Relationship between the structure of the flavone-C-glycosides of flax (Linum usitatissimum L.) and their biological activities

International audienceAtibiotics are one of the most important discoveries that have saved and is saving millions of lives in the world, but the emergence of resistant bacteria induces little or not effective for these synthetic products. In some situations the appearance of resistance prevents the treatment of infections caused by bacteria. The discovery of alternative antimicrobial agents has become urgently required.Many products of plant origin, in particular the class of flavonoids, exhibit antibacterial activity often associated with a high level of antioxidant power. Despite the many studies on this issue, the relationship between structure and function is currently poorly understood. To fill this gap, the biological activity of 12 flavone C-glycosides structurally close was studied. The structural variability of these compounds (derived from apigenin and luteolin) depends on the position and nature of the sugars, the number of hydroxyl groups and the presence of a methyl group.Thus, orientin, isoorientin, vitexin, isovitexin, swertisin, swertiajaponin, carlinoside, schaftoside, lucenin-1, lucenin-2, vicenin-1 and vicenin-2 were extracted from the aerial part of winter flax (Linum usitatissimum). The hydroalcoholic extract was purified by preparative HPLC and by the drowning-out crystallization method. Then, the control of the purity (greater than 99%) and the confirmation of the chemical structures were carried out by NMR and LC/MS. Antioxidant activity was tested by methods such as DPPH and FRAP and antimicrobial potential was assessed using common foodborne pathogens such as P. aeruginosa, E. coli, L. monocytogenes, L. innocua, S. arizonae, E. faecalis, S. aureus, B. subtilis

Relationship between the structure of the flavone-C-glycosides of flax (Linum usitatissimum L.) and their biological activities

International audienceAtibiotics are one of the most important discoveries that have saved and is saving millions of lives in the world, but the emergence of resistant bacteria induces little or not effective for these synthetic products. In some situations the appearance of resistance prevents the treatment of infections caused by bacteria. The discovery of alternative antimicrobial agents has become urgently required.Many products of plant origin, in particular the class of flavonoids, exhibit antibacterial activity often associated with a high level of antioxidant power. Despite the many studies on this issue, the relationship between structure and function is currently poorly understood. To fill this gap, the biological activity of 12 flavone C-glycosides structurally close was studied. The structural variability of these compounds (derived from apigenin and luteolin) depends on the position and nature of the sugars, the number of hydroxyl groups and the presence of a methyl group.Thus, orientin, isoorientin, vitexin, isovitexin, swertisin, swertiajaponin, carlinoside, schaftoside, lucenin-1, lucenin-2, vicenin-1 and vicenin-2 were extracted from the aerial part of winter flax (Linum usitatissimum). The hydroalcoholic extract was purified by preparative HPLC and by the drowning-out crystallization method. Then, the control of the purity (greater than 99%) and the confirmation of the chemical structures were carried out by NMR and LC/MS. Antioxidant activity was tested by methods such as DPPH and FRAP and antimicrobial potential was assessed using common foodborne pathogens such as P. aeruginosa, E. coli, L. monocytogenes, L. innocua, S. arizonae, E. faecalis, S. aureus, B. subtilis

Effect of general anaesthesia on functional outcome in patients with anterior circulation ischaemic stroke having endovascular thrombectomy versus standard care: a meta-analysis of individual patient data

Background: General anaesthesia (GA) during endovascular thrombectomy has been associated with worse patient outcomes in observational studies compared with patients treated without GA. We assessed functional outcome in ischaemic stroke patients with large vessel anterior circulation occlusion undergoing endovascular thrombectomy under GA, versus thrombectomy not under GA (with or without sedation) versus standard care (ie, no thrombectomy), stratified by the use of GA versus standard care. Methods: For this meta-analysis, patient-level data were pooled from all patients included in randomised trials in PuMed published between Jan 1, 2010, and May 31, 2017, that compared endovascular thrombectomy predominantly done with stent retrievers with standard care in anterior circulation ischaemic stroke patients (HERMES Collaboration). The primary outcome was functional outcome assessed by ordinal analysis of the modified Rankin scale (mRS) at 90 days in the GA and non-GA subgroups of patients treated with endovascular therapy versus those patients treated with standard care, adjusted for baseline prognostic variables. To account for between-trial variance we used mixed-effects modelling with a random effect for trials incorporated in all models. Bias was assessed using the Cochrane method. The meta-analysis was prospectively designed, but not registered. Findings: Seven trials were identified by our search; of 1764 patients included in these trials, 871 were allocated to endovascular thrombectomy and 893 were assigned standard care. After exclusion of 74 patients (72 did not undergo the procedure and two had missing data on anaesthetic strategy), 236 (30%) of 797 patients who had endovascular procedures were treated under GA. At baseline, patients receiving GA were younger and had a shorter delay between stroke onset and randomisation but they had similar pre-treatment clinical severity compared with patients who did not have GA. Endovascular thrombectomy improved functional outcome at 3 months both in patients who had GA (adjusted common odds ratio (cOR) 1·52, 95% CI 1·09–2·11, p=0·014) and in those who did not have GA (adjusted cOR 2·33, 95% CI 1·75–3·10, p<0·0001) versus standard care. However, outcomes were significantly better for patients who did not receive GA versus those who received GA (covariate-adjusted cOR 1·53, 95% CI 1·14–2·04, p=0·0044). The risk of bias and variability between studies was assessed to be low. Interpretation: Worse outcomes after endovascular thrombectomy were associated with GA, after adjustment for baseline prognostic variables. These data support avoidance of GA whenever possible. The procedure did, however, remain effective versus standard care in patients treated under GA, indicating that treatment should not be withheld in those who require anaesthesia for medical reasons