Influence of isolation techniques on the composition of glucosinolate breakdown products, their antiproliferative activity and gastrointestinal stability of allyl isothiocyanate

Mustard seeds are used as a food, and spice due to their nutritive value, the presence of biologically active compounds, and specific taste. Its morphology was investigated by optical microscopy and scanning electron microscopy before and after isolation by hydrodistillation and microwave assisted distillation. The chemical composition of volatile compounds in different mustard seeds ( Brassica juncea L. and Brassica nigra L.) was determined using GC–MS, after applying various techniques (Clevenger hydrodistillation, microwave assisted distillation—MAD, and microwave hydrodiffusion and gravity—MHG). Allyl isothiocyanate, degradation product of allyl glucosinolate, was the main volatile compound in B. juncea essential oils and extract after all applied extraction techniques (91.07–99.01%). Gastrointestinal stability of allyl isothiocyanate was determined employing two-phase digestion model (gastric and duodenal) by two methods (in vitro digestion method using commercial and ex vivo digestion method using human digestive enzymes). The stability rate of allyl isothiocyanate was higher after the gastric digestion phase by both methods. In B. nigra seeds but-3-enyl and allyl isothiocyanate were the main compounds after Clevenger hydrodistillation (80.58% and 15.39%, respectively). After MAD, and MHG the main compounds were 4,5-epithiopentanenitrile (50.70% and 59.93%, respectively), and 3,4-epithiobutanenitrile (7.61% and 25.97%, respectively), originating from the same glucosinolates, i.e. but-3-enyl and allyl glucosinolate, respectively. Antiproliferative activity of mustard seed EOs and extracts was evaluated against human cancer cell lines (MDA-MB-231 and TCCSUP). The best antiproliferative activity was shown for B. nigra MHG extract against MDA-MB-231 cell line with IC 50 value of 9.1 µg/mL.