A new technological procedure using sucrose as porogen compound to manufacture porous biphasic calcium phosphate ceramics of appropriate micro- and macrostructure

In the domain of implantable materials, the porosity and pore size distribution of a material in contact with bone is decisive for bone ingrowth and thus the control of the porosity is of great interest. The use of a new porogen agent, i.e. sucrose is proposed to create a porosity in biphasic calcium phosphate blocks. The technological procedure is as follows: sucrose and mineral powder are mixed, then compressed by isostatic compression and sintering finally eliminates sucrose. Blocks obtained were compared to a manufactured product: Triosite® (Zimmer, Etupes, France) which porosity is created through a naphthalene sublimation process.Results have shown that the incorporation of sucrose allows the preparation of porous blocks with controlled porosity varying from 40 to 80% and with macro-, meso- and microporosity characteristics depending on the percentage of sucrose added as well as on the granulometry of both sucrose and mineral powder

Propriétés antibactériennes d’extraits de propolis contre des souches de Staphylococcus aureus sensibles ou résistantes à la méthicilline

La résistance aux antibiotiques est devenue l\u27un des problèmes majeurs de santé publique du XXIème siècle. Il existe donc un réel intérêt thérapeutique dans la recherche de composés ou d\u27extraits naturels capables de limiter cette résistance. La propolis est un mélange complexe composé de substances résineuses collectées par les abeilles sur différentes parties des plantes et arbres, de cires et de sécrétions salivaires de l\u27abeille. Elle sert principalement à colmater les interstices des parois de la ruche et comme véritable arme chimique contre les microorganismes. La propolis est utilisée depuis longtemps en médecine traditionnelle puisqu\u27elle possède des propriétés pharmacologiques intéressantes notamment antioxydante, anti-inflammatoire mais aussi antimicrobienne. Un échantillon de propolis, composé de 24 lots collectés en France (majoritairement dans le sud-ouest) en 2010 et 2011, a été extrait par différents solvants : EtOH 70%, MeOH, DCM et DCM/MeOH/eau 31/19/4 (mixte). La composition chimique des extraits a préalablement été déterminée au moyen d’analyses HPLC/DAD/MS et RMN 1H et 13C. L\u27activité antibactérienne a été évaluée sur des bactéries responsables d\u27infections nosocomiales, et plus spécifiquement sur 13 souches de Staphylococcus aureus [ATCC25923, six isolats cliniques de souches résistantes à la méthiciline (SARM) et six isolats cliniques de souches sensibles à la méthiciline (SASM)] par détermination de la concentration minimum d\u27inhibition (CMI) en milieu gélosé [1]. Les résultats ont montré que, parmi les quatre extraits, le DCM et le "mixte" présentaient une bonne activité antibactérienne contre S. aureus (SA) avec des CMI respectives de 60±10 et 67±15 µg/mL mais également sur quasiment toutes les souches SARM et SASM testées (CMI entre 30 et 97 µg/mL). Ces bonnes activités des extraits DCM et mixte peuvent être reliées à des teneurs élevées en polyphénols totaux et en flavonoïdes [1]. Diverses études ont en effet montré que ce type de mélange complexe, riche en polyphénols, était plus actif que les composés isolés les constituant. Les polyphénols agiraient ainsi de façon synergique, potentialisant l\u27activité antibactérienne de ces extraits [2]. D\u27autres études, menées in vitro, ont par ailleurs mis en évidence un réel synergisme entre propolis et antibiotiques [3], [4]. Ainsi, ces extraits de propolis présentent-ils un réel potentiel dans une lutte alternative contre des infections à staphylocoques.   Références [1]          S. Boisard et al., "Antifungal and Antibacterial Metabolites from a French Poplar Type Propolis", Evid. Based Complement. Alternat. Med., vol. 2015, p. e319240, 2015. [2]          A. Kujumgiev, I. Tsvetkova, Y. Serkedjieva, V. Bankova, R. Christov, et S. Popov, "Antibacterial, antifungal and antiviral activity of propolis of different geographic origin", J. Ethnopharmacol., vol. 64, no 3, p. 235‑240, 1999. [3]          S. Stepanović, N. Antić, I. Dakić, et M. Švabić-Vlahović, "In vitro antimicrobial activity of propolis and synergism between propolis and antimicrobial drugs", Microbiol. Res., vol. 158, no 4, p. 353‑357, 2003. [4]          A. Fernandes Júnior, E. C. Balestrin, J. E. C. Betoni, R. de O. Orsi, M. de L. R. de S. da Cunha, et A. C. Montelli, "Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs", Mem. Inst. Oswaldo Cruz, vol. 100, no 5, p. 563‑566, 2005

Identification of coumarins in DCM bark, leaf and fruit extracts from Mammea neurophylla (Calophyllaceae) by LC-PDA-MSn

4-phenyl and 4-propylcoumarins display a wide variety of biological activities including anti-oxidant and anti-inflammatory effects, antiparasitical activities against Leishmania or Plasmodium as well as antibacterial, antiviral (HIV) and cytotoxic activities. Using LC-PDA-MSn we have developed a specific protocol allowing the simultaneous and qualitative detection of 4-phenyl and 4-propylcoumarins in DCM bark, fruit and leaf extracts obtained from Mammea neurophylla. By comparison of their retention times, MS and UV data with that of authentic samples, nine, seven and five 4-phenylcoumarins could be directly identified in bark, leaf and fruit extracts respectively. On the other hand, interlocking UV spectra and ESI-MSn data analysis allowed us to deduce plausible structures of five, eight and four other coumarins in bark, leaf and fruit respectively by comparison with their reported spectral data. During this study new Mammea A/AA 9-hydroxy-cyclo F and Mammea A/AB 9-hydroxy-cyclo F were identified. We believe that this protocol will be useful in case of dereplicative studies of Mammea and related species

Effets anti-inflammatoire et immunomodulateur de composés polyphénoliques isolés de Clusiaceae et de Calophyllaceae

L’endothélium vasculaire joue un rôle central dans le développement des réponses inflammatoires et immunitaires conduisant notamment au phénomène de rejet de greffe1. Les Clusiaceae et Calophyllaceae, plantes des régions pantropicales, biosynthétisent des dérivés polyphénoliques originaux présentant des activités anti-inflammatoires intéressantes2-3. Divers polyphénols isolés de ces plantes ont été sélectionnés, afin d’évaluer in vitro leur potentiel anti-inflammatoire et immunomodulateur sur des cellules endothéliales humaines. Plusieurs coumarines et une benzophénone se sont alors révélées inhibitrices de l’expression de marqueurs de l’inflammation et de l’immunité. Parallèlement à cette étude, les extraits dichlorométhaniques (DCM) et méthanoliques d’un panel de plantes issues des genres Garcinia (Clusiaceae), Calophyllum et Mesua (Calophyllaceae), originaires de Malaisie, ont été analysés par déréplication (HPLC-PDA-MSn). Deux extraits contenant des pharmacophores d’intérêt ont ainsi été sélectionnés pour une étude phytochimique approfondie : l’extrait DCM de fruits de Mesua lepidota, duquel ont été identifiés sept phénylcoumarines originales, que nous avons baptisées lépidotols et lépidotines, et l’extrait DCM de feuille de Calophyllum tetrapterum, ce dernier riche en benzophénones polyprénylées. Références : 1.         Brick C, Atouf O, Benseffaj N, et al. Rejet de la greffe rénale : mécanisme et prévention. Nephrol Ther 2011;7:18-26. 2.         Ali M, Arfan M, Ahmad M, et al. Anti-inflammatory xanthones from the twigs of Hypericum oblongifolium Wall. Planta Med 2011;77:2013-2018. 3.         Santa-Cecilia FV, Freitas LAS, Vilela FC, et al. Antinociceptive and anti-inflammatory properties of 7-epiclusianone, a prenylated benzophenone from Garcinia brasiliensis. Eur J Pharmacol 2011;670:280-285

Voltage Sensor Probes (VSPs) as an Efficient Tool to Screen for Inhibitors of Voltage-Gated Sodium Channels

Voltage-gated sodium channels (Nav) represent a therapeutically validated group of targets for the development of antiepileptic drugs, analgesics and antiarrhythmics [1]. However most of the existing drugs acting as Nav blockers suffer from multiple side effects, but the existence of a multigene family of Nav [2] suggests that the identification of new compounds that selectively block Nav isoforms might have better therapeutic efficiency and reduced side effects. Due to their molecular interference with numerous ion channels, alkaloids represent a group of natural products of particular interest. This is the reason why we have evaluated the efficiency of an in-house method to screen a library of isoquinoline alkaloids formerly isolated in our laboratory. Mammalian GH3 cells constitutively expressing Nav where used in conjunction with Voltage Sensor Probes (VSPs), the signals being read on a fluorescence plate reader. Thanks to this technique, we were able to precisely detect Nav channels activators or blockers. Among 62 compounds tested, 5 isoquinolines appeared as potent Nav channels inhibitors. References: 1. Salat, K. et al. (2014) EOID 23:1093-1104 2. Yu, F.H. et al (2003) Genome Biol. 4

Screening an in house alkaloids library using Voltage-Sensor Probes for new modulators of voltage-gated sodium channels

Voltage-gated sodium channels (Nav) are molecular targets of clinically used drugs for treatments of various diseases (epilepsy, chronic pain, cardiac arrhythmia…) and also of numerous animal and plant neurotoxins. The development of easy-to-use screening assays for searching new ligands from chemicals libraries, animal venoms or plant extracts represents a challenge of a great interest to generate therapeutic hits. Here, we used the mammalian GH3B6 pituitary cell line, which constitutively expresses three different neuronal Nav channel isoforms (Nav1.2, Nav1.3 and Nav1.6), to identify novel compounds of pharmacological interest from a library of in-house vegetal alkaloids. The screening is based on a method using Voltage-Sensor Probes (VSPs) that we adapted to detect both activators and blockers of Nav channels. Over the 84 pure alkaloids or plant extracts that were screened, 17 increased the VSP signal. They operated as gating modifier, showing an action mechanism similar to that of batrachotoxin (BTX), known to strongly inhibit Nav channel inactivation. The remaining 67 plant products were assessed for their potency to inhibit BTX-induced VSP signal. We further selected 11 alkaloids as efficient Nav channels inhibitors. We focused our attention on two structural analogs belonging to the aporphine family, liriodenine and oxostephanine, which differ only by a methoxy group. Whereas liriodenine has been already described as a Nav channels blocker, oxostephanine has not been yet documented as an ion channel modulator. In conclusion, the novel VSPs-based screening assay we developed is a suitable method to challenge the discovery and to assess the activity of novel ligands on Nav channels

Identifying Natural Products (NPs) as potential UPR inhibitors for crop protection

As far as the future of agriculture is concerned, one major challenge will be to face an expected increase in health risks due to pesticides together with a lower efficiency of crop treatments. Therefore it is today necessary to develop new strategies to enhance the effectiveness and sustainability of current control methods. The so-called “Alternaria Leaf Spot“ is a common disease of crucifers caused by the fungal pathogen Alternaria brassicicola which affects different crops including cabbage, kale, Brussels sprout, cauliflower and broccoli. Indole phytoalexins camalexin and brassinin play in planta a key role in crop protection against this necrotrophic agent. However it has been shown that mutants become phytoalexin-resistant by activating at least three signaling pathways named as Cell Wall Integrity (CWI), High Osmolarity Glycerol (HOG) and Unfolded Protein Response (UPR) [1,2]. The latter is particularly involved in the fungus protection against phytoalexins since UPR deficient avirulent mutants of A. brassicicola appear as hypersensitive to camalexin and brassinin [3]. Since very few UPR inhibitors such as the synthetic STF-083010 [4] are known we decided to develop an original screening assay, detecting the production of a HAC1 fluorescence-induced protein, i.e. a transcriptional activator involved in the UPR pathway, in Saccharomyces cerevisiae cultures (Figure 1). The preliminary screening of an in-house NPs library [c.a. 70 compounds (polyphenols, terpenoids and alkaloids)] clearly revealed aescin (Aesculus hippocastanum)] as a potential UPR inhibitor

Chemical composition and antiglycoxidant activities of French organic propolis extracts

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