Browsing by Author "Giordano, Ady"

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    Eucryphia cordifolia extracts: Phytochemical screening, antibacterial and antioxidant activities
    (2021) Viteri, Rafael; Giordano, Ady; Montenegro, Gloria; Zacconi, Flavia C. M.
    Eucryphia cordifolia is a native and dominant species from the Temperate Forest in the southern region of Chile. It is a crucial melliferous species producing unifloral honey with outstanding antibacterial properties with great commercial value at international markets. A phytochemical screening was developed by colorimetric and gravimetric methods. Antioxidant activities were assessed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and ferric ion reducing antioxidant power (FRAP) method. The minimum bactericidal concentration (MBC) was the method used to determine the antibacterial activity. The results revealed the highest antioxidant activity for the methanolic extracts of branches (IC50 35.7 mu g/mL for DPPH, IC50 11.0 mu g/mL for ABTS, and 4.6 mM FeSO4 center dot 7H(2)O/g in FRAP), attributed to its high content of total phenols (332.8 mg GAE/g). The quantification of the MBC led to values in the range of 0.78-12.5 mg/mL for S. aureus and S. pyogenes, and 6.25-50 mg/mL for E. coli and P. aeruginosa, respectively. The presented work provides valuable first in vitro evidence regarding the potential application of E. cordifolia extracts as antioxidants and antibacterial agents in the nutraceutical and phytopharmaceutical industry.
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    Influence of chitin nanofibers and gallic acid on physical-chemical and biological performances of chitosan-based films
    (2024) Cabrera-Barjas, Gustavo; Albornoz, Karin; Belchi, Maria Dolores Lopez; Giordano, Ady; Bravo-Arrepol, Gaston; Moya-Elizondo, Ernesto; San Martin, Juan; Valdes, Oscar; Nesic, Aleksandra
    In this work, chitosan films loaded with gallic acid and different content of chitin nanofibers were prepared and subjected to different characterization techniques. The results showed that the inclusion of gallic acid to chitosan films caused moderate decrease in water vapor permeability (by 29 %) and increased tensile strength of films (by 169 %) in comparison to the neat chitosan films. Furthermore, it was found that the addition of chitin nanofibers up to 30 % into chitosan/gallic acid films additionally improved tensile strength (by 474 %) and reduced plasticity of films (by 171 %), when compared to the chitosan/gallic acid films. Increased concentration of chitin nanofibers in films reduced the overall water vapor permeability of films by 51 %. In addition, gallic acid and chitin nanofibers had synergic effect on high chitosan film's antioxidant and antifungal activity toward Botrytis cinerea (both above 95 %). Finally, chitosan/gallic acid/chitin nanofibers films reduced decay incidence of strawberries, increased total soluble solid content, and promoted high production of some polyphenols during cold storage, in comparison to the control chitosan films and uncoated strawberry samples. Hence, these results suggest that chitosan/gallic acid/chitin nanofibers can present eco-sustainable approach for preservation of strawberries, giving them additional nutritional value.