A novel conversion of sesamolin to sesaminol by acidic cation exchange resin

Abstract

Sesame (Sesamum indicum L.) seed and its oil contain abundant lignans, including sesamin, sesamolin, sesamol, sesaminol, and their glycosides. In the present study, a novel reaction pathway, using an anhydrous solvent system, cation exchange resin catalyst, and HPLC for detection, was employed for the conversion of sesamolin into sesaminol. Under optimal conditions of 5 mL toluene, 908C, initial sesamolin concentration of 6 mM, and catalyst dosage of 16.66 g/mmol of sesamolin, a 75.0% yield of sesaminol was achieved. The reaction mechanism was inferred to be that of a Friedel-Crafts reaction, with the catalyst showing remarkable catalytic activity and producing only slightly decreased yield after reuse in five subsequent batches. Owing to excellent reusability, low cost, and ready availability, this catalyst provides a very satisfactory option for converting sesamolin to sesaminol.Practical applications: Sesaminol is a potential natural antioxidant for use as a food additive and in medicinal applications, but it is a naturally occurring trace compound, and could be transformed from sesamolin under proper, specific conditions. The cation exchange resin 732 provides a satisfactory option for catalyzing the conversion of sesamolin into sesaminol. This suggests encouraging prospects for practical or industrial applications utilizing its notable catalytic performance, reusability, low cost, and easy availability.

Examination of the Modified Villavecchia Test for Detecting Sesame Oil

“…We also observed that sesaminol accumulated during the first 40 min of incubation whereas the content of sesamol stayed relatively constant during the 100 min of hydrochloric acid treatment. Therefore, we agree with Huang et al [16] and consider the mechanism of the Villavecchia test for detecting sesame oil as follows. In brief, the unreliable sesamolin is firstly decomposed by concentrated hydrochloric acid into the primary products, sesamol and an intermediate oxonium ion, and afterward, the primary products undergo an electrophilic addition reaction of rearrangement for each other to generate sesaminol, and/or a portion of sesamol reacts with furfural to produce the chromogenic complex (Fig.…”

“…Although both sesamolin and sesamol were contributive to the chromogenic reaction, sesamol was considered the real reactant of the Villavecchia reaction which was able to react with furfural to produce color complex. According to the results of Huang et al [16] and this study, we speculated that sesamolin was very unreliable with hydrochloric acid and would be decomposed into sesamol and an intermediate oxonium ion during the Villavecchia test, and subsequently the reactant sesamol could react with furfural to form the chromogenic complex and/or rearrange with the oxonium ion at the ortho position through the electrophilic addition to generate sesaminol. In our study, sesaminol could not be quantified directly due to the lack of a commercial standard.…”

“…However, sesamol was considerably depleted during oil deodorization, whereas sesaminol was maintained in the oil [14,15]. Recently, Huang et al [16] investigated the conversion of sesamolin to sesaminol by acidic cation exchange resin, and provided a rational mechanism of conversion in that sesamolin was decomposed under acidic conditions to produce primary products including sesamol and an oxonium intermediate, then the intermediate was able to react further with sesamol to produce sesaminol. In this work, we discovered that sesamol is a degradation product of sesamolin treated with concentrated HCl, but the amount of sesamol generation is not proportional to that of sesamolin degradation.…”

Lignans of Sesame (Sesamum indicum L.): A Comprehensive Review

“…The mechanism of these transformations has not been conclusively established. Based on their study on the conversion of sesamolin to sesaminol under anhydrous conditions catalyzed by sulfonic acid and on Fukuda’s original work [ 131 ], Huang and coworkers [ 132 ] suggested a two-step mechanism. According to their hypothesis, protonated sesamolin brakes down into sesamol and oxonium ion, both of which subsequently recombine into the products.…”

Purification, Gene Cloning, and Biochemical Characterization of a β-Glucosidase Capable of Hydrolyzing Sesaminol Triglucoside from Paenibacillus sp. KB0549

“…It is important to note that STG displays only a negligible level of antioxidant activity in vitro [8], [9]. Moreover, the formation of bioactive sesaminol in sesame oils does not arise from the hydrolysis of STG; it is produced from sesamolin through acid catalysis during the bleaching step of the refining process of sesame oil production [10], [11]. STG occurs abundantly in sesame oil cake, and is produced as a by-product of sesame oil production in a large amount and can serve as an inexpensive source for the industrial production of sesaminol.…”