Lívia Cordi

Phenolic compounds and total antioxidant potential of commercial wines

Abstract Growing evidence of the role of free radicals and antioxidants in health and ageing has focussed great interest on these compounds. The relationship between the total antioxidant potential and the phenolic content of commercial wines was evaluated. A close relationship between total phenolic content and total antioxidant potential for all wines was observed. Capillary zone electrophoresis showed that, in red wines, gallic acid was the highest of the phenolic acids and (+)-catechin and (−)-epicatechin were the next most abundant phenolics. Also, these compounds were strictly correlated with the total antioxidant potential of wines. Total antioxidant potential, by bleaching of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cations, using gallic acid as standard, could be a practical and simple measurement to evaluate the characteristics of different wines. Furthermore, capillary electrophoresis is a powerful and high-performing tool for evaluating principal antioxidant wine components.

Violacein: properties and biological activities.

The violet pigment violacein is an indole derivative, isolated mainly from bacteria of the genus Chromobacterium, which exhibits important antitumoural, antimicrobial and antiparasitary properties. Furthermore, the formulation of violacein in different polymeric carriers developed so far offers alternative approaches to overcoming physiological barriers and undesirable physicochemical properties in vivo, thus improving its efficacy.

Chitosan-solid lipid nanoparticles as carriers for topical delivery of tretinoin

Tretinoin (TRE) or all-trans retinoic acid is employed in the topical treatment of various skin diseases including acne and psoriasis. However, its use is strongly limited by side effects and high chemical instability. TRE encapsulation in nanostructured systems reduces these problems. Chitosan is a biopolymer that exhibits a number of interesting properties such as bioadhesion and antibacterial activity. The aim of this work was to prepare and characterize solid lipid nanoparticles (SLN) containing TRE, with and without addition of chitosan, to assess their in vitro cytotoxicity in keratinocytes and to evaluate their antibacterial activity against bacteria related to acne. SLN without (SLN-TRE) and with (SLN-chitosan-TRE) chitosan were prepared by hot high pressure homogenization. The hydrodynamic mean diameter and zeta potential were 162.7±1.4 nm and -31.9±2.0 mV for SLN-TRE, and 284.8±15.0 nm and 55.9±3.1 mV for SLN-chitosan-TRE. The SLN-chitosan-TRE exhibited high encapsulation efficiency, high physical stability in the tested period (one year), were not cytotoxic to keratinocytes and showed high antibacterial activity against P. acnes and S. aureus. Therefore chitosan-SLN can be good candidates to encapsulate TRE and to increase its therapeutic efficacy in the topical treatment of acne.

Advances in Chromobacterium violaceum and properties of violacein-Its main secondary metabolite: A review

Chromobacterium violaceum is important in the production of violacein, like other bacteria, such as Alteromonas, Janthinobacterium, Pseudoalteromonas, Duganella, Collimonas and Escherichia. Violacein is a versatile pigment, where it exhibits several biological activities, and every year, it shows increasing commercially interesting uses, especially for industrial applications in cosmetics, medicines and fabrics. This review on violacein focuses mainly on the last five years of research regarding this target compound and describes production and importance of quorum sensing in C. violaceum, mechanistic aspects of its biosynthesis, monitoring processes, genetic perspectives, pathogenic effects, antiparasitic and antimicrobial activities, immunomodulatory potential and uses, antitumor potential and industrial applications.

Biogenic silver nanoparticles associated with silver chloride nanoparticles (Ag@AgCl) produced by laccase from Trametes versicolor

In the present study, semi-purified laccase from Trametes versicolor was applied for the synthesis of silver nanoparticles, and the properties of the produced nanoparticles were characterized. All of the analyses of the spectra indicated silver nanoparticle formation. A complete characterization of the silver nanoparticles showed that a complex of silver nanoparticles and silver ions was produced, with the majority of the particles having a Ag2+ chemical structure. A hypothetical mechanistic scheme was proposed, suggesting that the main pathway that was used was the interaction of silver ions with the T1 site of laccase, producing silver nanoparticles with the concomitant inactivation of laccase activity and posterior complexing with silver ions.

Silver nanoparticles incorporated into nanostructured biopolymer membranes produced by electrospinning: a study of antimicrobial activity

This study examines the antimicrobial activity of silver nanoparticles incorporated into nanostructured membranes made of cellulose acetate (CA) and blends of chitosan/poly-(ethylene oxide, CTS/PEO) and prepared by electrospinning. The formation of chemically synthesized Ag nanoparticles (AgNPs) was monitored by UV-visible spectroscopy (UV-Vis) and characterized by transmission electron microscopy (TEM). The size distribution of the AgNPs was measured by dynamic light scattering (DLS), with an average size of approximately 20 nm. The presence of AgNPs on the surface of electrospun nanofibers was observed by field emission electron microscopy (FEG) and confirmed by TEM. The antimicrobial activity of AgNPs incorporated into nanostructured membranes made of CA and CTS/PEO electrospun nanofibers was evaluated in the presence of both Gram-positive bacteria, such as Staphylococcus aureus ATCC 29213 and Propionibacterium acnes ATCC 6919, and Gram-negative bacteria, such as Escherichia coli ATCC 25992 and Pseudomonas aeruginosa ATCC 17933. Microbiological results showed that the presence of AgNPs in CA and CTS/PEO nanostructured membranes has significant antimicrobial activity for the Gram-positive bacteria Escherichia coli and Propionibacterium acnes.

Identification of Microbiota for Activated Sludge Acclimated By Paper Mill Effluent Kraft E1 Bioremediation

Conventional systems treating paper effluents and cellulose are quite efficient in the reduction of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). In general, there is primary stage clarification followed by secondary treatment, usually with a biological system (activated sludge). However, for the efficient degradation of some organic compounds in this effluent, adapted microorganism accomplish the treatment which are necessary resulting in effluents with low concentrations of recalcitrant compounds. There are two methods for microorganism acclimation: genes cloning or natural. In this work, the original biomass collected from a domestic sewage treatment plant was adapted for application in the bioremediation of paper mill effluent, Kraft E 1 . So, the aim of this work was verifying the correlation of protozoa organisms and physical-chemical parameters during the acclimation period. The acclimation of the biomass was verified mainly through the reduction of COD. The monitoring of biomass growth was followed by measurement of suspended solids and volatile suspended solids. Parameters such as pH, Dissolved Oxygen (DO) and temperature were also monitored daily. The biological study was accomplished microscopically through the identification of protozoa that are considered bioindicators of the activated sludge system. The biomass acclimation period was 39 days. The stabilization of the system was observed through constant rates of total COD (56%). The suspended solids at the beginning of the acclimation phase were from 1580 mg L ¹ to 3580 mg L ¹, indicating biomass growth. A small acclimation period was necessary to observe the diversity of protozoa, mainly free ciliates, but nematodes were also present, indicating poor sludge sediment. At the end of the acclimation phase predominantly rotifers, but some free ciliates, ciliated communities and fixed ciliated were observed, indicating a good purification capacity of the system. Within the organisms amoeba was observed and this indicates good quality to the final effluent. Then, it is possible to correlate the biota presence with the high capacity of COD removal from the activated sludge system.

Bacterial remediation from effluent containing multi-walled carbon nanotubes

Multi-wall carbon nanotubes (MWCNT) were functionalized with functional groups containing oxygen, mainly carboxylic groups (-COOH), through reaction with a mixture of H2SO4/HNO3 (3:1 v/v). The oxidized multi-wall carbon nanotubes (MWCNTOOH) were used to prepare an effluent, 2 mg L−1 in a saline solution of NaCl (0.9%), to study of remediation of MWCNTOOH in aqueous suspension by utilization of Escherichia coli. The suspensions of E. coli (4.5 × 105 CFU mL−1 and 4.5 × 108 CFU mL−1) in test tubes with MWCNTOOH effluent caused the precipitation of a large amount of MWCNTOOH and supernatant clearing. The scanning electron microscopy (SEM) analysis of the precipitate and supernatant showed the adhesion and interlace of MWCNTOOH in bacteria surface. Although the precipitate consist of a large quantity of MWCNTOOH and bacteria, it was verified their presence in the supernatant. The spread plate technique showed that MWCNTOOH caused no cellular death of E. coli in the supernatant.