Antioxidant, Mineralogenic and Osteogenic Activities of Spartina alterniflora and Salicornia fragilis Extracts Rich in Polyphenols.

Osteoporosis 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) was rich 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 250 µg/mL). A strong osteogenic effect was also observed in vivo using zebrafish operculum assay (2.5-fold at 10 µg/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.

Structural elucidation, in vitro antioxidant and photoprotective capacities of a purified polyphenolic-enriched fraction from a saltmarsh plant.

In temperate saltmarshes, halophytic plants have to daily protect their internal tissues against sunlight and UV rays. Consequently, they develop adaptive responses such as the synthesis of secondary metabolites, including polyphenols. The present study focused on the biological activities of fractions enriched in polyphenols from Salicornia ramosissima. Three different extracts were obtained by purification processes to concentrate polyphenols: a crude hydroalcoholic extract, and two purified fractions: an ethyl acetate fraction (EAF) and an aqueous fraction. Phenolic and flavonoid contents, antioxidant (DPPH radical-scavenging activity, reducing activity, ß-carotene linoleic acid system and the ORAC method) and sunscreen properties (Sun Protection Factor and UVA-Protection Factor) were assessed by in vitro tests. The purification process was effective in increasing phenolic and flavonoid contents as well as antioxidant and sunscreen capacities of the EAF. The EAF appeared to be a broad spectrum UV absorber. The chemical structure of 10 EAF polyphenols was elucidated using 2D NMR and mass spectrometry spectra. Furthermore, a correlation was observed between phenolic composition and biological activity. These findings are encouraging for the future use of S. ramosissima as a potential source of antioxidant and photoprotectant molecules for industrial applications.

Development of a new in vitro method to evaluate the photoprotective sunscreen activity of plant extracts against high UV-B radiation.

Sunscreen efficiency of biomolecules against UV-B radiation was generally determined in vitro by cosmetic methods which are not well-adapted for routine ecophysiological and bio-guidance studies in plant research laboratories. In this article, we propose a new in vitro method to evaluate the sunscreen photoprotective activity of plant extracts against high UV-B radiation. Because photosynthetic pigments are one of the first targets of UV-B radiation in plants, the experimental design is based on the ability of the tested substances to limit the degradation of sodium magnesium chlorophyllin (SMC), a derivative compound of natural chlorophyll. SMC photodegradation comparatively to natural chlorophyll and related to temperature, concentration and sample solvent were analyzed in order to optimize the experimental parameters. Then, the method was validated by testing nine standard UV filters used in the European cosmetic industry and by comparing results of their activity with those of a reference in vitro procedure. Finally, the method was applied to coastal and marine crude plant extracts. Results have shown that our procedure can be a good alternative to cosmetic methods with a rapid, sensitive and reproducible evaluation of the sunscreen activity of either pure standards or crude plant extracts in small amounts (30 mg).

Relationship between heavy fuel oil phytotoxicity and polycyclic aromatic hydrocarbon contamination in Salicornia fragilis.

Greenhouse experiments were carried out to study the effects of heavy fuel oil contamination on the growth and the development of Salicornia fragilis Ball and Tutin, a salt-marsh edible species. Plants were sampled in spring at the "Aber du Conquet" (Finistère, France), and artificially exposed by coating shoot sections with N degrees 6 fuel oil or by mixing it in their substratum. The impact of petroleum on plant development was followed by phytotoxicity assessments and PAH shoots assays. The plants exhibited visual symptoms of stress, i.e. chlorosis, yellowing, growth reduction and perturbations in developmental parameters. The contamination of plants by shoot coating appeared to be less than through soil. Moreover, the increase of the degree of pollution induced more marked effects on plants, likely because of the physical effects of fuel. However, bioaccumulation of PAHs in shoot tissues was also found to be significant, even at very low levels of contamination, and highly related to the conditions of exposure to oil. The strong relationships between the PAH contents of Salicornia plants and growth reduction suggest a chemical toxicity of fuel oil, compounds like PAHs being known to inhibit physiological processes in plants.