Photodynamic effects of a novel series of silicon(IV) phthalocyanines against human colon adenocarcinoma cells

Lo, Pui-Chi; Leung, Stanley C.H.; Chan, Elaine Y.M.; Fong, Wing-Ping; Ko, Wing-Hung; Ng, Dennis K.P.

doi:10.1016/j.pdpdt.2007.03.001

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Volume 4, Issue 2 , Pages 117-123, June 2007

Photodynamic effects of a novel series of silicon(IV) phthalocyanines against human colon adenocarcinoma cells

Pui-Chi Lo
- Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Stanley C.H. Leung
- Department of Biochemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Elaine Y.M. Chan
- Department of Biochemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Wing-Ping Fong
- Department of Biochemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Wing-Hung Ko
- Department of Physiology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
Dennis K.P. Ng, DPhil
- Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
- Corresponding author. Tel.: +852 2609 6375; fax: +852 2603 5057.

published online 10 May 2007.

Summary

The photodynamic activities of a novel series of silicon(IV) phthalocyanines with different axial substituents including the 1,3-bis(dimethylamino)-2-propoxy group, isopropylidene-protected galactose, and polyethylene glycol have been investigated against HT29 and T84 human colon adenocarcinoma cells. While these compounds are not cytotoxic in the absence of light, they exhibit high photocytotoxicities with IC₅₀ values as low as 17nM. The photodynamic activities of these compounds against HT29 are correlated with the cellular uptake as reflected by the relative intracellular fluorescence intensity and the Q-band absorbance of the dyes in the organic extracts. The most potent compound 1, having a 1,3-bis(dimethylamino)-2-propoxy group and a methoxy group as the axial substituents, has a high and selective affinity to the mitochondria of HT29 cells, as revealed by fluorescence microscopy.