Laboratory of Photodynamic Inactivation of Microorganisms, Department of Materials Science and Physics, University of Salzburg, Hellbrunnerstraße 34, Salzburg, Austria.
Photochem Photobiol Sci. 2013 Oct;12(10):1795-802. doi: 10.1039/c3pp50095k.
Photodynamic inactivation (PDI), the light-induced and photosensitizer-mediated overproduction of reactive oxygen species in microorganisms, represents a convincing approach to treat infections with (multi-resistant) pathogens. Due to its favourable photoactive properties combined with excellent biocompatibility, curcumin derived from the roots of turmeric (Curcuma longa) has been identified as an advantageous photosensitizer for PDI. To overcome the poor water solubility and the rapid decay of the natural substance at physiological pH, we examined the applicability of polyvinylpyrrolidone curcumin (PVP-C) in an acidified aqueous solution (solubility of PVP-C up to 2.7 mM) for photoinactivation of Gram(+) and Gram(-) bacteria. Five micromolar PVP-C incubated for 5 minutes and illuminated using a blue light LED array (435 ± 10 nm, 33.8 J cm(-2)) resulted in a >6 log10 reduction of the number of viable Staphylococcus aureus. At this concentration, longer incubation periods result in a lower phototoxicity, most likely due to degeneration of curcumin. Upon an increase of the PVP-C concentration to 50 μM (incubation for 15 or 25 min) a complete eradication of Staphylococcus aureus can be achieved. As expected for a non-cationic photosensitizer, cell wall permeabilization with CaCl2 prior to addition of 50 μM PVP-C for 15 min is necessary to induce a drop in the count of the Gram(-) Escherichia coli for more than 3 log10. As both constituents of the formulation, curcumin (E number E100) and polyvinylpyrrolidone (E1201), have been approved as food additives, a PDI based on PCP-C might allow for a very sparing clinical application (e.g. for disinfection of wounds) or even for employment in aseptic production of foodstuffs.
光动力灭活（PDI）是一种利用光和光敏剂在微生物中过度产生活性氧的方法，是治疗（多耐药）病原体感染的一种有效方法。由于其具有良好的光活性特性和优异的生物相容性，从姜黄（Curcuma longa）根部提取的姜黄素被鉴定为用于 PDI 的一种有优势的光敏剂。为了克服天然物质在生理 pH 值下的低水溶性和快速衰减，我们研究了在酸化水溶液中（PVP-C 的溶解度高达 2.7 mM）聚维酮基姜黄素（PVP-C）在革兰氏阳性和革兰氏阴性细菌光灭活中的适用性。孵育 5 分钟后，用蓝光 LED 阵列（435 ± 10nm，33.8 J cm(-2))照射 5 微米的 PVP-C，可使金黄色葡萄球菌的活菌数减少>6log10。在该浓度下，较长的孵育时间会导致较低的光毒性，这很可能是由于姜黄素的退化。当 PVP-C 浓度增加到 50μM（孵育 15 或 25 分钟）时，可完全消除金黄色葡萄球菌。由于 PVP-C 是非阳离子型光敏剂，因此在添加 50μM PVP-C 孵育 15 分钟之前，用氯化钙进行细胞壁渗透，以诱导革兰氏阴性大肠杆菌的数量下降超过 3log10，这是预期的。由于制剂的两种成分，姜黄素（E 编号 E100）和聚乙烯吡咯烷酮（E1201）已被批准为食品添加剂，基于 PCP-C 的 PDI 可能允许非常谨慎地临床应用（例如，用于伤口消毒），甚至用于无菌生产食品。
