Redox cycling of beta-lapachone and structural analogues in microsomal and cytosol liver preparations.

摘要: Publisher Summary Quinones are widely distributed in nature and make up an important group of substrates for flavoenzymes. Lipophilic o-naphthoquinones possess antibacterial, antifungal, trypanocidal, cytostatic effects. Among those quinones, β-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphtho [1,2b]pyran- 5,6-dione) isolated from the lapacho tree ( Tabebuia avellanedae ) has proved to be effective agent different human tumor cells, such as murine leukemia, melanoma, hepatoma, colon carcinoma, lymphoma, glioma, well epidermoid laryngeal, ovarian, breast, lung, prostate cancer . On these grounds, is suggested clinical use; its effects have often been described apoptosis or necrosis, depending on target time, drug dose. In presence molecular oxygen, semiquinone radical can transfer electron generate O 2 - Unlike most other cellular reductases, two-electron reduction quinine also catalyzed by cytosolic mitochondrial DT-diaphorase (DTD), quinone oxidoreductase, E.C. 1.6.99.2 (NQO1), directly hydroquinone. Observations with related indicate that corresponding hydroquinones must included second agreement (1) spectrum, demonstrated ESR spectroscopy; (2) (or quinone) production, optical (3) effect dicoumarol redox cycling oxygen consumption NADPH/o-naphthoquinone/ DTD system. These reactions associated activity seem rule out contention proposing antioxidant enzyme protecting against toxicity.