Chemistry of Advanced Materials 3(2) (2018) 36-59 Antioxidant, Anti-inflammatory and Neuroprotective Activities of a Plant Extract Derived from Traditional Chinese Medicine: SuHeXiang Wan (AT000)

International audienceIn this paper, we present SuHeXiang Wan, a medicine used in traditional Chinese medicine for the treatment of epilepsy and convulsions. We investigated the antioxidant, anti-inflammatory and neuroprotective activities of the same treatment designated as AT000. The synergy of the two plants, Dryobalanops aromatica and Saussurea lappa, of which the use in alimentary supplements is considered controversial, was evaluated for the first time. The antioxidant activity of the extract was assessed by DPPH and ORAC tests while the anti-inflammatory activity was determined by measuring the capacity of macrophages to generate a strong inflammatory response when stimulated with antigens, inducing NO release. The extract efficacy on the attenuation of the Aβ25-35-induced learning deficits (spatial working memory: spontaneous alternation in the Y-maze and contextual long-term memory: passive avoidance test) was evaluated in vivo in mice seven days after the peptide administration. The impact on lipid peroxidation in the hippocampus, an index of oxidative Chemistry of Advanced Materials (CAM) Journal homepage: http://issrpublishing.com/cam/ Iskandar et al., Chemistry of Advanced Materials 3(2) (2018) 36-59 37 stress, was also evaluated. AT000 extract showed a strong antioxidant activity at 2 mg/mL, 10 mg/mL and 301774 Trolox equivalents according to the DPPH and ORAC tests respectively. The 21-days AT000 treatment dose-dependently alleviated Aβ25-35-induced deficits, with significant prevention at the highest dose tested (250 mg/Kg/day) on the spontaneous alternation, step-through latency and escape latency parameter. 21-days AT000 treatment dose-dependently attenuated also Aβ25-35-induced increase lipid peroxidation, with a significant and complete blockade at the highest doses tested. Synergistic experiments showed that the presence of Dryobalanops aromatica and Saussurea lappa is crucial to obtain a neuroprotective effect. According to these results, AT000 could be a candidate compound in the development of therapeutic drugs for the prevention and treatment of Alzheimer's disease

Nod factors thin-layer chromatography profiling as a tool to characterize symbiotic specificity of rhizobial strains : application to Sinorhizobium saheli, S. teranga, and Rhizobium sp. strains isolated from Acacia and Sesbania

Rhizobia isolated from #Acacia or #Sesbania belong to several taxonomic groups, including the newly described species #Sinorhizobium saheli, #Sinorhizobium teranga, and the so-called cluster U. A collection of strains belonging to these different groups was analyzed in order to determine whether the host range of a strain could be correlated with various molecular nodulation determinants. Nodulation tests showed that, independently of their taxonomic position, all the strains isolated from the same plant genus exhibited a similar host range, which was different for #Sesbania and #Acacia isolates. The fact that #S. teranga strains nodulate either #Acacia or #Sesbania led us to subdivide this species into biovars #acaciae and #sesbaniae. Thin-layer chromatography (TLC) analysis of the Nod factors synthesized by overproducing strains showed that strains isolated from the same plant genus exhibited similar TLC profiles and profiles of #Acacia and #Sesbania symbionts were easily distinguishable, #Acacia strains producing, in particular, sulfated molecules. In contrast, no correlation could be established between the host range of a strain and its plasmid content, the nature of the nod gene inducers or the presence of DNA sequences homologous to specific nod genes. We thus propose that Nod factor TLC profiling may be used as an easy and powerful tool for the classification of rhizobial strains on the basis of their symbiotic properties. (Résumé d'auteur

L'acacia au Sénégal

L'intérêt agronomique et écologique des rhizobiums repose essentiellement sur leurs propriétés symbiotiques. Il est donc capital de pouvoir apprécier la diversité des souches sur la base de leur pouvoir de nodulation. L'objectif de ce travail est de proposer une nouvelle approche, alternative aux tests de nodulation, permettant de classer les souches en fonction de leur spécificité symbiotique. Au cours des premières étapes de l'interaction rhizobium-légumineuses, les rhizobiums excrètent des molécules signal, appelées facteurs Nod, qui jouent un rôle déterminant dans l'infection et la nodulation des plantes-hôtes. Leur utilisation potentielle comme marqueur de la spécificité de nodulation a été évaluée à partir de l'étude d'une collection de souches isolées d'#Acacia et de #Sesbania au Sénégal. L'analyse chromatographique des facteurs Nod de ces souches a montré que les profils chromatographiques sont parfaitement corrélés à la fois à la structure chimique des facteurs Nod et à la spécificité d'hôte des souches, et plus particulièrement à la plante d'isolement. Une telle méthode de caractérisation globale des facteurs Nod pourrait donc être utilisée pour la caractérisation symbiotique des rhizobiums, en particulier pour l'étude taxonomique, l'étude de la biodiversité des souches ou pour le contrôle des inoculums. (Résumé d'auteur

Quelques aspects importants du metabolisme du NADP dans le latex d'hevea brasiliensis. Etude de l'HMGCoA reductase et de la NAD kinase

SIGLEINIST T 76348 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

New insights and advances on pyomelanin production: from microbial synthesis to applications

International audiencePyomelanin is a brown-black phenolic polymer and results from the oxidation of homogentisic acid (HGA) in the L-tyrosine pathway. As part of the research for natural and active ingredients issued from realistic bioprocesses, this work re-evaluates the HGA pigment and makes an updated inventory of its syntheses, microbial pathways, and properties, with tracks and recent advances for its large-scale production. The mechanism of the HGA polymerization is also well documented. In alkaptonuria, pyomelanin formation leads to connective tissue damage and arthritis, most probably due to the ROS issued from HGA oxidation. While UV radiation on human melanin may generate degradation products, pyomelanin is not photodegradable, is hyperthermostable, and has other properties better than L-Dopa melanin. This review aims to raise awareness about the potential of this pigment for various applications, not only for skin coloring and protection but also for other cells, materials, and as a promising (semi)conductor for bioelectronics and energy

Hydroxytyrosol from tyrosol using hydroxyphenylacetic acid-induced bacterial cultures and evidence of the role of 4-HPA 3-hydroxylase

International audienc

Mise en évidence d'une NAD kinase dans le compartiment membranaire du latex d'Hevea brasiliensis

Une NAD kinase (EC 2.7.1.23) a été mise en évidence dans le latex d'#Hevea brasiliensis$. Elle est localisée dans la fraction membranaire de latex ultracentrifugé et serait liée soit aux lutoïdes (microvacuoles lysosomales) soit à une autre structure membranaire et catalyse la formation du NADP faiblement présent dans le cytosol (< 1 microM). Le pH optimal de son activité est 8,0 et l'affinité de l'enzyme à ce pH est comprise entre 0,5 et 1,0 mM pour le NAD et entre 1,0 et 1,5 mM pour l'ATP. Il s'agit d'une enzyme de type allostérique présentant une coopérativité positive aux faibles concentrations en substrats. En régénérant du NADP(H), molécule activatrice et cofacteur d'enzymes clefs de la biosynthèqe du caoutchouc, cette enzyme pourrait jouer un rôle important dans la physiologie de la production du latex. (Résumé d'auteur

Production and properties of non-cytotoxic pyomelanin by laccase and comparison to bacterial and synthetic pigments

International audienceAbstract Pyomelanin is a polymer of homogentisic acid synthesized by microorganisms. This work aimed to develop a production process and evaluate the quality of the pigment. Three procedures have been elaborated and optimized, (1) an HGA-Mn 2+ chemical autoxidation (Pyo CHEM yield 0.317 g/g substrate), (2) an induced bacterial culture of Halomonas titanicae through the 4-hydroxyphenylacetic acid-1-hydroxylase route (Pyo BACT , 0.55 g/L), and (3) a process using a recombinant laccase extract with the highest level produced (Pyo ENZ , 1.25 g/g substrate) and all the criteria for a large-scale prototype. The chemical structures had been investigated by 13 C solid-state NMR (CP-MAS) and FTIR. C ar –C ar bindings predominated in the three polymers, C ar –O–C ar (ether) linkages being absent, proposing mainly C 3 -C 6 (α-bindings) and C 4 -C 6 (β-bindings) configurations. This work highlighted a biological decarboxylation by the laccase or bacterial oxidase(s), leading to the partly formation of gentisyl alcohol and gentisaldehyde that are integral parts of the polymer. By comparison, Pyo ENZ exhibited an M w of 5,400 Da, was hyperthermostable, non-cytotoxic even after irradiation, scavenged ROS induced by keratinocytes, and had a highly DPPH-antioxidant and Fe 3+ -reducing activity. As a representative pigment of living cells and an available standard, Pyo ENZ might also be useful for applications in extreme conditions and skin protection