Covalent binding of the natural antimicrobial peptide indolicidin to DNA abasic sites

Indolicidin is a host defense tridecapeptide that inhibits the catalytic activity of HIV-1 integrase in vitro. Here we have elucidated its mechanism of integrase inhibition. Using crosslinking and mass spectrometric footprinting approaches, we found that indolicidin interferes with formation of the catalytic integrase-DNA complex by directly binding DNA. Further characterization revealed that the peptide forms covalent links with abasic sites. Indolicidin crosslinks single- or double-stranded DNAs and various positions of the viral cDNA with comparable efficiency. Using truncated and chemically modified peptides, we show that abasic site crosslinking is independent of the PWWP motif but involves the indolicidin unique lysine residue and the N- and C- terminal NH₂ groups. Because indolicidin can also inhibit topoisomerase I, we believe that multiple actions at the level of DNA might be a common property of antimicrobial peptides.     

Identification of potent,highly constrained CGRP receptor antagonists

A novel series of potent CGRP receptor antagonists containing a central quinoline ring constraint was identified. The combination of the quinoline constraint with a tricyclic benzimidazolinone left hand fragment produced an analog with picomolar potency (14, CGRP K_i = 23 pM). Further optimization of the tricycle produced a CGRP receptor antagonist that exhibited subnanomolar potency (19, CGRP K_i = 0.52 nM) and displayed a good pharmacokinetic profile in three preclinical species.     

Effect of the standardized Cimicifuga foetida extract on Hsp 27 expression in the MCF-7 cell line

Cimicifuga foetida, an Asian Cimicifuga species, has been employed as a cooling and detoxification agent in traditional Chinese medicine since ancient times. For this herb, two cycloartane triterpene glycosides isolated from the rhizomes have demonstrated cytotoxicity on rat tumor and human cancer cell lines. Since human Hsp27 is increased in various human cancers and exhibits cytoprotective activity that affects tumorigenesis and the susceptibility of tumours to cancer treatment, the purpose of this research was to study the expression of this protein in MCF-7 breast cancer cells. To accomplish this aim, MCF-7 cells were exposed to different concentrations of Cimicifuga foetida extract showing a reduction in cell number measured by the sulforhodamine assay. In addition, the expression of Hsp-27 mRNA detected by RT-PCR and Hsp-27 protein detected by immnofluorescence was present in all conditions, except when using the highest concentration of Cimicifuga foetida extract (2,000 jig /L). We conclude that Hsp 27 expression at 2,000 jig /L Cimicifuga foetida extract is diminished. This is the first report showing the Hsp-27 expression after exposure to Cimicifuga foetida extract in MCF-7 cells.     

Astragalus Root and Elderberry Fruit Extracts Enhance the IFN-β Stimulatory Effects of Lactobacillus acidophilus in Murine-Derived Dendritic Cells

Many foods and food components boost the immune system, but little data are available regarding the mechanisms by which they do. Bacterial strains have disparate effects in stimulating the immune system. Indendritic cells, the gram-negative bacteria Escherichia coli upregulates proinflammatory cytokines, whereas gram-positive Lactobacillus acidophilus induces a robust interferon (IFN)-β response. The immune-modulating effects of astragalus root and elderberry fruit extracts were examined in bone marrow-derived murine dendritic cells that were stimulated with L. acidophilus or E. coli. IFN-β and other cytokines were measured by ELISA and RT-PCR. Endocytosis of fluorescence-labeled dextran and L. acidophilus in the presence of elderberry fruit or astragalus root extract was evaluated in dendritic cells. Our results show that both extracts enhanced L. acidophilus-induced IFN-β production and slightly decreased the proinflammatory response to E. coli. The enhanced IFN-β production was associated with upregulation of toll-like receptor 3 and to a varying degree, the cytokines IL-12, IL-6, IL-1β and TNF-α. Both extracts increased endocytosis in immature dendritic cells, and only slightly influenced the viability of the cells. In conclusion, astragalus root and elderberry fruit extracts increase the IFN-β inducing activity of L. acidophilus in dendritic cells, suggesting that they may exert antiviral and immune-enhancing activity.