Potential of using medicinal plant extracts as photosensitizers for antimicrobial photodynamic therapy

In this study, we used commercially available preparations (Calendulae officinalis floridis extract,Chamomillae recutitae floridis extract,Achillea millefolii herbae extract;Hypericum perforatum extract;Eucalyptus viminalis folia extract) as photosensitizers for inactivation of gram-negative (Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacteria. Spectral-luminescent analysis has shown that the major chromophores are of chlorophyll (mainly chlorophylla andb) and hypericin nature. The extracts are efficient generators of singlet oxygen with quantum yield (γΔ) from 0.40 to 0.64 (reference compound, methylene blue withγΔ =  0.52). In APDT assays, bacteria before irradiation were incubated with extracts for 30 min. After irradiation and 24 h of incubation, colony-forming units (CFU) were counted. Upon exposure ofP. aeruginosa to radiation of 405  nm, 590 nm, and 660 nm at equal energy dose of 30 J/cm2 (irradiance – 100 mW/cm2, exposure time – 5 min), the most pronounced effect is observed with blue light (>3 log10 reduction); in case ofS. aureus, the effect is approximately equivalent for light of indicated wavelengths and dose (>4 log10 reduction).
Source: Photochemistry and Photobiology - Category: Science Authors: Tags: RESEARCH ARTICLE Source Type: research