The influence of β-cyclodextrin encapsulation on the binding of 2'-hydroxyflavanone with calf thymus DNA

Inclusion complexation of 2'-hydroxyflavanone (2'HF) with β-cyclodextrin (β-CD) was studied, both in solution phase and as solid inclusion complexes, by UV-visible and fluorescence spectroscopic, scanning electron microscopic and X-ray diffractometric techniques. The interaction of 2'HF with calf thymus DNA (ctDNA) in the presence and the absence of β-CD were compared. Fluorescence enhancement was observed for 2'HF due to the formation of 1:1 complex with β-CD. The structure of 1:1 complex is proposed based on spectral observation, molecular modeling and by calculated theoretical bond lengths. The possible mode of interaction between 2'HF and DNA was analyzed by molecular modeling method. The interaction of 2'HF with calf thymus DNA (ctDNA) was investigated by absorption and fluorescence measurements in the presence and the absence of β-CD as capping agent. Both in the presence and the absence of β-CD, 2'HF showed hyper-chromic effect, red shift of absorption spectra, and quenching of fluorescence due to binding of 2'HF with ctDNA. The results reveal that the phenolic moiety is involved in inclusion complexation with β-CD and interaction with DNA. In the presence of β-CD, the phenolic moiety may be included in cyclodextrin cavity, whereas the dihydrobenzopyran-4-one moiety interacts with DNA. Further, β-CD selectively blocks a part of the 2'HF molecule binding with DNA. This renders the remaining portion of the flavanone available for interaction with DNA.

Effects of 4',7-dimethoxyflavanone on cell cycle arrest and apoptosis in human breast cancer MCF-7 cells

The present study was designed to investigate the anticancer activity of 4,7-dimethoxyflavanone in vitro. When human breast cancer MCF-7 cells were treated with 4',7-dimethoxyflavanone at various concentrations (1-200 μM) for 24 h, antiproliferative effects were first observed at 1 μM and the IC(50) was 115.62 μM. Conversely, 4',7-dimethoxyflavanone was not cytotoxic (measured as lactate dehydrogenase release in CHO-K1 cells) under the same conditions. MCF-7 cells exposed to the 4',7-dimethoxyflavanone at the IC(50) concentration showed cell cycle arrest and apoptosis. Compared to the respective control level, exposure to 4',7-dimethoxyflavanone resulted in a remarkable increase of small DNA fragments at the sub-G1 phase and an increase in the G2/M phase cell population. Moreover, when 4',7-dimethoxyflavanone treatment caused G2/M phase arrest, an increase in CDK1 together with an increase in cyclin B was observed. Based on these results, 4',7-dimethoxyflavanone may be a useful anticancer agent.