The interplay between antimicrobial activity and reactivity of isothiocyanates. (December 2020)

• Record Type: Journal Article
• Authors: Andini, Silvia; Araya-Cloutier, Carla; Waardenburg, Leonie; den Besten, Heidy M.W.; Vincken, Jean-Paul
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 134(2020)
• Publication Date: 2020-12
• Subjects: Antibacterial -- Brassicaceae -- Electrophilic -- Food preservative -- Glucosinolate; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2020.109843
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: This study aimed to determine antimicrobial activity (minimum inhibitory concentration, MIC; minimum bactericidal/fungicidal concentration, MBC/MFC) of novel ITCs against food spoilage and pathogenic Gram – bacteria, Gram + bacteria, and fungi. The activity of the long-chain ( C9 ) 9-(methylthio)nonyl ITC (9-MTITC), 9-(methylsulfinyl)nonyl ITC (9-MSITC), and 9-(methylsulfonyl)nonyl ITC (9-MSoITC) was determined for the first time. Due to the electrophilicity of ITCs, the activity of ITCs was evaluated in nucleophile-rich and nucleophile-poor growth media. ITCs reacted via conjugation with components in a nucleophile-rich growth medium at a rate of 39–141 μmol L −1 h −1, depending on their side chain configuration and temperature. The reaction rates were lowered by a factor of 2–21 when using nucleophile-poor growth media. Consequently, the activity of ITCs was generally improved, with MSITC and MSoITC being the most positively affected (activity increased by a factor of > 4). 9-MSITC and 9-MSoITC had good activity (MIC ≤ 25 μg/mL) against Gram + bacteria and fungi. The short-chained ( C3 ) analogues had good activity against Gram + bacteria and Gram – bacteria. The highest bactericidal/fungicidal activity was obtained for 9-MSITC and 9-MSoITC (MBC/MFC 17.5–25 μg/mL). Overall, MSITC and MSoITC might be potential new natural food preservatives, but their reactivity with food matrix components should be considered. Graphical abstract: Image 1 Highlights: Antimicrobial activity of long-chained C9 sulfinyl and sulfonyl ITCs was for the first time assessed. Chain-length specific antimicrobial activity of sulfinyl and sulfonyl ITCs was observed. The highest activity (MIC 12.5 μg/mL) was obtained for 9-MSITC against Bacillus cereus. The effect of nucleophile richness of growth media on ITC antimicrobial activity was assessed. Amino acid composition of growth media affects antimicrobial activity of ITCs.