Chitosan is a cationic natural polysaccharide, which has emerged as an increasingly interesting biomaterialover the past few years. It constitutes a novel perspective in drug delivery systems and nanocarriers’ formulations due to its beneficial properties, including biocompatibility, biodegradability and low toxicity. The potentiality of chemical or enzymatic modifications of the biopolymer, as well as its complementary use with other polymers, further attract the scientific community, offering improved and combined properties in the final materials. As a result, chitosan has been extensively used as a matrix for the encapsulation of several valuable compounds. In this review article, the advantageous character of chitosan as a matrix for nanosystemsis presented, focusing on the encapsulation of natural products. A five-year literature review is attempted covering the use of chitosan and modified chitosan as matrices and coatings for the encapsulation of natural extracts, essential oils or pure naturally occurring bioactive compounds are discussed.

The encapsulation of clove essential oil (CEO) in hydroxypropyl-β-cyclodextrin (HP-β-CD) and the subsequent incorporation of the inclusion complex in an elastic chitosan film in order to achieve a controlled release profile of the volatile CEO are herein presented. Freshly distilled CEO was found to contain eugenol in concentrations higher than 70%. The kneading method was implemented for the preparation of a CEO-HP-β-CD inclusion complex, resulting in a 50% inclusion efficiency of the essential oil in particles sized 214.40 nm with ζ-potential −27.5 mV. Free CEO and CEO-HP-β-CD inclusion complex were tested for their ability to scavenge the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical, and it was found that the CEO-HP-β-CD complex presented enhanced antioxidant activity (88%) compared to the free CEO (71%). Choline chloride-containing chitosan (CS) films were prepared, incorporating either the pure CEO or the CEO-HP-β-CD inclusion complex, and their mechanical properties were determined. The study of the release profile in different pH values demonstrated the capacity of the CS-HP-β-CD system to provide sustained release of CEO, noting its potential use in food processing as smart packaging.

In this work, the preparation of inclusion complexes, (ICs) using magnesium phthalocyanine (MgPc) and various cyclodextrins (β-CD, γ-CD, HP-β-CD, Me-β-CD), using the kneading method is presented. Dynamic light scattering (DLS) indicated that the particles in dispersion possessed mean size values between 564 to 748 nm. The structural characterization of the ICs by infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy provides evidence of the formation of the ICs. The release study of the MgPc from the different complexes was conducted at pH 7.4 and 37 °C, and indicated that a rapid release (“burst effect”) of ~70% of the phthalocyanine occurred in the first 20 min. The kinetic model that best describes the release profile is the Korsmeyer–Peppas. The photodynamic therapy studies against the squamous carcinoma A431 cell line indicated a potent photosensitizing activity of MgPc (33% cell viability after irradiation for 3 min with 18 mW/cm²), while the ICs also presented significant activity. Among the different ICs, the γ-CD-MgPc IC exhibited the highest photokilling capacity under the same conditions (cell viability 26%). Finally, intracellular localization studies indicated the enhanced cellular uptake of MgPc after incubation of the cells with the γ-CD-MgPc complex for 4 h compared to MgPc in its free form.

The aim of the present study was the encapsulation of cedar (Juniperus phoenicea) essential oil (CEO) of Greek origin in β-cyclodextrin (β-CD) through the formation of inclusion complexes (ICs) using the co-precipitation method with different β-CD-to-CEO weight ratios (90:10, 85:15, 80:20, 70:30 (w/w)). The encapsulation of CEO in β-CD through host–guest interactions was confirmed by Nuclear Magnetic Resonance (NMR) spectroscopy, FT-IR spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The obtained ICs exhibited nanoscale size (315.9 nm to 769.6 nm),Polydispersity Index from 0.326 to 0.604 and satisfactory stability in suspension (−37.0 mV to −17.0 mV). The process yield was satisfactory, ranging between 65% and 78%, while the inclusion efficiency ranged from 10% to 27%. The in vitro release study conducted for the IC with the optimal characteristics (β-CD:CEO 80:20 (w/w)) exhibited a sustained release profile, with an initial burst effect in the first 5 h. The release profile could be well expressed by the Higuchi equation: Q = 18.893 t^1/2 + 9.5919, R² = 0.8491. The cedar EO presented significant acetylcholinesterase inhibition (IC₅₀ 37 μg/mL), which was prolonged by its encapsulation into the β-CD cavity.

Sunflower press cake (SPC), a by-product of the edible oil industry, represents a promising source of plant-based protein. This study aimed to investigate and optimize protein recovery from SPC using conventional (CE) and advanced extraction techniques, including Ultrasound and Microwave-Assisted Extraction (UMAE), Pressurized Liquid Extraction (PLE) and Enzyme-Assisted Extraction (EAE). The protein content both in extracts and in the precipitated mass was measured through Lowry assay, while the amino acid profile of the extracted proteins under optimal conditions was analyzed via High-Performance Liquid Chromatography (HPLC). Extraction parameters were optimized using response surface methodology (RSM) for each method. Among the novel methods studied, UMAE and PLE demonstrated superior efficiency over CE, yielding higher protein recovery in significantly shorter extraction times. Optimal UMAE conditions (10 min, 0.03 g/mL, 450 W microwave power, and 500 W ultrasound power) yielded a precipitation yield (PY) of 21.2%, protein recovery in extract (PR_E) of 79.9%, and protein recovery in precipitated mass (PR_P) of 66.3%, with a protein content (PC_P) of 902.60 mg albumin eq./g. Similarly, optimal PLE conditions (6 min, 0.03 g/mL, and 50 °C) resulted in PY, PR_E, and PR_P of 17.7, 68.9, and 47.4%, respectively, with a PC_P of 932.45 mg albumin eq./g. EAE using Aspergillus saitoi protease was comparatively less effective. The amino acid profiling confirmed SPC as a valuable protein source, with glutamic acid, arginine, and aspartic acid being the most abundant. These results highlight the potential of UMAE and PLE as efficient strategies for valorizing edible oil industry by-products into high-quality protein ingredients for food and biotechnological applications.

The present study focuses on the synthesis of the natural product 4-methyl-umbelliferone (4-MU, hymecromone), the preparation, characterization, and biological activity evaluation of 4-MU inclusion complexes with β-cyclodextrin (β-CD), as well as their incorporation into pharmaceutical tablets. The inclusion complexes (ICs) were characterized using DLS, SEM, TGA as well as FT-IR, UV-vis, and NMR spectroscopies. The release profile of 4-MU from the β-CD-4-MU ICs was studied in three different pH: 1.2 (aqueous hydrochloric acid), 7.4, and 6.8 (phosphate-buffered solutions), to simulate the stomach, physiological, and intestine pH, respectively. The ICs were incorporated in pharmaceutical tablets which were prepared by direct compression and were characterized for their mechanical properties. The optimal composition of 4-MU as the active pharmaceutical ingredient (API) and excipients was determined using design of experiment (DoE), and the dissolution studies were performed at pH 1.2 at 37 ± 0.5 °C. The sustained release profile of the pharmaceutical tablets showed a delayed burst release effect at 20 min (20% drug release) compared to that of the ICs at the same time interval (70%). The results indicated that the kinetic model describing the release profile of 4-MU from the ICs and tablets is the Higuchi model, while the release mechanism is swelling and diffusion, as was indicated by the Korsmeyer–Peppas kinetic model. The optimization analysis revealed that the optimum composition contains x₁ = 150.95 mg of β-CD-4-MU ICs, x₂ = 82.65 mg of microcrystalline cellulose, and x₃ = 12.40 mg of calcium phosphate.