In Vitro Fungicidal Photodynamic Effect of Hypericin on Candida Species

Hypericin is a natural photosensitizer considered for the new generation of photodynamic therapy (PDT) drugs. The aim of this study was to evaluate the in vitro fungicidal effect of hypericin PDT on various Candida spp., assessing its photocytotoxicity to keratinocytes (HaCaT) and dermal fibroblasts (hNDF) to determine possible side effects. A 3 log fungicidal effect was observed at 0.5 McFarland for two Candida albicans strains, Candida parapsilosis and Candida krusei with hypericin concentrations of 0.625, 1.25, 2.5 and 40 mu m, respectively, at a fluence of 18 J cm-2 (LED lamp emitting at 602 +/- 10 nm). To obtain a 6 log reduction, significantly higher hypericin concentrations and light doses were needed (C. albicans 5 mu m, C. parapsilosis 320 mu M and C. krusei 320 mu M; light dose 37 J cm-2). Keratinocytes and fibroblasts can be preserved by keeping the hypericin concentration below 1 mu m and the light dose below 37 J cm-2. C. albicans appears to be suitable for treatment with hypericin PDT without significant damage to cutaneous cells.