Atmospheric Pressure Ionization LC-MS-MS Determination of Urushiol Congeners

Abstract

This paper describes atmospheric pressure ionization (API) LC-MS-MS determination of urushiols, 3-n-alkenyl- and -alkyl-substituted catechols responsible for poison oak dermatitis. Urushiol was isolated from Western poison oak according to the method of Elsohly et al. (1) (J. Nat. Prod. 1982, 45, 532-538)-the purified preparation contained C(17)- and C(15)-substituted urushiols with zero, one, two, and three double bonds as determined from GC-MS analysis of trimethylsilyl derivatives. Urushiol mixtures were separated on a C(18) reversed phase HPLC column with a methanol-water gradient with urushiols eluting in 100% methanol. Atmospheric pressure chemical ionization (APCI) produced primarily [M - H](-) and MH(+) molecule ions. Electrospray ionization (ESI) yielded [M - H](-) and adduct ions including [M + Cl](-). Daughter ions of [M - H](-) included quinoid radical anions ([M - H - H(2)](-) and m/z 122(-)) and a benzofuran phenate (m/z 135(-)). A suite of hydrocarbon fragments were produced by collision-induced dissociation of MH(+) directly or via an intermediate [MH - H(2)O](+) daughter ion. Six urushiol congeners, one not previously reported in poison oak, were determined by negative ion API-LC-MS-MS with detection limits of approximately 8 pg/microL (ESI) and approximately 800 pg/microL (APCI). API-LC-MS-MS was used to determine urushiol in surface wipes, air samples, and plant materials.

Electrochemical Single‐Molecule AFM of the Redox Metalloenzyme Copper Nitrite Reductase in Action

“…Compound 8 was therefore assigned to a C 17 ‐triene. An almost identical product ion mass spectrum was obtained by CID of the protonated 3‐heptadecatetraenylcatechol in a recent LC/MS study on the determination of urushiols from poison oak 21. However, in contrast to the product ion structures proposed in the present study (Fig.…”

“…2. Most constituents showed a similar UV‐spectral behavior, with absorption maxima at 275–276 and 280 nm, typical of a 1,3‐dihydroxybenzene chromophore of AR, thus allowing their differentiation from alkylcatechols,21 which do not show an additional band at 280 nm. Since only pentyl‐, pentadecyl‐, heptadecyl‐, and nonadecylresorcinol were available as reference compounds, HPLC coupled to mass spectrometry proved to be extremely helpful for peak assignment and further characterization of individual substances.…”

HPLC in Natural Product Analysis: The Detection Issue

“…For example, HPLC-MS-MS was evaluated for the quantification of urushiol congeners, which are responsible for poison oak dermatitis. ESI (NI) in the MRM mode yielded LODs in the low ppm range that are relevant for toxicological, clinical, and environmental studies of these allergens [110]. Similarly, pyrrolizidine alkaloids, a class of hepatotoxic and tumorigenic phytochemicals, have been analysed in honey samples and in extracts of Echium plantagineum.…”

“…Similarly, pyrrolizidine alkaloids, a class of hepatotoxic and tumorigenic phytochemicals, have been analysed in honey samples and in extracts of Echium plantagineum. ESI (PI) provided good detection limits for these compounds; however, previous sample enrichment with strong cation-exchange SPE was mandatory [110]. The consumption of slimming regimens made of Chinese herbal preparations has caused intoxications associated with species of the Aristolochia genus, which contain highly nephrotoxic and carcinogenic metabolites called aristolochic acids.…”

Effect of the Extracts from Fermented-Rhus verniciflua Stem Bark with Fomitella fraxinea on the Growth and Enzyme Activity of Soybean Product-fermenting Microorganisms

“…옻은 혈액순환 촉진, 위장질환, 심장 질환, 부인과 질환 (Namba, 1980) 등에 효과가 있으나 urushiol을 함유하고 있어 수포, 가려움, 발진 등을 동반한 접촉성피부염을 유발하기 때문에 (Epstein, 1974) 그 사용 에 주의를 기울여 왔다. 서양인들은 동양인 보다 urushiol 에 민감한 탓에 (Draper et al, 2002) 옻에 의해 유발된 접 촉성 피부염을 치료하기 위한 분야가 발전된 반면 (Vidmar and Iwane, 1999;Patterson et al, 1999;Saary et al, 2005) 동양에서는 옻의 독성을 제거하고 약리적으로 이용 하고자 하였다 (Kim et al, 2002). 우리나라 및 중국의 전 통의학에서 사용되는 옻은 1차적으로 자연 건조시키거나 끓여 말린 후 2차적으로 잘게 갈아서 충분히 볶아 그 독 성을 제거하여 사용하였는데 (Eom and Kim, 2008) 이는 urushiol이 비교적 산화되기 쉽고 열안정성이 낮아 중합되 거나 휘발되어 제거되는 원리를 이용한 것이다 (Choi et al, 2007b).…”