Preparation of low-molecular-weight chondroitin sulfates by complex enzyme hydrolysis and their antioxidant activities

•LMWCSs were prepared by complex enzyme hydrolysis from whole CS.•The optimized CEH conditions enhanced the antioxidant activities of LMWCSs.•Basic structures of LMWCSs and sulfate groups were well preserved after hydrolysis.•CEH provide an efficient and safe strategy to obtain LMWCSs. Chondroitin sulfate (CS) has attracted widespread attention because of its numerous pharmacological activities. Low-molecular-weight chondroitin sulfates (LMWCSs) derived from the degradation of CS are reported to have better biological properties than whole CS. In this study, to obtain LMWCSs with high antioxidant activity, we depolymerized CS using complex enzymes, namely, chondroitinase ABC I (ChSase ABC I) and ChSase ABC II. The conditions of the complex enzyme hydrolysis (CEH) were optimized, and the structures and antioxidant activities of CS and LMWCSs were investigated. The results showed that the CEH conditions enhanced the antioxidant activities of the products as compared to CS. The basic structures of the LMWCSs and sulfate groups were well preserved after hydrolysis. Therefore, CEH provides an efficient and safe strategy to obtain LMWCSs, which can be used in antioxidant drugs, healthy foods, and cosmetics.