Synthesis And Antioxidant Activity Of Sesamol Analogues

Sesamol is a natural phenolic compound with strong antioxidant activity and is the stabilizer of sesame oil. There are a lot of reports about sesamol’s properties, however, few studies on the antioxidant activity of it’s analogues are reported. So this paper aims to synthesize analogues of sesamol and determine their antioxidant activity. The main contents are as followed:(1) Taking catechol and 1, 2-dichloroethane as starting materials, by cyclization reaction, then through Friedel-Crafts acylation, followed by Bayer-Villiger oxidation, the final product was obtained. The dosages and concentration of Na OH in the cyclization reaction, the amount of catalyst and acylation reagent, the solvent in Friedel-Crafts acylation and the selection of oxidants in Bayer-Villiger oxidation were discussed. Optimum conditions for reactions were confirmed. Cyclization reaction: when the concentration of sodium hydroxide solution was 50% and the molar ratio of m(Na OH): m(catechol) was 1.8, the synthesis rate was 88.2%. Acylation reaction: solvent for nitrobenzene, chloride dosage of 20 m L, mole ratio of m(Al Cl3): m(benzo-1, 4-dioxane) was about 2:1, the rate of 6-acetyl-1, 4-benzodixane was 69.3%; Selected 3-Chloroperoxybenzoic acid as oxidant in Bayer-Villiger oxidation and it with a molar ratio to reactants was 1.2, the synthesis rate of 2, 3-dihydro-benzo [1, 4] dioxin-6-ol was 59.1%. Using Infrared spectroscopy, mass spectrometry and nuclear magnetic resonancespectroscopy for structure identification and characterization, the final product was identified as 2, 3-dihydro-benzo [1, 4] dioxin-6-ol.(2) Taking catechol and 1, 3-Dibromopropan as starting materials, refer to the synthesis method of 2, 3-dihydro-benzo [1, 4] dioxin-6-ol. Using Infrared spectroscopy, mass spectrometry and nuclear magnetic resonance spectroscopy for structure identification and characterization, the final product was identified as 3,4-Dihydro-2H-benzo[b] [1, 4] dioxepin-7-ol.(3) Antioxidant capacity of sesamol and its analogues was determined. The results showed that with the addition of antioxidants increased, antioxidant capacity of them improved. The order of reducing power and scavenging hydroxyl free radical ability as follows: sesamol > 2, 3-dihydrobenzo [1, 4] dioxin-6-ol > 3, 4-dihydro-2H-benzo [b] [1, 4] dioxepin-7-ol. The ability of remove DPPH free radical of 2, 3-dihydro-benzo [1, 4] dioxin-6-ol was the strongest while 3, 4-dihydro-2H-benzo [b] [1, 4] dioxepin-7-ol was the weakest.(4) By the experiment of accelerated oxidation of oils, the antioxidative effect of sesamol and its analogues in peanut oil, corn oil, sun flower oil and lard was determined. The results showed that 2, 3-dihydro-benzo [1, 4] dioxin-6-ol had obvious antioxidantive effect in oils, 3, 4-dihydro-2H-benzo[b] [1, 4] dioxepin-7-ol was relatively poor and sesamol was the best, compared with vegetable oils, the three exhibited better antioxidant activity in lard.