Heteroauxin Indole-3-acetic acid

According to [3], drimenol (2) has the plant growth regulatory activity comparable with that of heteroauxin (indole-3-acetic acid). 

SYNS HETEROAUXIN IA. p-INDOLEACETIC ACID p-INDOLE-3-ACETIC ACID 3-INDOLE-ACETIC ACID INDOLYLACETIC ACID a-INDOL-3-YL-ACETIC ACID P-INDOLYLACETIC ACID ... 

Rysanek, K. and Vitek, V., Increased excretion of 5-hydroxyindoIe acetic acid after the administration of 3-indole acetic acid (heteroauxine), Experientia 15, 217 (1959). 

A remarkable advance in plant physiology occurred when Kogl and coworkers (496) isolated a plant growth hormone, called heteroauxin, from human urine. This was identified as indole-3-acetic acid and was shown (497, 498) also to occur in plants, and in yeast from which it was isolated. 

Indole-3-acetic acid (heteroauxin) [87-51-4] M 175.2, m 167-169 (dec), pK -6.13 (aqueous H2SO4), pKl 4.54 (CO2H). Recrystallise heteroauxin from EtOH/water [James Ware y P/iyi C/iem 89 5450 1985]. [Beilstein 22111/lV 65.] Alternatively recrystallise 30g of the acid with lOg of charcoal in IL of hot water, filter and cool when 22g of colourless acid separate. Dry it and store it in a dark bottle away from direct sunlight [Johnson Jacoby Org Synth Coll Vol V 654 1973]. The picrate has m 178-180°. [Beilstein 22 H 66, 22 1 508,22 11 50, 22 111/lV 1088.] It is a plant growth substance. 

Indole-3-acetic acid 50, also known as heteroauxin, is a phytohormone. It is mainly formed in buds, seeds and in young blossoms and is a plant growth regulator. 

The chemical structure of heteroauxin was established to be indole-3-acetic acid (indole-P-acetic acid (lAA)). It is considered that lAA is formed by the enzymatic oxidation of indole-3-acetaldehyde derived from tryptophan via indole-3-pyruvic acid or tryptamine. Between these two routes, the main route is thought to be through indole-3-pyruvic acid. 

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