Claus Kilpert

Hydroxytyrosol Is the Major Anti-Inflammatory Compound in Aqueous Olive Extracts and Impairs Cytokine and Chemokine Production in Macrophages

Substances in olive products contribute to improved health as suggested by epidemiological data. In this study we assessed the effects of hydroxytyrosol (HT) on inflammatory mediators, cytokines and chemokines, and identified anti-inflammatory constituents of aqueous olive extracts, I.E., olive vegetation water (OVW). Murine macrophages (RAW264.7 cells) were stimulated with lipopolysaccharide (LPS) in the absence or presence of substances; inflammatory mediators [nitric oxide (NO), prostaglandin E₂ (PGE₂), cytokines, interleukins, chemokines] were determined by the Griess reaction, EIA, or multiplex ELISA (Luminex technology). Expression of inflammatory genes was determined by RT-PCR. Aqueous olive extracts were fractionated by preparative HPLC and the fractions investigated for their effects on NO and PGE₂ production. Results were further analyzed by principal component analysis. HT inhibited production of NO and PGE₂ with an IC₅₀ of 11.4 and 19.5 µM, respectively, reflecting strong anti-inflammatory activity. HT and OVW diminished secretion of cytokines (IL-1 α, IL-1 β, IL-6, IL-12, TNF- α), and chemokines (CXCL10/IP-10, CCL2/MCP-1). HT and OVW concentration-dependently reduced the expression of genes of inducible nitric oxide synthase (iNOS), IL-1 α, CXCL10/IP-10, MIP-1 β, matrix metalloproteinase-9, and prostaglandin E₂ synthase (PGES). The effects of HT were partly mediated VIA the NF- κB pathway, as shown by RT-PCR analysis. HT was identified as the main bioactive compound of OVW. The data provide a molecular basis for elucidating the effects of HT on inflammatory processes. The effects of HT on NO and chemokine production point to their impact on chronic inflammatory processes in endothelium or arthritis.

A Nonradioactive High-Throughput/High-Content Assay for Measurement of the Human Serotonin Reuptake Transporter Function In Vitro

Both the tricyclic and specific serotonin reuptake inhibitor classes of antidepressants act primarily by inhibiting the reuptake of released serotonin by the human serotonin reuptake transporter (hSERT). In this article, the authors describe the use of a fluorescent substrate of the transporter (4-(4-(dimethylamino)-styrl)-N-methylpyridinium, ASP) to develop a microplate-based high-throughput screen for hSERT function. The assay is sensitive to known inhibitors of serotonin uptake, including fluoxetine (Prozac), with the correct rank order of potency and IC50 values close to those reported in the literature for tritiated serotonin uptake. The authors also describe the validation of the assay for natural product screening using a test set of 2400 pure phyto-chemicals and 80 plant extracts. The mean Ź of the screened plates was 0.53. Hit rates, confirmation rates, and validation of the hits in a “classical” assay for serotonin uptake are all reported. The assay can also be read in “high-content” mode using a subcellular imaging device, which allows direct detection of possible assay interference by acutely cytotoxic compounds. Among the compounds identified were several previously reported inhibitors of the hSERT, as well as compounds having structural similarity to the tricyclic antidepressant drugs.

Monoamine reuptake inhibition and mood-enhancing potential of a specified oregano extract

A healthy, balanced diet is essential for both physical and mental well-being. Such a diet must include an adequate intake of micronutrients, essential fatty acids, amino acids and antioxidants. The monoamine neurotransmitters, serotonin, dopamine and noradrenaline, are derived from dietary amino acids and are involved in the modulation of mood, anxiety, cognition, sleep regulation and appetite. The capacity of nutritional interventions to elevate brain monoamine concentrations and, as a consequence, with the potential for mood enhancement, has not been extensively evaluated. The present study investigated an extract from oregano leaves, with a specified range of active constituents, identified via an unbiased, high-throughput screening programme. The oregano extract was demonstrated to inhibit the reuptake and degradation of the monoamine neurotransmitters in a dose-dependent manner, and microdialysis experiments in rats revealed an elevation of extracellular serotonin levels in the brain. Furthermore, following administration of oregano extract, behavioural responses were observed in mice that parallel the beneficial effects exhibited by monoamine-enhancing compounds when used in human subjects. In conclusion, these data show that an extract prepared from leaves of oregano, a major constituent of the Mediterranean diet, is brain-active, with moderate triple reuptake inhibitory activity, and exhibits positive behavioural effects in animal models. We postulate that such an extract may be effective in enhancing mental well-being in humans.