Photophysical properties of sinoporphyrin sodium and explanation of its high photo-activity

Sinoporphyrin sodium (DVDMS) is a novel photosensitizer with high photodynamic therapy (PDT) effect. Reasons for its high photo-activity were investigated according to the study of photophysical characteristics of DVDMS. Extinction coefficients (e) of DVDMS at 405 nm and 630 nm are 4.36 × 105 and 1.84 × 104 M−1.cm−1; fluorescence quantum yield (ΦF) is 0.026; quantum yield of lowest triplet state formation is 0.94 and singlet oxygen quantum yield (ΦΔ) is 0.92. Although ΦΔ of DVDMS is only 10% higher than that of Photofrin®; (0.83), the extinction coefficient of DVDMS at 630 nm is 10-fold greater than that of Photofrin®;. This leads to its higher singlet oxygen generation efficiency (eΦΔ). The higher eΦΔ of DVDMS can result in an effective reduction of dosage (1/10 of Photofrin®;) reaching the same cytotoxic effect as Photofrin®;. Even though ΦF is approximately equal to that of Photofrin®;, brightness (eΦF) of DVDMS is 10-fold greater than that of Photofrin®; because of the 10-fold greater extinction coeff...