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Pullulan-Tween 40 emulsified films containing geraniol: production and characterization as potential food packaging materials

Publication . Simões, Alexandra; Ramos, Ana; Domingues, F.C.; Luís, Ângelo

Petroleum-based plastics have been widely used as packaging materials because of their low-cost availability and good mechanical properties. However, the use of plastics has become restricted as they are highly resistant to biodegradation, causing environmental problems. This work aimed to produce and characterize emulsified pullulan films incorporating geraniol for application as food packaging materials with potential to substitute the conventional plastics. When geraniol was incorporated in the films, they showed antimicrobial activity against Enterococcus faecalis ATCC 29212 (inhibition zone diameter = 15.19 ± 0.66 mm) and Pseudomonas aeruginosa ATCC 27853 (inhibition zone diameter = 10.99 ± 1.82 mm). Furthermore, scanning electron microscopy showed the inhibition of Enterococcus faecalis ATCC 29212 biofilms when they were directly formed on the emulsified pullulan films incorporating geraniol. The produced films also demonstrated high transparency (> 90%) and hydrophilic surfaces (water contact angle < 90°). This work demonstrated the viability of using geraniol to produce pullulan active films as new food packaging materials.

2024-03-27Journal article

Open access

Action of Curcumin on Glioblastoma Growth: A Systematic Review with Meta-Analysis of Animal Model Studies

Publication . Luís, Ângelo; Amaral, Leonor; Domingues, F.C.; Pereira, L.; Cascalheira, José

Gliomas are aggressive brain tumors with poor prognosis even after surgical removal and radio-chemotherapy, stressing the urgency to find alternative therapies. Several preclinical studies evaluating the anticancer effect of curcumin in animal models of glioma are reported, but a systematic review with meta-analysis of these studies, considering the different experimental conditions used, has not been made up to this date. A search in different databases (Pubmed, Web of Science, Scopus, and SciELO) following the PRISMA statement was conducted during November 2023 to systematically identify articles assessing the effect of curcumin in murine xenograft models of glioma and identified 15 articles, which were subdivided into 24 studies. Tumor volume before and after treatment with curcumin or vehicle was extracted and the efficacy of curcumin was evaluated by performing a random effects meta-analysis of the data. Publication bias and the impact of different experimental conditions on curcumin efficacy were assessed. Treatment with curcumin decreased tumor volume. Comparing curcumin with control groups, the overall weighted standardized difference in means was −2.079 (95% CI: −2.816 to −1.341; p-value < 0.001). The curcumin effect was observed for different animal models, types of glioma cells, administration routes, and curcumin formulations. Publication bias was identified but does not invalidate curcumin’s effectiveness. The findings suggest the potential therapeutic efficacy of curcumin against glioma.

2024-01-24Journal article

Open access

Comparative study of sample preparation procedures to determine the main compounds in ayahuasca beverages by QuEChERS and high‐performance liquid chromatography analysis

Publication . Gonçalves, Joana; Rosado, Tiago; Barroso, Mário; Restolho, José; Fernández, Nicolás; Luís, Ângelo; Gallardo, Eugenia; Duarte, Ana Paula

Introduction Ayahuasca is a psychoactive drink originally consumed by indigenous people of the Amazon. The lack of regulation of this drink leads to uncontrolled consumption, and it is often consumed in religious contexts. Objective The aim of this work is to compare three miniaturised extraction techniques for extracting the main ayahuasca compounds from beverages. Methodology Three sample pretreatment techniques were evaluated (dispersive liquid–liquid microextraction [DLLME], microextraction by packed sorbent [MEPS] and QuEChERS [Quick, Easy, Cheap, Effective, Rugged and Safe]) for the simultaneous extraction of N,N-dimethyltryptamine (DMT), tetrahydroharmine (THH), harmine, harmaline, harmol and harmalol from ayahuasca beverage samples. Then, the most promising technique (QuEChERS) was chosen to pre-concentrate the analytes, subsequently detected by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD). Results The procedure was optimised, with the final conditions being 500 μL of extractor solvent, 85 mg of primary secondary amine (PSA) and 4 s of vortexing. The analytical method was validated, showing to be linear between 0.16 and 10 μg/mL for β-carbolines and between 0.016 and 1 μg/mL for DMT, with coefficients of determination (R2) between 0.9968 and 0.9993. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 0.16 μg/mL for all compounds, except for DMT (0.016 μg/mL) and extraction efficiencies varied between 60.2% and 88.0%. Conclusion The analytical methodology proved to be accurate and precise, with good linearity, LODs and LLOQs. This method has been fully validated and successfully applied to ayahuasca beverage samples.

2024-04-13Journal article

Open access

Quorum sensing inhibition evaluation method: An experiment-based microbiology laboratory course

Publication . Luís, Ângelo Filipe Santos ; Domingues, Fernanda

Bacteria have developed a cell-to-cell communication system called quorum sensing (QS), allowing them to regulate group behavior and synchronize the expression of virulence factors, responsible for increasing their infection capacity and resistance to antimicrobials. Although the control of microbial infections through the inhibition of microbial growth has traditionally been the basis of antimicrobial chemotherapy, the emergence of antimicrobial resistance has led to the search for new microbial control strategies, namely through the inhibition of QS. Among the agents studied to inhibit this bacterial communication are essential oils (EO), which are considered very effective QS inhibitors. When searching for new QS inhibitor agents, it is essential to have a cheap and easy-to-perform method that allows the evaluation of this activity. Chromobacterium violaceum is a Gram-negative bacterium that has been widely used as a model organism in QS research laboratories because it produces the violet-colored pigment violacein, which is regulated by QS and is an easily observable and quantifiable characteristic marker. The objective of this work is to describe a method to evaluate the inhibition of the QS using Cymbopogon martinii EO as a potential inhibitory agent for violacein production by C. violaceum, which can be applied in the Microbiology laboratory course as a part of the programs of several science degrees. The proposed method is inexpensive and does not require specific equipment, enabling its easy implementation by the laboratory team and professors.

2024-12-12Journal article

Restricted access

Characterization and evaluation of Achillea erba-rotta subsp. moschata (Wulfen) I. Richardson and Achillea millefolium L. as potential ingredients for skin applications

Publication . Marengo, Arianna; Cagliero, Cecilia; Sgorbini, Barbara; Menzio, Giulia ; Fusani, Pietro; Duarte, Ana Paula; Luís, Ângelo Filipe Santos ; Fonseca, Lara R. S.; Feijó, Mariana Pombal ; Socorro, Sílvia; Bertea, Cinzia Margherita; Rubiolo, Patrizia

Ethnopharmacological relevance: Despite their different geographical distribution Achillea millefolium L. and Achillea erba-rotta subsp. moschata (Wulfen) I. Richardson are characterized by a consolidated traditional knowledge. Although this is not their first traditional use, they have also long been used as ingredients for skin healing and skin care. Aim of the study: The aim of this work was to characterize the two Achillea species from a chemical and biomolecular point of view in order to find a simple tool for their discrimination. At the same time, the biological activity of the extracts as inhibitors of the enzymes tyrosinase and elastase and as antimicrobial agents was evaluated. Materials and methods: The biomolecular analysis was performed on the DNA region trnL-F. The hydroalcholic (EtOH50 %) extracts were quali-quantitatively characterized by HPLC-PDA-MS/MS and tested for their inhibitory effect on the enzymes tyrosinase and elastase as well as for their antimicrobial activity. Cytotoxicity towards human fibroblasts was tested to evaluate their safety for potential applications. Results: Restriction Fragment Length Polymorphism (RFLP) analysis of the trnL-F DNA region was a useful tool for species discrimination. Both extracts are rich in polyphenols and showed moderate tyrosinase (26-5 %) and elastase (22-14 %) inhibitory activity at 17 μg/mL. They were also able to inhibit the growth of the bacteria and yeasts studied, generally exhibiting cytotoxicity to human fibroblasts at concentrations of 500 μg/mL or higher. Conclusions: The hydroalcoholic extracts from the aerial parts of A. millefolium and A. erba-rotta subsp. moschata can be considered good candidates for the cosmetic and health sectors, also supporting the traditional use of these species in the treatment of skin diseases.

2025-06-09Journal article

Restricted access