Qi H, Takano H, Kato Y, Wu Q, Ogata C, Zhu B, Murata Y, Nakamura Y. Hydrogen [corrected] peroxide-dependent photocytotoxicity by phloxine B, a xanthene-type food colorant.
Biochim Biophys Acta Gen Subj 2011;
1810:704-12. [PMID:
21565256 DOI:
10.1016/j.bbagen.2011.04.010]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 04/14/2011] [Accepted: 04/25/2011] [Indexed: 11/30/2022]
Abstract
BACKGROUND
Phloxine B (PhB; 2',4',5',7'-tetrabromo-4,5,6,7-tetrachloro-fluorescein), an artificial xanthene colorant, has been used as a red coloring agent in drugs and cosmetics as well as foods in some countries. However, little effort has been devoted to the study of this colorant as a potentially useful medicinal agent.
METHODS
We investigated the daily light-induced photocytotoxicity of PhB in two human leukemia cells, HL-60 and Jurkat, and its underlying mechanisms by in vitro experiments using antioxidants. REUSLTS AND CONCLUSIONS: PhB inhibited cell proliferation more preferentially to HL-60 cells than to Jurkat cells. Co-treatment of catalase completely blocked the photocytotoxicity by PhB in HL-60 cells, whereas the effect of histidine was only partial, suggesting that hydrogen peroxide (H(2)O(2)), rather than singlet oxygen, might be a prerequisite for the PhB-induced HL-60 cell death. Actually, PhB produced a significant amount of H(2)O(2) in the media as well as in the cells in concentration- and light-dependent manners. Furthermore, methionine, a hypochlorous acid (HOCl) scavenger, also significantly attenuated the cytotoxicity in HL-60 cells, but not in Jurkat cells, indicating the involvement of myeloperoxidase (MPO)-dependent hypohalous acid formation during the photocytotoxicity. In vitro experiments revealed that halogenated tyrosine was generated from the reaction of bovine serum albumin with PhB and HL-60 cell lysate. The present findings suggested that PhB induced a differential photodynamic action in the MPO-containing leukemia cells through an H(2)O(2)-dependent mechanism.
GENERAL SIGNIFICANCE
Our findings provide new insights into the molecular mechanisms underlying the PhB-induced apoptosis and also evaluated PhB as a promising PDT agent.
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