Formation of Samin Diastereomers by Acid-Catalyzed Transformation of Sesamolin with Hydrogen Peroxide

Abstract

The conversion of sesame lignans is of interest because the derived products may have potential applications. Here, in investigating the transformation of sesamin and sesamolin, main endogenous sesame lignans in sesame seeds, in both acidic aqueous and anhydrous systems, 7R,7′S-samin was identified as one of the major products of sesamolin in both systems catalyzed with common inorganic acids, but sesaminol was not generated. In investigating the effect of different oxidizing agents on the acid-catalyzed conversion of sesame lignans, 7R,7′S-samin was still the major product of sesamolin, whereas sesamolin as well as 7R,7′S-samin stereoselectively rendered 7R,7′R-samin in the presence of hydrogen peroxide. Hydrogen peroxide may play a role in stabilizing the transitional oxonium ions, derived from acid hydrolysis of sesamolin or 7R,7′S-samin by forming a seven-membered ring intermediate through hydrogen bonding, to consequently produce 7R,7′R-samin as the final product.

Kinetic modeling of the sesamin conversion into asarinin in the presence of citric acid loading on Hβ

“…During the kinetic modeling stage, the concentrations of sesamin and asarinin were used as observables. DDAPLUS solver, included in Athena Visual Studio, integrates ordinary differential equations (ODEs) ( 10 , 11 ). This solver is a modified Newton algorithm used in conjunction with a fixed leading coefficient backward difference formula for the approximation of first-order derivatives ( 31 ).…”

“…Asarinin is a geometrical isomer of sesamin generated under certain conditions of temperature and acidity ( 8 ). It is formed from sesamin during refining processes (i.e., acid clay bleaching and deodorization at high temperature) ( 9 , 10 ). Compared with homogeneous catalysts (e.g., hydrochloric acid and sulfuric acid), heterogeneous catalysts such as phosphotungstic acid ( 11 ), acid cation exchange resin ( 12 ), acid clay ( 13 ), and Hβ zeolite ( 14 ) have the advantages of easier separation and recycling.…”

“…The mechanism of sesamin conversion in a sesame oil system is illustrated in Figure 1 ( 8 , 10 ). In a sesame oil system, CA/Hβ attacks the O atom on the tetrahydrofuran ring of sesamin and absorbs it into the active center of CA/Hβ.…”

Sesame Seeds: A Nutrient-Rich Superfood

“…The results of a study by Nagarajan and Lee [74] have suggested that sesamolin could be a promising antileukemic agent in vivo based on its efficacy in a wehi-3B-induced leukemia model. According to Tsai et al [131] research, it has been demonstrated that the antioxidant activity of related derivatives of sesame lignans may surpass that of endogenous lignans present in sesame oil. In another research, the effectiveness of sesamolin in reducing serum and liver lipid levels, along with a simultaneous increase in liver fatty acid oxidation, was observed [132].…”

Studies on the highly efficient catalyzation of sesamin to asarinin by phosphotungstic acid

“…In the earlier researches, liquid mineral acids, such as HCl and H 2 SO 4 , were used as catalysts for sesamin conversion to asarinin (Kuo et al, 2011;Chen et al, 2018;Tsai et al, 2020). Nevertheless, the intrinsic catalytic activities are relatively low, and the use of these conventional mineral acids causes several problems such as environmental problems, corrosion problems, as well as difficulties of separation from products for reuse.…”