New materials from silk fibroin (FS-Ox) and chitin (CT-Ox) functionalized with Oxone^® salt were developed for application in the synthesis of Knoevenagel adducts. The experiments were performed using benzaldehyde derivatives, malononitrile, and a mixture of water and ethanol as green solvents. The efficiency of conventional and microwave irradiation as heating sources for this reaction was also investigated. When the reactions were performed for 60 min under optimized conditions with conventional heating, twelve Knoevenagel adducts 2a–l were obtained, with good yields for both catalysts (CT-Ox 60–98% and FS-Ox 71–98%). When microwave irradiation was used, the reaction periods were reduced twelvefold, with the same Knoevenagel adducts with good CT-Ox (39–99%) and FS-Ox (35–99%) yields obtained in most cases. The reuse of these materials as catalysts in successive reactions was also evaluated, and CT-Ox FS-Ox were successfully used for 4 and 2 cycles, respectively. The results presented prove the efficiency of the CT-OxFS-Ox catalyst as a promising low-cost and reusable material with suitable catalytic properties to be applied in the aldol condensation reaction in a sustainable way.

Bixin, an apocarotenoid from Bixa orellana seeds, is a valuable natural pigment with industrial and pharmacological applications. Traditional extraction methods rely on organic solvents, but eco-friendly alternatives like silk fibroin solution (SFS) are emerging. This study evaluated SFS for bixin extraction from annatto seeds, optimizing conditions using Box-Behnken Design (BBD). The optimal parameters 1.5% SFS, 60 °C, and 60 min yielded 10.87 mg/mL (liquid extract of annatto seeds, LEAS + SFS) and 150.72 mg/g (solid extract of annatto seeds, SEAS + SFS). Cell viability was assessed in human dermal fibroblasts (HDFn) and RAW 264.7 murine macrophages via MTT assay. After 24 and 72 h, LEAS + SFS, SEAS + SFS, purified bixin (PB), and SFS maintained >70% viability in HDFn cells. Similarly, RAW 264.7 cells showed >70% viability after 24 h, indicating low cytotoxicity. These results highlight the biocompatibility of SFS-extracted bixin, supporting its potential in food, cosmetics, and biomedicine. The study demonstrates that SFS is an effective, sustainable alternative to traditional solvents, offering high extraction efficiency and minimal toxicity. This method aligns with green chemistry principles, providing a promising solution for bixin production.