The Epimerization of Sesamin and Asarinin

Abstract

Sesamin (1) and asarinin (2) are two C-7′ epimeric lignans. Molecular modeling by semiempirical methods indicated that 1 is more stable than 2 by about 2.5 kcal/mol. However, epimerization under acidic conditions led to a 44.8/55.2 equilibrium ratio of 1 and 2. Single-crystal X-ray diffraction analyses indicated that 1 was monoclinic with a ) 10.0435(19) Å, b ) 6.9151(8) Å, c ) 11.8460(13) Å, and 2 was triclinic with a ) 5.595(5) Å, b ) 9.5910(18) Å, c ) 15.620(4) Å. The unexpected equilibrium ratio of 1 and 2 indicated that structural changes are dependent on the conditions of the extraction processes.

Comparison of Metabolism of Sesamin and Episesamin by Drug-Metabolizing Enzymes in Human Liver

“…Episesamin is rarely found in unrefined sesame oil but is generated from sesamin in equivalent amounts during acid-clay bleaching of the oil (Li et al, 2005); therefore, commercially available sesamin supplements contain both sesamin and episesamin at a ratio of approximately 1:1. Thus, effects of sesamin supplements depend on both sesamin and episesamin, which are known to have biological effects such as antioxidant effect (Ikeda et al, 2003;Nakai et al, 2003), anticarcinogenic effects (Hirose et al, 1992;Miyahara et al, 2000), and suppression of hypertension (Miyawaki et al, 2009).…”

Use of high resolution LC–MSn analysis in conjunction with mechanism-based stress studies: Identification of asarinin, an impurity from sesame oil in an animal health product

“…An examination of the product formulation suggested that the unknown species relates to one of the main excipients, sesame oil. The formula of the unknown species was then found to match that of sesamin and asarinin (an epimer of sesamin, also known as episesamin) that can be extracted from sesame oil [8]. Using an acidic stress condition known in the literature [8], asarinin was generated from sesamin via epimerization; the retention time and MS n fragmentation patterns of the stress generated asarinin match those of the unknown peak, confirming the proposed structure for the latter.…”

Absolute Configuration of Antifi brotic (+)-Episesamin Isolated from Lindera obtusiloba BLUME

“…1). The structure was solved in the monoclinic space group P2 1 , which is in contrast to Li et al (2005), who found the crystals of asarinin [synonym for (+)-episesamin] to be triclinic. None of six published X-ray analyses of sesamin and episesamin provides direct proof of their absolute confi gurations, but of their relatives only: Baures et al (1992), II´in et al (1994), Parmar et al (1998), Li et al (2005), Macias and Zubia (1992), Hsieh et al (2005).…”

“…The structure was solved in the monoclinic space group P2 1 , which is in contrast to Li et al (2005), who found the crystals of asarinin [synonym for (+)-episesamin] to be triclinic. None of six published X-ray analyses of sesamin and episesamin provides direct proof of their absolute confi gurations, but of their relatives only: Baures et al (1992), II´in et al (1994), Parmar et al (1998), Li et al (2005), Macias and Zubia (1992), Hsieh et al (2005). Mata et al (1998) showed an X-ray structure of asarinin obtained by Cu-K α radiation and mentioned a deposition of the X-ray data at the Cambridge Crystallographic Data Centre (CCDC), but no number was given, and the data were not found to contain any studies of Mata et al In addition, from the paper it was not clear whether episesamin exhibited a positive value of optical rotation or not, but the depicted X-ray structure points to (-)-asarinin.…”