Syringic acid

Syringic acid is a naturally occurring O-methylated phenolic acid that can be enzymatically degraded by some bacteria as a source of methane or methanol. It is also a component of phenolic extracts from various plants that have antioxidant and prooxidant activities. Syringic acid has been shown to inhibit aldose reductase (IC₅₀ = 213 μg/ml), proteasome activity, and cancer cell proliferation. Phenolic extracts containing syringic acid have been shown to inhibit α-amylase and α-glucosidase activities and reduce lipid peroxidation in vitro.

light brown powder

antiproliferative; antifungal

Syringic Acid is used in biological studies for electron transfer from plant phenolates to carotenoid radical cations with antioxidant interaction entering the Marcus theory inverted region.

ChEBI: A dimethoxybenzene that is 3,5-dimethyl ether derivative of gallic acid.

Recrystallise syringic acid from H2O using charcoal [Bogert & Coyne J Am Chem Soc 51 571 1929, Anderson & Nabenhauer J Am Chem Soc 48 3001 1926.] The methyl ester has m 107o (from MeOH), the 4-acetyl derivative has m 190o and the 4-benzoyl derivative has m 229-232o. [Hahn & Wassmuth Chem Ber 67 2050 1934, UV: Lemon J Am Chem Soc 69 2998 1947 and Pearl & Beyer J Am Chem Soc 72 1743 1950, Beilstein 10 IV 1995.]

[1] H HARA. The 4-oxalomesaconate hydratase gene, involved in the protocatechuate 4,5-cleavage pathway, is essential to vanillate and syringate degradation in Sphingomonas paucimobilis SYK-6.[J]. Journal of Bacteriology, 2000, 182 24: 6950-6957. DOI: 10.1128/jb.182.24.6950-6957.2000
[2] MILENA COTORAS. In vitro and in vivo evaluation of the antioxidant and prooxidant activity of phenolic compounds obtained from grape (Vitis vinifera) pomace.[J]. Molecules, 2014, 19 12: 21154-21167. DOI: 10.3390/molecules191221154
[3] XIAOYONG WEI. Syringic Acid Extracted from Herba dendrobii Prevents Diabetic Cataract Pathogenesis by Inhibiting Aldose Reductase Activity.[J]. Evidence-based Complementary and Alternative Medicine, 2012, 2012: 426537. DOI: 10.1155/2012/426537
[4] KHALED Y ORABI. Selective growth inhibition of human malignant melanoma cells by syringic acid-derived proteasome inhibitors.[J]. Cancer Cell International, 2013, 13 1: 82. DOI: 10.1186/1475-2867-13-82
[5] GANIYU OBOH. Inhibition of key enzymes linked to type 2 diabetes and sodium nitroprusside induced lipid peroxidation in rats’ pancreas by phenolic extracts of avocado pear leaves and fruit.[J]. International Journal of Biomedical Science: IJBS, 2014, 10 3: 208-216.