Antibacterial Activity of Nigella sativa L. Seed Extracts

Abstract: Most of the bacterial pathogens are resistant to existing synthetic antibacterial agents demanding an increasing effort to seek effective phytochemicals as antibacterial agents against such pathogens. Nigella sativa L. (black cumin) seeds play an important role in folk medicine and some of its major constituents are reported to be pharmacologically active. In this present work, black cumin seed extracts were obtained using supercritical carbon dioxide (SCCO 2 ) and conventional soxtec extraction using various organic solvents. The antibacterial activities of the extracts were investigated by the agar dilution method against Gram-positive bacteria (Bacillus cereus F 4810 and Staphylococcus aureus FRI 722) and Gram-negative bacteria (Escherichia coli MTCC 108 and Yersinia enterocolitica MTCC 859). SCCO 2 -1 (120 bar/40ºC) extract showed effective growth inhibition than conventional solvent extracts against all the tested bacteria. Further the antibacterial principle present in the extract was isolated and characterized found to be thymoquinone

Phenylalanine and isoleucine containing protein-based polymers as new biomaterials: Synthesis and solid state properties

1487-1493Protein-based polymers exhibit elasticity and plasticity in accordance with the nature of the repeating sequence. Analogs of parent plastic sequence AVGVP are synthesized, polymerized and characterized in their solid state. The thermal behaviour of these polymers have been studied by differential scanning calorimetry. Phe-containing and Ile-containing polypentapeptides, poly(XVGVP) where X = F (Phe), I (Ile), exhibits both melting and decomposition transitions in contrast to the decomposition alone for parent poly(AVGVP). And also incorporation of FVGVP or IVGVP into AVGVP in equal molar ratios, described as poly[(AVGVP),(XVGVP)] where X = F, I induces the polymer to exhibit both melting and decomposition and shifted the values relatively to higher temperatures due to their thermal stability. Further, the appearance of clear exothermic crystalline transition at 251ºC, before melting at 328ºC, for poly(IVGVP), contributes towards a typical behaviour of thermoplasticity. Secondary structure in trifluoroethanol for all the polymers shows, well behaved -helix as evident from the circular dichroism studies, in association with a significant amount of random structure contributes to extended stability

Infrared spectroscopic study of the structural transitions of C<SUB>60</SUB>Br<SUB>24</SUB>

Variable temperature infrared spectroscopy and differential scanning calorimetry measurements show that C60Br24 under-goes two structural transitions at 171 and 180 K with &#916;H values of 0.87 and 3.94 kJ mol-1 respectively. Only one transition is clearly visible in IR which is manifested by the hardening of certain IR peaks and narrowing of the 1400 cm-1 transition. The results support an orientational change although ordering of the solvated bromine molecules could also be a reason for the observed changes

Elastic protein-based polymers a step towards plasticity: Thermal stability of glu-containing co-polypeptides as analyzed by differential scanning calorimetry

Plastic protein-based polymers with the same conformational potential, but with different degree of thermal stability have been synthesized and thermally characterized by differential scanning calorimetry to provide the conception of behavior of thermoplasticity. Dramatic increase in the temperature between melting and decomposition transitions has been observed, upon inclusion of glutamic acid residue into the hydrophobic sequence of FVGVP. Glu-containing co-polymers of IVGVP showed a markedly different behavior by exhibiting exothermic crystallization transition before melting shows the typical thermoplasticity. Secondary structure in trifluoroethanol for all the polymers show, a well behaved α-helix as evident from the circular dichroism studies, in association with a significant amount of random structure contributes to extended stability