584P - Controlled release of anti-cancer flutamide-related escape products under exposure to magnetic fields

Date 18 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Cytotoxic agents
Presenter Hidenori Nakagawa
Citation Annals of Oncology (2016) 27 (suppl_9): ix184-ix189. 10.1093/annonc/mdw603
Authors H. Nakagawa, K. Nakamura, H. Kamei, M. Ohuchi, H. Kawase
  • Department Of Electrical And Electronic Engineering, Tokyo Denki University, 120-8551 - Tokyo/JP

Abstract

Background

Magnetic field effects on radical pair mechanisms are known as the one and only phenomenon by which magnetic fields can switch over chemical reaction paths despite their low energies. A radical pair is an extremely short-lived reactive intermediate; therefore, it is necessary to prolong the lifespan of the pair for the most efficient magnetic field effects. As far as that is concerned, it is strongly desired that liposomal membranes (phospholipid bilayers) can be made applicable with pair mechanisms. In our present research, we considered examining the application of the mechanisms to drug release controlling of liposomal carriers under exposure to magnetic fields.

Methods

The instrument mainly consists of: a computer-controlled monochromator (Nikon, G250), two of regulated DC power supplies (Kikusui, PAK6 and PMC18) and an original detector enabled to monitor the degree of the photoreactivity of anti-cancer flutamide (FM) in liposomal membranes. Small unilamellar vesicles containing FM were prepared by the membrane filtration method. Under exposure to static/pulsating magnetic fields, FM in the liposomal membrane was excited by an emission wavelength of 325 nm. To compare magnetic field effects on the behaviour of the model membranes, we measured the delayed fluorescence as well as the spectral changes with absorbance at 380 and 260 nm after the emission.

Results

For measurements of magnetic field effects with the release of FM-related escape products, up to 20 min after the emission, the increase in the products’ release was relatively consistent with a S-T level intersystem crossing for a radical pair mechanism. Under a static magnetic field (0.2 T), the extent of the products’ release was more extensive by 71%, than that obtained with geomagnetic fields. What is more, we found the possibility that a pulsating field influences the pair mechanism in the process of membrane peroxidations induced by reactive oxygen species––mainly, excited singlet oxygen (1O2).

Conclusions

Because our findings can be expected to reveal new knowledge for resolving important clinical problems, we strongly propose a new drug release technology using liposomes equipped with magnetic controls.

Clinical trial indentification

Legal entity responsible for the study

N/A

Funding

Japan Society for the Promotion of Science (JSPS)

Disclosure

All authors have declared no conflicts of interest.