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- Characterization and evaluation of Achillea erba-rotta subsp. moschata (Wulfen) I. Richardson and Achillea millefolium L. as potential ingredients for skin applicationsPublication . 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, PatriziaEthnopharmacological 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.
- Insect-based chitin and chitosan from whole body sources and rearing by-products: extraction, physicochemical, structural and bioactivity characterisationPublication . Navarro, Pedro; Ribeiro, José Carlos Reis ; Luís, Ângelo Filipe Santos ; Domingues, Fernanda; Anjos, Ofélia; Cunha, LuisFractionation of edible insects and their rearing by-products can lead to expanded industrial applications and extraction of value-added products. The main goal of this study was to extract chitin and synthesise chitosan from three different insect sources – Tenebrio molitor larvae, adult Acheta domesticus and A. domesticus rearing by-products (legs and wings). Furthermore, the physicochemical, structural, and bioactive properties of insectderived chitin and chitosan were characterised and compared to commercial crustacean-based samples. Chitin was isolated from defatted sources through chemical hydrolysis followed by decolourisation and was deacetylated with a strong alkaline solution to synthesise chitosan. Notably, A. domesticus rearing by-products yielded the highest chitin and chitosan content. Chitin and chitosan derived from insects exhibited physicochemical and structural characteristics consistent with the α-polymorphic form, similar to the commercial samples. Differences were found in surface morphology, with insect-derived samples presenting large and irregular flakes and porosity, while the crustacean-derived samples presented irregularly arranged fibres and a more regular and smoother surface. As for antioxidant activity, although all chitosan samples demonstrated poor DPPH radical scavenging activity, this study showed for the first time that insect-derived chitosan presents lipid peroxidation inhibition ability. All chitosan samples presented antimicrobial activity against different pathogenic bacteria, with K. pneumoniae being the most susceptible strain. Nevertheless, there is potential for enhancement of the biological properties through modifications on the molecular weight and deacetylation degree. This research introduces the potential of cricketrearing by-products as sustainable sources of chitosan with functional bioactive properties.
- Quorum sensing inhibition evaluation method: An experiment-based microbiology laboratory coursePublication . Luís, Ângelo Filipe Santos ; Domingues, FernandaBacteria 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.