Isolation, Identification, and Biological Activities of a New Chlorin e6 Derivative.

Area of Science:

• Photochemistry
• Organic Synthesis
• Cancer Research

Background:

• Chlorin e6 is a photosensitizer used in photodynamic diagnosis and therapy.
• A novel process-related impurity was identified during chlorin e6 synthesis.
• This impurity, rhodin g7 71-ethyl ester, originates from chlorophyll b.

Purpose of the Study:

• To identify and characterize a novel impurity in chlorin e6 synthesis.
• To evaluate the cytotoxic effects and photodynamic properties of the novel impurity.
• To explore the potential of rhodin g7 71-ethyl ester as an alternative photosensitizer for cancer therapy.

Main Methods:

• Nuclear Magnetic Resonance (NMR) and High-Resolution Mass Spectrometry (HRMS) for structural elucidation.
• High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) for monitoring synthesis intermediates.
• In vitro cytotoxicity assays on five cancer cell lines and one normal cell line under dark and light conditions.
• Singlet oxygen generation and reactive oxygen species (ROS) production studies.

Main Results:

• A novel impurity, rhodin g7 71-ethyl ester, was identified and structurally elucidated.
• Rhodin g7 71-ethyl ester demonstrated significantly higher cytotoxicity (2-fold) compared to chlorin e6 against most cancer cell lines upon irradiation.
• The novel compound also exhibited superior dark cytotoxicity compared to chlorin e6.
• Studies confirmed enhanced singlet oxygen generation and ROS production by rhodin g7 71-ethyl ester.

Conclusions:

• Rhodin g7 71-ethyl ester is a potent photosensitizer with superior cytotoxic activity compared to chlorin e6.
• Its efficacy in both dark and light conditions suggests a promising role in photodynamic therapy.
• Rhodin g7 71-ethyl ester could serve as a valuable alternative or complementary agent for cancer treatment.