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Several kinds of natural woods and isolated lignins with various syringyl to guaiacyl (S/G) ratios were subjected to thioacidolysis followed by Raney nickel desulfuration to elucidate the relationships between the S/G ratio and the interunit linkage types of lignin. Furthermore, enzymatic dehydrogenation polymers (DHP) were produced by the Zutropf (gradual monolignol addition) method from mixtures of various ratios of coniferyl alcohol and sinapyl alcohol. The analysis of DHPs and natural wood lignins exhibited basically a similar tendency. The existence of both syringyl and guaiacyl units is effective for producing higher amounts of beta-O-4 and 4-O-5 structures, but it lowers the total amount of cinnamyl alcohol and aldehyde end groups. The relative frequency of the beta-beta structure increased, whereas that of beta-5 and 5-5 structures decreased with increasing syringyl units.

An assay for the Maillard reaction has been developed to screen efficiently inhibitors from natural resources such as extracts of plants. The fluorometric analysis of fluorescent material based on advanced glycation endproducts (AGEs) was applied to measurement of an inhibitory index of the Maillard reaction to detect all of the inhibitors at each step of the complicated reaction. To solve the two major problems, slowness of the reaction rate and the existence of interfering substances such as quencher and fluorescent material in the screening sources, we devised the following procedures. Slowness of the reaction rate was solved by raising the reaction temperature to 60°C at which the conformation of bovine serum albumin (BSA) did not change greatly. To remove the interfering substances, AGEs-BSA was precipitated from the reaction mixture. Thus, an efficient assay system by measuring the fluorescent intensity based on AGEs was established to isolate the glycation inhibitors from natural product extracts.