****************************************************************************** From: Gunter Kuhnle Date: 22 May 2000 08:36:49 +0200 Subject: CID spectrum of (epi)catechin Organization: Uni Leipzig Hallo, working with several flavonoids and their glucoconjugates, I have a question on fragments occuring during CID: (Epi)catechin (m=290) gives a pretty intense fragment at m/z 139, which is said to be the product of a retro diels-alder reaction (A-Ring + =O+ and =CH2). Another signal which is said to origine from the A-Ring is m/z 123. Unfortunately, I have no idea what kind of structure this fragment may have. Furthermore, using methylated epicatechin (methylation at one of the catecholic OH-group at the B-ring), the signal 123 m/z disappears, whereas a signal at 137 m/z appears. For this reason, it seems very unlikely to me that 123 m/z originates from the A-Ring. What is your opinion? TIA, Gunter -- Gunter Kuhnle * Uni-Leipzig * Institut fuer Biochemie ****************************************************************************** From: cody@jeol.com (Chip Cody) Subject: Re: CID spectrum of (epi)catechin Date: Fri, 26 May 2000 14:02:00 GMT Organization: JEOL USA, Inc. Our applications laboratory examined catechins in tea by APCI/MS/MS and they came to the same conclusions as Dr. Cren-Olive. The two major fragments are 139 and 123 and they arise from the retro Diels-Alder (m/z 139) and from the B-ring with cleavage at the carbon adjacent to the ether oxygen in the A-ring. Under the in-source CID conditions used, m/z 139 was the base peak for EGC and EGCg, while m/z 123 was the base peak for ECg. This was presented at the ASMS Meeting in Orlando in 1998. Chip Cody JEOL Usa, Inc. -- "For purposes of ... New Jersey Right to Know Act. Contents partially unknown." |____________ |_ Robert B. Cody, Ph.D |________________________________ Product Development Manager |__ Mass Spectrometry |________________________ JEOL USA, Inc. |_ http://www.jeol.com |__________ e-mail: cody@nojunkmail.jeol.com |_ (REMOVE 'nojunkmail' TO REPLY) ============== Do not send me spam or advertising via e-mail !! ========= ****************************************************************************** From: "Cécile Cren-Olivé" Date: Wed, 24 May 2000 19:39:39 +0200 Subject: Re: CID spectrum of (epi)catechin Organization: Universite des Sciences et Technologies de LILLE, France We have recently worked on the identification and characterization of (methylated) flavanols by LC MS/MS and we have submitted a paper at RCMS. CID spectra of (epi)catechin gives indeed two major fragments at m/z 123 and 139. The fragment at m/z 139 is, as you said, a product of retro Diels Alder; the one at m/z 123 origines from the B-ring and presents a quinone methide structure. For further information, you can contact me. Cécile Cren. Université des Sciences et Technologies de Lille (Lille1) UFR de Chimie, Bâtiment C4, 2ième étage UPRESA CNRS 8009, Chimie Organique et Macromoléculaire 59655 Villeneuve d'Ascq Cedex, France Téléphone: 03 20 33 61 35; Télécopie : 03 20 33 61 36