Monitoring the Effect of Micro-oxygenation before Malolactic Fermentation on South African Pinotage Red Wine with Different Colour and Phenolic Analyses

The use of micro-oxygenation and its effect on the quality of the red wine varietal, Pinotage, is largelyunknown. The influence of adding different oxygen dosages before malolactic fermentation on thephenolic composition and colour stabilisation of wine made from Pinotage was studied, and thesuitability of certain spectrophotometric and RP-HPLC analyses to determine these changes wereassessed in tanks of commercial lengths. Total oxygen dosages of 0 mg/L, 16 mg/L and 32 mg/L wereapplied, after which the wines underwent malolactic fermentation and maturation in the same tanks fortwo additional months. Decreases in anthocyanin concentration showed a strong inversely proportionalcorrelation with increasing polymeric pigment concentration. This suggests that the addition ofoxygen contributed to the early stabilisation of wine colour in Pinotage red wine. Overall, tanninconcentrations were not significantly influenced by the oxygen treatments, although lower levels wereobserved in wines treated with oxygen. An important finding of the study was that there appeared to belittle difference in the colour and phenolic composition of the wines between the 16 mg/L and 32 mg/Loxygen treatments. Good correlations were found between certain spectrophotometric techniques andthe RP-HPLC analysis used to study changes induced by micro-oxygenation (total anthocyanins, totalphenols). The colour and phenolic composition of Pinotage wine can be influenced before malolacticfermentation by micro-oxygenation. Some spectrophotometric phenolic analyses showed the sametendencies as observed with RP-HPLC (anthocyanins, monomeric flavan-3-ols, tannins), indicating theirsuitability to follow phenolic and colour changes induced by micro-oxygenation in Pinotage red wine

Biochemical control of the mitochondrial protein MitoNEET by biological thiols and lipid-derived electrophiles

MitoNEET is a mitochondrial [2Fe-2S]-containing protein known for its involvement in cellular metabolism, iron regulation, and oxidative stress. The protein has been associated with diseases ranging from diabetes to Parkinson's disease, prompting the development of compounds designed to target mitoNEET selectively. Unfortunately, drug development is limited due to a lack of mechanistic understanding of how mitoNEET integrates into pathophysiological processes, and biological compounds that govern mitoNEET function are still ill-defined. We demonstrate an oxygen-dependent reaction with biological thiols catalyzed by mitoNEET. Specifically, we observed that mitoNEET converts L-cysteine to cystine. Finally, we showed that reduced glutathione (L-GSH) regulates the reactivity of two lipid-derived biomarkers of oxidative stress, 4-HNE and 4-ONE, towards mitoNEET. We found that exposure to L-GSH before treatment with either of the electrophilic aldehydes prevents the formation of a covalently linked mitoNEET dimer. Meanwhile, adding L-GSH after electrophile treatment recovers mitoNEET from the 4-HNE induced modification but not from the modification induced by 4-ONE. These results indicate a possible role for mitoNEET in thiol-mediated oxidative stress and may facilitate the development of drugs designed to modulate mitoNEET activity to improve pathophysiological states