Search

The present work aimed to study the composition and antibacterial properties of the essential oils (EO) ofOcotea zahamenensisleaves (LEO), stem (SEO) and root (REO) barks from two harvest periods (March and June). All EOs were extracted by hydrodistillation from fresh plant parts with yields up to 4.5%. They are colourless, clear, with a strong odour, heavy, levogyre, with a low acid index and an ester index up to 14.89. Gas chromatography/flame ionisation detection analysis of these EOs identified 5 to 12 components representing 96.06 to 99.96% of the overall composition. Safrole was by far the most predominant constituent with contents ranging from 77.45% (SEO, June) to 97.05% (REO, March). The antibacterial activity was tested against eight pathogenic bacteria including 4 Gram (-) and 4 Gram (+) using microdilution assays. With Minimum Inhibitory Concentration (MIC) values of less than 1 mg/mL, all EOs showed antibacterial activity which varied according to the strain. There was not much difference between the activities of March and June Eos, and in both cases SEO were slightly more effective than LEO and REO. All EOs had bacteriostatic action onBacillus cereusandVibrio fischeriand bactericidal on almost other strains. When administered orally to mice at 0.5 mg/kg body weight, all EOs caused symptoms of intoxication. Their LD50varied from 1.019 to 2.73 g/kg body weight. These EOs could be a new source of safrole and could be used for various purposes with further toxicological studies.

For the valorization of endemic plants of Madagascar’s flora, the study of plant Breonia perrieri (Rubiaceae) was performed. This study aimed to assess the potential antioxidant and antimicrobial activities from the bark of Breonia perrieri. The methanolic crude extract, the fractions resulting from the fractionation of the methanolic extract and the isolated compound from the active extract were tested. The antimicrobial activities were evaluated by disc diffusion method and microdilution technic and the potential antioxidant by the method of DPPH assay. Streptococcus pneumonia is the most sensitive bacterium tested with crude methanolic extract and soluble ethyl acetat (IZD = 11mm, MIC = 250 µg/mL). Soluble ethyl acetat showed the most powerful extract in scavenging ability on DPPH free radicals (IC50 = 5.43 ± 0.15µg/mL). The bioassay-guided of the ethyl acetate extract resulted in the isolation of iridoid glycoside namely Loganin. Its structure was established by spectroscopic methods. This compound exhibited strong DPPH scavenging activity with IC50 value of 1.50 µg/mL and showed antibacterial activity against Streptococcus pneumonia (IZD = 10 ± 0.5 mm). This is the first work of chemical and biological studies on B. perrieri.

Contexte. La surveillance de l’efficacité thérapeutique et des marqueurs génétiques de la résistance aux antipaludiques est primordiale afin de détecter le plus tôt possible l’émergence des parasites potentiellement résistants. Dans ce contexte, notre étude a pour objectif de réaliser le typage du gène Plasmodium falciparum chloroquine resistance transporter ou Pfcrt et Plasmodium falciparum multidrug resistant gene 1 ou Pfmdr1 sur des isolats provenant des enfants du district de Vatomandry. Méthodologies. Au total, 142 isolats de P. falciparum collectés lors d’un dépistage actif du paludisme chez des enfants âgés de moins de 15 ans, entre février et mars des années 2016 et 2017 à Vatomandry, ont été analysés. Le typage du codon K76T du gène Pfcrt et du codon N86Y du gène Pfmdr1 a été ensuite effectué par la technique de polymérisation en chaîne suivie de digestion enzymatique (restriction fragment length polymorphism) ou PCR-RFLP. Résultats. Le taux de succès d’amplification des gènes Pfcrt et Pfmdr1 était faible, de l’ordre de 27 % et 39 % respectivement. La prévalence des isolats mutants pour le codon K76T de Pfcrt était de 2,6 % [intervalle de confiance à 95 % (IC95%) : 0,1 - 15,0 %] et de 36 % [IC95% : 23,7 - 49,7 %] pour le codon N86Y du gène Pfmdr1. Conclusion. Notre étude a mis en évidence la présence d’isolats portant à la fois la mutation au niveau du codon K76T de Pfcrt et N86Y de Pfmdr1. Bien que le taux de mutation que nous avons observé soit faible, d’autres études méritent d’être effectuées afin de suivre l’évolution de ces marqueurs dans le temps et dans l’espace à Madagascar. PCR-RFLP genotyping of Pfcrt and Pfmdr1 in Plasmodium falciparum isolates from children Background. Malaria is a parasitic disease caused by a hematozoan of the genus Plasmodium. Early diagnosis followed by effective treatment is one of the keys to control this disease. In Madagascar, after more than 60 years of use for the treatment of uncomplicated malaria, chloroquine (CQ) was abandoned in favor of artesunate + amodiaquine (ASAQ) combination because of high prevalence of CQ treatment failure. Surveillance based on the assessment of therapeutic efficacy and genetic markers of resistance to antimalarials is therefore essential in order to detect the emergence of potentially resistant parasites as early as possible. In this context, our study aimed to genotype the Plasmodium falciparum chloroquine resistance transporter gene or Pfcrt and Plasmodium falciparum multidrug resistance gene 1 or Pfmdr1 in isolates collected from children in the district of Vatomandry. Methods. A total of 142 P. falciparum isolates collected during active case detection of malaria in children under 15 years old, between February and March of 2016 and 2017 in Vatomandry district, were analyzed. Pfcrt (K76T codon) and Pfmdr1 (N86Y codon) genotyping was carried out by polymerase chain reaction followed by enzymatic digestion (restriction fragment length polymorphism) or PCR-RFLP. Results. The successful rates of amplification of Pfcrt and Pfmdr1 genes were low, around 27% and 39% respectively. The prevalence of isolates carrying the mutant Pfcrt K76T codon and the mutant Pfmdr1 N86Y codon was 2.6% [95% confidence interval (95% CI): 0.1 - 15.0%] and 36% [95% CI: 23.7 - 49.7%] respectively. Conclusion. Despite the limited number of samples analyzed, our study highlighted the circulation of isolates carrying both the mutant Pfcrt K76T and Pfmdr1 N86Y alleles. Although the prevalence of mutations in Pfcrt and Pfmdr1 genes that we observed was low, other studies should be carried out in order to follow the evolution of these markers in time and space. The use of more sensitive methods will better characterize P. falciparum strains circulating in Madagascar. Artesunate-amodiaquine is used as a first-line treatment for uncomplicated malaria in the country; it is also crucial to monitor the other codons, i.e. 184 and 1246 of the Pfmdr1 gene, implicated in the resistance of P. falciparum to amodiaquine in Africa., MTSI, Vol. 2 No 2 (2022): MTSI-Revue

This work was designed to study the toxic effects ofAlbizia mahalaoextracts on various organisms and explore their possible usesto fight against noxious organisms. Methanolic extracts of leaves (LME), stem (SME) and root (RME) barks, alkaloids (Alk) and saponosides (Sap) from leaves were tested. All extracts were toxic to mice with LD50values by intraperitoneal route ranging from 69.18 (RME) to 135.52 mg/kg body weight (Alk). By oral route, at doses 5 and 10 times higher than intraperitoneal LD100those extracts were not toxic. LME, SME and RME were toxic to carp alvins, frog tadpoles but not to chicks and mosquitoCulex quinquefasciatuslarvae. LC50on carp alvins varied from 63.78 (RME) to 86.89 µg/mL (SME) and LC50on frog tadpoles from 68.43 (RME) to 153.4 µg/mL (SME). All the methanolic extracts inhibited the germination of 53.8 % of the seed plants tested with inhibition percentages ranging from 20 to 100 %. In previous study, the sameAlbizia mahalaoextracts were found to be efficient against many pathogenic bacteria at low doses. The extracts non-toxicity by oral route allowed envisaging their use to treat some diseases associated with these bacteria.

Background Timely and accurate identification of uropathogens and determination of their antimicrobial susceptibility is paramount to the management of urinary tract infections (UTIs). The main objective of this study was to develop an assay using LAMP (Loop mediated isothermal amplification) technology for simple, rapid and sensitive detection of the most common bacteria responsible for UTIs, as well as for the detection of the most prevalent genes (encoding cefotaximases from CTX-M group 1) responsible for resistance to 3rd generation of cephalosporins. Method We designed primers targeting Proteus mirabilis, while those targeting Escherichia coli, Klebsiella pneumoniae and Enterococcus faecalis and the CTX-M group 1 resistance gene were benchmarked from previous studies. The amplification reaction was carried out in a warm water bath for 60 min at 63 ± 0.5 °C. The amplicons were revealed by staining with Sybr Green I. Specificity and sensitivity were determined using reference DNA extracts spiked in sterile urine samples. The analytical performance of the assays was evaluated directly on pellets of urine samples from patients suspected of UTI and compared with culture. Results We found a high specificity (100%) for LAMP assays targeting the selected bacteria (P. mirabilis, E. coli, K. pneumoniae, E. faecalis) and the CTX-M group 1 when using DNA extracts spiked in urine samples. The sensitivities of the assays were around 1.5 103 Colony Forming Units (CFU) /mL corresponding to the cut-off value used to define bacteriuria or UTIs in patients with symptoms. Out of 161 urine samples tested, using culture as gold standard, we found a sensitivity of the LAMP techniques ranging from 96 to 100% and specificity from 95 to 100%. Conclusion We showed that the LAMP assays were simple and fast. The tests showed high sensitivity and specificity using a simple procedure for DNA extraction. In addition, the assays could be performed without the need of an expensive device such as a thermal cycler. These LAMP assays could be useful as an alternative or a complementary tool to culture reducing the time to diagnosis and guiding for more effective treatment of UTIs but also as a powerful diagnostic tool in resource-limited countries where culture is not available in primary health care structures.

The present work aims to study the chemical composition and the antimicrobial and antioxidant properties of the essential oil of Senecio longiscapus (SLEO) leaves. SLEO was extracted from fresh leaves by hydrodistillation with a yield of 3%. It is clear, yellow, with a relative density of 0.7466 at 20°C, a refractive index of 1.4959, an optical rotation of +3°47, an acid number of 1.53 and an ester number of 12.49. Gas chromatography/mass spectrometry (GC/MS) analysis of the SLEO identified 17 components, representing more than 99.09% of the overall composition. The main component of SLEO was sabinene (53.28%) and elemicin (15%), β-pinene (9.85%), methyleugenol (5.58%), α-pinene (4.84%) and mircene (2.37%) were the major components. At 7.48 mg/disk, SLEO inhibited the growth of all germs tested including four GRAM (+) and five GRAM (-) bacteria and one yeast. The zones of inhibition (ZI) ranged from 12 mm (Yersinia enterolitica) to 40 mm (Bacillus subtilis). The antioxidant activity of SLEO by the DPPH method was IC50 = 4.601 µg/ml. When administered orally at doses as high as 5 g/kg body weight, SLEO was not toxic to mice. Its non-toxicity, antimicrobial and antioxidant activities could make SLEO an alternative in the treatment of infectious diseases.

The present work aims to study the chemical composition and the antimicrobial and antioxidant properties of the essential oil ofSenecio longiscapus(SLEO) leaves. SLEO was extracted from fresh leaves by hydrodistillation with a yield of 3%. It is clear, yellow, with a relative density of 0.7466 at 20°C, a refractive index of 1.4959, an optical rotation of +3°47, an acid number of 1.53 and an ester number of 12.49. Gas chromatography/mass spectrometry (GC/MS) analysis of the SLEO identified 17 components, representing more than 99.09% of the overall composition. The main component of SLEO was sabinene (53.28%) and elemicin (15%), β-pinene (9.85%), methyleugenol (5.58%), α-pinene (4.84%) and mircene (2.37%) were the major components. At 7.48 mg/disk, SLEO inhibited the growth of all germs tested including four GRAM (+) and five GRAM (-) bacteria and one yeast. The zones of inhibition (ZI) ranged from 12 mm (Yersinia enterolitica) to 40 mm (Bacillus subtilis). The antioxidant activity of SLEO by the DPPH method was IC50 = 4.601 µg/ml. When administered orally at doses as high as 5 g/kg body weight, SLEO was not toxic to mice. Its non-toxicity, antimicrobial and antioxidant activities could make SLEO an alternative in the treatment of infectious diseases.

The antimicrobial activity of methanolic extract, butanolic and saponosidic fractions of different organs (leaf, seed, stem bark, root bark) fromAlbizia tulearensiswere tested against 14 pathogenic germs including 5 bacteria Gram-positive (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes), 6 Gram-negative (Clostridium perfringens, Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Yersinia entericolitica) and 3 yeasts (Candida albicans, Candida tropicalis, Cryptococcus neoformans) using disc diffusion and microdilution methods. At the concentration of 1 mg/disc, the methanolic extracts and fractions of seeds, stem and root bark exhibited selective antimicrobial activity with Inhibition Zone Diameters ranking from 8.67 to 16.5 mm. When using microdilution method, all the methanolic extracts and fractions displayed higher antimicrobial activities while saponosidic fractions were by far the most efficient. Saponosides from leaves (Lsap), seeds (Ssap), stem bark (Bsap) and root bark (Rsap) also exhibited excellent effects with Minimum Inhibitory Concentrations lower than 100 µg/mL against 71.4 %, 21.4 %, 7.14 % and 64.3 % of the germs tested respectively. The most sensitive germs were:S. aureus(4.87 µg/mL) with Rsap andS. pyogenes(9.75 µg/mL) with Lsap in Gram-positive bacteria;E. coliandY. entericolitica(19.5 µg/mL) with Lsap in Gram-negative bacteria andC. albicans(4.87, 19 and 19.5 µg/mL) with Lsap, Ssap and Rsap respectively in yeasts. The saponosidic fractions had bactericidal and fungicidal effects against the vast majority of the microorganisms tested. The phytochemical screening carried out on plant organs powders revealed the presence of desoxyoses, saponosides, triterpens, unsaturated sterols and phenolic compounds.&nbsp

This work was designed to evaluate the antibacterial and antioxidant activities of the fruit extracts from bemavo, a variety ofRavenala madagascariensis.Methanolic extracts from pericarp (PME), seed (SME) and aril (AME) were tested against 5 Gram positive and 6 Gram negative of pathogenic bacteria using disk diffusion and microdilution methods. At 1000 µg/ml, all extracts prevented selectively the growth of at least 5 of the tested bacteria with Inhibition Zone Diameter (IZD) ranking from 8.5 mm to 19 mm. The best activity was recorded with PME which was active against 81.8 % of the studied bacteria with 63.6 % of IZD higher than 14 mm: 15 mm onYersinia enterocolitica, Salmonella enterica, Shigella flexneri,andListeria monocytogenes,16 mm onStaphylococcus aureus,18 mm onEnteroacter aerogenes,and 19 mm onVibrio fischeri.Clostridium perfringensandBacillus cereuswere resistant to the three extracts. The great majority (97 %) of MCI recorded were ≤1000 µg/ml, 84.8 % were ≤500 µg/ml, 12.1 % between 500 µg/ml and 1000 µg/ml.Enterobacter aerogeneswas the most sensitive to the three extracts. The three extracts were bactericidal againstEnterobacter aerogenesandClostridium perfringens,bacteriostatic againstSalmonella entericaandBacillus cereusand bactericidal or bacteriostatic against the remaining strains. The antioxidant activity of extracts was determined by the method using free radical scavenging against DPPH. Compared with ascorbic acid (IC50=7.320 µg/ml), SME (IC50=0.568 µg/ml) and AME (IC50=3.792 µg/ml) were 12.9 and 6.5 times more active respectively. Phenolic compounds present in three extracts could be responsible for antimicrobial and antioxidant activities of the bemavo fruit methanol extracts.

International audience; Kitoza is a traditional product from Madagascar manufactured either with strips of pork or beef meat. lt is an artisanal product manufactured in rural and urban regions. The first step of the process is salting with coarse salt mixed with spices and then either a drying or smoking step is carried out. Samples from pork and beef and both processes have been analysed. The microbiological analyses revealed the process allowed the selection of microorganisms with potential technological interest. Thus a high level of coagulase negative staphylococci (CNS) was noticed: between 5 to7 log CFU/g. These technological bacteria seemed well adapted to the two processes drying or smoking. 811 isolates of presumed CNS from Manitol Salt agar have been identified. Two approaches have been applied: a PCR multiplex as developed by Corbière Morot-Bizot et al. (2004. J. Appl. Microbial. 97, 1087-1094) or a staph array developed by Giammarinaro et al. (2005. J. Clin. Microbiol., 3673-3680) allowing the identification of 36 CNS species. A total of 9 species of CNS were identified in the Kitoza with 7 species for the beef and 8 for the pork meats. Staphylococcus saprophyticus was the dominant species in all the products and the major one in dried pork and beef smoked or dried. While in smoked pork, in addition of S. saprophyticus (50%), S. xy/osus (13%), S. equorum (15%), S. succinus (13%) and S. epidermidis (9%) were identified. This study highlighted that the process: salting and drying or smoking allowed the selection of coagulase negative staphylococci. These CNS are well described in the literature as contributing to the quality of meat products, with some species such as S. xylosus already used as starter cultures for the manufacture of meat products. This work was funded by EU, 7th Framework Programme, AFTER project (grant agreement 245025). (Résumé d'auteur)

International audience; Deux composés à propriétés antibactériennes contre deux germes préjudiciables pour les crevettes : Vi-brio harveyi et Vibrio fisheri ont été découverts à partir d'une plante médicinale endémique de Madagas-car. Il s'agit de deux dérivés phénoliques connus (le 4-aminophénol (P1) et le 4- hydroxybenzaldéhyde (P2) isolés à partir d'extraits bruts d'acétate d'éthyle de feuille de Dilobeia thouarsii, une Proteaceae utili-sée pour soigner les plaies infectées dans la zone géographique Est d'Antananarivo. La recherche de la concentration minimale inhibitrice (CMI) et de la concentration minimale bactéricide (CMB) a révélé des activités significatives de P1 (CMI =CMB=110 ?g/ml) et de P2 (CMI=438 ?g/ml et CMB= 875?g/ml) vis-à-vis de ces pathogènes alimentaires. D'après le rapport CMB/CMI, ces deux composés ont un effet bactéri-cide sur Vibrio harveyi et Vibrio fisheri d'une efficacité similaire aux antibiotiques couramment utilisés contre ces germes. Des perspectives de recherches sont proposées, notamment des tests de toxicités de ces 2 composés et de leurs applications directes en crevetticulture. Ces travaux devraient permettre de lutter efficacement contre la prolifération de ces bactéries dans d'autres procédés alimentaires. (Résumé d'auteur)

International audience; Le Kitoza est un aliment traditionnel malgache à base de viande de boeuf ou de porc. Il peut être produit au niveau des ménages ou dans des charcuteries. La viande découpée en lanières est salée puis séchée au soleil et/ou fumée. Trois Kitozas : 2 de boeuf et 1 de porc ont été sélectionnés d'après les analyses physi-co-chimiques, microbiologiques et sensorielles des produits finis. Un diagramme synthétique de trans-formation traditionnelle a été établi pour chaque Kitoza. La qualité du produit au cours du procédé a été étudiée sur des échantillons prélevés aux étapes critiques. Du point de vue physico-chimique, la teneur et l'Aw diminuent au cours du procédé pour les 3 types de Kitoza. La teneur en lipides du Kitoza de porc est plus élevée que celle des Kitoza de boeuf. L'indice TBARS des produits finis est très variable : 0,3±0,18 mg/kg pour le boeuf 1 ; 5,01±0,83 mg/kg pour le boeuf 2 et 0,06±0,10mg/kg pour le porc. Pour le boeuf 2, cette valeur élevée pourrait s'expliquer par la teneur élevée en sel (2,41±0,11 g/100g). Le taux d'acide lactique demeure sous le seuil de détection et le pH ne diminue pas, indiquant l'absence de fermentation. Les teneurs en phénols sont plus faibles que celles du Boucané. Le contenu en B(a)P d'un Kitoza de boeuf n'est pas conforme aux normes françaises. Les microorganismes augmentent suite au découpage en la-nières, mais décroissent après le salage et le fumage. Pour tous les produits finis, Escherichia coli est infé-rieur au seuil de détection. Les bactéries lactiques sont toujours présentes. Le boeuf 2 qui est laissé mari-ner au moins 45 minutes à plus de 30°C pourrait présenter des contaminations. Aucun germe pathogène (Salmonella) n'a été détecté. En vue de procéder à la réingénierie, les points à améliorer ont été identifiés et des corrections sont proposées. (Résumé d'auteur)

The sensory profile and consumer acceptance of Kitoza, a traditional Malagasy meat product, was explored. Kitoza sensory profile was performed with a panel (n=18) on 8 smoked Kitoza provided by 5 different producers, with 14 attributes generated in consensus. PCA representation showed that there was a clear difference between pork and beef samples. Pork Kitoza were more associated to fatty, salty, wet and smoked sensory characteristics. Beef Kitoza were associated to fibrous, darker, harder, roasted and elastic or, depending of the process, to spicy and sweet sensory characteristics. Four samples into four different clusters were selected for a consumer study with 200 Malagasy and European consumers. The mean overall acceptability of the four smoked Kitoza was 6.6 (like moderately). One way ANOVA showed that the least liked was a Beef Kitoza BZ Ivan described as fibrous and harder by the panellists and which significantly differed from the three others with a score of 6.2. Four groups of consumers were identified using a Cluster Analysis: Kitoza indifferent likers (29%), Pork Kitoza likers (25%), Beef Kitoza likers (25%) and BE BZ Ivan dislikers (20%). Consumption attitudes both by Malagasy and European consumers were analysed. Among the Europeans who accepted to participate to the study (36% of all the consumers), 61% were Kitoza likers against 51% among the Malagasy. However, the frequency of consumption was very low for both groups: 61% of Europeans never consumed and 51% of the Malagasy consumed rarely smoked Kitoza, which is an expensive product in Madagascar. 48% of Europeans declared that they would eat smoked Kitoza alone during a cocktail (38%) or with a vary sosoa rice (29%) while 34% of Malagasy consumers would prefer to eat it at breakfast with a vary sosoa rice (36%). Malagasy eat either beef (49%) or pork (51%) while 67 % of Europeans eat Beef Kitoza mainly. Their favourite piece of meat was for both the fillet. 64% of Europeans would prefer Kitoza added with salt while 70% of the Malagasy would prefer smoked Kitoza added with salt and other ingredients. All the consumers, almost unanimously, whether Europeans or Malagasy, responded they prefer a tender meat, grilled, smooth, with a dark or light colour.

The toxicity of the bamboo shoots of Cephalostachium viguieri, eaten by Hapalemur aureus, has been tested before and after mixing the crushed plant material with the soil which is also consumed by the animal. Although in most instances, geophagy allows primates to detoxify plant secondary compounds such as tannins or glycoalkaloids, in the present case, the adsorption by the soil was not efficient. Other physiological or behavioral responses are still to be found to explain how the Golden Hapalemur copes with the bamboo toxicity., Jeannoda Vololoniaina,Rakotonirina Ony,Randrianarivo Hanitra,Rakoto Danielle Doll Aurore,Wright Patricia C.,Hladik Claude Marcel. Le principe toxique du bambou consommé par Hapalemur aureus n’est pas neutralisé par la terre ingérée. In: Revue d'Écologie (La Terre et La Vie), tome 58, n°1, 2003. pp. 151-153.