Novel neurological and immunological targets for salicylate-based phytopharmaceuticals and for the anti-depressant imipramine.

Inflammatory processes are increasingly recognised to contribute to neurological and neuropsychatric disorders such as depression. Thus we investigated whether a standardized willow bark preparation (WB) which contains among other constituents salicin, the forerunner of non-steroidal antiphlogistic drugs, would have an effect in a standard model of depression, the forced swimming test (FST), compared to the antidepressant imipramine. Studies were accompanied by gene expression analyses. In order to allocate potential effects to the different constituents of WB, fractions of the extract with different compositions of salicyl alcohol derivative and polyphenols were also investigated. Male Sprague Dawley rats (n=12/group) were treated for 14 days (p.o.) with the WB preparation STW 33-I (group A) and its fractions (FR) (groups FR-B to E) in concentrations of 30 mg/kg. The FRs were characterized by a high content of flavone and chalcone glycosides (FR-B), flavonoid glycosides and salicyl alcohol derivatives (FR-C), salicin and related salicyl alcohol derivatives (FR-D) and proanthocyanidines (FR-E). The tricyclic antidepressant imipramine (20 mg/kg) (F) was used as positive control. The FST was performed on day 15. The cumulative immobility time was significantly (p<0.05) reduced in group A (36%), group FR-D (44%) and by imipramine (16%) compared to untreated controls. RNA was isolated from peripheral blood. RNA samples (group A, group FR-D, and imipramine) were further analysed by rat whole genome microarray (Agilent) in comparison to untreated controls. Quantitative PCR for selected genes was performed. Genes (>2 fold, p<0.01), affected by WB and/or FR-D and imipramine, included both inflammatory (e.g. IL-3, IL-10) and neurologically relevant targets. Common genes regulated by WB, FR-D and imipramine were GRIA 2 ↓, SRP54 ↓, CYP26B ↓, DNM1L ↑ and KITLG ↓. In addition, the hippocampus of rats treated (27 d) with WB (15-60 mg/kg WB) or imipramine (15 mg/kg bw) showed a slower serotonin turnover (5-hydroxyindol acetic acid/serotonin (p<0.05)) depending on the dosage. Thus WB (30 mg/kg), its ethanolic fraction rich in salicyl alcohol derivatives (FR-D) (30 mg/kg) and imipramine, by being effective in the FST, modulated known and new targets relevant for neuro- and immunofunctions in rats. These findings contribute to our understanding of the link between inflammation and neurological functions and may also support the scope for the development of co-medications from salicylate-containing phytopharmaceuticals as multicomponent mixtures with single component synthetic drugs.

Anti-inflammatory effects of the willow bark extract STW 33-I (Proaktiv(®)) in LPS-activated human monocytes and differentiated macrophages.

INTRODUCTION: Willow bark extract is frequently used in the treatment of painful rheumatological diseases, such as arthritis and back pain. Its effect has been attributed to its main component salicin, but pharmacological studies have shown that the clinical efficacy of the willow bark extract cannot be explained by its salicin content alone. Therefore different modes of action have been suggested for the anti-inflammatory effect of willow bark extract. Here, we report in vitro data revelling the effect and mode of action of the aqueous willow bark extract STW 33-I as well as a water-soluble fraction (fraction E [Fr E]) in comparison with well-known non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin (ASA) and diclofenac (Diclo) on pro-inflammatorily activated human monocytes and differentiated macrophages. RESULTS: STW 33-I and the water-soluble Fr E showed concentration-dependent and significant anti-inflammatory effects in lipopolysaccharide-activated monocytes. Both inhibited the intracellular protein expression of tumour necrosis factor-alpha (TNFα) as well as the mRNA expression of TNFα and cyclooxygenase 2 (COX-2), and the release of nitric oxide (NO). In addition, apoptosis of pro-inflammatorily activated monocytes was induced. Furthermore, treatment of activated macrophages with STW 33-I inhibited the nuclear translocation of the p65 subunit of the nuclear transcription factor-kappa B (NF-κB p65). CONCLUSIONS: The present in vitro investigations suggest a significant anti-inflammatory activity of willow bark water extract STW 33-1 and of its water-soluble fraction by inhibiting pro-inflammatory cytokines (TNFα), COX-2 and nuclear translocation of the transcription factor NF-κB in pro-inflammatorily activated monocytes. Our results provide further evidence for the therapeutic use of STW 33-I in inflammation-related disorders.