Antimicrobial activity of Agave sisalana

This study was carried out to evaluate the antimicrobial activity of extracts of the leaves and leaf waste discarded in the process of obtaining the hard fibers of Agave sisalana. The antimicrobial activity was determined by the paper disk diffusion method using Gram-positive and Gram-negative bacteria (nonresistant and resistant to antibiotics) and a fungus. The hydroalcoholic extract obtained from leaves and from sisal waste showed significant inhibition of Candida albicans, on the other hand, it was inactive against three strains of Staphylococcus aureus, two strains of Escherichia coli, a strain ofMicrococcus luteus, Bacillus cereus, Pseudomonas aeruginosa and Salmonella choleraesuis. The methanol extract of leaves showed weaker reduction in the inhibitory action of C. albicans when compared with the above extracts, and it was also inert against the other microorganisms tested

Comparative study of chemical approaches to the solid-phase synthesis of a tumor-seeking alpha-MSH analogue

The synthesis of a cyclic melanocortin analogue (H-pz-beta Ala-Nle-cyclo[Asp-His-DPhe-Arg-Trp-Lys]-NH(2)), where the Boc-protected derivative of a metal-chelating pyrazolyl ligand (pz) was inserted as N-terminal residue, was addressed by several different Fmoc/tBu and Boc/Bzl solid-phase strategies. On-resin cyclization was achieved immediately following incorporation of Asp, by condensation of the Asp side chain carboxyl with the Lys side chain primary amine after selective and simultaneous removal of side chain protecting groups. The success of the synthesis was highly dependent on the chemical strategy employed, with Boc/Bzl chemistry giving the best results. On the light of our findings, Fmoc/tBu strategies are not advantageous for the solid-phase synthesis of this particular type of lactam-bridged peptides. Last, but not least, the target peptide was recently found to have promising tumor-seeking properties (J Biol Inorg Chem 13:449-459, 2008)