Bergamot (Citrus bergamia Risso) fruit extracts as gamma-globin gene expression inducers: Phyto-chemical and functional perspectives

Epicarps of Citrus bergamia fruits from organic farming were extracted with the object to obtain derived products differently rich in coumarins and psoralens. The extracts were chemically characterized by 1H-NMR (nuclear magnetic resonance), GC-FID (gas chromatography-flame ionization detector), GC-MS (gas chromatography-mass spectrometry) and HPLC (high pressure liquid chromatography) for detecting and quantifying the main constituents. Both bergamot extracts and chemical standards corresponding to the main constituents detected were then assayed for their capacity to increase erythroid differentiation of K562 cells and expression of gamma-globin genes in human erythroid precursor cells. Three experimental cell systems were employed: (a) the human leukemic K562 cell line, (b) K562 cell clones stably transfected with a pCCL construct carrying green-EGFP (enhanced green fluorescence protein) under the gamma-globin gene promoter and (c) the two-phase liquid culture of human erythroid progenitors isolated from healthy donors. The results suggest that citropten and bergapten are powerful inducers of differentiation and gamma-globin gene expression in human erythroid cells. These data could have practical relevance, since pharmacologically-mediated regulation of human gamma-globin gene expression, with the consequent induction of fetal hemoglobin, is considered a potential therapeutic approach in hematological disorders, including beta-thalassemia and sickle cell anemia.