A modified method based on DMSO/NMI dissolved system for the isolation of dissolved lignin (DL) from bamboo was presented. Milled wood lignin (MWL) and alkaline lignin (AL) were isolated for comparison. The chemical structures of the lignin fractions were characterized by wet chemistry and spectroscopy methods. Quantitative 13C NMR and 2D-HSQC spectra indicated that the lignin samples are HGS-type and partially acylated at the ?-carbon of the side chain by p-coumarate. In addition, benzyl ether LCC and phenyl glycoside LCC as well as acetylated �-D-xylopyranoside could be distinguished from HSQC spectra in the specific lignin samples. The S/G ratios as well as functional groups involved in the lignin samples were quantitatively estimated via NMR methodology. The classical coupling units among the lignin fractions were �-O-4, �-�, and �-5, and their abundances were estimated quantitatively by different methodology based on NMR. It was revealed that the amount of �-O-4 coupling decreased in the order of DL in vitro results showed that the radical scavenging index (RSI) decreasing in the order DL (16.7)>MWL (10.0)>AL (9.1)>BHT (Commercial antioxidant, 1.2), which is correlated to the phenolic hydroxyl groups involved in the lignin samples.

Study on the quantitative structure and antioxidant activity of lignin extracted by different methodologies from bamboo

243rd National Meeting (2012)

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