Sinalbin

Abstract: The mustard oil glucosides, sinigrin, sinalbin, and glucocheirolin and the musard oil, allyl isothiocyanate, as well as the enzyme myrosin, were prepared from the seeds of cruciferous plants. Pieri...

Abstract: Glucosinolates, anionic sulfur rich secondary metabolites, have been extensively studied because of their occurrence in the agriculturally important brassicaceae and their impact on human and animal health. There is also increasing interest in the biofumigant properties of toxic glucosinolate hydrolysis products as a method to control agricultural pests. Evaluating biofumigation potential requires rapid and accurate quantification of glucosinolates, but current commonly used methods of extraction prior to analysis involve a number of time consuming and hazardous steps; this study aimed to develop an improved method for glucosinolate extraction. Three methods previously used to extract glucosinolates from brassicaceae tissues, namely extraction in cold methanol, extraction in boiling methanol, and extraction in boiling water were compared across tissue type (root, stem leaf) and four brassicaceae species (B. juncea, S. alba, R. sativus, and E. sativa). Cold methanol extraction was shown to perform as well or better than all other tested methods for extraction of glucosinolates with the exception of glucoraphasatin in R. sativus shoots. It was also demonstrated that lyophilisation methods, routinely used during extraction to allow tissue disruption, can reduce final glucosinolate concentrations and that extracting from frozen wet tissue samples in cold 80% methanol is more effective. We present a simplified method for extracting glucosinolates from plant tissues which does not require the use of a freeze drier or boiling methanol, and is therefore less hazardous, and more time and cost effective. The presented method has been shown to have comparable or improved glucosinolate extraction efficiency relative to the commonly used ISO method for major glucosinolates in the Brassicaceae species studied: sinigrin and gluconasturtiin in B. juncea; sinalbin, glucotropaeolin, and gluconasturtiin in S. alba; glucoraphenin and glucoraphasatin in R. sativus; and glucosatavin, glucoerucin and glucoraphanin in E. sativa.

Abstract: Meal produced from Sinapis alba seed by crushing to remove oil contains a glucosinolate that when hydrolyzed produces phytotoxic allelochemicals; however, the responsible compounds and pathways for their production have not been elucidated. S. alba seed meal and partially purified extracts containing 4-hydroxybenzyl glucosinolate were included in experiments to identify and monitor enzymatically released products using GC−MS and HPLC−MS. The initial product, 4-hydroxybenzyl isothiocyanate, was unstable in aqueous media, showing a half-life of 321 min at pH 3.0, decreasing to 6 min at pH 6.5. More alkaline pH values decrease the stability of 4-hydroxybenzyl isothiocyanate by promoting the formation of a proposed quinone that hydrolyzes to SCN-. Measurement of SCN- showed stoichiometric release from S. alba meal at 48 h when buffered at pH values as low as 4.0, demonstrating that SCN- production in soil is not only probable but likely responsible for observed phytoxicity of the meal. Keywords: Glucosinolate...

Abstract: Sinapis alba is less susceptible to damage by insect pests than Brassica napus. We investigated the composition and distribution of glucosinolates in different plant parts in three populations of S. alba; two populations selected for low-seed-glucosinolate content and one commercial cultivar. We have assessed the susceptibility of low-seed-glucosinolate content populations of S. alba to four insect pests, a flea beetle, a pollen beetle, and two species of aphids. Over 90% of the total glucosinolates in the cotyledons of the three populations of S. alba consisted of sinalbin. There was no difference in feeding damage by flea beetles on different S. alba populations at the cotyledon stage, nor was there a difference in sinalbin concentration of cotyledons. Total glucosinolate levels were highest in younger plant tissues. Sinalbin declined as a proportion of total glucosinolate content in later growth stages, especially in the “low” breeding lines. Reproduction by aphids was the same on all three populations despite differences in sinalbin content of the S. alba leaves at the growth stage tested. The specialist aphid, Brevicoryne brassicae, was found mainly on young tissues, while the generalist aphid, Myzus persicae, was found predominantly on older plant parts. There was no difference in oviposition by pollen beetles between the S. alba populations, despite the fact that on one population total glucosinolate concentration and the proportion of sinalbin found in the buds were much lower than on the other two populations.