In order to identify new, immune modulating compounds, aqueous extracts of plants pre-selected on ethno-pharmacological knowledge were screened for inhibitory effects in an anti-CD3 driven lymphocyte proliferation assay (MTT-assay). We found for the extract of the inner bark of Tabebuia avellanedae (Tabebuia) dose dependent and reproducible inhibitory effects on lymphocyte proliferation. We further analyzed Tabebuia in flow cytometry based whole blood T-cell function assays. We found that Tabebuia inhibited dose dependent ConA stimulated T-cell proliferation. Decreased T-lymphocyte proliferation was associated with dose dependent reduction of CD25 and CD71 expression on T-lymphocytes. In contrast Tabebuia exerted no effects on cytokine expression (Il-2 and TNF-alpha) by PMA/Ionomycin stimulated T-lymphocytes. Concentrations of Tabebuia used were not toxic for lymphocytes as verified by trypan blue exclusion assay. Further experiments showed that the immune inhibitory effects by Tabebuia were not mediated by its pharmacological lead compound beta-lapachone and only observed in aqueous but not in ethanol plant extracts.
"Tabebuia avellanedae Lorentz ex Griseb., a Bignoniaceae , is a representative herbal plant used for treating various skin inflammatory diseases including eczema, psoriasis, fungal infections and even skin cancers for over 1,000 years (Casinovi et al., 1963; de Santana et al., 1968; Woo and Choi, 2005). Recent pharmacological studies have also increased the under-standing of its therapeutic efficacies including astringent, antiinflammatory , antibacterial, antifungal, diuretic, anticoagulational and laxative properties as well as an anticancer effect (Choi et al., 2003; Machado et al., 2003; Awale et al., 2005; Bohler et al., 2008). So far, the variety of pharmacologically active ingredients with such biological activities from the plant such as naphthoquinones, *Corresponding author. "
[Show abstract][Hide abstract] ABSTRACT: Tabebuia sp. (Bignoniaceae) is representative traditional herbal plants, found in tropical rain forest areas throughout Central and South America. These plants have been mostly used as a folk medicine to treat bacterial infection, blood coagulation, cancer and inflammatory diseases. In this study, we aimed to demonstrate the modulatory role of Tabebuia avellanedae in various macrophage-or monocyte-mediated immune responses using its water extract (Ta-WE). Ta-WE was able to up-regulate cell-cell interaction by decreasing the migration of cells and by enhancing CD29-mediated cell-cell adhesion, and the surface levels of adhesion molecules (CD18, CD29, and CD82) and costimulatory molecules (CD80 and CD86) linked to macrophage stimulation as seen in up-regulation of ROS release. In addition, this fraction also suppressed an alteration in the membrane levels of macrophages such as phagocytic uptake and morphological changes. Therefore, these results suggest that the water extract of T. avellanedae can strongly modulate an ability of macrophages and monocytes to manage immune cell-cell interaction in host defence system.
[Show abstract][Hide abstract] ABSTRACT: In order to validate previous findings in ethnopharmacological studies, the effects on the hemogram of Wistar female rats after the oral administration of aqueous and methanolic extracts from Phenax rugosus (Poir.) Wedd and Tabebuia chrysantha G. Nicholson leaves were evaluated for 10 days. Except for the eosinophils count with the aqueous extract of Phenax rugosus (Poir.) Wedd, no significant changes in the hemogram were observed after
[Show abstract][Hide abstract] ABSTRACT: Previous Ethnopharmacological studies have showed the use of Phenax rugosus (Poir..) Wedd. and Tabebuia chrysantha G. Nicholson leaves for the treatment of infectious diseases and in inflammatory processes. Aqueous and methanolic extracts of each plant was obtained in order to determine the capacity of these extracts to induce significant changes in the seric levels of IgM and IgG2b antibodies in Wistar rats. The results obtained show that these extracts do not produce a response with statistical significance when comparing the antibody levels between the control and treatments groups.
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