Influence of glyphosate and aminomethylphosphonic acid on the mobility of trace elements in uncontaminated and contaminated agricultural soils.

Glyphosate is one of the most widely used herbicides in the world. In addition to its herbicidal effect, glyphosate is a chelating agent that can form complexes with trace elements. Yet, agricultural soils can be contaminated with both organic and mineral substances, questioning the possible influence of glyphosate application on the trace element mobility. In this context, we specifically studied the extractability of trace elements in uncontaminated and metal-contaminated agricultural soils by adding glyphosate, formulated glyphosate, and aminomethylphosphonic acid (AMPA, a degradation product of glyphosate) in batch experiments from 0 to 100 mg L-1. Results showed that, on average, glyphosate enhanced the extractability of the elements considered (e.g., As, Cd, Cu, Pb, and Zn) at 20 and 100 mg L-1. Surprisingly, the uncontaminated soil highlighted the highest influence of glyphosate compared to the contaminated ones, likely resulting from a higher natural element extractability in the contaminated soils. Although formulated glyphosate presented an overall higher impact than unformulated glyphosate, it was evidenced that AMPA showed lower influence meaning that glyphosate degradation is beneficial to limit deleterious effects.

3-Sulfanyl-4-methylpentan-1-ol in Dry-Hopped Beers: First Evidence of Glutathione S-Conjugates in Hop (Humulus lupulus L.).

Monovarietal dry-hopped beers were produced with the dual-purpose hop cultivars Amarillo, Hallertau Blanc, and Mosaic. The grapefruit-like 3-sulfanyl-4-methylpentan-1-ol was found in all three beers at concentrations much higher than expected on the basis of the free thiol content in hop. Even cysteinylated precursors proved unable to explain our results. As observed in wine, the occurrence of S-glutathione precursors was therefore suspected in hop. The analytical standards of S-3-(4-methyl-1-hydroxypentyl)glutathione, never described before, and of S-3-(1-hydroxyhexyl)glutathione, previously evidenced in grapes, were chemically synthesized. An optimized extraction of glutathionylated precursors was then applied to Amarillo, Hallertau Blanc, and Mosaic hop samples. HPLC-ESI(+)MS/MS revealed, for the first time, the occurrence of S-3-(1-hydroxyhexyl)glutathione and S-3-(4-methyl-1-hydroxypentyl)glutathione in hop, at levels well above those reported for their cysteinylated counterparts. S-3-(1-Hydroxyhexyl)glutathione emerged in all cases as the major adduct in hop. Yet, although 3-sulfanylhexan-1-ol seems relatively ubiquitous in free, cysteinylated, and glutathionylated forms, the glutathione adduct of 3-sulfanyl-4-methylpentan-1-ol, never evidenced in other plants up to now, was found only in the Hallertau Blanc variety.