Fluorinated meso-tetraaryl Pt(II)-porphyrins: structure, photophysical, electrochemical, and phosphorescent oxygen sensing studies
NEW JOURNAL OF CHEMISTRY
Authors: Arunkumar, Chellaiah; Kooriyaden, Fasalu Rahman; Zhang, Xiaochen; Sujatha, Subramaniam; Zhao, Jianzhang
Abstract
Fluorinated Pt(II)-porphyrins (F1-F8) were synthesized, characterized; photophysical and electrochemical studies were conducted. The electronic absorption spectra of the complexes exhibited an intense Soret band (392-402 nm) and two hypsochromically shifted visible (Q) bands (508-510 and 538-541 nm). They also exhibited two emission bands (701-721 nm and 651-658 nm), corresponding to the T -> S-0 transition. The cyclic voltammetric studies of the porphyrins revealed the order of electron deficiency is as follows; F2 > F7 approximate to F8 > F5 > F4 > F3. The crystals of F3, F4, and F7 were structurally characterized and the crystal packing was mainly controlled by F center dot center dot center dot H, O center dot center dot center dot H, O center dot center dot center dot O, C center dot center dot center dot H close contacts. The oxygen sensing studies of the synthesized Pt(II)-porphyrins demonstrate that the highest sensitivity was observed for F8 compared to other complexes. The modified Stern-Volmer or two-site model provides the highest weighted quenching constant (K-SV) of 0.068 Torr(-1) for F8, which is twofold of the reference compound F1.
Characterization and antifungal activity of a plant peptide expressed in the interaction between Capsicum annuum fruits and the anthracnose fungus
BIOSCIENCE REPORTS
Authors: Maracahipes, Alan Chrisleyr; Taveira, Gabriel Bonan; Sousa-Machado, Lorran Yves; Tavares Machado, Olga Lima; Rodrigues, Rosana; Carvalho, Andre Oliveira; Gomes, Valdirene Moreira
Abstract
Plant defensins are low molecular weight basic peptides ranging from 5 to 7 kDa, with capacity of inhibiting various pathogens, including fungi. They are present in different tissues of plants, including floral parts and fruits of Capsicum sp. The IIF48 extract, present in immature fruits of Capsicum annuum inoculated with C. gloeosporioides, was able to inhibit up to 100% growth 'in vitro' of the fungus Colletotrichum gloeosporioides. The main objective of this work was the purification and antifungal activity characterization of a defense-related plant defensin-like isolated of the IIF48 immature fruits extract. The IIF48 extract was subjected to HPLC purification and 13 fractions were obtained, followed by a tricine gel electrophoresis to obtain the protein profile. The different fractions were submitted to a growth inhibition assay against C. gloeosporioides fungus. Fraction 7 (F7) was the most active causing 73% inhibition. Because of the higher F7 activity and the presence of only a peptide of approximately 5 kDa this fraction was subjected to N-terminal sequencing. F7 fraction was carried out plasma membrane permeabilization assays, induction of intracellular ROS production analysis and investigated mitochondrial membrane potential. The F7 fraction showed significant inhibitory activity on the tested fungus, besides promoting membrane permeabilization, induction of endogenous ROS production in Colletotrichum cells and impairing mitochondrial functionality. The first 18 amino acid sequence of the F7 fraction peptide suggests homology to plant-like defensin and was named IIFF7Ca. We also concluded that IIFF7Ca peptide has an effective antimicrobial action against the fungus C. gloeosporioides.