PubMed · 5034163
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H Weitgasser. 1972-03-31. [Experience with Phlebex].. https://pubmed.ncbi.nlm.nih.gov/5034163/
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Reactions of the strong skin sensitizer hexadec-1-ene-1,3-sultone with sodium hydroxide, sodium methoxide, sodium metabisulfite, sodium butanethiolate, n-butylamine, and aniline have been investigated, and the reaction products have been identified. Most of the nucleophiles studied react by nucleophilic addition (Michael type addition) to the double bond at the 2-position, although in most cases the final products result from further reactions of the initital adducts. The findings are considered together with those reported by Meschkat, Barratt, and Lepoittevin for reactions of hex-1-ene-1,3-sultone and hexane-1,3-sultone, and the implications of the two sets of findings for the mechanism of skin-sensitizing action are discussed. It is concluded that nucleophilic attack at the 3-position of the alk-1-ene-1,3-sultones occurs only with those nucleophiles, which either have very low reactivity in nucleophilic addition or are unable to give rise to thermodynamically stable products via initial reaction at the 2-position. It is further concluded that the observed differences in electrophilic reactivity between alk-1-ene-1,3-sultones and alkane-1,3-sultones are not large enough to rationalize the differences in skin sensitization properties between the two types of sultone. It is suggested that the differences in specificity arise because the alk-1-ene-1,3-sultones act as Michael type electrophiles whereas the alkane sultones act as SN2 electrophiles. It is suggested that the reason for the greater potency of the alk-1-ene-1,3-sultones may be the ability of the initial C2 adducts with protein to undergo further reactions by substitution at C3, leading to cross-linking and consequent perturbation to the protein tertiary structure.
A method of test for residual isophorone diisocyanate (IPDI) trimer in experimental formulation polyester-polyurethane (PEPU) thermoset coatings on metal food packaging is described. The method involves extraction of coated panels using acetonitrile containing dibutylamine for concurrent derivatisation, and then high performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection (LC-MS/MS). Single laboratory validation was carried out using three different experimental PEPU-based coatings. The calibrations were linear, the analytical recovery was good, no interferences were seen, and substance identification criteria were met. The detection limit of the method is around 0.02 micro g/100 cm(2) of coating, which for a typical sized can and assuming complete migration of any residual IPDI trimer, corresponds to about 0.2 micro g/kg food or beverage. Separate studies indicated that, even if migration occurred at such low levels, the IPDI trimer would not be expected to persist in canned aqueous or fatty foodstuffs as it would hydrolyse to the corresponding aliphatic amine or react with food components to destroy the isocyanate moiety. The method of test developed here for residual IPDI trimer in thermoset polyester-polyurethane coatings should prove to be a valuable tool for investigating the cure kinetics of these novel coatings and help to guide the development of enhanced formulations.
Inoculation of leaf explants of Echinacea purpurea (Moench) with Agrobacterium rhizogenes induced hairy roots with the capacity to produce biologically active caffeic acid derivatives (CADs), especially cichoric acid. The kinetics of growth, the uptake of macronutrients, and the accumulation of CADs were investigated in heterotrophically cultured hairy roots for a 50 day period. A maximum of 12.2 g L(-1) dry biomass was achieved in MS nutrients supplemented with 30 g L(-1) sucrose on day 40. The mathematical relationship between hairy root growth and conductivity was established during the exponential phase in Erlenmeyer flasks. HPLC analyses of methanolic (0.1% phosphoric acid; 70:30, v/v) extracts from hairy roots revealed the presence of important CADs: cichoric acid (19.21 mg g(-1) dry biomass), caftaric acid (3.56 mg g(-1) dry biomass), and chlorogenic acid (0.93 mg g(-1) dry biomass). These results demonstrate that biotechnological production of CADs in hairy roots of E. purpurea is possible. Furthermore, these hairy root cultures offer, for the very first time, an excellent biological model to study the biosynthetic pathway of medicinally important CADs.