Characterization of Two Unknown Compounds in Methanol Extracts of Rosemary Oil

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• 作者：Evelyne H. A. Doolaege ; Katleen Raes ; Karen Smet ; Mirjana Andjelkovic ; Christof Van Poucke ; Stefaan De Smet ; Roland Verhé
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2007
• 出版时间：September 5, 2007
• 年：2007
• 卷：55
• 期：18
• 页码：7283 - 7287
• 全文大小：92K
• 年卷期：v.55,no.18(September 5, 2007)
• ISSN：1520-5118

文摘

In this study, two unknown compounds in rosemary oil, containing 3% carnosic acid and 0.3% carnosol,were identified and characterized. After methanol extraction, purification, and analysis by reversed-phase HPLC and LC-MS, a recovery of 92% (±8%) of carnosic acid was obtained, but no carnosolwas found. However, two unknown compounds with a molecular weight of 330.2 and 302.2 wereconsistently detected. From additional LC-MS-MS, ¹H NMR, and elemental analyses, it became clearthat the first compound (M_w = 330.2) could not be carnosol. It was hypothesized that it originatedfrom the breakdown of the intramolecular bond of carnosol, followed by the addition of a watermolecule. Possibly, an unsaturated double bond was formed after dehydration. Assuming that thiscompound was an intermediate in the conversion to rosmanol, the second unknown compound (M_w= 302.2) may have resulted from the breakdown of the intramolecular bond of rosmanol. Similarly,an unsaturated double bond may have been formed. After splitting off carbon oxide, a detectablemolecule with a molecular weight of 302.2 was observed.