Centaureidin

Preliminary study of the potential vasodilator effects on rat aorta of centaurein and centaureidin, two flavonoids from Centaurea corcubionensis.[Pubmed:9580164]

Planta Med. 1998 Mar;64(2):116-9.

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.

Flavonoids, centaurein and centaureidin, from Bidens pilosa, stimulate IFN-gamma expression.[Pubmed:17408892]

J Ethnopharmacol. 2007 Jun 13;112(2):232-6.

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.

Centaureidin promotes dendrite retraction of melanocytes by activating Rho.[Pubmed:16476521]

Biochim Biophys Acta. 2006 Mar;1760(3):487-94.

Melanosomes synthesized within melanocytes are transferred to keratinocytes through dendrites, resulting in a constant supply of melanin to the epidermis, and this process determines skin pigmentation. During screening for inhibitors of melanosome transfer, we found a novel reagent, Centaureidin, that induces significant morphological changes in normal human epidermal melanocytes and inhibits melanocyte dendrite elongation, resulting in a reduction of melanosome transfer in an in vitro melanocyte-keratinocyte co-culture system. Since members of the Rho family of small GTP-binding proteins act as master regulators of dendrite formation, and activated Rho promotes dendrite retraction, we studied the effects of Centaureidin on the small GTPases. In in vitro binding assay, Centaureidin activated Rho and furthermore, a Rho inhibitor (C. botulinum C3 exoenzyme), a Rho kinase inhibitor (Y27632) and a small GTPase inhibitor (Toxin B) blocked dendrite retraction induced by Centaureidin. These results suggest Centaureidin could act via the Rho signaling pathway, and it may directly or indirectly activate Rho. Thus, Centaureidin appears to inhibit dendrite outgrowth from melanocytes by activating Rho, resulting in the inhibition of melanosome transfer from melanocytes to keratinocytes.