Wang Y, Casadevall A
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Antimicrob Agents Chemother. 1996 Mar;40(3):541-5. doi: 10.1128/AAC.40.3.541.
Cryptococcus neoformans is an opportunistic fungal pathogen which becomes heavily melanized in the presence of phenolic substrates such as L-dopa. Various drugs are known to bind to melanin with high affinity, including the antipsychotic agent trifluoperazine and the antimalarial agent chloroquine. We hypothesized that drugs which bind melanin may have different toxicities for melanized and nonmelanized C. neoformans cells. The effects of trifluoperazine and chloroquine or C. neoformans were determined by measuring cell viability after exposure to these drugs. Cell viability was measured by CFU determination and flow cytometry with propidium iodide staining. Melanized cells were more susceptible than nonmelanized cells to the fungicidal effects of trifluoperazine. Chloroquine had no fungicidal effect on either melanized or nonmelanized C. neoformans under the conditions studied. Flow cytometry of trifluoperazine-treated C. neoformans cells stained with the mitochondrial stain dihydrorhodamine 123 revealed fluorescence changes consistent with mitochondrial damage. Our results indicate that melanized and nonmelanized C. neoformans cells can differ in susceptibility to certain drugs and suggest that strategies which target melanin may be productive for antifungal-drug discovery.
新型隐球菌是一种机会性真菌病原体，在存在酚类底物（如左旋多巴）的情况下会大量黑化。已知多种药物能与黑色素高亲和力结合，包括抗精神病药物三氟拉嗪和抗疟药物氯喹。我们推测，与黑色素结合的药物对黑化和未黑化的新型隐球菌细胞可能具有不同的毒性。通过测量暴露于这些药物后的细胞活力来确定三氟拉嗪和氯喹对新型隐球菌的影响。通过菌落形成单位（CFU）测定和碘化丙啶染色的流式细胞术来测量细胞活力。黑化细胞比未黑化细胞对三氟拉嗪的杀菌作用更敏感。在所研究的条件下，氯喹对黑化或未黑化的新型隐球菌均无杀菌作用。用线粒体染料二氢罗丹明123染色的经三氟拉嗪处理的新型隐球菌细胞的流式细胞术显示，荧光变化与线粒体损伤一致。我们的结果表明，黑化和未黑化的新型隐球菌细胞对某些药物的敏感性可能不同，并表明针对黑色素的策略可能有助于抗真菌药物的发现。
