title: Differential apoptotic effect of wogonin and nor-wogonin via stimulation of ROS production in human leukemia cells.
abstract: We investigate the roles of methoxyl (OCH(3)) and hydroxyl (OH) substitutions at C8 of flavonoids on their apoptosis-inducing activities. Wogonin (Wog) and nor-wogonin (N-Wog) are structurally related flavonoids, and respectively contain an OH and OCH(3) at C8. In leukemia HL-60 cells, N-Wog exhibited more-potent cytotoxicity than Wog according to the MTT and LDH release assays, and the IC(50) values of Wog and N-Wog in HL-60 cells were 67.5 +/- 2.1 and 21.7 +/- 1.5 microM, respectively. Apoptotic characteristics including DNA ladders, apoptotic bodies, and hypodiploid cells accompanied by the induction of caspase 3 protein processing appeared in Wog- and N-Wog-treated HL-60 cells. Interestingly, an increase in intracellular peroxide production was detected in N-Wog- but not Wog-treated HL-60 cells by the DCHF-DA assay, and the reduction of intracellular peroxide by catalase (CAT) induced by N-Wog significantly reduced the N-Wog- but not the Wog-induced cytotoxic effect according to the MTT assay in accordance with the blocking of DNA ladder formation and caspase 3 and PARP protein processing elicited by N-Wog. We further analyzed the effect of six structurally related compounds, including 5-OH, 7-OH, 5,7-diOH, 5,7-diOCH(3), 7,8-diOCH(3), and 7-OCH(3)-8-OH flavones, on apoptosis induction in HL-60 cells. Results suggested that OH at C5 and C7 is essential for both the apoptosis-inducing activity of flavonoids, and OH at C8 may contribute to apoptosis induction ability. Evidence to support a distinct structure-activity relationship in apoptosis induction of flavonoids is provided for the first time in this study.
authors.affiliation: Section of Hematology-Oncology, Department of Internal Medicine, Taipei Municipal Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Jyh-Ming
authors.initials: JM
authors.lastname: Chow
authors.forename: Guan-Cheng
authors.initials: GC
authors.lastname: Huang
authors.forename: Shing-Chuan
authors.initials: SC
authors.lastname: Shen
authors.forename: Chin-Yen
authors.initials: CY
authors.lastname: Wu
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Lin
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D044950:Flavanones / Q000737:chemistry / Q000494:pharmacology*; D047309:Flavones; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D044950:Flavanones; D047309:Flavones; D005419:Flavonoids; D017382:Reactive Oxygen Species; C055505:norwogonin; C505407:CASP3 protein, human; D053148:Caspase 3; C085514:wogonin