Shikonin: Extraction, properties and applications in active and intelligent packaging

Shikonin is a naphthoquinone compound, generally extracted from the roots of the Oriental medicinal herb Lithospermum erythrorhizon or the Indian medicinal herb Arnebia euchroma. It has a rich history of being utilized as a pharmacological compound to treat various diseases such as inflammation, wounds and microbial infections. Besides, it also possesses anticancer, antiviral and antioxidant properties, which interest current medical researchers. Food packaging researchers have recently utilized shikonin's antimicrobial and antioxidant properties for active food packaging. Its halochromic properties and ability to change colour with pH variation have attracted tremendous attention for intelligent packaging applications. This review article covers the important extraction processes for shikonin. Further, the important properties of these functional compounds have been discussed. Finally, the advancements in applying shikonin as a multifunctional material in biopolymer-based films for smart packaging applications have been reviewed for the first time.