Direct modification of bioactive phenothiazines by exposure to laser radiation

Recent Pat Antiinfect Drug Discov. 2011 May;6(2):147-57. doi: 10.2174/157489111796064515.


Whereas exposure of combinations of a phenothiazine and bacterium to incoherent UV increases the activity of the phenothiazine, exposure of the phenothiazine alone does not yield an increase of its activity. Because the laser beam energy is greater than that produced by the incoherent UV sources, exposure of phenothiazines to specific lasers may yield molecules with altered activities over that of the unexposed parent. Chlorpromazine, thioridazine and promethazine active against bacteria were exposed to two distinct lasers for varying periods of time. Absorption and fluorescence spectra were conducted prior to and post-exposure and the products of laser exposure evaluated for activity against a Staphylococcus aureus ATCC strain via a disk susceptibility assay. Exposure to lasers alters the absorption/fluorescence spectra of the phenothiazines; reduces the activity of thioridazine against the test bacterium; produces a highly active chlorpromazine compound against the test organism. Exposure of phenothiazines to lasers alters their structure that results in altered activity against a bacterium. This is the first report that lasers can alter the physico-chemico characteristics to the extent that altered bioactivity results. Exposure to lasers is expected to yield compounds that are difficult to make via chemical manipulation methods. A survey of selected patents of interest, even co-lateral for the subject of this article is shortly made.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / radiation effects*
  • Chemistry, Pharmaceutical
  • Chlorpromazine / pharmacology
  • Chlorpromazine / radiation effects
  • Disk Diffusion Antimicrobial Tests
  • Drug Discovery
  • Lasers, Solid-State*
  • Molecular Structure
  • Patents as Topic
  • Phenothiazines / chemistry
  • Phenothiazines / pharmacology*
  • Phenothiazines / radiation effects*
  • Promethazine / pharmacology
  • Promethazine / radiation effects
  • Spectrometry, Fluorescence
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / growth & development
  • Structure-Activity Relationship
  • Technology, Pharmaceutical / methods
  • Thioridazine / pharmacology
  • Thioridazine / radiation effects


  • Anti-Bacterial Agents
  • Phenothiazines
  • Promethazine
  • Thioridazine
  • Chlorpromazine