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International audience; We have previously demonstrated that out of the butyrolactones series synthesized based on the natural lichen metabolite lichesterinic acid, compound (B-13) was the most effective against oral bacteria. However, its antibacterial mechanism is still unknown. In this study, we have investigated its bacterial localization by synthesizing a fluorescently labeled B-13 with NBD while maintaining its antibacterial activity. We showed that this compound binds to Streptococcus gordonii cell surface, as demonstrated by HPLC analysis. By adhering to cell surface, B-13 induced cell wall disruption leading to the release of bacterial constituents and consequently, the death of S. gordonii, a Gram-positive bacterium. A Gram-negative counterpart, Porphyromanas gingivalis, showed also cracked and ruptured cells in the presence of B-13. Besides, we also demonstrated that the analog of B-13, B-12, has also induced disruption of P. gingivalis and S. gordonii. This study revealed that butyrolactones can be considered as potent antibacterial compounds against oral pathogens causing medical complications.

International audience; The genus Roseburia consists of obligate Gram-positive anaerobic bacteria that are slightly curved, rod-shaped and motile by means of multiple subterminal flagella. It includes five species: Roseburia intestinalis, R. hominis, R. inulinivorans, R. faecis and R. cecicola. Gut Roseburia spp. metabolize dietary components that stimulate their proliferation and metabolic activities. They are part of commensal bacteria producing short-chain fatty acids, especially butyrate, affecting colonic motility, immunity maintenance and anti-inflammatory properties. Modification in Roseburia spp. representation may affect various metabolic pathways and is associated with several diseases (including irritable bowel syndrome, obesity, Type 2 diabetes, nervous system conditions and allergies). Roseburia spp. could also serve as biomarkers for symptomatic pathologies (e.g., gallstone formation) or as probiotics for restoration of beneficial flora.

Aim The purpose of this study was to conduct phytochemical analysis of sea buckthorn pulp oil and to evaluate the antimicrobial, anti-biofilm and antioxidant activities of its mouthwash form. Methods and results Fatty acid composition of the sea buckthorn pulp oil was determined by GC-MS analysis, which revealed that, mono-unsaturated fatty acid, palmitoleic acid and saturated fatty acid, palmitic acid, were the major constituents. The antimicrobial and the anti-biofilm capacities of sea buckthorn pulp oil mouthwash form were evaluated against Streptococcus gordonii, Porphyromonas gingivalis, Actinomyces viscosus and Candida albicans, according to the European Norms, and the Biofilm Ring Test® , respectively. These activities were then compared with those of chlorhexidine and herbal mouthwashes. The sea buckthorn-based mouthwash was bactericidal against S. gordonii and P. gingivalis, bacteriostatic against A. viscosus and showed no antifungal effect. Regardless of the strains used, complete inhibition of biofilm formation was achieved. The antioxidant activity of this experimental mouthwash was also assessed by DPPH and NBT assays. Conclusion Sea buckthorn mouthwash showed anti-biofilm activities against select single and multiple oral bacterial species. Significance and impact of the study In this study, a mouthwash derived from sea buckthorn (Hippophae rhamnoides) pulp oil has been experimented, for the first time, in order to overcome the problem of a large number of available synthetic mouthwashes which have side effects on teeth, gums and mucous membranes. This mouthwash seemed to be a suitable alternative for a preventive agent for periodontal inflammation.

International audience; Objective: This work is the first to investigate the in vitro anti-acne and cytotoxic activities of the leaves of Ludwigia peploides. With its important seasonal biomass production, this plant has great potential in several therapeutic and cosmetic applications.Methods: The antibacterial activity of the extract was screened against a consortium of skin microorganisms that cause acne vulgaris disease, using disc diffusion and broth microdilution methods. The antioxidant activity of methanolic leaf extract of L. peploides was evaluated by DPPH and NBT assays to assess the free radical scavenging activity of L. peploides, which in turn has a great importance related to its role in minimizing the oxidative stress linked to the pathophysiology of diseases like acne vulgaris. Its putative cytotoxicity was examined against human macrophage-like monocytic leukemia (THP-1) and human keratinocytes (HaCaT) cell lines. In addition, antiproliferative activity was screened against B16 cancer cell lines. Results: The extract displayed antioxidant effect by DPPH (IC50= 58 ± 6.0 µg mL-1) and NBT (IC50= 30 ± 2.8 µg mL-1) assays, and it was not toxic on HaCaT cells (IC50 > 200 µg mL-1). A strong inhibitory activity against Propionibacterium acnes (MIC = 1.9 µg mL-1) was registered for the extract, which had a bactericidal effect against Staphylococcus aureus, Staphylococcus epidermidis, and Salmonella enterica. Finally, the extract was shown to have an antiproliferative activity (IC50=5.5 ± 2.3 µgmL-1).Conclusion: The extract displays antioxidant and anti-acne effects as well as inhibition potential of B16 melanoma cells proliferation.

63rd International Congress and Annual Meeting of the Society-for-Medicinal-Plant-and-Natural-Product-Research (GA), Budapest, HUNGARY, AUG 23-27, 2015; International audience; Introduced from South America in the 19th century as an ornamental aquatic plant, Ludwigia has since invaded almost every continent. L. grandiflora is widespread and invasive in France, forming dense aquatic stands, which cause major ecological and economic problems and reduce local biodiversity. The eradication of L. grandiflora is either very difficult or even impossible. The purpose of this study was the valorization of potential antibacterial and antioxidant compounds in the leaf extract of L. grandiflora using a bioassay-guided fractionation approach. Antibacterial activity was assessed using the disc diffusion and microdilution methods against 14 strains of Gram-positive and Gram-negative bacteria. Crude methanolic leaf extract showed strong activity against most of the tested strains, sometimes being more active than common antibiotics. Maximum antibacterial activity was measured against two pathogenic bacteria, Staphylococcus aureus and Salmonella enterica. The bioassay guided fractionation led to the isolation of several fractions more active than the crude extract; antibacterial activity of fraction (A) was 52% higher than that of the crude extract against S. aureus.The antioxidant activity was evaluated by the scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) and was expressed as EC50 (µg/mL), the extract dose required to cause a 50% inhibition. The fraction (A) exhibited a higher antioxidant activity (EC50= 6 µg/mL), as compared to the crude extract (EC50= 26.3 µg/mL) and the Trolox (EC50= 15.9 µg/mL), which was used as reference standard. RP-HPLC analysis showed that myricetin was the major phenolic compound. However, there was insufficient time to determine the active molecules.This innovative study, which allowed the submission of a patent, suggests that Ludwigia may be considered as an interesting source of antibacterial and antioxidant compounds for therapeutic uses and for the cosmetic and nutraceutical industries.

International audience; Ludwigia peploides subsp. montevidensis and Ludwigia grandiflora subsp. hexapetala, form aquatic dense stands, which cause major ecological and economical problems in many aquatic ecosystems in France. However, these species are known to release allelopathic compounds. Here, antibacterial properties were assessed on samples from different plant organs, during June, July and August for L. peploides and throughout the development period, from April to September, for L. grandiflora. The disk diffusion method was used here to screen dimethylsulfoxide plant extracts against 5 Gram positive and 9 Gram negative bacterial strains. The sensitivity of the bacteria tested to L. grandiflora extracts was greater than that to those of L. peploides. Maximum antibacterial activity was measured in June, July or August, depending on the plant organ, principally in leaf and flower extracts. Activity also varied according to the bacterial strains tested. A principal component analysis (PCA) showed that sensitivity to the plant extracts did not depend' on whether the bacterial strains are Gram positive or Gram negative. Thus, we found that a Gram positive strain, Staphylococcus aureus (CIP 76.25), and a Gram negative strain, Salmonella enterica (DSM 10062), were similar in sensitivity. Antibacterial activities of certain leaf or flower extracts of both species of Ludwigia were revealed superior to those of several classic antibiotics tested. The interest of this study concerns the therapeutical potential of the two Ludwigia species. (C) 2014 Elsevier B.V. All rights reserved.