Syringic acid is a naturally occurring O-methylated trihydroxybenzoic acid, a type of chemical compound. Syringic acid can be prepared by selectively hydrolyzing trimethylgallic acid (3,4,5-trimethyloxybenzoic acid) with 20% sulfuric acid. Syringic acid can be enzymatically polymerised. Laccase and peroxidase induced the polymerization of syringic acid to give a poly(1,4-phenylene oxide) bearing a carboxylic acid at one end and a phenolic hydroxyl group at the other. Oral administration of syringic acid (50 mg/kg b.w) for 30 d positively modulates the glycemic status in alloxan induced diabetic rats. The levels of plasma glucose were decreased with significant increase of plasma insulin and C-peptide level. The altered levels of plasma and tissue glycoprotein components were restored to near normal. No significant changes were noticed in normal rats treated with syringic acid.
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