Quercus pedunculata

Purpurogallin (= 2,3,4,6-Tetrahydroxy-5H-benzocyclohepten-5-one) (bicyclic phenolic) Dryophanta divisa gall on Quercus pedunculata (Fagaceae) PEP (16 pM) [119]... 

Dryophanta divisa gall on Quercus pedunculata (Fagaceae)... 

Pedunculate oaks (Quercus robur or Quercus pedunculata) grow most widely in the Limousin. They are also present in Bourgogne, as well as the south of France. They have a high extractable polyphenol content and relatively low concentrations of odoriferous compounds. 

In two particular cases.Quercus pedunculata (Ref. 20) and Aesculus hippocastanum (Ref. 19) two PAL isoenzymes,se-parated on DEAE-cellulose columns. eathibit different regulatory properties. One isoform is sensitive to feedback by c6-C3 units, whereas the other is inhibited only by C6-C1 units. Moreover, in Quercus, the C6-C3 sensitive form cosediments in microsomes with enzymes of the phciyl-propanoid pathway, while the C6-C1 sensitive form is located with benzoate synthase in a heavier fraction microbodies and mitochondria (Ref. 13). Aesculus, one of the isoforms is linked in an enzyme complex with the enzyme system giving rise to benzoic acid. 

In roots of Quercus pedunculata, for instance, two forms of PAL were found, one in the mito-chondria-microbody fraction and the other in the microsome fraction, which differed in their sensitivity to cinnamic and benzoic acids and obviously belonged to different metabolic pathways. From the glandular tissue of Aesculus hippocastanum. two PAL species were isolated which were differently inhibited either by cinnamic acid and flavonoids or by benzoic acid derivatives. One of these enzymatic forms is present in plastids, the other in ER. 

Boudet A, Gadal P, Alibert G, Marigo G 1967 Biosynthesis and metabolism of aromatic compounds in higher plants. Demonstration of the alicyclic precursors quinic, 5-dehydroquinic, shikimic, and 5-dehydroshikimic acids in Quercus pedunculata. C R Acad Sci 265 119-122... 

Two isozymes of PAL were reported earlier in Quercus pedunculata leaves, one form being sensitive to repression by hydroxycinnamate and the other to repression by hydroxybenzoate (see last year s Report ). These two isozymes have now been isolated from the roots of the same plant and a study of their localization indicates that the cinnamate-sensitive isozyme is present in the microsomal fraction, whereas the benzoate-sensitive isozyme is present in the mitochondrial and microbody fraction. The distributions of the two forms of PAL are correlated with those of two other enzymes of phenolic biosynthesis. The enzyme cinnamate 4-hydroxylase accompanies the first isozyme in the microbodies whereas benzoate synthetase is present with the second in the microbodies. Thus phenolic acid biosynthesis is closely comjrartmented in the oak plant, Cg—C3 acids being produced exclusively in the microsomes and Cs—C, acids in the microbodies. 

Pedunculagin (43) Quercus pedunculata Q. sessiflora (galls) s-( — )-hexahydroxydiphenic acid linked 2,3 and 4,6 D-glucopyranose conformation — c-1 32. 102)... 

Illicium religiosum Casuarina equisetifolia Anogeissus tatifolia Sapium japonicum S. siebiferum Aleurites cordata Quercus stenophylla Q. pedunculata Ginkgo biloba Mammea americana Hama metis spp. 

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