Development of green encapsulation processes of bioactive compounds in modified release carriers

The subject of the present doctoral dissertation was the development and optimization of green processes for the encapsulation of bioactive compounds in natural or synthetic biodegradable carriers. The micro/nanosystems that were prepared were used as carriers for bioactive molecules which are suitable for applications in the pharmaceutical, food, and cosmetic industries. An innovative aspect of this research was the exploration of the possibility of using biodegradable green solvents (Natural Deep Eutectic Solvents, NADESs) at various stages of the process (e.g., as solvents, as gelling agents, as reducing agents, as cross-linking agents, etc.). The targeted selection of the components of the green solvents imparts desired properties depending on the final application, resulting in a multifunctional micro/nanosystem with added value. Each encapsulation process was optimized through Experimental Design (Design of Experiments, DOE), and the release kinetics of the bioactive substances from the nanocarriers was also studied. Finally, the innovative micro/nanosystems were evaluated for their bioactivity, while their incorporation into pharmaceutical forms, functional foods, or cosmetic products was explored.Αντικείμενο της παρούσας διδακτορικής διατριβής αποτέλεσε η ανάπτυξη και η βελτιστοποίηση πράσινων διεργασιών για τον εγκλωβισμό βιοδραστικών ενώσεων σε φυσικούς ή συνθετικούς βιοδιασπώμενους φορείς. Τα μικρο/νανοσυστήματα που παρασκευάστηκαν, αξιοποιήθηκαν ως φορείς βιοδραστικών μορίων κατάλληλων για εφαρμογές στη φαρμακευτική, τα τρόφιμα και τα καλλυντικά. Ένα σημαντικό στοιχείο καινοτομίας της παρούσας έρευνας ήταν η διερεύνηση της δυνατότητας να χρησιμοποιηθούν βιοαποικοδομήσιμοι πράσινοι διαλύτες (φυσικοί βαθέως ευτηκτικοί διαλύτες, NADESs) σε διάφορα στάδια της διεργασίας (π.χ. ως διαλύτες, ως γαλακτωματοποιητές, ως αναγωγικά μέσα, ως παράγοντες διασταύρωσης κ.ά.). Η στοχευμένη επιλογή των συστατικών που αποτελούν τους πράσινους διαλύτες τους προσδίδει επιθυμητές ιδιότητες ανάλογα με την τελική εφαρμογή, ώστε να λαμβάνεται τελικά ένα πολυλειτουργικό μικρο/νανοσύστημα με προστιθέμενη αξία. Για κάθε κατηγορία διεργασίας εγκλωβισμού πραγματοποιήθηκε βελτιστοποίηση μέσω Πειραματικού Σχεδιασμού (Design of Experiments, DOE) και μελέτη κινητικής μοντελοποίησης του προφίλ αποδέσμευσης των δραστικών ουσιών από τους νανοφορείς. Τέλος, τα καινοτόμα μικρο/νανοσυστήματα αξιολογήθηκαν ως προς τη βιοδραστικότητά τους και διερευνήθηκε η δυνατότητα ενσωμάτωσής τους σε φαρμακοτεχνικές μορφές, λειτουργικά τρόφιμα ή καλλυντικά σκευάσματα

Νανο-συστήματα στόχευσης και μεταφοράς φαρμακομορίων : εφαρμογές στην σύγχρονη θεραπευτική και κλινική πρακτική

Τα συστήματα μεταφοράς φαρμάκων έχουν την δυνατότητα να ελέγχουν τη φαρμακολογική δράση ενός φαρμάκου, επηρεάζοντας την φαρμακοκινητική του και, συνεπώς, το θεραπευτικό του αποτέλεσμα. Η επιλογή του κατάλληλου συστήματος που θα χρησιμοποιηθεί για την μεταφορά του φαρμάκου είναι ιδιαιτέρως σημαντική αφού θα καθορίσει τις τελικές ιδιότητες του φαρμακευτικού ιδιοσκευάσματος. Στη παρούσα διπλωματική εργασία παρουσιάζονται τα συστήματα μεταφοράς φαρμάκων, με έμφαση στους φορείς της νανοτεχνολογίας. Η πλειονότητα αυτών των συστημάτων εκμεταλλεύεται τους μηχανισμούς παθητικής στόχευσης χρησιμοποιώντας τα φυσικά χαρακτηριστικά των φορέων σε συνδυασμό με τους μηχανισμούς κάθαρσης στον οργανισμό, ενώ τα αντισώματα είναι το κύριο σύστημα που προσφέρει ενεργητική στόχευση. Αξίζει να σημειωθεί, ότι ο συνδυασμός των αντισωμάτων με τα συστήματα μεταφοράς μπορεί να συμβάλλει στη μελλοντική ανάπτυξη της ενεργητικής στόχευσης σε κλινικά προϊόντα. Καθοριστικοί παράμετροι για την ασφάλεια των νανοσυστημάτων αποτελούν το μέγεθος, η κατανομή μεγέθους, η σύσταση, η επιφάνεια, το φορτίο, το σχήμα τους, οι επιφανειακές τους ιδιότητες καθώς και η σταθερότητα τους σε συγκεκριμένες συνθήκες. Η ανάπτυξη νανοτεχνολογικών προϊόντων δημιουργεί την ανάγκη ύπαρξης νομοθετικού πλαισίου, το οποίο θα ακολουθεί τις τεχνολογικές εξελίξεις. Η σημαντική επίδραση της νανοτεχνολογίας και των εφαρμογών της αναμένεται να είναι περισσότερο αισθητή στο μέλλον, ωστόσο από τον FDA έχουν ήδη εγκριθεί πολλά νανοτεχνολογικά προϊόντα.Drug delivery systems can control the pharmacological action of a drug, affecting its pharmacokinetics and, consequently, its therapeutic effect. The choice of the appropriate system used for the transportation of the drug is particularly important as it will determine the final properties of the medicinal product. The following dissertation presents drug delivery systems, with emphasis on nanosystems. Most of these systems take advantage of the passive targeting mechanisms by using the physical characteristics of the carrier, in combination with the purification mechanisms in the body, while the antibodies are the primary system that offers active targeting. It is worth mentioning that the combination of antibodies with delivery systems may contribute to the future development of active targeting in clinical products. Important parameters for the safety of nanosystems are their size, size distribution, composition, surface, charge, shape, surface properties, and stability under specific conditions. The growth of nanotechnology products requires the establishment of a legislative framework, which will follow technological developments. The significant impact of nanotechnology and its applications will be more noticeable in the future. However, many nanotechnology products have already been approved by the FDA

“Novel chitosan/alginate hydrogels as carriers of phenolic-enriched extracts from saffron floral by-products using natural deep eutectic solvents as green extraction media”

The current saffron production system is generating several hundreds of tons of tepal waste, because only stigmas are used for food. Consequently, the valorization of saffron floral by-products by developing stable functional ingredients could lead to the environmental impact minimization. Thus, the main aim of this study was to develop innovative green extraction processes from saffron floral by-products by using Natural Deep Eutectic Solvents (NaDES) and ultrasound-assisted extraction (UAE) as ecological extraction method. Response surface methodology was used to optimize process parameters. To improve the stability of the optimal extracts, they were incorporated into chitosan/alginate hydrogels, studying their water-uptake and water retention capacity and the total phenolic content (TPC) during the in vitro digestion. The results indicated that the optimal extraction, regarding total phenolic and flavonoid content, was achieved in 20 min, using 180 W ultrasound power and 90% of NaDES. The results of the DPPH assay revealed the potent antioxidant activity of saffron floral by-products. The chitosan/alginate hydrogels incorporating the as-obtained NaDES extracts showed favorable properties whereas the TPC remained stable under intestinal conditions. Therefore, NaDES combined with UAE was an efficient technique to isolate high added-value compounds from saffron flowers, succeeding also the valorization of discarded waste by using green and low-cost strategies. Furthermore, these novel hydrogels could be used as promising candidates for food or cosmetic applications

Preparation, Characterization, and Acetylcholinesterase Inhibitory Ability of the Inclusion Complex of β-Cyclodextrin–Cedar (Juniperus phoenicea) Essential Oil

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 t1/2 + 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

Green Extraction of Greek Propolis Using Natural Deep Eutectic Solvents (NADES) and Incorporation of the NADES-Extracts in Cosmetic Formulation

In this work, a greener approach for the extraction of Greek propolis using ultrasound-assisted extraction method in combination with Natural Deep Eutectic Solvents (NADES) is presented. Propolis is a natural material of outmost interest as it possesses various biological and pharmacological activities and is therefore used for the manufacturing of extracts useful to various fields, such as pharmaceutics, cosmetics etc. Herein, five NADES were task-specifically selected as appropriate extraction solvents since they provide important assets to the final NADES-extracts, comparing to the conventionally used organic solvents. The screening study of the prepared solvents indicated the NADES L-proline/D,L-Lactic acid as the most effective medium for the raw propolis extraction due to the extract’s high total phenolic content as well as its’ significantly higher antioxidant activity. Then, the extraction using the selected NADES, was optimized by performing Experimental Design to study the effect of extraction time, propolis-to-solvent ratio and the %NADES content in the NADES-water system. All the extracts were characterized regarding their antioxidant activity and total phenolic content. The optimum NADES-extract as well as an extract derived by extraction using a conventional hydroethanolic solution were further characterized by performing LC/MS/MS analysis. The results showed that the NADES-extracts composition was similar or superior to the hydroethanolic extracts regarding the presence of valuable phytochemicals such as apigenin, naringenin etc. A disadvantage that is usually mentioned in the literature regarding the extractions using NADES is that the extracted bioactive compounds cannot be easily separated from the NADES in order to obtain dry extracts. However, this drawback can be converted to an asset as the task-specifically designed NADES that are used in this study add value to the end product and the optimum as-obtained NADES-extract has been successfully incorporated in a cosmetic cream formulation. In this work, The antioxidant activity and organoleptic characteristics of the cream formulation were also determined