Browsing by Author "Pimentel, Madalena"
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- Chemical Characterization and Bioactivity of Commercial Essential Oils and Hydrolates Obtained from Portuguese Forest Logging and ThinningPublication . Ruas, Ana; Graça, A.; Marto, Joana; Gonçalves, Lídia; Oliveira, Ana; Silva, Alexandra Nogueira da; Pimentel, Madalena; Moura, Artur Mendes; Serra, Ana Teresa; Figueiredo, Ana Cristina; Ribeiro, HelenaEssential oils (EOs) and hydrolates (Hds) are natural sources of biologically active ingredients with broad applications in the cosmetic industry. In this study, nationally produced (mainland Portugal and Azores archipelago) EOs (11) and Hds (7) obtained from forest logging and thinning of Eucalyptus globulus, Pinus pinaster, Pinus pinea and Cryptomeria japonica, were chemically evaluated, and their bioactivity and sensorial properties were assessed. EOs and Hd volatiles (HdVs) were analyzed by GC-FID and GC-MS. 1,8-Cineole was dominant in E. globulus EOs and HdVs, and α- and β-pinene in P. pinaster EOs. Limonene and α-pinene led in P. pinea and C. japonica EOs, respectively. P. pinaster and C. japonica HVs were dominated by α-terpineol and terpinen-4-ol, respectively. The antioxidant activity was determined by DPPH, ORAC and ROS. C. japonica EO showed the highest antioxidant activity, whereas one of the E. globulus EOs showed the lowest. Antimicrobial activity results revealed different levels of efficacy for Eucalyptus and Pinus EOs while C. japonica EO showed no antimicrobial activity against the selected strains. The perception and applicability of emulsions with 0.5% of EOs were evaluated through an in vivo sensory study. C. japonica emulsion, which has a fresh and earthy odour, was chosen as the most pleasant fragrance (60%), followed by P. pinea emulsion (53%). In summary, some of the studied EOs and Hds showed antioxidant and antimicrobial activities and they are possible candidates to address the consumers demand for more sustainable and responsibly sourced ingredients.
- Cryptolepis sanguinolenta activity against diarrhoeal bacteriaPublication . Paulo, Alexandra; Pimentel, Madalena; Viegas, Silvia; Pires, Ilda; Duarte, Aida; Cabrita, José; Gomes, Elsa T.Cryptolepine is the main alkaloid of Cryptolepis sanguinolenta (Lindl.) Schlechter, a plant used in traditional medicine in West Africa. The minimal inhibitory concentrations (MICs) of cryptolepine, ethanol and aqueous extracts of Cryptolepis sanguinolenta root were determined for 65 strains of Campylobacter jejuni, 41 strains of Campylobacter coli isolated from sporadic cases of gastroenteritis in Portugal and 86 strains of Vibrio cholerae isolated from patients with enteric infections in Angola, Brazil and Portugal. The ethanol extract activity against Campylobacter strains (MIC90% = 25 microg/ml) is higher than that of co-trimoxazole and sutfamethoxazole and Campvlobacter strains susceptibility for cryptoleprne (MIC90% = 12.5 microg/ml) is equal for ampicillin. The ethanot extract and cryptolepine show some activity against the Vibrio cholerae strains, although their activities are tower than that of tetracycline. lhe results suggest that these roots could be a therapeutic alternative for bacterial etiologic diarrhoea in West Africa.
- Modification of the mycobacteriophage Ms6 attP core allows the integration of multiple vectors into different tRNA(ala) T-loops in slow- and fast-growing mycobacteriaPublication . Dos Vultos, Tiago; Mederle, Isabelle; Abadie, Valerie; Pimentel, Madalena; Moniz-Pereira, Jose; Gicquel, Brigitte; Reyrat, Jean-Marc; Winter, NathalieBackground: Mycobacteriophage Ms6 integrates into Mycobacterium smegmatis and M. bovis BCG chromosome at the 3' end of tRNA(ala) genes. Homologous recombination occurs between the phage attP core and the attB site located in the T-loop. Integration-profic
- The lytic cassette of mycobacteriophage Ms6 encodes an enzyme with lipolytic activityPublication . Gil, Filipa; Catalao, Maria Joao; Moniz-Pereira, Jose; Leandro, Paula; McNeil, Michael; Pimentel, MadalenadsDNA bacteriophages use the dual system endolysin-holin to achieve lysis of their bacterial host. In addition to these two essential genes, some bacteriophages encode additional proteins within their lysis module. In this report, we describe the activity of a protein encoded by gene lysB from the mycobacteriophage Ms6. lysB is localized within the lysis cassette, between the endolysin gene (lysA) and the holin gene (hol). Analysis of the deduced amino acid sequence of LysB revealed the presence of a conserved motif (Gly-Tyr-Ser-Gin-Gly) characteristic of enzymes with lipolytic activity. A BLAST search within the sequences of protein databases revealed significant similarities to other putative proteins that are encoded by mycobacteriophages only, indicating that LysB and those proteins may be specific to their mycobacterial hosts. A screening for His(6)-LysB activity on esterase and lipase substrates confirmed the lipolytic activity. Examination of the kinetic parameters of recombinant His(6)-LysB for the hydrolysis of p-nitrophenyl esters indicated that although this protein could use a wide range of chain length substrates (C-4-C-18), it presents a higher affinity for p-nitrophenyl esters of longer chain length (C-16 and C-18). Using p-nitrophenyl butyrate as a substrate, the enzyme showed optimal activity at 23 degrees C and pH 7.5-8.0. Activity was increased in the presence of Ca2+ and Mn2+. To the best of our knowledge, this is the first description of a protein with lipolytic activity encoded within a bacteriophage.