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BackgroundIt has been suggested that combined effect of natural products may improve the treatment effectiveness in combating proliferation of cancer cells. The present study was undertaken to evaluate the possibility that the combination of xanthorrhizol and curcumin might show synergistic growth inhibitory effect towards MDA-MB-231 human breast cancer cells via apoptosis induction. The effective dose that produced 50% growth inhibition (GI50) was calculated from the log dose-response curve of fixed-combinations of xanthorrhizol and curcumin generated from the sulforhodamine B (SRB) assay. The experimental GI50 value was used to determine the synergistic activity of the combination treatment by isobolographic analysis and combination-index method. Further investigation of mode of cell death induced by the combination treatment was conducted in the present study.ResultsIsobole analysis revealed that substances interaction was synergistic when xanthorrhizol and curcumin were added concurrently to the cultures but merely additive when they were added sequentially. The synergistic combination treatment was then applied to the cultures to investigate the mode of cell death induced by the treatment. Immunofluorescence staining using antibody MitoCapture™ revealed the possibility of altered mitochondrial transmembrane potential, which is one of the hallmark of apoptosis. Hoechst 33258 nuclear staining assay showed the rate of apoptosis of MDA-MB-231 cells to increase in response to the treatment. Apoptotic cell death was further confirmed by DNA fragmentation assay, where internucleosomal excision of DNA was induced upon treatment with xanthorrhizol-curcumin.ConclusionThis is the first time the combined cytotoxic effect of xanthorrhizol and curcumin on MDA-MB-231 cells has been documented and our findings provide experimental support to the hypothesis that combined xanthorrhizol-curcumin showed synergistic growth inhibitory activity on MDA-MB-231 cells via apoptosis induction.

Some chalcones have been designed and synthesized using Claisen-Schmidt reactions as inhibitors of the ferredoxin and ferredoxin-NADP + reductase interaction to pursue a new selective antimalaria agent. The synthesized compounds exhibited inhibition interactions between PfFd-PfFNR in the range of 10.94%-50%. The three strongest inhibition activities were shown by (E)-1-(4-aminophenyl)-3-(4-methoxyphenyl)prop-2-en-1-one (50%), (E)-1-(4-aminophenyl)-3-(2,4-dimethoxyphenyl)prop-2-en-1-one (38.16%), and (E)-1-(4-aminophenyl)-3-(2,3-dimethoxyphenyl)prop-2-en-1-one (31.58%). From the docking experiments we established that the amino group of the methoxyamino chlacone derivatives plays an important role in the inhibition activity by electrostatic interaction OPEN ACCESSMolecules 2014, 19 21474 through salt bridges and that it forms more stable and better affinity complexes with FNR than with Fd.

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