Structural variation of lignin-carbohydrate complexes (LCC) in Chinese quince (Chaenomeles sinensis) fruit as it ripens

Chinese quince (Chaenomeles sinensis) fruits are rich in lignin, and too sour, astringent and woody to be eaten raw. More than 50 % of lignin in plant cell walls is covalently associated with carbohydrates to form lignin -carbohydrate complexes (LCC). In this study, LCC preparations were extracted from fruits harvested on the 15th day of the month from May-October 2019. A variety of chemical and instrumental analytical approaches were used to characterize the LCC fractions, including HPAEC, TGA, GPC, FT-IR, and 2D HSQC NMR. Antioxidant activities were evaluated by DPPH radical scavenging assays. Results showed that the LCC fractions from October fruits had better thermal stability and homogeneity. NMR results revealed that the lignin-lignin linkages in LCC-AcOH preparations included beta-O-4 ', beta-beta' and beta-5 ', but beta-5 ' linkages were not present in LCC preparations. And the NMR signals of carbohydrate confirmed the presence of lignin-pectin complexes, which was consistent with sugar analysis. All LCC preparations showed good antioxidant activity, among which Bjo center dot rkman LCC from October fruits showed best. This study will facilitate understanding the chemical bonds of LCC macromolecules in the plant cell wall. More specifically, it provides information critical for specific industrial applications of quince fruits.

Automated summary

In this study, LCC preparations were extracted from Chinese quince fruits and analyzed using various chemical and instrumental approaches. The results showed that LCC fractions from October fruits were more stable and homogeneous, and exhibited good antioxidant activity. NMR analysis revealed the presence of different types of lignin linkages and lignin-pectin complexes in the LCC preparations. This study is significant for understanding the chemical bonds of LCC macromolecules in plant cell walls and the industrial applications of Chinese quince fruits.