Supply chain waste gives rise to significant challenges in terms of disposal, making upcycling a promising and sustainable alternative for the recovery of bioactive compounds from by-products. Lignocellulosic by-products like STF231, which are derived from the medicinal plant extract industry, offer valuable compounds such as polyphenols and iridoids that can be recovered through upcycling. In an unprecedented study, we explored and compared conventional hydroethanolic extraction, ultrasound hydroethanolic extraction, and natural deep eutectic solvents–ultrasound extraction methods on STF231 to obtain extracts with antioxidant activity. The extraction profile of total polyphenols (TPCs) was measured using the Folin–Ciocalteu test and the antioxidant capacity of the extracts was tested with FRAP and DPPH assays. HPLC-UV was employed to quantify the phenolic and iridoid markers in the extracts. Additionally, the sustainability profile of the process was assessed using the green analytical procedure index (GAPI), AGREEprep, and analytical GREEnness metric approach (AGREE) frameworks. Our findings indicate that a choline chloride and lactic acid mixture at a 1:5 ratio, under optimal extraction conditions, resulted in extracts with higher TPC and similar antioxidant activity compared with conventional hydroethanolic extracts. The innovative aspect of this study lies in the potential application of sustainable upcycling protocols to a previously unexamined matrix, resulting in extracts with potential health applications.

Black garlic peels (BGPs) are a largely underutilized by-product despite representing an untapped source of bioactive compounds. This study presents a sustainable upcycling protocol for black garlic peels, evaluating natural deep eutectic solvents (NaDES) to develop multifunctional extracts for green cosmetics. Following the screening of four eutectic mixtures, the choline chloride–lactic acid (ChCl:LA) system demonstrated the highest extraction efficiency. The optimized extract yielded a remarkable total phenolic content (5216.61 µg GAE/mL) and strong antioxidant capacity, confirmed by DPPH and FRAP assays, associated with recovering both free and bound phenolic fractions. Subsequent HPLC profiling characterized the extract, and the comparative analysis explicitly demonstrated that antimicrobial activity is entirely driven by and identical to the pure eutectic solvent vehicle rather than the extracted garlic biomass, with broad-spectrum efficacy against C. albicans, P. aeruginosa, and S. aureus. To evaluate its cosmeceutical potential, the extract was incorporated into emulsions (5%, 10%, 15% w/w) with inorganic or organic UV filters. Although the direct Sun Protection Factor (SPF) and the UVA Protection Factor (UVA-PF) did not show enhancing results, a photochemiluminescence (PCL) analysis revealed a synergistic behaviour with organic filters, successfully boosting the formulation’s biological antioxidant shield. This pioneering work highlights BGP’s upcycling potential, proposing NaDES extracts as highly promising multifunctional, antioxidant, and antimicrobial ingredients for next-generation cosmeceuticals.

Zinc oxide (ZnO) is increasingly used as a mineral UV filter, but its efficacy may be underestimated by conventional spectrophotometric in vitro methods based on mass application. This study investigated whether this underestimation reflects intrinsic ZnO performance or the residual film formed on the test substrate. Two formulations containing 10% w/w ZnO—an oil-in-water (O/W) emulsion and an anhydrous formulation—were compared with an O/W formulation containing organic UV filters, all targeting SPF 15. Dry-residue analysis showed approximately 99% mass retention for the anhydrous formulation versus 41% for the O/W ZnO emulsion, corresponding to estimated residual film thicknesses of ~12 and ~4 µm, respectively. ISO 24443-derived SPF values were 13.8 and 7.1, whereas the Helio2 method yielded 15.2 and 17.3, respectively. UVA-induced intracellular ROS in HaCaT keratinocytes showed significant protection with the anhydrous ZnO and organic-filter formulations, but not with the O/W ZnO emulsion. The BASF Sunscreen Simulator also underestimated both ZnO formulations (SPF 5). These findings suggest that poor performance of the O/W ZnO emulsion primarily reflects formation of a thin, discontinuous residual film rather than lower intrinsic ZnO efficacy, highlighting limitations of current in vitro and in silico approaches.

Bioconversion of cortisone leads to the synthesis of the steroid derivatives 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), which have been identified as biologically active molecules in affections associated with oxidative stress and inflammation, particularly in the skin and eye. To date, the synthesis of SCA and SCB can only be achieved through a biocatalytic approach, following a biotransformation process catalyzed by Rhodococcus rhodnii DSM 43960, a synthetic pathway that adheres to the principles of green chemistry. To further enhance the sustainability of this process, this study demonstrated that SCA and SCB can be synthesized by bioconversion in a complex medium derived from a dual upcycling process involving olive leaves (UOLM). By formulating a medium based on olive leaves, a by-product derived from the previously reported biotechnological production of lactic acid, and using a concentration of 10% v/v UOLM and 1 g/L cortisone at pH 7.5, bioconversion yields of 90 ± 4.5% were achieved, with a predominance of SCB. Investigations into the addition of supplements, such as tryptone, peptone, and corn steep liquor (CSL), to assess potential improvements in yield were conducted, but no significant positive variations were observed. For the first time, bioactive steroids were synthesized from a medium obtained through a dual upcycling process of olive leaves, introducing an innovative method that opens new possibilities for the investigation of a second generation of biosteroids synthesized from lignocellulosic feedstocks.