Involvement of a glucosinolate (sinigrin) in the regulation of water transport in Brassica oleracea grown under salt stress.

Members of the Brassicaceae are known for their contents of nutrients and health-promoting phytochemicals, including glucosinolates. The concentrations of these chemopreventive compounds (glucosinolate-degradation products, the bioactive isothiocyanates) may be modified under salinity. In this work, the effect of the aliphatic glucosinolate sinigrin (2-propenyl-glucosinolate) on plant water balance, involving aquaporins, was explored under salt stress. For this purpose, water uptake and its transport through the plasma membrane were determined in plants after NaCl addition, when sinigrin was also supplied. We found higher hydraulic conductance (L0 ) and water permeability (Pf ) and increased abundance of PIP2 aquaporins after the direct administration of sinigrin, showing the ability of the roots to promote cellular water transport across the plasma membrane in spite of the stress conditions imposed. The higher content of the allyl-isothiocyanate and the absence of sinigrin in the plant tissues suggest that the isothiocyanate is related to water balance; in fact, a direct effect of this nitro-sulphate compound on water uptake is proposed. This work provides the first evidence that the addition of a glucosinolate can regulate aquaporins and water transport: this effect and the mechanism(s) involved merit further investigation.

A new ultra-rapid UHPLC/MS/MS method for assessing glucoraphanin and sulforaphane bioavailability in human urine.

Sulforaphane (SFN) is the product of the enzymatic hydrolysis of glucoraphanin (GR), the main glucosinolate present in broccoli sprouts. The beneficial actions attributed to SFN are mainly supported by in dietary study not clear. Surely the panellists ate more than just the broccoli portion - please clarify vitro experiments; further in vivo assays are necessary to analyse the described biological actions in humans. A new ultra-fast, accurate, robust, and selective UHPLC/MS/MS procedure (2-min chromatogram; >87% recovery; LOQ and LOD of 20-156 and 4-20nmol L(-1), respectively; and intra- and inter-day variations lower than 10%) was used for the simultaneous determination of GR and SFN in human urine. The analytical capacity of this novel method was further tested by determining the bioavailability of GR and its metabolic derivatives in urine from volunteers after the consumption of ½ and 1 servings of broccoli sprouts (30 and 60g, respectively). Bioavailability values for SFN of up to 40% after a single intake of both ½ and 1 servings showed the suitability of the new method for the determination of exogenous metabolites following dietary interventions.