Secondary Products - II

Phenolics

Phenolics

Synthesis of Phenolics

Phenolics are synthesized by a number of different pathways

Two most important: Shikimic acid pathway - more important in plants Malonic acid pathway - more important in fungi

Shikimic Acid Pathway

Converts intermediates from glycolysis (phosphoenol-pyruvate) and the PPP (erythrose-4-PO4) into the aromatic amino acids: phenylalanine, tryptophan, and tyrosine

See Shikimic Acid Pathway

See Pathway for Phenolic Secondary Products

Simple Phenolics

Allelopathic compounds Defense cmpds against insect herbivores and fungi

Certain phenolics (furanocoumarins) are phototoxic - not toxic till activated by sunlight (near UV-A)

Activated furanocoumarins can insert into DNA and bind to pyrimidine bases - blocks transcription and leads to cell death

Abundant in Apiaceae Urushiol in poison ivy

Urushiol

Poison ivy urushiol

Poison oak urushiol

Coumarins

Large group – 1300 coumarins have been identified

Basic coumarin is a 2 ring structure, phenol and pyrone

Many anticoagulants including Warfarin

Lignin a complex phenolic

Polymer of three phenolic alochols Different species have different ratios of these

monomers Lignin in beech has 100:70:7 of coniferyl: sinapyl:

para-coumaryl

Lignin monomers

Flavinoids

One of the largest classes of phenolics Carbon skeleton has 15 carbons with two

benzene rings connected by a 3-C bridge

-C3-

Flavinoids

Flavinoids classified into different groups based on the degree of oxidation of the 3-C bridge Anthocyanins Flavones Flavonols Isoflavones

Majority of flavinoids exist as glycosides

Anthocyanins

Tannins

Tannin a general name for a large group of complex phenolic substances that are capable of tanning animal hides into leather by binding collagen

Tetrahydrocannabinol