Johnnatan Duarte de Freitas

Bio: Johnnatan Duarte de Freitas is an academic researcher from Federal University of Alagoas. The author has contributed to research in topics: Chemistry & Propolis. The author has an hindex of 5, co-authored 27 publications receiving 68 citations.

Modified release microcapsules loaded with red propolis extract obtained by spray-dryer technique

Abstract: Biopolymers are currently one of the most interesting materials applied in the medical and pharmaceutical fields. The objective of this work was to develop the modified release microcapsules loaded with red propolis extract (RPE) using a spray-dryer technique. In addition, this manuscript characterizes this red propolis microcapsules using phytochemicals, thermal, physicochemical and dissolution test. The RPE was incorporated in the biopolymer solution, and then submitted to spray-dryer technique to obtain modified release microcapsules loaded with RPE; then, they were submitted to different physicochemical characterization technique through SEM analysis, FTIR, thermal analysis (TG and DSC), dissolution test and phytochemical assays. The red propolis microcapsules presented spherical morphology with particle size between 2.5 and 35 μm, when analyzed by SEM technique. The thermal analysis showed that the coating material decreases the thermo-oxidative degradation of the RPE in the microcapsules and according to the calorimetric curves (DSC) and infrared spectra the microencapsulation of the red propolis extract was obtained. The quantification of the bioactive compounds showed high amounts of total phenols (98.3%) and total flavonoids (92.9%) contents, and it was possible determinate the encapsulation degree in microcapsules. The red propolis microcapsules present high antioxidant capacity (90.6%) in sequestering the free radical DPPH˙. The dissolution tests demonstrate slow flavonoids release (between 70 and 100%) from the microcapsules and have proven to be modified release microcapsules during 12 h experiments. The red propolis microcapsules can be applied in pharmaceutical and nutraceutical areas due to modified release property, antioxidant and antibacterial activities.

Caseinates loaded with Brazilian red propolis extract: preparation, protein-flavonoids interaction, antioxidant and antibacterial activities

Abstract: This study aimed to evaluate the physical–chemical properties (particle size, zeta potential, encapsulation, and thermal stability), antioxidant properties, antibacterial properties and casein-flavonoid interaction studies of soluble complexes, called caseinates of red propolis. The caseinates of red propolis were successfully prepared using the spray-dryer technique, which presented two populations of nanometre and micrometre particles, and were able to encapsulate flavonoids and isoflavonoids from the red propolis extract as a soluble complex. SEM analysis demonstrated casein nanoparticles and fat globules combined with lipophilic compounds (terpenes) from red propolis extract. FTIR analysis proved the encapsulation of flavonoids into caseinates. The thermogravimetric assays demonstrated thermal stability of red propolis caseinates and DTA analysis observed the denaturation during the coagulation temperature. The fluorescence, antioxidant, Folin–Ciocalteu method and chromatographic assays have shown that flavonoids bind to the amino acid residues present in the casein protein matrix, demonstrating a reversible interaction between flavonoids and casein amino acids. Dissolution studies prove the formation of a casein-flavonoids soluble complex and can bring benefits and increase the process of absorption of flavonoids by biological membranes. Despite the interaction of flavonoids with casein amino acids, caseinates of red propolis demonstrated antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The caseinates of red propolis can be easily incorporated in foods such as cakes, pies, dairy and cocoa such as foods bio-preservatives. The caseinates of red propolis can be manufactured by the pharmaceutical and nutraceuticals industries as intermediary bioproduct in the powder form for supplements, capsules and oral emulsion systems for beverages as yogurts.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Abstract: During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.