Compounds, Volume 3, Issue 4 (December 2023) – 5 articles

Introduction: The antibiofilm activity of silver nanoparticles has been extensively investigated in common bacteria. Metallo-β-lactamase-producing Gram-negative bacteria are hard-to-treat microorganisms with few therapeutic options, and silver nanoparticles were not evaluated on the biofilm of these bacteria. Objectives: The aim of this study was to evaluate the antibiofilm activity of a bone scaffold impregnated with silver nanoparticles in NDM-producing Gram-negative bacilli. Methods: Bone scaffolds from bovine femur were used for the tests and impregnated with silver nanoparticles (50 nm) by physical adsorption. Silver nitrate minimal inhibitory and bactericidal concentrations (MIC and MBC) were performed on NDM-producing Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Disc diffusion tests for silver nanoparticles’ susceptibility and the quantification of biofilm production on plate and bone with sessile cell count were performed. Results: The MIC results demonstrated that silver nitrate had an antimicrobial effect on all microorganisms, inactivating the growth of isolates from a concentration of 8 µg/mL. MBC results showed that E. coli 16.211 was the only isolate to present MIC that were different from MBC, with a value of 16 µg/mL. Conclusion: Bone scaffolds impregnated with silver nanoparticles can significantly reduce the biofilm of multidrug-resistant bacteria. This is a strategical material that can be used as bone implant in different clinical conditions. Full article

Several methods have been used to determine the volatile organic compounds emitted by Ophrys orchids. The use of different methods results in incomparable data. Solid-phase microextraction (SPME) has not been used extensively on Ophrys orchids. The main components found in the SPME analysis of the scent in Ophrys orchids were as follows: O. apifera: benzyl benzoate and α-copaene; O. crabronifera subsp. biscutella: pentadecane, heptadecane, and nonadecane; O. bertolonii subsp. bertolonii: pentadecane and heptadecane; O. passionis subsp. garganica: i-propyl palmitate and heptadecane; O. holosericea subsp. apulica: α-copaene, pentadecane, and heptadecane; O. lacaitae: α-copaene, pentadecane, and heptadecane; O. bombyliflora: cyclosativene, pentadecane, and ethyl dodecanoate; O. insectifera: 8-heptadecene and pentadecane; O. lutea: heptadecane and docosane; O. tenthredinifera subsp. neglecta: α-copaene, caryophyllene, and i-propyl palmitate. Full article

As biological material, wood is distinctly affected by to various environmental influences during use. Reductions in durability can come from ultraviolet (UV) radiation, insects, fungi, and microorganisms in both exterior and interior applications. Wood can be easily protected from living organisms via the control of moisture content; however, UV radiation is not so easily managed. Wood components subject to this degradation are damaged and decomposed at a molecular level leading to deterioration of surface quality, especially in visible application areas. A potential remedy to this is using the UV-stabilizing properties of zinc oxide nanoparticles. Zinc oxide nano-dispersions based on propylene glycol (PG) were introduced into the microscopic structure of fir (Abies alba) and beech (Fagus sylvatica) wood by whole-cell impregnation to overcome problems associated with surface coatings. In this work the material uptake of ZnO nano-dispersions in concentrations of 1%, 2%, and 3% w/v were investigated and their effect on the stability of the optical appearance to UV exposure in short-term weathering were evaluated. Untreated reference samples showed significant photo-yellowing. A 1% w/v ZnO dispersion significantly increased the UV stability of treated surfaces. It was found that the uptake of the nano-dispersions was independent of the proportion of ZnO, and that the impregnating agents penetrated fir wood (about 200%) stronger than beech wood (about 70%). Already, a 2% w/v ZnO nano-dispersion led to a saturation of ZnO in the cell structure of the treated wood, for fir as well as beech, and no further ZnO uptake was achieved with 3% w/v nano-dispersions. Scanning electron microscopy shows an agglomeration of ZnO-NP in the cellular pathways impacting penetration, reducing leachability at higher concentrations. Full article

Betel leaves are widely used as herbal medicine in Asia due to their antimicrobial properties. These properties have been attributed to the phenolic compound eugenol and its derivative, hydroxychavicol. Hydroxychavicol has also been shown to inhibit cancer cell proliferation. The main objective of this study was to investigate which structural components of hydroxychavicol are responsible for the antiproliferative property of this compound. Jurkat-E6 cells (JE6) were treated with increasing concentrations (5, 15, and 45 µM) of hydroxychavicol and structural variants of it for 48 h. The results of this study demonstrate that the catechol structure in hydroxychavicol is the structural component that exhibits the highest antiproliferative effect. More specifically, the data show that the six-carbon ring must be aromatic with the two hydroxyl groups attached in an ortho position. Furthermore, this study establishes that the oxygen in the hydroxyl groups has a vital role in the antiproliferative properties of catechol and hydroxychavicol. Full article

Crithmum maritimum, commonly known as rock samphire, is a plant species with a long history of use in traditional medicine and cuisine, especially in the Mediterranean region. Despite its potential therapeutic and commercial applications, the number of studies on this plant species are scanty and sparse. The aim of this study was to optimize the solid–liquid extraction of bioactive compounds from C. maritimum leaves through response surface methodology (RSM) and to comprehensively analyze the resulting extracts. Experimental parameters including liquid-to-solid ratio, solvent composition, extraction time, and temperature were investigated. The results of the RSM revealed a notable variation in the values of the extracted bioactive compounds (polyphenols, carotenoids, and chlorophylls), indicating the selection of optimum extraction conditions. Partial least squares analysis showed that solvent composition and extraction temperature had a significant impact on the extraction of the bioactive compounds. Consequently, these conditions required a 145-min extraction at 80 °C, using a solvent consisting of 45% v/v ethanol, and a 40:1 liquid-to-solid ratio. The optimum extract was analyzed using a range of assays to determine their polyphenol content, their content in chlorophylls and carotenoids, and their antioxidant potential via FRAP and DPPH assays. The total polyphenol content was measured at 15.11 mg gallic acid equivalents (GAE)/g. High-performance liquid chromatography–diode array detector (HPLC-DAD) analysis revealed that chlorogenic acid was the most prevalent polyphenol (9.35 mg/g) in C. maritimum leaves. Kaempferol 3-glycoside (1.81 mg/g), naringin (1.24 mg/g), and hesperidin (0.79 mg/g) were some polyphenolic compounds that had also been quantified. Total carotenoids (0.32 μg/g) and total chlorophylls (0.62 μg/g) were also measured. Multivariate correlation analysis and principal component analysis revealed that total carotenoids and chlorophylls had a strong negative correlation with total polyphenol content. The reducing power (FRAP assay) of the optimized extract had a value of 85.52 μmol ascorbic acid equivalents (AAE)/g, whereas the antiradical activity (DPPH assay) was measured at 25.57 μmol AAE/g. Given the high quantity of polyphenols, these results highlight the potential use of C. maritimum as a source of bioactive compounds in the food and pharmaceutical industries. Full article