Chemo-Enzymatic Synthesis of Renewable Sterically-Hindered Phenolic Antioxidants with Tunable Polarity from Lignocellulose and Vegetal Oil Components

• Published in: International Journal of Molecular Sciences
• Main Authors: Louis Hollande, Sandra Domenek, Florent Allais
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2018
• Subjects: ferulic acid; fatty acid ethyl esters; CAL-B; antioxidant; DPPH; Biology (General); QH301-705.5; Chemistry; QD1-999; Antarc*; Antarctica
• Online Access: https://doi.org/10.3390/ijms19113358; https://doaj.org/article/f46776f2ddc8485e81202c8873e886e7

Despite their great antioxidant activities, the use of natural phenols as antioxidant additives for polyolefins is limited owing to their weak thermal stability and hydrophilic character. Herein, we report a sustainable chemo-enzymatic synthesis of renewable lipophilic antioxidants specifically designed to overcome these restrictions using naturally occurring ferulic acid (found in lignocellulose) and vegetal oils (i.e., lauric, palmitic, stearic acids, and glycerol) as starting materials. A predictive Hansen and Hildebrand parameters-based approach was used to tailor the polarity of newly designed structures. A specific affinity of Candida antarctica lipase B (CAL-B) towards glycerol was demonstrated and exploited to efficiently synthesized the target compounds in yields ranging from 81 to 87%. Antiradical activity as well as radical scavenging behavior (H atom-donation, kinetics) of these new fully biobased additives were found superior to that of well-established, commercially available fossil-based antioxidants such as Irganox 1010 ® and Irganox 1076 ® . Finally, their greater thermal stabilities (302 < T d 5% < 311 °C), established using thermal gravimetric analysis, combined with their high solubilities and antioxidant activities, make these novel sustainable phenolics a very attractive alternative to current fossil-based antioxidant additives in polyolefins.