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Phytochemistry
Krizevski, R., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel, Albert Katz Department of Dryland Agriculture, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer 84990, Israel
Bar, E., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel
Shalit, O., Department of Biology, University of Haifa-Oranim, Tiv'on 36006, Israel
Sitrit, Y., Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Bergman Campus, P.O. Box 653, Beer-Sheva 84105, Israel
Ben-Shabat, S., Department of Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel
Lewinsohn, E., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel
Ephedra sinica Stapf (Ephedraceae) is a widely used Chinese medicinal plant (Chinese name: Ma Huang). The main active constituents of E. sinica are the unique and taxonomically restricted adrenergic agonists phenylpropylamino alkaloids, also known as ephedrine alkaloids: (1R,2S)-norephedrine (1S,2S)-norpseudoephedrine, (1R,2S)-ephedrine, (1S,2S)-pseudoephedrine, (1R,2S)-N-methylephedrine and (1S,2S)-N-methylpseudoephedrine. GC-MS analysis of freshly picked young E. sinica stems enabled the detection of 1-phenylpropane-1,2-dione and (S)-cathinone, the first two putative committed biosynthetic precursors to the ephedrine alkaloids. These metabolites are only present in young E. sinica stems and not in mature stems or roots. The related Ephedra foemina and Ephedra foliata also lack ephedrine alkaloids and their metabolic precursors in their aerial parts. A marked diversity in the ephedrine alkaloids content and stereochemical composition in 16 different E. sinica accessions growing under the same environmental conditions was revealed, indicating genetic control of these traits. The accessions can be classified into two groups according to the stereochemistry of the products accumulated: a group that displayed only 1R stereoisomers, and a group that displayed both 1S and 1R stereoisomers. (S)-cathinone reductase activities were detected in E. sinica stems capable of reducing (S)-cathinone to (1R,2S)-norephedrine and (1S,2S)-norpseudoephedrine in the presence of NADH. The proportion of the diastereoisomers formed varied according to the accession tested. A (1R,2S)-norephedrine N-methyltransferase capable of converting (1R,2S)-norephedrine to (1R,2S)-ephedrine in the presence of S-adenosylmethionine (SAM) was also detected in E. sinica stems. Our studies further support the notion that 1-phenylpropane-1,2-dione and (S)-cathinone are biosynthetic precursors of the ephedrine alkaloids in E. sinica stems and that the activity of (S)-cathinone reductases directs and determines the stereochemical branching of the pathway. Further methylations are likely due to N-methyltransferase activities. © 2010 Elsevier Ltd.
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Composition and stereochemistry of ephedrine alkaloids accumulation in Ephedra sinica Stapf
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Krizevski, R., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel, Albert Katz Department of Dryland Agriculture, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer 84990, Israel
Bar, E., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel
Shalit, O., Department of Biology, University of Haifa-Oranim, Tiv'on 36006, Israel
Sitrit, Y., Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Bergman Campus, P.O. Box 653, Beer-Sheva 84105, Israel
Ben-Shabat, S., Department of Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel
Lewinsohn, E., Department of Aromatic, Medicinal and Spice Crops, Newe ya'Ar Research Center, Agricultural Research Organization, P.O. Box 1021, Ramat Yishay 30095, Israel
Composition and stereochemistry of ephedrine alkaloids accumulation in Ephedra sinica Stapf
Ephedra sinica Stapf (Ephedraceae) is a widely used Chinese medicinal plant (Chinese name: Ma Huang). The main active constituents of E. sinica are the unique and taxonomically restricted adrenergic agonists phenylpropylamino alkaloids, also known as ephedrine alkaloids: (1R,2S)-norephedrine (1S,2S)-norpseudoephedrine, (1R,2S)-ephedrine, (1S,2S)-pseudoephedrine, (1R,2S)-N-methylephedrine and (1S,2S)-N-methylpseudoephedrine. GC-MS analysis of freshly picked young E. sinica stems enabled the detection of 1-phenylpropane-1,2-dione and (S)-cathinone, the first two putative committed biosynthetic precursors to the ephedrine alkaloids. These metabolites are only present in young E. sinica stems and not in mature stems or roots. The related Ephedra foemina and Ephedra foliata also lack ephedrine alkaloids and their metabolic precursors in their aerial parts. A marked diversity in the ephedrine alkaloids content and stereochemical composition in 16 different E. sinica accessions growing under the same environmental conditions was revealed, indicating genetic control of these traits. The accessions can be classified into two groups according to the stereochemistry of the products accumulated: a group that displayed only 1R stereoisomers, and a group that displayed both 1S and 1R stereoisomers. (S)-cathinone reductase activities were detected in E. sinica stems capable of reducing (S)-cathinone to (1R,2S)-norephedrine and (1S,2S)-norpseudoephedrine in the presence of NADH. The proportion of the diastereoisomers formed varied according to the accession tested. A (1R,2S)-norephedrine N-methyltransferase capable of converting (1R,2S)-norephedrine to (1R,2S)-ephedrine in the presence of S-adenosylmethionine (SAM) was also detected in E. sinica stems. Our studies further support the notion that 1-phenylpropane-1,2-dione and (S)-cathinone are biosynthetic precursors of the ephedrine alkaloids in E. sinica stems and that the activity of (S)-cathinone reductases directs and determines the stereochemical branching of the pathway. Further methylations are likely due to N-methyltransferase activities. © 2010 Elsevier Ltd.
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