability was fully restored, even increasing to 142.9 ± 9.3% after treatment with (+) taxifolin. In the antioxidant assays, (+) taxifolin was observed to efficiently scavenge •OH, DPPH• and ABTS+• radicals, and to increase the relative Cu2+- and Fe3+-reducing levels. In the PTIO•-scavenging assay, its IC50 values varied with pH. In the Fe2+-binding reaction, (+) taxifolin was found to yield a green solution with two UV-Vis absorbance peaks: λmax = 433 nm (ε =5.2 × 102 L mol−1 cm −1) and λmax = 721 nm (ε = 5.1 × 102 L mol−1 cm −1). These results indicate that (+) taxifolin can act as an effective •OH-scavenger, protecting bmMSCs from •OH-induced damage. Its •OH-scavenging action consists of direct and indirect antioxidant effects. Direct antioxidation occurs via multiple pathways, including ET, PCET or HAT. Indirect antioxidation involves binding to Fe2+.Electronic supplementary materialThe online version of this article (10.1186/s11658-017-0066-9) contains supplementary material, which is available to authorized users.

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Osteoporosis, an imbalance in the bone-forming process mediated by osteoblasts and the bone-resorbing function mediated by osteoclasts, is a bone degenerative disease prevalent among the aged population. Due to deleterious side effects of currently available medications, probiotics as a potential treatment of osteoporosis is an appealing approach. Hence, this study aims to evaluate the beneficial effects of two novel Lactobacilli strain probiotics on bone health in ovariectomized (OVX) induced osteoporotic mice model and its underlying mechanisms. Forty-five 9-week-old Institute of Cancer Research (ICR) mice underwent either a sham-operation (n = 9) or OVX (n = 36). Four days after the operation, OVX mice were further divided into four groups and received either saline alone, Lactobacillus plantarum GKM3, Lactobacillus paracasei GKS6 or alendronate per day for 28 days. After sacrifice by decapitation, right distal femur diaphysis was imaged via micro-computed tomography (MCT) and parameters including bone volume/tissue volume ratio (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and bone mineral density (BMD) were measured. Moreover, GKM3 and GKS6 on RANKL-induced osteoclast formation and osteoblast differentiation using in vitro cultures were also investigated. The results showed that both probiotics strains inhibited osteoporosis in the OVX mice model, with L. paracasei GKS6 outperforming L. plantarum GKM3. Besides this, both GKS6 and GKM3 promoted osteoblast differentiation and inhibited RANKL-induced osteoclast differentiation via the Bone Morphogenetic Proteins (BMP) and RANKL pathways, respectively. These findings suggested that both strains of Lactobacilli may be pursued as potential candidates for the treatment and management of osteoporosis, particularly in postmenopausal osteoporosis.

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The present study evaluated the prebiotic effect of a standardised aqueous extract of Anoectochilus formosanus (SAEAF) and its effects on osteoporosis in ovariectomised (OVX) rats. The OVX rats were randomly divided into five groups and orally treated with water, SAEAF (200 and 400 mg/kg daily) and inulin (400 mg/kg daily) for 12 weeks. The sham group was orally treated with water. The SAEAF treatment enhanced the number of faecal bifidobacteria in OVX rats. The results of a Ca-balance experiment showed that SAEAF increased apparent Ca absorption and retention. The OVX rats were killed after SAEAF treatment lasting 12 weeks. The SAEAF decreased the caecal pH values and increased the caecal wall weight, caecal mucosa calbindin-D9k mRNA expression, free-Ca concentration and levels of SCFA in the caecum. The mineral content, density and biomechanical strength of bones were lower in OVX rats than the sham group, but these bone losses were prevented by SAEAF administration. Microtomography scanning showed that the SAEAF-treated rats had higher trabecular bone volume than the OVX rats. These results suggest that SAEAF prevented bone loss associated with ovarian hormone deficiency in the rats.Key words: Anoectochilus formosanus: Prebiotics: Calcium balance studies: Osteoporosis Prebiotics are non-digestible food ingredients that benefit the host by selectively stimulating the favourable growth and/or activity of one or more indigenous probiotic bacteria that could deliver potential beneficial health effects (1) .Microbial fermentation products of prebiotics, such as SCFA, are responsible for an increase in Ca absorption in the large intestine. A high concentration of SCFA in the caecum leads to decreased caecal pH, which increases the concentration of soluble Ca (2) . In addition, butyrate, a SCFA, belongs to a new class of anti-osteoporotic agents that may be useful in treating bone loss (3 -5) . Furthermore, several reports have indicated that the ingestion of prebiotics such as inulin and fructo-oligosaccharides might help prevent osteoporosis (2,6) .Anoectochilus formosanus (Orchidaceae) is an orchidaceous perennial herb, of which the entire plant has been used as a folk medicine for treating underdevelopment in children in Taiwan. This traditional use of the herb suggests that it might enhance Ca absorption (7) . Several studies in rats have found that A. formosanus ameliorated the osteoporosis induced by ovariectomy (OVX) (8,9) . Masuda et al. (9) have shown that ethanolic extracts of A. formosanus suppress the bone loss otherwise caused by oestrogen deficiency, by inhibiting osteoclast formation. Our previous study has shown that aqueous extracts of A. formosanus ameliorated bone loss caused by OVX by stimulating bone formation (8) .A bioactivity-guided fractional study of the use of A. formosanus in mice has shown that the ethyl acetate fraction enhances hepatitis induced by carbon tetrachloride (10) . The present study developed a dietary supplement from A. formosanus to prevent bone loss. A standard...