In vitro antioxidant and antidiabetic activities of biomodified lignin from Acacia nilotica wood.

The antioxidant and antidiabetic activity of biomodified alkali lignin extracted from a deciduous plant Acacia nilotica, was evaluated in vitro. The extracted alkali lignin was subjected to microbial biotransformation by ligninolytic fungus Aspergillus flavus and Emericella nidulans. These modifications were done under varying concentration of carbon to nitrogen sources. The structural feature of the lignin samples were compared by FTIR, functional group analysis and (13)C solid state NMR. All lignin samples were tested for antioxidant efficiency, reducing power and H2O2 scavenging power. Modifications in all lignin samples showed correlation with their antioxidant scavenging activity and reducing power. Antidiabetic properties were evaluated in terms of in vitro glucose movement inhibition and α-amylase inhibition assay. Modified samples exhibited increased glucose binding efficiency as demonstrated by the decreased glucose diffusion (55.5-76.3%) and 1.16-1.18-fold enhanced α-amylase inhibition in comparison to their control samples. The results obtained demonstrate that the structure and functional modifications in lignin significantly affects its bioefficacy in term of antioxidant and antidiabetic activities.