Bacteriochlorophyll a, and its derivatives: chemistry and perspectives for cancer therapy.
ABSTRACT The review summarizes the chemistry of the third generation of photosensitizers, namely, the derivatives of natural bacteriochlorophyll a, for photodynamic treatment of cancer. The compounds of this class strongly absorb light at lambda=770-850 nm. This unique property opens new therapeutic opportunities due to deeper tissue penetration of light, thereby increasing the photodamage for tumor eradication. Analyzed are the modifications of bacteriochlorophyll a, that improve physico-chemical characteristics of compounds and enhance accumulation in tumors. Focusing on the delivery of photosensitizers to the tumor site and to specific intracellular compartments, we describe the conjugates of bacteriochlorophyll a, derivatives with carbohydrate and protein carriers. Boronated bacteriochlorins can be used in both photodynamic and boron neutron capture therapy.
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ABSTRACT: Bacteriochlorins are attractive candidates as photosensitizers for photodynamic therapy (PDT) due to their intense absorption in the near-infrared (NIR) region of the spectrum where light transmission through tissue is maximal. Many naturally occurring bacteriochlorins are inherently unstable due to adventitious atmospheric oxidation. A de novo synthesis affords bacteriochlorins that contain a geminal dimethyl group in each reduced pyrrole ring to increase stability against oxidation. Here, three new synthetic bacteriochlorins, each bearing a single side-chain containing one or two positive charges, were investigated for their in vitro PDT activity against HeLa human cancer cells. All bacteriochlorins were active at low nanomolar concentration when activated with NIR light; those bearing a single positive charge exhibited faster uptake and higher activity. The bacteriochlorins were localized in mitochondria, lysosomes and endoplasmic reticulum as shown by organelle specific fluorescent probes. Cell death was via apoptosis as shown by cell morphology and nuclear condensation. Taken together, the results show the importance of appropriate peripheral groups about a photosensitizer for effective PDT applications.Journal of Porphyrins and Phthalocyanines 01/2013; 17(1-2):73-85. · 1.43 Impact Factor