Core shell silica particles with a hydrodynamic diameter of 28nm, an IEP of 7.1 and a zeta potential of +35mV at pH 4.0 were synthesised. The role of freeze-drying for the conservation of zwitterionic nanoparticles and the usefulness of different lyoprotective agents (LPA) for the minimisation of particle aggregation were studied. The activity of the nanoparticles was measured as DNA-binding capacity and transfection efficiency in Cos-1 cells before and after lyophilisation. It was found that massive aggregation occurred in the absence of LPA. Of the various LPAs screened in the present investigations, trehalose and glycerol were found to be well suited for conservation of cationically modified silica nanoparticles with simultaneous preservation of their DNA-binding and transfection activity in Cos-1 cells.

The polyphenol-enriched fraction of an ethanolic hops extract (Humulus lupulus) was separated to provide four acylphloroglucinol-glucopyranosides (1-4). 1-(2-Methylpropanoyl)phloroglucinol-glucopyranoside 1 has been isolated from hops before, whereas 1-(2-methylbutyryl)phloroglucinol-glucopyranoside 2, known as multifidol glucoside, and 1-(3-methylbutyryl)phloroglucinol-glucopyranoside 3 were found in hops for the first time. 5-(2-Methylpropanoyl)phloroglucinol-glucopyranoside 4 was identified as a new natural product. The compounds were tested for inhibition of COX-1 activity. The aglycon 5, obtained by acid hydrolysis of 1, was equally effective as phloroglucinol, with an IC(50) of 3.8 microM. The inhibitory potential of the glucosides was 1>2>3 and decreased with increasing length of the acyl side chain. Compound 4 was about 2.5-fold less active than 1 (IC(50): 23.7 and 58.7 microM, respectively).

—The activities of five lysosomal enzymes, acid phosphatase, β‐glucosidase, β‐glucuronidase, β‐galactosidase and N‐arylamidase (classified according to Marks (1970)) were measured by means of sensitive microchemical techniques in frozen‐dried rat neural lobe tissue after experimental and physiological stimulation of hormone release from the hypothalamo–neurohypophysial system i.e. water deprivation (3 and 6 days), delivery and lactation (10 days). During all conditions of stimulation increases of 29 to 106 per cent were measured for lysosomal enzyme activity, expressed as mmol/ng DNA/h. With histochemical staining methods the acid phosphatase activity appears to be mainly localized in the pituicytes, but it was impossible to visualize the microchemically measured acid phosphatase activity increase within the two main compartments of the neurohypophysis, i.e. axonal endings and the neurohypophysial glial cells, the pituicytes.

Phytochemical analysis and chemopreventive testing of a special “α-/β-acid free” hops extract led to the identification of isohumulones (hops iso-α-acids) as potent inducers of NAD(P)H:quinone reductase (QR) activity. CD values (concentrations required to double the specific activity of QR in Hepa1c1c7 cell culture) were in the range of 1.3 to 10.2 μg/mL, with CD value of trans-isohumulone < cis-isoadhumulone < cis-isocohumulone < cis-isohumulone (+ trans-isoadhumulone). Humulones (hops α-acids) were equally active with CD values of 3.4 to 7.6 μg/mL. However, these activities were accompanied by cytotoxicity. Cohumulinone and humulinone, oxidation products of co- and n-humulone, were inactive. We further identified isohumulones as potent inhibitors of lipopolysaccharide-induced inducible nitric oxide synthase (iNOS) activity in Raw264.7 cell culture, with IC50 values of 5.9 – 18.4 μg/mL. Humulones and humulinones were inactive at concentrations < 20 μg/mL. These results indicate that isohumulones, which are considered as the most abundant class of polyphenols in beer, should by further investigated for chemopreventive efficacy in animal models.

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