Activité
- Thèmes de recherches :
- Multi-Drug Resistance
- Chemical Ecology : plant-microbes interactions
Chimie des substances naturelles ; chimiobiodiversité ; métabolites secondaires et interactions biotiques ; modulation de la MultiDrug Résistance ; substances naturelles bioactives.
Parcours scientifique
- Pharm D
- Ph D
Enseignement/Encadrement
- Maître de Conférences en Pharmacognosie à l’Institut des Sciences Pharmaceutiques et Biologiques de Lyon (UCB Lyon1) dans l’UMR-5557 CNRS/UCB : Ecologie Microbienne
- Pharmacognosie, Biologie Végétale, Botanique, Phytothérapie dans le cursus de Pharmacie (ISPB – UCB Lyon 1). Encadrement et jury de stage du master Phytoressources (Département de Biologie – UCB Lyon1)
Publications
2019
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Lebot V, Michalet S, Legendre L. 2019. Kavalactones and Flavokavins Profiles Contribute to Quality Assessment of Kava (Piper methysticum G. Forst.), the Traditional Beverage of the Pacific. Beverages. 5:34. doi: 10.3390/beverages5020034. -
Maaloul A, et al. 2019. Effect of Short and Long Term Irrigation with Treated Wastewater on Chemical Composition and Herbicidal Activity of Eucalyptus camaldulensis Dehn. Essential Oils. Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 47:1374-1381. doi: 10.15835/nbha47411374.Résumé : Water shortage throughout the world, especially in arid regions in the later decades has led to search for alternatives to save potable fresh water. Treated wastewater (TWW) appears to be an opportunity for irrigation. However, it could represent a stress factor for plants, and influence their metabolism, changing their secondary metabolites and, consequently, their biological properties. Eucalyptus camaldulensis essential oil (EO) had been reported to possess phytotoxic activity. The main objective of this work was to compare the chemical composition and herbicidal activity of E. camaldulensis EO obtained from leaves of young plants and old trees irrigated with well water (WW) and TWW. Germination tests were performed in vitro against Amaranthus hybridus, Chenopodium album, Echinochloa crus-galli and Lolium perenne. The EOs composition was analyzed by gas chromatography and gas chromatography/mass spectrometry. A high percentage of oxygenated monoterpenes, with 1,8-cineole as main compound, was found in the EOs from leaves of young plants irrigated with both types of water. The EO from leaves of old trees irrigated with WW contained a main fraction of monoterpene hydrocarbons (45.17%) with p-cymene as principal compound. The highest herbicidal potential was shown by the EO from young plants irrigated with TWW. It completely inhibited A. hybridus and L. perenne germination, and nearly blocked the others at all concentrations assayed. It also showed strong phytotoxic activity on seedling length. The results suggest the possible use of TWW to irrigate Eucalyptus crops as it enhances the EOs herbicidal potential that could be used as natural herbicides. -
Michalet S, et al. 2019. Identification of human skin bacteria attractive to the Asian Tiger mosquito. Environmental Microbiology. 21:4662-4674. doi: 10.1111/1462-2920.14793.Résumé : Aedes albopictus is a vector of arboviruses and filarial nematodes. Originating from Asia, this mosquito has rapidly expanded its geographical distribution and colonized areas across both temperate and tropical regions. Due to the increase in insecticide resistance, the use of environmentally friendly vector control methods is encouraged worldwide. Using methods based on semiochemicals in baited traps are promising for management of mosquito populations. Interestingly, human skin microbiota was shown to generate volatile compounds that attract the mosquito species Anopheles gambiae and Aedes aegypti. Here, we investigated the composition of skin bacteria from different volunteers and the attractive potential of individual isolates to nulliparous Ae. albopictus females. We showed that three out of 16 tested isolates were more attractive and two were more repulsive. We identified dodecenol as being preferentially produced by attractive isolates and 2-methyl-1-butanol (and to a lesser extent 3-methyl-1-butanol) as being overproduced by these isolates compared with the other ones. Those bacterial volatile organic compounds represent promising candidates but further studies are needed to evaluate their potential application for baited traps improvement.
2017
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El Moujahid L, et al. 2017. Effect of plant diversity on the diversity of soil organic compounds. PLOS ONE. 12:e0170494. doi: 10.1371/journal.pone.0170494.Résumé : The effect of plant diversity on aboveground organisms and processes was largely studied but there is still a lack of knowledge regarding the link between plant diversity and soil characteristics. Here, we analyzed the effect of plant identity and diversity on the diversity of extractible soil organic compounds (ESOC) using 87 experimental grassland plots with different levels of plant diversity and based on a pool of over 50 plant species. Two pools of low molecular weight organic compounds, LMW1 and LMW2, were characterized by GC-MS and HPLC-DAD, respectively. These pools include specific organic acids, fatty acids and phenolics, with more organic acids in LMW1 and more phenolics in LMW2. Plant effect on the diversity of LMW1 and LMW2 compounds was strong and weak, respectively. LMW1 richness observed for bare soil was lower than that observed for all planted soils; and the richness of these soil compounds increased twofold when dominant plant species richness increased from 1 to 6. Comparing the richness of LMW1 compounds observed for a range of plant mixtures and for plant monocultures of species present in these mixtures, we showed that plant species richness increases the richness of these ESOC mainly through complementarity effects among plant species associated with contrasted spectra of soil compounds. This could explain previously reported effects of plant diversity on the diversity of soil heterotrophic microorganisms. -
Guyonnet JP, et al. 2017. The effects of plant nutritional strategy on soil microbial denitrification activity through rhizosphere primary metabolites. FEMS Microbiology Ecology. 93. doi: 10.1093/femsec/fix022.Résumé : The aim of this study was to determine (i) whether plant nutritional strategy affects the composition of primary metabolites exuded into the rhizosphere and (ii) the impact of exuded metabolites on denitrification activity in soil. We answered this question by analysing primary metabolite content extracted from the root-adhering soil (RAS) and the roots of three grasses representing different nutrient management strategies: conservative (Festuca paniculata), intermediate (Bromus erectus) and exploitative (Dactylis glomerata). We also investigated the impact of primary metabolites on soil microbial denitrification enzyme activity without carbon addition, comparing for each plant RAS and bulk soils. Our data show that plant nutritional strategy impacts on primary metabolite composition of root extracts or RAS. Further we show, for the first time, that RAS-extracted primary metabolites are probably better indicators to explain plant nutrient strategy than root-extracted ones. In addition, our results show that some primary metabolites present in the RAS were well correlated with soil microbial denitrification activity with positive relationships found between denitrification and the presence of some organic acids and negative ones with the presence of xylose. We demonstrated that the analysis of primary metabolites extracted from the RAS is probably more pertinent to evaluate the impact of plant on soil microbial community functioning. -
Lebot V, Lawac F, Michalet S, Legendre L. 2017. Characterization of taro [Colocasia esculenta (L.) Schott] germplasm for improved flavonoid composition and content. Plant Genetic Resources. 15:260-268. doi: 10.1017/S1479262115000581.Résumé : The starchy corms of taro (Colocasia esculenta) are consumed throughout the tropics and are essential for food security in many developing countries. Taro corms are increasingly processed into fries, chips, flours or flakes in urban areas, and varieties with attractive corm flesh colours are now needed. The identification of flavonoids in taro corms would add value to this crop. The present study developed a high-performance thin layer chromatography (HPTLC) protocol for the high-throughput screening of flavonoids in taro germplasm. Overall, 350 different accessions were analysed including 259 varieties from Vanuatu, one from Vietnam, eight from Thailand, eight from the Philippines, six from Malaysia, two from Japan and 18 from Indonesia. Forty-eight breeding lines (hybrids) including 21 from Vanuatu, 21 from Samoa, four from Hawaii and two from Papua New Guinea were also analysed. Ten flavones, namely luteolin-6-C-hexoside-8-C-pentoside, schaftoside, luteolin-3′,7-di-O-glucoside, homoorientin, isovitexin, orientin, luteolin-4′-O-glucoside, luteolin-7-O-glucoside, vitexin and apigenin-7-O-glucoside, were successfully detected in the corm and are responsible for the attractive yellow colour of the flesh and fibres. Quantitatively, luteolin-6-C-hexoside-8-C-pentoside and schaftoside were the most important of all the detected flavonoids. However, only 18% of the varieties analysed presented these two compounds and 80% presented poor flavonoid composition. No geographical structure of the variation was detected and the most flavone-rich varieties originated from Vanuatu, Thailand, the Philippines, Malaysia and Indonesia. The compounds detected in the present study were significantly and positively correlated, suggesting that there is potential for fast improvement through controlled crosses, subsequent evaluation of full-sib progenies and cloning of elite individuals. -
Michalet S, et al. 2017. Tolerance of Japanese knotweed s.l. to soil artificial polymetallic pollution: early metabolic responses and performance during vegetative multiplication. Environmental Science and Pollution Research. 1-11. doi: 10.1007/s11356-017-9716-8.Résumé : The expansion of invasive Japanese knotweed s.l. is of particular concern because of its aptitudes to rapidly colonize diverse environments, especially anthropized habitats generally characterized by their pollution with heavy metals. Whether the presence of heavy metals impacts the performance traits of this plant is a central question to better understand its invasive properties, though no controlled approach to assess these effects was yet reported. In this aim, we undertook greenhouse experiments where rhizome fragments of Japanese knotweed s.l. (Fallopia japonica and Fallopia × bohemica) were grown during 1 and 3 months, in a soil pot artificially polluted or not with heavy metals added in mixture (Cd, Cr, Pb, Zn). Our results showed that (i) the presence of heavy metals delayed rhizome regeneration and induced lowered plant part weights but did not affect plant height after 3 months; (ii) the effect of metals on the metabolic profiles of belowground part extracts was only detectable after 1 month and not after 3 months of growth, though it was possible to highlight the effect of metals independently of time and genotype for root extracts, and torosachrysone seemed to be the most induced compound; and (iii) the hybrid genotype tested was able to accumulate relatively high concentrations of metals, over or close to the highest reported ones for this plant for Cr, Cd and Zn, whereas Pb was not accumulated. These findings evidence that the presence of heavy metals in soil has a low impact on Fallopia sp. overall performance traits during rhizome regeneration, and has a rather stimulating effect on plant growth depending on pollution level.
2016
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Chaabane F, et al. 2016. In vitro and in vivo anti-melanoma effects of Daphne gnidium aqueous extract via activation of the immune system. Tumor Biology. 37:6511-6517. doi: 10.1007/s13277-015-4492-x.Résumé : The purpose of this study was to assess the antitumor and immunomodulatory effects of the aqueous extract from Daphne gnidium in mice-bearing melanoma tumor. Balb/C mice were subcutaneously implanted with B16-F10 cells and treated intraperitoneally with the aqueous extract at 200 mg/Kg b.w for 21 days. After euthanization on day 22, the tumors were weighed; lymphocyte proliferation, cytotoxic T lymphocyte (CTL), and natural killer (NK) cell activities were evaluated using the MTT assay. Macrophage phagocytosis was studied by measuring the lysosomal activity. In addition to its potential to inhibit the growth of the transplantable tumor, the aqueous extract remarkably induced splenocyte proliferation and both NK and CTL activities in tumor-bearing mice. The aqueous extract was also seen to have promoted lysosomal activity of host macrophages. -
Lebot V, Michalet S, Legendre L. 2016. Identification and quantification of phenolic compounds responsible for the antioxidant activity of sweet potatoes with different flesh colours using high performance thin layer chromatography (HPTLC). Journal of Food Composition and Analysis. 49:94-101. doi: 10.1016/j.jfca.2016.04.009.Résumé : The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones. -
Muñoz-Cuervo I, Malapa R, Michalet S, Lebot V, Legendre L. 2016. Secondary metabolite diversity in taro, Colocasia esculenta (L.) Schott, corms. Journal of Food Composition and Analysis. 52:24-32. doi: 10.1016/j.jfca.2016.07.004.Résumé : Taro, Colocasia esculenta (L.) Schott, is one of the oldest major staple food crops of tropical regions. This study represents one the first in-depth surveys of taro biodiversity based on corms flesh secondary metabolites fingerprints. Out of the 167 analyzed cultivars, 70 UV-absorbing substances were annotated according to their retention time, UV/Vis absorption spectrum, high resolution mass (by HRMS) and fragmentation pattern (tandem MS-MS). They included 6 carotenoids, 35 flavones/flavonols, 6 flavanones, 2 flavanols and 1 indol. Twenty flavones that were glycosylated forms of apigenin, luteolin and chrysoeriol conferred to the corms a yellow color and defined a low abundance (ca. 10% of cultivars) chemotype. Their accumulation negatively correlated with flavanones which were annotated for the first time in taro. Orange flesh corms were characterized by high levels of β-carotene. Secondary metabolite-based chemotypes displayed no geographical distribution pattern.
2013
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Michalet S, et al. 2013. Phytochemical analysis of mature tree root exudates <i>in situ</i> and their role in shaping soil microbial communities in relation to tree N-acquisition strategy. Plant Physiology and Biochemistry. 72:169-177. doi: 10.1016/j.plaphy.2013.05.003.Résumé : Abstract Eperua falcata (Aublet), a late-successional species in tropical rainforest and one of the most abundant tree in French Guiana, has developed an original strategy concerning N-acquisition by largely preferring nitrate, rather than ammonium [1].Given the preference of this species for nitrate, we hypothesized that root exudates would promote nitrate availability by a) enhancing nitrate production by stimulating ammonium oxidation or b) minimizing nitrate losses by inhibiting denitrification. Root exudates were collected in situ in monospecific planted plots. The phytochemical analysis of these exudates and of several of their corresponding root extracts was achieved using UHPLC/DAD/ESI-QTOF and allowed the identification of diverse secondary metabolites belonging to the flavonoid family. Our results show that (i) the distinct exudation patterns observed are related to distinct root morphologies, and this was associated with a shift in the root flavonoid content, (ii) a root extract representative of the diverse compounds detected in roots showed a significant and selective metabolic inhibition of isolated denitrifiers in vitro, and (iii) in soil plots the abundance of nirK-type denitrifiers was negatively affected in rhizosphere soil compared to bulk. Altogether this led us to formulate hypothesis concerning the ecological role of the identified compounds in relation to N-acquisition strategy of this species. -
Rakotomalala G, et al. 2013. Extract from Mimosa pigra attenuates chronic experimental pulmonary hypertension. Journal of Ethnopharmacology. 148:106-116. doi: 10.1016/j.jep.2013.03.075.Résumé : AbstractEthnopharmacological relevance Different parts of Mimosa pigra (MPG) are used in traditional medicine in Madagascar, tropical Africa, South America and Indonesia for various troubles including cardiovascular disorders. Aim of the study To investigate the mechanisms underlying the vascular effects of MPG by assessing in vitro its antioxidant and anti-inflammatory properties, and its vascular relaxing effects, and in vivo, its action on hypoxic pulmonary hypertension (PAH) in rats. Material and methods The antioxidant activity of MPG leaf hydromethanolic extract was determined by using both the 1,1-diphenyl-2-picrylhydrazyl radical scavenging and the oxygen radical absorbance capacity in vitro assays. Anti-inflammatory properties were assayed on TNFα-induced VCAM-1 expression in endothelial cells. The vasorelaxant effect of MPG extract was studied on rat arterial rings pre-contracted with phenylephrine (1 μM) in the presence or absence of the endothelium. In vivo MPG extract effects were analyzed in chronic hypoxic PAH, obtained by housing male Wistar rats, orally treated or not with MPG extract (400 mg/kg/d), in a hypobaric chamber for 21 days. Results MPG leaf extract had antioxidant and anti-inflammatory properties. It induced endothelium-dependent, NO-mediated relaxation of rat aorta and pulmonary artery. In vivo, chronic MPG treatment reduced hypoxic PAH in rat by decreasing by 22.3% the pulmonary arterial pressure and by 20.0% and 23.9% the pulmonary artery and cardiac remodelling, respectively. This effect was associated with a restoration of endothelium function and a 2.3-fold increase in endothelial NO synthase phosphorylation. MPG leaf hydromethanolic extract contained tryptophan and flavonoids, including quercetin glycosides. Both compounds also efficiently limit hypoxia-induced PAH. Conclusions Our results show endothelial protective action of MPG leaf hydromethanolic extract which is likely to be due to its antioxidant action. MPG successfully attenuated the development of PAH, thus demonstrating the protective effect of MPG on cardiovascular diseases.
2011
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Zaabat N, et al. 2011. Antioxidant and antigenotoxic properties of compounds isolated from <i>Marrubium deserti</i> de Noé. Food and Chemical Toxicology. 49:3328-3335. doi: 10.1016/j.fct.2011.08.026.
2010
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Zaabat N, et al. 2010. Preliminary study of Marrubium deserti de Noe, an endemic Algerian Lamiaceae. Phytotherapie. 8:353-358.
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Zaabat N, et al. 2010. Étude préliminaire de <i>Marrubium deserti</i> de Noé, une Lamiaceae endémique algérienne. Phytothérapie. 8:353-358. doi: 10.1007/s10298-010-0589-y.Résumé : Connue pour ses propriétés médicinales, aromatiques ou culinaires, la famille des Lamiacées présente un intérêt économique majeur, notamment comme source d’huiles essentielles. Dans le cadre de l’étude de la biodiversité de la flore algérienne, l’analyse phytochimique et la recherche des activités biologiques des parties aériennes de Marrubium deserti de Noé ont été entreprises. L’extraction par des solvants de polarité croissante tels que le dichlorométhane, l’acétate d’éthyle et le butanol, puis la purification des extraits obtenus ont permis d’isoler et d’identifier à ce jour un diterpène original de type labdane, un flavonoïde et des phénylpropanoïdes glycosylés. Les extraits et les composés isolés ont fait l’objet d’une étude biologique comme antioxydants, antibactériens et antigénotoxiques. Known for its medicinal, aromatic or culinary properties, the Lamiaceae family represents a major economic interest, in particular as a source of essential oils. The purpose of this research concerns the phytochemical and the biological study of one of the Algerian flora’s medicinal plants known as Marrubium deserti de Noé. The extraction by solvents of increasing polarity: dichloromethane, ethyl acetate and butanol led to the isolation and identification of a novel labdane-type diterpene, a flavonoid and phenylpropanoid glycosides. Extracts and pure compounds were tested as antioxidant, antibacterial as well as antigenotoxic.
2008
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Michalet S, Mariotte AM, Gibbons S, Dijoux-Franca MG. 2008. Use of Efflux Pump Inhibitors (EPIs) to overcome bacterial Multi-Drug Resistance (MDR): plants as a source of chemodiversity and their adaptive response toward bacterial stress. Planta Medica. 74. doi: 10.1055/s-0028-1083948. -
Michalet S, et al. 2008. New components from barks of Christiana africana DC.(Tiliaceae) and interest of cyclopeptide alcaloids. Helvetica Chimica Acta. 91:1106-1117.
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Michalet S, et al. 2008. New Components Including Cyclopeptides from Barks of Christiana africana DC. (<i>Tiliaceae</i>). Helvetica Chimica Acta. 91:1106-1117. doi: 10.1002/hlca.200890118. -
Oughlissi-Dehak K, et al. 2008. Sesquiterpenes from aerial parts of <i>Ferula vesceritensis</i>. Phytochemistry. 69:1933-1938. doi: 10.1016/j.phytochem.2008.03.010.
Chapitre d’ouvrages
2009
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Michalet S, Dijoux-Franca MG. 2009. ABC Transporters and Resistance to Antibiotics. In: ABC Proteins and Multidrug Resistance. John Wiley & Sons p. .
Article de journal
2008
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Doléans-Jordheim A, et al. 2008. Les phénomènes de résistance aux antibiotiques liés aux pompes à efflux: exemple de <i>Staphylococcus aureus</i>. Annales de Biologie Clinique http://www.jle.com/fr/revues/bio_rech/abc/e-docs/00/04/41/89/resume.phtml.
Vulgarisation
Communications Orales
Posters
