The Mass Spectrometry society of Japan - The 71st Annual Conference on Mass Spectrometry, Japan
Japanese

Abstract

Table of contents

Timetable

Plenary Lecture

Symposium Sessions (Day1, Day2, Day3)

Basic Sessions (Day1, Day2, Day3)

Young Researchers' Sessions (Day1, Day2, Day3)

Poster Presentations (Day1, Day2, Day3)

Special Evening Sessions

Corporate Program

Young Researchers' Sessions

Day 3, May 17（Wed.）　10:15-10:30　Room C (Room 1009)

3C-O-1015　　PDF

Analysis of the Photoproducts of the Photosensitizer, Protoporphyrin IX, used in Photodynamic Therapy of Cancers

(1Grad. Sch. Eng., Osaka Univ., 2Grad. Sch. Med., Kyoto Univ., 3MEI Center, Osaka Univ.)
oOgbonna Sochi1, Hisanao Hazama1, Katsuyoshi Masuda1,2, Kunio Awazu1,3

Photodynamic therapy (PDT) is a cancer treatment technique gaining popularity due to its highly-selective and minimally-invasive characteristics compared to other treatment techniques.
The efficacy of PDT is affected by photosensitizer photobleaching and the formation of its photoproducts during treatment. Conventionally, these are analyzed based on fluorescence. However, quantitative analysis is difficult due to the similar optical properties between the photosensitizer and the photoproducts. Mass spectrometry (MS) offers quantitative identification of compounds based on chemical compositions, making it better suited for photobleaching and photoproduct analyses.
This study uses MS to investigate the photoproducts of protoporphyrin IX (PpIX), a commonly used photosensitizer in PDT, formed during photosensitizer irradiation and photobleaching. The emergence of a peak at m/z 595.3 attributed to the monoisotopic protonated peak of the chlorin-type PpIX photoproduct, photoprotoporphyrin was observed with laser irradiation of PpIX. Previous analysis has indicated that the rate of photoproducts formation affects the photobleaching rates of the photosensitizer, and the photosensitizer photobleaching rate is necessary for the dosimetry estimation of PDT. Thus, a detailed analysis of the photoprotoporphyrin formation relative to the PpIX photobleaching and the analysis of the formation of other photoproducts of PpIX would be helpful in improving the treatment efficacy of PDT.