Photodynamic inactivation of conidia of the fungi Aspergillus nidulans, Colletotrichum acutatum and Colletotrichum gloeosporioides with phenothiazinium and coumarinium photosensitizers

Author(s)

Henrique Dantas de Menezes

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2012-08-29

Examining board members

Gilberto Ubida Leite Braga; Marcia Regina von Zeska Kress; Antonio Claudio Tedesco

• Advisor: Gilberto Ubida Leite Braga

Abstract

Antifungal photodynamic treatment (APDT) is a promising method that combines a nontoxic photosensitizer (PS), oxygen and visible light to cause selective killing of microbial cells. The development of APDT depends on identifying effective PS for the different pathogenic species. In the present study, the in vitro susceptibilities of Colletotrichum acutatum, C. gloeosporioides (both are phytophatogenic species) and Aspergillus nidulans conidia to APDT with four phenothiazinium PS [methylene blue (MB), new methylene blue N (NMBN), toluidine blue O (TBO) and the novel pentacicyclic phenothiazinium S137 (S137)] in combination with red light were investigated. We also evaluated the susceptibilities of C. acutatum and A. nidulans conidia to APDT with the psoralen 8-methoxypsoralen (8-MOP), with two coumarins (7-methoxicoumarin and 5,7-dimethoxycoumarin) and one furanocoumarin (isopimpinelin) in combination with solar radiation. Both the coumarins and the furanocoumarin were extracted, in the present work, from Tahiti lemon (Citrus latifolia). The effects of the treatments with all the PS on Citrus sinensis leaves were also evaluated. NMBN and S137 were the more effective phenothiazinium PS. APDT with NMBN (50 ?M) and S137 (10 ?M) and light dose of 25 J cm-2 resulted in a reduction of approximately 5 logs in the survival of the conidia of the three species. APDT with 8-MOP and with the coumarins resulted in a reduction of approximately 4 logs in the survival of C. acutatum and A. nidulans conidia. APDT with the furanocumarin was less effective and resulted in the reduction of approximately 2 logs for C. acutatum and 3 logs for A. nidulans. No damages to the leaves were observed when the PS were spotted on the adaxial surface of the leaves and the plants were exposed to solar radiation. Histological studies showed that the phenothiazinium PS did not cross the leave cuticle. (AU)

• FAPESP's process: 10/01712-6 - Evaluation of the fungicidal and fungistatic activities of phenothiazines and cumarins photosensitizers in Aspergillus nidulans, Colletotrichum gloesporioides, Colletotrichum acutatum and Scherotinia scherotiorum.
• Grantee: Henrique Dantas de Menezes
• Support Opportunities: Scholarships in Brazil - Master