9,10-Dihydrophenanthrenes as phytoalexins of Orchidaceae. Biosynthetic studies in vitro and in vivo proving the route from L-phenylalanine to dihydro-m-coumaric acid, dihydrostilbene and dihydrophenanthrenes.

Hydroxy derivatives of 9,10-dihydrophenanthrenes, orchinol and hircinol, were isolated from bulbs of Orchidaceae which had been induced to accumulate phytoalexins. Incorporation of radioactive precursors, L-phenylalanine and various hydroxycinnamic acids, has been investigated by feeding experiments in vivo. m-Coumaric acid and dihydro-m-coumaric acid were found to be efficiently incorporated into the dihydrophenanthrene derivatives. Dihydro-m-coumaric acid was not only converted into the dihydrophenanthrenes but was also formed from L-phenylalanine in the same tissue; it was thus proved to be an intermediate. The role of dihydro-m-coumaric acid was substantiated by studies in vitro. An active stilbene synthase was detected in enzyme preparations from induced orchid bulbs and assayed with different CoA esters. The enzyme, characterized on the basis of its substrate specificity, selectively converted dihydro-m-coumaroyl-CoA plus malonyl-CoA into 3,3',5-trihydroxybibenzyl. The role of 3,3',5-trihydroxybibenzyl as physiological intermediate was further corroborated by investigations with intact plants. Both its formation from phenylpropanoids and its conversion into orchinol was demonstrated. The data provided evidence for a biosynthetic sequence originating from L-phenylalanine and leading to 9,10-dihydrophenanthrenes via m-coumaric acid, dihydro-m-coumaric acid, and 3,3',5-trihydroxybibenzyl.

[1]  J. Hart.  Role of Phytostilbenes in Decay and Disease Resistance , 1981 .

[2]  A. A. Bell.  Biochemical Mechanisms of Disease Resistance , 1981 .

[3]  A. Stoessl.  Phytoalexins – a Biogenetic Perspective1)2) , 1980 .

[4]  H. Kindl,et al.  Substrate specificity in vivo and in vitro in the formation of stilbenes. Biosynthesis of rhaponticin. , 1980, Archives of biochemistry and biophysics.

[5]  H. Kindl,et al.  Stilbene synthase (pinosylvine synthase) and its induction by ultraviolet light , 1979, FEBS letters.

[6]  L. Wooltorton,et al.  The Biosynthesis of Phenolic Compounds in Wounded Plant Storage Tissues , 1978 .

[7]  J. Atwood,et al.  ANTINEOPLASTIC AGENTS. 3. THE STRUCTURE OF JUNCUSOL. A NOVEL CYTOTOXIC DIHYDROPHENANTHRENE FROM THE ESTUARINE MARSH PLANT JUNCUS REOMERIANUS , 1977 .

[8]  M. Zenk,et al.  Chemical Syntheses and Properties of Hydroxycinnamoyl- Coenzyme A Derivatives , 1975, Zeitschrift fur Naturforschung. Section C, Biosciences.

[9]  M. Fisch,et al.  Structure and antifungal activity of hircinol, loroglossol and orchinol , 1973 .

[10]  K. Mothes,et al.  Biosynthesis of aristolochic acid. , 1967, European journal of biochemistry.

[11]  J. Brodie,et al.  The synthesis of mevalonic acid by non-particulate avian and mammalian enzyme systems. , 1960, Biochemical and biophysical research communications.

[12]  R. Adams,et al.  Preparation and Reactions of o-Hydroxycinnamic Acids and Esters , 1952 .

[13]  H. Kindl.  COMPARTMENTS AND MICROCOMPARTMENTS CHANNELLING INTERMEDIATES IN PHENYLPROPANOID METABOLISM , 1979 .

[14]  J. Stockigt.  Chemical synthesis and properties of hydroxycinnamoyl-coenzyme A derivatives , 1975 .

[15]  G. Billek.  Stilbene im Pflanzenreich , 1964 .

[16]  H. Corrodi,et al.  Welkstoffe und Antibiotika. 28. Mitteilung. Synthese von 2,4‐Dimethoxy‐6‐hydroxy‐phenanthren und Konstitution des Orchinols , 1963 .

[17]  H. Kindl,et al.  Über die phenolischen Inhaltsstoffe der Familie Saxifragaceae , 1962 .

[18]  H. Corrodi,et al.  Welkstoffe und Antibiotika. 27. Mitteilung. Über induzierte Abwehrstoffe bei Orchideen II , 1957 .