Quantification of Methylisothiazolinone and Methylchloroisothiazolinone Preservatives by High-Performance Liquid Chromatography.

Isothiazolinone preservatives (methylisothiazolinone (MIT) and methylchloroisothiazolinone (CMIT) are commonly used in cosmetics, industrial and household products. However, these isothiazolinone derivatives are known to cause allergic contact dermatitis. Hence, a sensitive, accurate, and reliable method for the detection of these compounds is thus warranted. The study aims to analyze concentrations of MIT and CMIT by high performance liquid chromatography. The analytical method used for quantification of MIT and CMIT in cosmetic products (leave-on-baby wet wipes) complies with the validation acceptance criteria (international standards ISO 5725, EU25 European Union for cosmetic regulations). MIT and CMIT were extracted and analyzed in leave-on baby wet-wipes collected from different stores in Riyadh city. Extraction was performed by ultrasonication of the samples, solid-phase extraction, and liquid-liquid extraction. Ten (10) µL of the sample was injected into the HPLC system and samples were analyzed with a mixture of acetic acid and methanol (80:20 v/v) in an isocratic mode. The flow rate was maintained at 1 mL/min. UV detection was performed at 274 nm. The results demonstrated recoveries between 90 and 106%, measurement uncertainty of C +/- 0.4% for methylisothiazolinone and C +/- 0.03% for methylchloroisothiazolinone, repeatability limit (r = 0.2%) and intermediate precision limit; R = 2% and R2 of 0.9996.

Glutathione and oxidized nicotinamide adenine dinucleotide (NAD+) redox status in plasma and placental tissue of Saudi patients with intrauterine growth restriction.

OBJECTIVES: To assess the oxidation state and gene expression profiles of relevant enzymes in intrauterine growth restriction (IUGR) patients in Saudi Arabia. METHODS: Current case-control study involved plasma and placental tissue samples from 25 IUGR patients and 25 healthy pregnant (HP) women attending the Obstetrics and Gynecology Clinic, King Khalid University Hospital, Riyadh, Saudi Arabia, between April and November 2017. We compared hydrogen peroxide, superoxide anions, malondialdehyde, and oxidative stress markers levels and the activities of glutathione-related enzymes (glutathione peroxidase [GPx], glutathione reductase [GR], glutathione S-transferase [GST], glutamate cysteine ligase [GCL], glutathione synthetase [GS], reduced glutathione [GSH], oxidized glutathione [GSSG], and oxidized nicotinamide adenine dinucleotide [NAD+], and reduced NAD [NADH]) between the 2 groups. We also compared differential expression levels of glutathione-related enzyme genes using reverse transcription-quantitative polymerase chain reaction. RESULTS: Oxidative stress markers significantly differed in IUGR samples, while GSH levels and GPx, GR, GST, GCL, and GS activities and their placental mRNA transcriptional levels were significantly lower. Plasma and placental NAD+ levels were also significantly lower, while NADH levels were significantly higher, causing lowered NAD+-NADH ratios in the IUGR group compared to control. CONCLUSIONS: Intrauterine growth restriction patients show a metabolic shift in favor of oxidation compared to HP women.