Leucocyanidin Explained

Leucocyanidin is a colorless chemical compound that is a member of the class of natural products known as leucoanthocyanidins.

Chemistry

(+)-Leucocyanidin can be synthesized from (+)-dihydroquercetin by reduction with sodium borohydride.[1]

Molar equivalents of synthetic (2R,3S,4R or S)-leucocyanidin and (+)-catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-[4,8]- and [4,6]-bi-[(+)-catechins] (procyanidins B3, B6) the all-trans-[4,8:4,8]- and [4,8:4,6]-tri-[(+)-catechins] (procyanidin C2 and isomer).[2]

Metabolism

Leucocyanidin oxygenase uses leucocyanidin, 2-oxoglutarate, and O2 to produce cis-dihydroquercetin, trans-dihydroquercetin (taxifolin), succinate, CO2, and H2O. Leucoanthocyanidin reductase (LAR or leucocyanidin reductase LCR) uses (2R,3S)-catechin, NADP+, and H2O to produce 2,3-trans-3,4-cis-leucocyanidin, NADPH, and H+. Its gene expression has been studied in developing grape berries and grapevine leaves.[3] Its activity has also been measured in leaves, flowers, and seeds of the legumes Medicago sativa, Lotus japonicus, Lotus uliginosus, Hedysarum sulfurescens, and Robinia pseudoacacia.[4]

The C-4 stereochemistry of leucocyanidin substrates affects anthocyanidin synthase (ANS) products. This enzyme is an iron(II) and 2-oxoglutarate (2OG) dependent oxygenase.[5]

Occurrence

Leucoyanidin can be found in these plants:[6]

Notes and References

  1. Heller. Werner. Britsch. Lothar. Forkmann. Gert. Grisebach. Hans. 1985-02-01. Leucoanthocyanidins as intermediates in anthocyanidin biosynthesis in flowers of Matthiola incana R. Br.. Planta. en. 163. 2. 191–196. 10.1007/BF00393505. 24249337. 0032-0935.
  2. Synthesis of condensed tannins. Part 9. The condensation sequence of leucocyanidin with (+)-catechin and with the resultant procyanidins. Jan. A. Delcour, Daneel Ferreira and David G. Roux, J. Chem. Soc., Perkin Trans. 1, 1983, pages 1711-1717,
  3. Bogs. Jochen. Downey. Mark O.. Harvey. John S.. Ashton. Anthony R.. Tanner. Gregory J.. Robinson. Simon P.. 2005-10-01. Proanthocyanidin Synthesis and Expression of Genes Encoding Leucoanthocyanidin Reductase and Anthocyanidin Reductase in Developing Grape Berries and Grapevine Leaves. Plant Physiology. en. 139. 2. 652–663. 10.1104/pp.105.064238. 0032-0889. 16169968. 1255985.
  4. Skadhauge. B.. Gruber. M. Y.. Thomsen. K. K.. Wettstein. D. V.. 1997-04-01. Leucocyanidin reductase activity and accumulation of proanthocyanidins in developing legume tissues. American Journal of Botany. en. 84. 4. 494. 0002-9122. 10.2307/2446026. 2446026.
  5. http://cat.inist.fr/?aModele=afficheN&cpsidt=15176584 The C-4 stereochemistry of leucocyanidin substrates for anthocyanidin synthase affects product selectivity TURNBULL Jonathan J.; NAGLE Michael J.; SEIBEL Jürgen F.; WELFORD Richard W. D.; GRANT Guy H.; SCHOFIELD Christopher J. 2003
  6. Web site: Liber Herbarum II: DK: Leucocyanidin/ UK: Leucocyanidin/ D: Leucocyanidin. www.liberherbarum.com. 2017-12-03.

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