centaurein and centaureidin

Bidens pilosa is used as an ethnical medicine for bacterial infection or immune modulation in Asia, America and Africa. Here, we employed an IFN-gamma promoter-driven luciferase reporter construct and T cells to characterize immunomodulatory compounds from this plant based on a bioactivity-guided isolation principle. We found that PHA, a positive control, caused a six-fold increase in IFN-gamma promoter activity. In contrast, hot water crude extracts from Bidens pilosa and its butanol subfraction increased IFN-gamma promoter activity to two- and six-fold, respectively. Finally, centaurein (EC(50)=75 microg/ml) and its aglycone, centaureidin (EC(50)=0.9 microg/ml), isolated from this butanol subfraction, augmented IFN-gamma promoter activity by approximately four-fold. Consistent with the role of centaurein or its aglycone in IFN-gamma regulation, we showed that centaurein induced the activity of NFAT and NFkappaB enhancers, located within the IFN-gamma promoter, in Jurkat cells. Overall, our results showed that centaurein regulated IFN-gamma transcription, probably via NFAT and NFkappaB in T cells.

Topics: Bidens; Flavonoids; Glucosides; Humans; Interferon Inducers; Interferon-gamma; Jurkat Cells; NF-kappa B; Plant Extracts; Promoter Regions, Genetic; Spleen; T-Lymphocytes; Tetrazolium Salts; Thiazoles; Transfection; Up-Regulation

In this work, the potential vasorelaxant activity of centaurein and centaureidin, two flavonoids from Centaurea corcubionensis, were studied for the first time in rat aorta. Centaureidin (10 microM-0.1 mM) totally relaxed, in a concentration-dependent manner and with almost equal effectiveness, the contractions induced by NA (IC50 = 16.7 +/- 1.9 microM) or by a high K+ concentration (IC50 = 16.1 +/- 3.1 microM) in intact rat aortic rings. Mechanical removal of endothelium did not significantly modify the vasoralexant effects of this flavone (IC50 = 20.8 +/- 2.4 microM for NA; IC50 = 21 +/- 2.9 microM for K+). On the other hand, centaurein (1 microM-0.1 mM) had no effect on NA- and high K(+)-induced contractions in rubbed and intact rat aortic rings. These results indicate that substitution by glucose in the chemical structure of centaureidin leads to the loss of its vasodilator activity.

Topics: Animals; Aorta; Female; Flavonoids; Glucosides; In Vitro Techniques; Molecular Structure; Muscle Contraction; Muscle, Smooth, Vascular; Plants, Medicinal; Rats; Rats, Wistar; Vasodilation; Vasodilator Agents