Sustainable green chemistry approaches to bioactive compounds and advanced materials in pharmaceutical development

Questa ricerca applica i principi della chimica verde e della bioeconomia circolare in tre ambiti interconnessi: la sintesi sostenibile di steroidi bioattivi, l’upcycling di sottoprodotti industriali e lo sviluppo di filtri UV di nuova generazione progettati secondo i criteri Safe-and-Sustainable-by-Design (SSbD). La bioconversione del cortisone mediante Rhodococcus rhodnii DSM 43960 ha permesso la produzione di due biosteroidi, SCA e SCB, con rese ottimizzate utilizzando il mezzo MN79 e un mezzo a base di foglie d’olivo ottenuto tramite upcycling dagli scarti della produzione biotecnologica di acido lattico. Le differenze nella distribuzione relativa di SCA e SCB nei diversi mezzi hanno evidenziato il potenziale biotecnologico delle biomasse lignocellulosiche e dell’approccio del double-upcycling. L’applicazione di downstream sostenibile, tramite cloud point extraction, ha consentito un’elevata efficienza estrattiva per entrambi i biosteroidi. SCA ha mostrato, inoltre, una marcata attività antiossidante e antinfiammatoria in vitro, suggerendone il potenziale impiego nel trattamento della degenerazione maculare e altre patologie oculari; SCA è stato pertanto derivatizzato in Lauryl-SCA e SCA-ialuronato tramite metodiche sintetiche ad elevato carattere sostenibile. Secondariamente, il sottoprodotto STF231 derivante dalla produzione di tinture officinali è stato valorizzato attraverso estrazione con solventi eutettici naturali e fermentazione allo stato solido, ottenendo estratti ricchi in polifenoli con rilevanti attività biologiche. La valutazione delle metriche di sostenibilità ha confermato la green compliance del processo ottimizzato. Una cloud point extraction a micelle miste con Polisorbato 80 e surfattina ha inoltre consentito un efficiente recupero di molecole bioattive-oltre il 93% per sistemi con Polisorbato 80- dalle acque di processo di STF231, producendo coacervati direttamente formulabili. Infine, nell’ottica dei nanomateriali SSbD, nanoparticelle di TiO₂ sono state funzionalizzate con surfattina nell’ambito del progetto SBD4Nano. Il materiale risultante, TiO₂@SS, ha mostrato ridotta attività fotocatalitica, maggiore disperdibilità e migliori prestazioni filtranti UV, rappresentando un’alternativa più sicura e sostenibile ai sistemi convenzionali basati su TiO₂.

This research implements green chemistry principles across three interconnected domains: the synthesis and derivatization of biotechnological steroids with potential applications against oxidative stress- and inflammation-related pathologies, the upcycling of by-products from officinal extract industry into multifunctional, high-value extracts, and the development of next-generation UV filters that combine safety, sustainability, and efficacy for the prevention of skin affections. The biocatalytic conversion of cortisone with Rhodococcus rhodnii DSM 43960 enabled the synthesis of novel biosteroids, 1,9β,17,21-tetrahydroxy-4-methyl-19-nor-9β-pregna-1,3,5(10)-trien-11,20-dione (SCA) and 1,9β,17,20β,21-pentahydroxy-4-methyl-19-nor-9β-pregna-1,3,5(10)-trien-11-one (SCB), optimized and scaled up using organic medium 79 (MN79) and plate count broth (PCB). MN79, at 10% concentration, outperformed reference PCB medium, providing higher yields at 88% reduced cost and 93±2.27% overall biotransformation products. According with circular bioeconomy principles, exhausted olive leaf from biotechnological production of lactic acid were further valorised to formulate an upcycled olive leaf medium, supporting bioconversion with 91 ± 2.30% yields. Interestingly, the relative distribution of SCA and SCB differed depending on the medium, highlighting that the potential of lignocellulosic biomass valorisation and the strategy of double upcycling could drive second generation biosteroids through first paradigmatic shift. To ensure green approach across the process chain, cloud point extraction (CPE) was applied as sustainable downstream process, enabling SCA recovery at 96% and SCB at 86%. In vitro studies confirmed that SCA exerts potent dualistic antioxidant and anti-inflammatory activity, protecting ARPE19 and 661W cell lines and supporting its potential use in macular degeneration treatments. Based on this activity, SCA was further derivatized. Lauryl-SCA was synthesized via enzymatic esterification while SCA-hyaluronate via aqueous grafting, optimized by central composite orthogonal design with more than 10% degree of substitution, exemplifying sustainable derivatization strategies. The second research objective concerned STF231, a by-product from officinal tincture manufacture, which was subjected to multiple upcycling protocols, including natural deep eutectic solvents-based ultrasound-assisted extraction, and solid-state fermentation with Pleurotus ostreatus DSM1020 and Ganoderma lucidum DSM 3534. Optimization identified ChCl:LA as optimal, yielding 8687.72±127.44 µg GAE/mL polyphenols, and significant caffeic acid and gentiopicroside. Sustainability assessment through GAPI, AGREE, and AGREEprep validated the green credentials of this method. Fermented extracts exhibited strong antioxidant, antifungal, antidiabetic coadjutant, and cholesterol-lowering activities. For the first time, mixed-micelle CPE with polysorbate 80 and sodium surfactin (SS) was applied and achieved 93.76±0.96% phenolic recovery from STF231 manufactory wastewater, providing directly usable coacervates with health-compatible surfactants, thus advancing sustainable wastewater valorisation. Finally, to address the European Green Deal’s call for Safe-and-Sustainable-by-Design (SSbD) nanomaterials, this research focused on TiO2 nanoparticles (NPs). Despite toxicity concerns, TiO₂ remains a cornerstone UV filter in skin cancer prevention. Within the SBD4Nano project, TiO₂ NPs were surface-modified with SS to suppress photocatalytic activity and enhance dispersibility. The TiO₂@SS improved colloidal stability and reduced toxicity while improving UV-filtering performance, demonstrating the role of biosurfactants in SSbD strategies. This approach provides a proof-of-concept for designing safer nanomaterials, addressing environmental and human health concerns, and filling critical regulatory and methodological gaps in the field of TiO₂ coatings.