Fraxetin Induces Heme Oxygenase-1 Expression by Activation of Akt/Nrf2 or AMP-activated Protein Kinase α/Nrf2 Pathway in HaCaT Cells

BACKGROUND: Fraxetin (7,8-dihydroxy-6-methoxy coumarin), a coumarin derivative, has been reported to possess antioxidative, anti-inflammatory and neuroprotective effects. A number of recent observations suggest that the induction of heme oxygenase-1 (HO-1) inhibits inflammation and tumorigenesis. In the present study, we determined the effect of fraxetin on HO-1 expression in HaCaT human keratinocytes and investigated its underlying molecular mechanisms. METHODS: Reverse transcriptase-PCR and Western blot analysis were performed to detect HO-1 mRNA and protein expression, respectively. Cell viability was measured by the MTS test. The induction of intracellular reactive oxygen species (ROS) by fraxetin was evaluated by 2′,7′-dichlorofluorescin diacetate staining. RESULTS: Fraxetin upregulated mRNA and protein expression of HO-1. Incubation with fraxetin induced the localization of nuclear factor-erythroid-2-related factor-2 (Nrf2) in the nucleus and increased the antioxidant response element-reporter gene activity. Fraxetin also induced the phosphorylation of Akt and AMP-activated protein kinase (AMPK)α and diminished the expression of phosphatase and tensin homolog, a negative regulator of Akt. Pharmacological inhibition of Akt and AMPKα abrogated fraxetin-induced expression of HO-1 and nuclear localization of Nrf2. Furthermore, fraxetin generated ROS in a concentration-dependent manner. CONCLUSIONS: Fraxetin induces HO-1 expression through activation of Akt/Nrf2 or AMPKα/Nrf2 pathway in HaCaT cells.

Antitumor and antibacterial activity of ethylacetate extract of ludwigia hyssopifolia linn and its active principle piperine

An alkaloid constituent 1-[5-[1,3-benzodioxol-5-yl]-1-oxo-2,4-pentadienyl]piperidine, trivial name piperine was isolated from Ludwigia hyssopifolia Linn. [Family-Onagraceae]. The ethylacetate extract of the plant and the isolated compound piperine were studied for antitumor and in vitro antibacterial activity. Ethylacetate extract showed 73.05 and 84.14% inhibition of Agrobacterium tumefaciens-induced crown gall tumor formation in potato disc. Piperine exhibited antitumor activity with IC50 value of 13.50