12 research outputs found
Chemical composition and antibacterial activity of essential oils from the medicinal plant Mentha cervina L. grown in Portugal
Mentha cervina is a medicinal plant traditionally
used in Portugal in folk medicine, in different gastric
disorders and inflammations of the respiratory tract. In
order to validate those traditional uses, M. cervina essential
oils (EOs) were characterized by GC and GC–MS and their
antimicrobial activity was tested against 23 bacterial strains
(including multiresistant strains). The EOs were dominated
by the monoterpenes pulegone (52–75%), isomenthone
(8–24%), limonene (4–6%), and menthone (1–2%). The
antibacterial activity of these EOs was compared to that of
the main components standards. The most effective antibacterial
activity was expressed by the EOs against the
Gram-negative bacteria, Escherichia coli and Acinetobacter
baumanni, with MIC values of 1 mg/ml. The EOs complex mixtures were more active than the individual
aromatic components supporting the hypothesis that the
EOs antibacterial activity is a function of the synergistic
effect of their different aromatic components. These results
show the potential role of M. cervina EOs as antibacterial
agents and validate the traditional use of this plant
Highly active and efficient catalysts for alkoxycarbonylation of alkenes
Carbonylation reactions of alkenes constitute the most important industrial processes in homogeneous catalysis. Despite the tremendous progress in this transformation, the development of advanced catalyst systems to improve their activity and widen the range of feedstocks continues to be essential for new practical applications. Herein a palladium catalyst based on 1,2-bis((tert-butyl(pyridin-2-yl)phosphanyl)methyl)benzene L3 (py(t)bpx) is rationally designed and synthesized. Application of this system allows a general alkoxycarbonylation of sterically hindered and demanding olefins including all kinds of tetra-, tri- and 1,1-disubstituted alkenes as well as natural products and pharmaceuticals to the desired esters in excellent yield. Industrially relevant bulk ethylene is functionalized with high activity (TON: >1,425,000; TOF: 44,000 h(−1) for initial 18 h) and selectivity (>99%). Given its generality and efficiency, we expect this catalytic system to immediately impact both the chemical industry and research laboratories by providing a practical synthetic tool for the transformation of nearly any alkene into a versatile ester product