The development of new medicines and alternatives to existing
antimicrobial agents represents a high priority in treating infections caused by multidrug
resistant bacteria. This is reported mainly, as multiple resistance acquired by
bacteria at treatment with antibiotics. The use of laser radiation to photo-generate new
compounds from known medicines can be an effective method to obtain a better
antimicrobial activity against infections with bacteria and fungi. The irradiation with a
laser beam emitted at 266 nm of 2 mg/ml aqueous chlorpromazine and thioridazine
solutions for periods of time varying from 1 to 240 min leads to photochemical changes
in the molecular structure of the parental compounds and to generation of new
photoproducts with enhanced antimicrobial, antifungal and antibiofilm activity. The
susceptibility of broad panels of Gram-negative and Gram-positive bacteria and fungi
in planktonic and biofilm state, to the unirradiated and irradiated CPZ and TZ were
performed in order to highlight the possible use of these substances for the
development of novel antimicrobial agents. The antimicrobial activity was evaluated by
quantitative methods, i.e. minimum inhibitory concentration and minimum biofilm
eradication concentration assays. Both CPZ and TZ irradiated solutions presented, as
cocktails of medicines obtained after laser irradiation, enhanced antimicrobial,
antifungal and antibiofilm activity when compared to the unirradiated samples.
Keywords: ABC 230, Antimicrobial activity, Bacteria, Biofilm, Candida
albicans, Chlorpromazine, Cryptococcus neoformans, Fungi, Klebsiella
pneumoniae, Laser, MBEC, MDR, MIC, Multiple drug resistance, Pseudomonas aeruginosa, Susceptibility, Thioridazine, Staphylococcus aureus,
UV laser radiation.
