Dark and Photoinduced Cytotoxicity of Chlorophyll a Derivatives and Their Analogues towards HeLa Cells: Some Structure - Activity Relationships

In the present work, we have systematically studied the dark and photoinduced cytotoxicity of a series of chlorophyll a derivatives (a sampling of 36 compounds, the quantitative measure of toxicity is HeLa cell survival and IC 50 value) in experiments in vitro. It has been shown that chlorins without an exocycle, such as chlorin e 6 , its 15,17-dimethyl ether and 13-amide derivatives, regardless of the substituent at the 13-amide nitrogen atom, as well as substituents in positions 3, 15 and 17, as a rule, have the highest cytotoxicity (IC 50 ( dark ) < 10 µM). It has been established that the IC 50 value during the dark exposure is more than 10 µM for the most part of phorbin pounds with different dark toxicity showed that substances with both high and low dark toxicity have high IC 50(dark) /IC 50(photo) values, so the effectiveness of the photosensitizer is not unambiguously associated with its low dark toxicity.