Antimicrobial, Antioxidant and Cytotoxic Activities and Phytochemical Screening of Some Yemeni Medicinal Plants

The traditional medicine still plays an important role in the primary health care in Yemen. The current study represents the investigation of 16 selected plants, which were collected from different localities of Yemen. The plants were dried and extracted with two different solvents (methanol and hot water) to yield 34 crude extracts. The obtained extracts were tested for their antimicrobial activity against three Gram-positive bacteria, two Gram-negative bacteria, one yeast species and three multiresistant Staphylococcus strains using agar diffusion method, for their antioxidant activity using scavenging activity of DPPH radical method and for their cytotoxic activity using the neutral red uptake assay. In addition, a phytochemical screening of the methanolic extracts was done. Antibacterial activity was shown only against Gram-positive bacteria, among them multiresistant bacteria. The highest antimicrobial activity was exhibited by the methanolic extracts of Acalypha fruticosa, Centaurea pseudosinaica, Dodonaea viscosa, Jatropha variegata, Lippia citriodora, Plectranthus hadiensis, Tragia pungens and Verbascum bottae. Six methanolic extracts especially those of A. fruticosa, Actiniopteris semiflabellata, D. viscosa, P. hadiensis, T. pungens and V. bottae showed high free radical scavenging activity. Moreover, remarkable cytotoxic activity against FL-cells was found for the methanolic extracts of A. fruticosa, Iris albicans, L. citriodora and T. pungens. The phytochemical screening demonstrated the presence of different types of compounds like flavonoids, terpenoids and others, which could be responsible for the obtained activities

Étude de l’influence de la carburation sur l’oxydation de l’alliage 330Cb (Fe-35Ni-18Cr-1Nb-2Si) à 900 °C

Ce travail présente les résultats obtenus lors de l’oxydation à 900 °C de l’alliage 330Cb préalablement carburé ou non. Avant oxydation, l’échantillon carburé renferme des carbures de niobium NbC et des carbures de chrome Cr7C3. Les résultats cinétiques obtenus lors de l’oxydation des échantillons carburés montrent un comportement identique à celui de l’alliage non carburé. Le 330Cb carburé se recouvre d’une couche d’oxyde plus adhérente que sur le 330Cb dans le cas des tests qui ont duré 160 h. Après oxydation, les quelques zones décollées sont dues aux affleurements des nodules métalliques riches en niobium. Comme sur les échantillons non carburés, on note la présence de chromite de manganèse à l’interface externe. La couche principale ne contient pas de fer et est constituée de Cr2O3. Cette structure est due à une accumulation du silicium et du niobium à l’interface interne. Les parties noires qui se situent sous la couche de chromine sont constituées de carbone. Cette présence du carbone sous la forme de nodules ne semble pas être défavorable à une bonne adhérence de la couche d’oxyde car ces nodules sont principalement localisés aux joints de grains du métal

Rôle joué par les dépôts sol gel de lanthane sur l’oxydation de l’alliage 330Cb (Fe-35Ni-18Cr-1Nb-2Si) à 900 °C

Cette étude a été menée afin de tester l’influence d’un dépôt sol-gel de lanthane sur l’adhérence des couches d’oxyde formées à 900 °C sur le 330Cb (Fe-35Ni-18Cr-1Nb-2Si). Le but de cette oxydation est de constituer une couche de chromine protectrice en vue d’améliorer la résistance des tapis de fours vis-à-vis de la carburation. Une attention toute particulière est portée sur le caractère protecteur du dépôt sol gel de lanthane en fonction de la température de son recuit préalable sous argon (entre 600 et 1000 °C)

Consequence of the diffusive hydrogen contents on tensile properties of martensitic steel during the desorption at room temperature

International audienc

Ocorrência de Calotropis procera (Ait.) R. Br. (Apocynaceae) como espécie invasora de restinga Occurrence of Calotropis procera (Ait.) R. Br. (Apocynaceae) as an invasive species in restinga vegetation

Apesar de possuírem grande importância ao nível de conservação ambiental, existe no Brasil uma acentuada escassez de trabalhos relacionados às invasões biológicas em ambientes terrestres. As restingas, sobretudo, são ambientes extremamente susceptíveis a este tipo de ameaça. Este estudo teve como objetivo avaliar a ocorrência e a estrutura populacional da espécie exótica Calotropis procera na Restinga do Xexé, Farol de São Thomé, Campos dos Goytacazes, RJ. Uma varredura que abrangeu uma área de 126 ha (1400m x 900m) foi realizada, sendo amostrado um total de 475 indivíduos, ou seja, uma média de 3,8 indivíduos por hectare. Para a avaliação da distribuição dos indivíduos num gradiente interior-praia, foram alocados três transectos (300m x 10m) nesta direção. A amostragem nos transectos indicou a ocorrência de 28 indivíduos com altura > 50 cm e nenhum com altura < 50 cm, sendo sua ocorrência restrita as áreas com vestígios de perturbação e não tendo sido constatado nenhuma relação com a distância da praia. A ausência de plântulas e jovens na amostragem ao longo dos transectos sugere o rápido desenvolvimento dos indivíduos após a germinação. Os resultados indicaram que Calotropis procera possui grande potencial invasor de áreas perturbadas de restinga. Um plano de ações para seu controle e erradicação deve ser urgentemente implementado pelos órgãos ambientais responsáveis.<br>Although invasive species are one of the main reasons for the loss of biodiversity, in Brazil there is little information about biological invasions in terrestrial ecosystems. Sandy coastal plain forests (restinga) and shrubby vegetation are places extremely susceptible to this kind of threat. The goal of this work was to evaluate the occurrence of the exotic species Calotropis procera in the Restinga do Xexé, Farol de São Tomé, Campos dos Goytacazes, RJ, Brazil. A survey covering an area of 126 ha (1400 m x 900 m) was carried out, where a total of 475 individuals were sampled (mean of 3.8 indiv.ha-1). To assess the spatial distribution and population structure of this species, three transects (300 m x 10 m) were created, which were perpendicular to the vegetation gradient from interior to shoreline, and all individuals of C. procera were sampled. A total of 28 individuals > 50 cm tall were sampled, and no individuals < 50 cm tall were found in the three transects. The plants were restricted to areas with vestiges of human disturbance. The absence of seedling samples within the transects is probably related to the fast growth of this species after germination. The results showed that C. procera has a great potential of invading disturbed areas in restinga vegetation. A plan to control and eradicate this species should be considered by the Brazilian environmental agency