Development of an analytic method for organosulfur compounds in Welsh onion and its use for nutritional quality analysis of five typical varieties in China

A reliable, simple, and sensitive method capable of quantifying six organosulfur compounds (OSCs) was established. The samples were extracted by water containing 3 % formic acid with a simple vortex, ultrasound, and centrifugation step, and the solutions were analyzed by ultra-high-performance liquid chromatography separation system coupled with a triple-quadrupole mass spectrometry (UHPLC - MS/MS). Then the method was applied for the analysis of six OSCs in five varieties of two types Welsh onions in China, and the moisture content, reducing sugar, total polyphenols, and 21 free amino acids were also analyzed to study the characters of these Welsh onions intensively. Multivariate statistical analysis was used to investigate the differences in OSCs and free amino acids profiles among the samples. This study showed that enzymatic inhibition method combined with UHPLC - MS/MS is an effective technique to analyze OSCs in Welsh onion, and could be valuable for the routine quantitation of OSCs in other foods.

Development of methods for quantitative determination of the total and reactive polysulfides: Reactive polysulfide profiling in vegetables

Alliaceous and cruciferous vegetables are rich in bioactive organosulfur compounds, including polysulfides, which exhibit a broad spectrum of potential health benefits. Here, we developed novel, accurate, and reproducible methods to quantify the total polysulfide content (TPsC) and the reactive polysulfide content (RPsC) using liquid chromatography-electrospray ionization-tandem mass spectrometry, and analyzed the reactive polysulfide profiles of 22 types of fresh vegetables, including onions, garlic, and broccoli. Quantitative analyses revealed that onions contained the largest amounts of polysulfides, followed by broccoli, Chinese chive, and garlic. A strong positive correlation was observed between the TPsC and RPsC, whereas only a moderate positive correlation was found between the total sulfur content and TPsC. These results suggest that reactive polysulfide profiling can be a novel criterion for evaluating the beneficial functions of vegetables and their derivatives, which may lead to an understanding of the detailed mechanisms underlying their bioactivities.

Diallyl trisulfide regulates rat colonic smooth muscle contractions by inhibiting L-type calcium channel currents

Diallyl trisulfide (DATS) is an active organosulfide component of allicin and has several beneficial effects, including antimicrobial, antioxidant, cardioprotective and anticancer effects. Few studies have shown the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle cells and colonic motility. To investigate the modulatory effect of DATS on L-type calcium channels in rat colonic smooth muscle and colonic contraction, L-type calcium channel currents were recorded, and colonic contractility in longitudinal and circular smooth muscle strips was measured. DATS attenuated L-type calcium channel currents without affecting steady-state activation or inactivation kinetics and inhibited the spontaneous contractions of both longitudinal and circular smooth muscle strips dose-dependently. In conclusion, DATS has an inhibitory effect on the contractions of colonic muscle strips that is related to its regulation of L-type calcium channels.