Vel Tech Dr. RR and Dr. SR Technical University, No. 42, Avadi, Vel Tech Road, Avadi, Chennai 600 062, Tamilnadu, India.
J Photochem Photobiol B. 2012 Nov 5;116:105-13. doi: 10.1016/j.jphotobiol.2012.08.002. Epub 2012 Aug 23.
Carvedilol (CVL), a β-adrenergic receptor, is insoluble under physiological conditions and hence its oral administration is difficult. Bile salts are widely used as drug delivery media for many hydrophobic drugs. CVL has a strong intrinsic fluorescence with a carbazole moiety. When excited at 320 nm, it exhibits dual emission at 347 and 357 nm. As the concentration of bile salt is increased there is an overall increase in the fluorescence intensity and also the ratio of the intensities at 347 and 357 nm (I(1)/I(2)) increases. This indicates that the CVL molecule can sense the non-polar nature of bile salts with increasing concentrations. It is showed that the new parameter (I(1)/I(2)) can be used as an indicative tool in determining the polarity of the medium. The increase in fluorescence anisotropy and fluorescence lifetimes is observed, indicating the micro-heterogeneity of the bile salt solutions as experienced by CVL molecules. The possibility of electrostatic interactions between CVL and bile salt micelles is ruled out in view of the results obtained here and their interaction is purely hydrophobic in nature. The results suggest that the CVL molecule associates with the steroidal moiety of bile salts through its carbazole moiety.
卡维地洛（CVL）是一种β肾上腺素能受体，在生理条件下不溶，因此其口服给药困难。胆汁盐被广泛用作许多疏水性药物的药物递送介质。CVL 具有带有咔唑部分的强固有荧光。在 320nm 激发时，它在 347nm 和 357nm 处表现出双重发射。随着胆汁盐浓度的增加，荧光强度整体增加，并且在 347nm 和 357nm（I(1)/I(2))处的强度比增加。这表明 CVL 分子可以随着浓度的增加感知胆汁盐的非极性性质。结果表明，新参数（I(1)/I(2)）可作为确定介质极性的指示工具。观察到荧光各向异性和荧光寿命的增加，表明 CVL 分子经历了胆汁盐溶液的微观不均匀性。鉴于此处获得的结果，排除了 CVL 和胆汁盐胶束之间静电相互作用的可能性，并且它们的相互作用本质上是疏水的。结果表明，CVL 分子通过其咔唑部分与胆汁盐的甾体部分缔合。
