Effects of photodynamic inactivation mediated by Zn(II) porphyrin on promastigote and amastigote forms of Leishmania amazonensis
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2021
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CONGRESS OF THE INTERNATIONAL UNION FOR PURE APPLIED BIOPHYSICS, 20th; ANNUAL MEETING OF THE BRAZILIAN SOCIETY FOR BIOCHEMISTRY AND MOLECULAR BIOLOGY, 50th; CONGRESS OF BRAZILIAN BIOPHYSICS SOCIETY, 45th; BRAZILIAN SOCIETY ON NUCLEAR BIOSCIENCES CONGRESS, 13th
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Photodynamic inactivation (PDI) has been attracting attention as an innovative technology to treat topical diseases,
such as cutaneous leishmaniasis (CL) and infections caused by multidrug-resistant microorganisms. Zn(II) mesotetrakis(
N-n-hexylpyridinium-2-yl)porphyrin (ZnTnHex-2-PyP4+) is a lipophilic water-soluble Zn(II) porphyrin with
improved photophysical properties, high chemical stability, and cationic/amphiphilic character that can enhance its
interaction with cells. Thus, this study aimed to investigate the PDI effects mediated by ZnTnHex-2-PyP4+ on
Leishmania amazonensis. Confocal fluorescence microscopy was explored to study the interaction of ZnTnHex-2-
PyP4+ with promastigotes. The PDI action was analyzed by cell membrane integrity, mitochondrial membrane
potential (ΔΨm), and cell morphology. Promastigotes were incubated with ZnTnHex-2-PyP4+ for 5 min at 0.62 and
1.25 μM and irradiated by a LED (410 nm) for 1 or 3 min (2.3 and 3.4 J/cm2, respectively). PDI on amastigotes and
the cytotoxicity on macrophages were also analyzed (3.4 J/cm2). Fluorescence microscopy revealed that parasites
efficiently uptake ZnTnHex-2-PyP4+ and displayed a punctate labeling pattern along with the cytoplasm. An intense
ΔΨm depolarization was also observed, which in association with microscopy results, suggests that ZnTnHex-2-
PyP4+ may accumulate in the mitochondrion, or other well-defined structures close to it. Moreover, ZnTnHex-2-PyP4+
at concentration as low as 0.62 μM led to the immediate inactivation of >95% of promastigotes, regardless of the light
dose used. Loss of the fusiform shape and plasma membrane wrinkling were also observed. After a single treatment
session in amastigotes, PDI led to a reduction of 70% in the infection index. No considerable toxicity was observed
on mammalian cells. Thus, PDI of Leishmania parasites showed in vitro efficiency at a submicromolar concentration
of ZnTnHex-2-PyP4+, with short pre-incubation and irradiation times. The results encourage further studies in CL pre-clinical
assays and PDI of other microorganisms.
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SOUZA, TIAGO H. dos S.; ANDRADE, CAMILA; CABRAL, FERNANDA; SARMENTO-NETO, JOSE; REBOUCAS, JULIO; SANTOS, BEATE; RIBEIRO, MARTHA; FIGUEIREDO, REGINA; FONTES, ADRIANA. Effects of photodynamic inactivation mediated by Zn(II) porphyrin on promastigote and amastigote forms of Leishmania amazonensis. In: CONGRESS OF THE INTERNATIONAL UNION FOR PURE APPLIED BIOPHYSICS, 20th; ANNUAL MEETING OF THE BRAZILIAN SOCIETY FOR BIOCHEMISTRY AND MOLECULAR BIOLOGY, 50th; CONGRESS OF BRAZILIAN BIOPHYSICS SOCIETY, 45th; BRAZILIAN SOCIETY ON NUCLEAR BIOSCIENCES CONGRESS, 13th, October 4-8, 2021, São Paulo, SP. Abstract... São Paulo, SP: Sociedade Brasileira de Bioquímica e Biologia Molecular (SBBq), 2021. p. 250-250. Disponível em: http://repositorio.ipen.br/handle/123456789/32870. Acesso em: 20 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.