Abstract:Propofol (2,6-diisopropyl phenol) is a widely used intravenous anesthetic. To define its pharmacokinetics and pharmacodynamics, methods for its quantitation in biological matrixes have been developed, but its pattern of mass spectral fragmentation is unknown. We found that fragmentation of the [M Ϫ H] Ϫ ion (m/z 177) of propofol in both APCI MS/MS and ESI MS/MS involves the stepwise loss of a methyl radical and a hydrogen radical from one isopropyl side chain to give the most intense product ion, [M ϪH Ϫ CH 4 … Show more
“…As in the case of DIC, the halogenated ring was untouched; MS (Paíga et al, 2015), most probably the isobutyl sidechain is hydroxylated. The found fragmentation pathway was similar to that described for alkyl-phenols in (Bajpai et al, 2005). …”
In the current study, decomposition of diclofenac, diflunisal, ibuprofen, mefenamic acid and piroxicam was tested using nine identified strains of endophytic and epiphytic fungi (from Ascomycota) adapted to natural products resembling the pharmaceuticals. The strains were isolated from a medicinal plant, Plantago lanceolata leaves. Metabolites were tentatively identified by liquid chromatography -tandem mass spectrometry ).Eighteen of the 45 combinations resulted in significant decrease of the concentration of the NSAIDs in model solutions. The most active strains were Aspergillus nidulans and Bipolaris tetramera, while Epicoccum nigrum and Aspergillus niger showed somewhat less potency. Piroxicam and diclofenac were most resistant to biotransformation, while ibuprofen and mefenamic acid were efficiently metabolized by most strains. Ten metabolites could be tentatively identified, includinghydroxy-metabolites of all tested NSAIDs, and a dihydroxy-metabolite of piroxicam. This biotransformation is likely to modify the toxicity and bioaccumulation potential of these pharmaceuticals.The results highlight the applicability of polyphenol-rich dried medicinal plant materials as an excellent source of fungi with high biotransforming potential. The results also suggest more in-depth testing of these fungi for biodegradation processes.
“…As in the case of DIC, the halogenated ring was untouched; MS (Paíga et al, 2015), most probably the isobutyl sidechain is hydroxylated. The found fragmentation pathway was similar to that described for alkyl-phenols in (Bajpai et al, 2005). …”
In the current study, decomposition of diclofenac, diflunisal, ibuprofen, mefenamic acid and piroxicam was tested using nine identified strains of endophytic and epiphytic fungi (from Ascomycota) adapted to natural products resembling the pharmaceuticals. The strains were isolated from a medicinal plant, Plantago lanceolata leaves. Metabolites were tentatively identified by liquid chromatography -tandem mass spectrometry ).Eighteen of the 45 combinations resulted in significant decrease of the concentration of the NSAIDs in model solutions. The most active strains were Aspergillus nidulans and Bipolaris tetramera, while Epicoccum nigrum and Aspergillus niger showed somewhat less potency. Piroxicam and diclofenac were most resistant to biotransformation, while ibuprofen and mefenamic acid were efficiently metabolized by most strains. Ten metabolites could be tentatively identified, includinghydroxy-metabolites of all tested NSAIDs, and a dihydroxy-metabolite of piroxicam. This biotransformation is likely to modify the toxicity and bioaccumulation potential of these pharmaceuticals.The results highlight the applicability of polyphenol-rich dried medicinal plant materials as an excellent source of fungi with high biotransforming potential. The results also suggest more in-depth testing of these fungi for biodegradation processes.
“…The mass spectral fragmentation of propofol and related phenols such as thymol was thoroughly studied by Bajpai et al [14] who used transitions 177.2 → 161.2 and 149.2 → 133.0 for propofol and thymol, respectively. These transitions correspond to the loss of methane by the sequential loss of CH 3 and H radicals.…”
“…Recently, Bajpai et al [13] reported the formation of the phenoxide radical anion in a CID experiment. The collision energy employed in their experiment was 30-45 eV, i.e.…”
Section: Resultsmentioning
confidence: 99%
“…[9] Sometimes, when competing reaction exit channels were not available, radical species appeared as the fragmentation products. [13] It was also proposed that a lower reverse activation barrier due to aromatic stabilization might kinetically favor the formation of radical fragments. [9] In almost all of the cases, the 'even-electron rule' was violated, the decomposition of evenelectron precursor ions was achieved by highly energetic EI or high-energy collisional activation.…”
Electrospray-generated precursor ions usually follow the 'even-electron rule' and yield 'closed shell' fragment ions. We characterize an exception to the 'even-electron rule.' In negative ion electrospray mass spectrometry (ES-MS), 2-(ethoxymethoxy)-3-hydroxyphenol (2-hydroxyl protected pyrogallol) easily formed a deprotonated molecular ion (M-H)(-) at m/z 183. Upon low-energy collision induced decomposition (CID), the m/z 183 precursor yielded a radical ion at m/z 124 as the base peak. The radical anion at m/z 124 was still the major fragment at all tested collision energies between 0 and 50 eV (E(lab)). Supported by computational studies, the appearance of the radical anion at m/z 124 as the major product ion can be attributed to the combination of a low reverse activation barrier and resonance stabilization of the product ions. Furthermore, our data lead to the proposal of a novel alternative radical formation pathway in the protection group removal of pyrogallol.
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