ABSTRACT
The antimicrobial photodynamic activity (aPDA) in fungal and bacterial strains of supramolecular adducts formed between the anionic photosensitizer (PS) Rose Bengal (RB2-) and aromatic polycations derived from (p-vinylbenzyl)triethylammonium chloride was evaluated. Stable supramolecular adducts with dissociation constants Kd ≈ 5 µM showed photosensitizing properties suitable for generating singlet oxygen (ΦΔ = 0.5 ± 0.1) with the added advantage of improving the photostability of the xanthenic dye. However, the aPDA of both free and supramolecular RB2- was highly dependent on the type of microorganism treated, indicating the importance of specific interactions between the different cell wall structures of the microbe and the PSs. Indeed, in the case of Gram-positive Staphylococcus aureus, the aPDA of molecular and supramolecular PSs was highly effective. Instead, in the case of Gram-negative Escherichia coli, only the RB2-:polycation adducts showed aPDA, while RB2- alone was inefficient, but in the case of Candida tropicalis, the opposite behavior was observed. Therefore, the present results indicate the potential of supramolecular chemistry to obtain aPDA à la carte depending on the target microbe and the PS properties.
Subject(s)
Anti-Infective Agents , Photochemotherapy , Anti-Infective Agents/pharmacology , Photochemotherapy/methods , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacology , Polyelectrolytes , Rose Bengal/chemistry , Rose Bengal/pharmacology , Singlet OxygenABSTRACT
Maize is one the most important staple foods in the world. However, numerous pests, such as fungal pathogens, e.g., Fusarium verticillioides, and insects, such as Sitophlilus zeamais, attack maize grains during storage. Many F. verticillioides strains produce fumonisins, one of the most important mycotoxin that causes toxic effects on human and animal health. This situation is aggravated by the insect fungal vector, Sitophlilus zeamais, which contributes to the dispersal of fungal spores, and through feeding damage, provide entry points for fungal infections. The aim of this study was to evaluate in vitro bioassays, the antifungal activity on F. verticillioides M3125 and repellent effects against S. zeamais of ketone terpenes. In addition, we performed Quantitative structure-activity relationship (Q-SAR) studies between physico-chemical properties of ketone terpenes and the antifungal effect. Thymoquinone was the most active compound against F. verticillioides (Minimum Inhibitory Concentration, MIC: 0.87) affecting the lag phase and the growth rate showing a total inhibition of growth at concentration higher than 2 mM (p < 0.05). The Q-SAR model revealed that the antifungal activity of ketone compounds is related to the electronic descriptor, Pi energy. Thymoquinone showed a strong repellent effect (-77.8 ± 8.5, p < 0.001) against S. zeamais. These findings make an important contribution to the search for new compounds to control two stored pests of maize.
ABSTRACT
The chemical composition of the leaf oils of five Juniperus species (Juniperus sabina L., Juniperus communis Lam., Juniperus scopulorum Sarg., Juniperus virginiana L., Juniperus chinensis L., Cupressaceae) was determined by co-chromatography with authentic samples, GC-MS and Kováts retention indices. Sabinene was the most abundant component in the oils of Juniperus from western Patagonia Argentina. However, limonene and germacrene B constituted 25.1 percent and 11.5 percent of the oil of J. sabina. J. virginiana showed high concentration of alpha-humulene and limonene (31.4 and 15.9 percent respectively), while isobornyl acetate and germacrene B were also the main compounds of J. chinensis. Essential oils extracted of Juniperus were evaluated in vitro for their efficacy against Fusarium verticillioides, Aspergillus flavus, Aspergillus parasiticus, Candida albicans and Rhodotorula infection. Candida albicans was not inhibited for the essential oils of Juniperus. However, F. verticillioides, A. flavus, A. parasiticus and Rhodotorula were inhibited for these oils.
La composición de los aceites esenciales de la hoja de cinco especies de Juniperus (Juniperus sabina L., Juniperus communis Lam., Juniperus scopulorum Sarg., Juniperus virginiana L., Juniperus chinensis L., Cupressaceae), se determinó mediante una co-cromatografía con muestras auténticas de dos columnas de diferente polaridad, CG-EM y los índices de retención de Kovats. El sabineno fue el componente más abundante en los aceites de Juniperus del oeste de la Patagonia Argentina. Sin embargo, el limoneno y el germacreno B son otros componentes importantes del aceite esencial de J. sabina con el 25,1 por ciento y 11,5 por ciento respectivamente. En J. virginiana el alfa-humuleno y el limoneno (con el 31,4 por ciento y 15.9 por ciento respectivamente) mostraron ser también importantes, mientras que el acetato de isobornilo y el germacreno B fueron también los principales componentes de la J. chinensis. Los aceites esenciales extraídos de Juniperus se evaluaron in vitro para determinar su eficacia contra Fusarium verticillioides, Aspergillus flavus, Aspergillus parasiticus, Candida albicans y Rhodotorula. Candida albicans no se inhibió por la acción de los aceites esenciales de Juniperus. Sin embargo, F. verticillioides, A. flavus, A. parasiticus y Rhodotorula fueron inhibidos.
