Green and Sustainable Production of Baphicacanthus cusia Extracts and Their Dyeing Effect and Wound-Healing Ability

Abstract

Baphicacanthus cusia (B. cusia) was traditionally used as raw material to prepare indigo naturalis; however, many factories have been shut down by local governments on account of their serious pollution contributions. In this study, a green and sustainable production of B. cusia leaf extracts is proposed. Namely, new indigo extract (NIE) and phenolic acid extract (PAE) were produced in an integrated fashion by enzyme transformation coupled membrane separation and freeze-drying technologies. The small-scale process was optimized, and its feasibility was verified by a pilot experiment. Moreover, the physicochemical properties, dyeing effect, and wound-healing ability of the two extracts were systematically evaluated. The NIE could be obtained within 1 day and exhibited more than 20 times the indigo content and 1.8 times the pure indigo yield than indigo naturalis. Moreover, the NIE showed superior dye-uptake rate and washing and rubbing fastness on pure cotton poplin compared with natural indigo from India. The PAE exhibited excellent broad spectrum antibacterial activities, especially S. aureus (IC₅₀ = 32 μg/mL). Significantly, the PAE had no toxicity and presented over 98% of the wound-healing rate on mice by increasing their collagen fiber content. All of above work is of great significance for the extension and sustained healthy development of a B. cusia industry chain.