Structural elucidation of hemicelluloses from oil-tea camellia fruit shell

Oil-tea camellia fruit shell (CFS) is a very abundant waste lignocellulosic resource. The current treatments of CFS, i.e. composting and burning, pose a severe threat on environment. Up to 50 % of the dry mass of CFS is composed of hemicelluloses. However, chemical structures of the hemicelluloses in CFS have not been extensively studied, which limits their high-value utilization. In this study, different types of hemicelluloses were isolated from CFS through alkali fractionation with the assistance of Ba(OH)2 and H3BO3. Xylan, galacto-glucomannan and xyloglucan were found to be the major hemicelluloses in CFS. Through methylation, HSQC and HMBC analyses, we have found that the xylan in CFS is composed of & RARR;4)-& beta;-D-Xylp-(1 & RARR; and & RARR;3,4)-& beta;-D-Xylp-(1 & RARR; linked by (1 & RARR;4)-& beta; glycosidic bond as the main chain; the side chains are & alpha;-L-Fucp-(1 & RARR;, & RARR;5)-& alpha;-L-Araf-(1 & RARR;, & beta;-D-Xylp-(1 & RARR;, & alpha;-L-Rhap- (1 & RARR; and 4-O-Me-& alpha;-D-GlcpA-(1 & RARR;, connected to the main chain through (1 & RARR;3) glycosidic bond. The main chain of galacto-glucomannan in CFS consists of & RARR;6)-& beta;-D-Glcp-(1 & RARR;, & RARR;4)-& beta;-D-Glcp-(1 & RARR;, & RARR;4,6)-& beta;-D-Glcp-(1 & RARR; and & RARR;4)-& beta;-D-Manp-(1 & RARR;; the side chains are & beta;-D-Glcp-(1 & RARR;, & RARR;2)-& beta;-D-Galp-(1 & RARR;, & beta;-D-Manp-(1 & RARR; and & RARR;6)-& beta;-D-Galp-(1 & RARR; connected to the main chain through (1 & RARR;6) glycosidic bonds. Moreover, galactose residues are connected by & alpha;-L-Fucp-(1 & RARR;. The main chain of xyloglucan is composed of & RARR;4)-& beta;-D-Glcp-(1 & RARR;, & RARR;4,6)-& beta;-D-Glcp-(1 & RARR; and & RARR;6)-& beta;-D-Glcp-(1 & RARR;; the side groups, i.e. & beta;-D-Xylp-(1 & RARR; and & RARR;4)-& beta;-D-Xylp-(1 & RARR;, are connected to the main chain by (1 & RARR;6) glycosidic bond; & RARR;2)-& beta;-D-Galp-(1 & RARR; and & alpha;-L-Fucp-(1 & RARR; can also connect to & RARR;4)-& beta;-D-Xylp-(1 & RARR; forming di-or trisaccharide side chains.

Automated summary

Oil-tea camellia fruit shell (CFS) is a highly abundant lignocellulosic waste resource. The current composting and burning treatments of CFS pose a severe environmental threat. However, the chemical structures of the hemicelluloses in CFS have not been extensively studied, which limits their high-value utilization.