In Vitro Photodynamic Inactivation of Plant-Pathogenic Fungi Colletotrichum acutatum and Colletotrichum gloeosporioides with Novel Phenothiazinium Photosensitizers

Author(s)

de Menezes, Henrique D. ^[1] ; Rodrigues, Gabriela B. ^[1] ; Teixeira, Simone de Padua ^[2] ; Massola, Jr., Nelson S. ^[3] ; Bachmann, Luciano ^[4] ; Wainwright, Mark ^[5] ; Braga, Gilberto U. L. ^{[1, 6]}

Affiliation

^[1] Univ Sao Paulo, Dept Anal Clin Toxicol & Bromatol, Fac Ciencias Farmaceut Ribeirao Preto, BR-14049 Ribeirao Preto - Brazil

^[2] Univ Sao Paulo, Dept Ciencias Farmaceut, Fac Ciencias Farmaceut Ribeirao Preto, BR-14049 Ribeirao Preto - Brazil

^[3] Univ Sao Paulo, Dept Fitopatol Nematol, Escola Super Agr Luiz de Queiroz, Piracicaba - Brazil

^[4] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Fis, Ribeirao Preto - Brazil

^[5] Liverpool John Moores Univ, Sch Pharm & Biomol Sci, Liverpool L3 5UX, Merseyside - England

^[6] Univ Sao Paulo, Res Support Ctr Nat & Synthet Prod, Fac Ciencias Farmaceut Ribeirao Preto, BR-14049 Ribeirao Preto - Brazil

• Document type: Journal article
• Source: Applied and Environmental Microbiology; v. 80, n. 5, p. 1623-1632, MAR 2014.
• Web of Science Citations: 22

Abstract

The increasing tolerance to currently used fungicides in both clinical and agricultural areas is of great concern. The nonconventional light-based approach of antimicrobial photodynamic treatment (APDT) is a promising alternative to conventional fungicides. We evaluated the effects of APDT with four phenothiazinium derivatives (methylene blue {[}MB], new methylene blue N {[}NMBN], toluidine blue O {[}TBO], and the novel pentacyclic phenothiazinium photosensitizer {[}PS] S137) on conidia of three fungal species (Colletotrichum acutatum, Colletotrichum gloeosporioides, and Aspergillus nidulans). The efficacy of APDT with each PS was determined, initially, based on photosensitizer MICs. Additionally, the effects of APDT with two selected PSs (NMBN and S137) on survival of conidia were evaluated. The subcellular localization of the PS in C. acutatum conidia was determined. The effects of photodynamic treatments on leaves of the plant host Citrus sinensis were also investigated. APDT with S137 showed the lowest MIC. MICs for S137 were 5 mu M for the three fungal species when a fluence of 25 J cm(-2) was used. APDT with NMBN (50 mu M) and S137 (10 mu M) resulted in a reduction in the survival of the conidia of all species of approximately 5 logs with fluences of >= 15 J cm(-2). Washing of the conidia before light exposure did not prevent photodynamic inactivation. Both NMBN and S137 accumulated in cytoplasmic structures, such as lipid bodies, of C. acutatum conidia. No damage to orange tree leaves was observed after APDT. (AU)

• FAPESP's process: 12/15204-8 - Mechanistic study of the photodynamic inactivation of human and plant pathogenic fungi
• Grantee: Gilberto Úbida Leite Braga
• Support Opportunities: Regular Research Grants