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- Antioxidant, mineralogenic and osteogenic activities of Spartina alterniflora and Salicornia fragilis extracts rich in polyphenolsPublication . Roberto, Vania Palma; Surget, Gwladys; Le Lann, Klervi; Mira, Sara; Tarasco, Marco; Guérard, Fabienne; Poupart, Nathalie; Laizé, Vincent; Stiger-Pouvreau, Valérie; Cancela, M. LeonorOsteoporosis is an aging-related disease and a worldwide health issue. Current therapeutics have failed to reduce the prevalence of osteoporosis in the human population, thus the discovery of compounds with bone anabolic properties that could be the basis of next generation drugs is a priority. Marine plants contain a wide range of bioactive compounds and the presence of osteoactive phytochemicals was investigated in two halophytes collected in Brittany (France): the invasive Spartina alterniflora and the native Salicornia fragilis. Two semi-purified fractions, prepared through liquid-liquid extraction, were assessed for phenolic and flavonoid contents, and for the presence of antioxidant, mineralogenic and osteogenic bioactivities. Ethyl acetate fraction (EAF) wasrich in phenolic compounds and exhibited the highest antioxidant activity. While S. fragilis EAF only triggered a weak proliferative effect in vitro, S. alterniflora EAF potently induced extracellular matrix mineralization (7-fold at 250µg/mL). A strong osteogenic effect was also observed in vivo using zebrafish operculum assay (2.5-fold at 10µg/mL in 9-dpf larvae). Results indicate that polyphenol rich EAF of S. alterniflora has both antioxidant and bone anabolic activities. As an invasive species, this marine plant may represent a sustainable source of molecules for therapeutic applications in bone disorders.
- The zebrafish operculum: a powerful system to assess osteogenic bioactivities of molecules with pharmacological and toxicological relevancePublication . Tarasco, Marco; Laizé, Vincent; Cardeira, João; Leonor Cancela, M.; Gavaia, PauloBone disorders affect millions of people worldwide and available therapeutics have a limited efficacy, often presenting undesirable side effects. As such, there is a need for novel molecules with bone anabolic properties. The aim of this work was to establish a rapid, reliable and reproducible method to screen for molecules with osteogenic activities, using the zebrafish operculum to assess bone formation. Exposure parameters were optimized through morphological analysis of the developing operculum of larvae exposed to calcitriol, a molecule with known pro-osteogenic properties. An exposure of 3 days initiated at 3 days post-fertilization was sufficient to stimulate operculum formation, while not affecting survival or development of the larvae. Dose dependent pro- and anti-osteogenic effects of calcitriol and cobalt chloride, respectively, demonstrated the sensitivity of the method and the suitability of the operculum system. A double transgenic reporter line expressing fluorescent markers for early and mature osteoblasts was used to gain insights into the effects of calcitriol and cobalt at the cellular level, with osteoblast maturation shown to be stimulated and inhibited, respectively, in the operculum of exposed fish. The zebrafish operculum represents a consistent, robust and rapid screening system for the discovery of novel molecules with osteogenic, anti-osteoporotic or osteotoxic activity.