Metabolismo do ácido 7- 14c - 2,3,5 triiodo benzóico (TIBA) em soja (Glycine max)

Resumo

A metabolic study was done in mature seeds of field grown soybeans sprayed with 7 - 14C - 2,3,5 triiodobenzoic acid (TIBA) at the onset of flowering. Seed extraction with 95% alcohol yielded only 65% of the total radioactivity present. No further studies were performed on the ethanol insoluble fraction. Upon acid base purification of the 14C seed extracts, the ether phase (pH 9,0) contained about 70% of the activity suggesting the existence of a low polarity compound(s). Acid hydrolysis of the alcoholic extracts increased the radioactivity in the ether soluble fraction, while the basic treatment decreased it to about the same level as for free TIBA. 

The latter behaviour seemed to indicate hydrolysis of a conjugation product(s). Alumina column chromatography was unsuccessful for separating the oil-acticity combination; however, three radioactive peaks were obtained. The first two peaks degraded to form the last one, which coincided with the TIBA peak. When the alcoholic extracts were run in a Sephadex LH-20 column, oils, proteins and pigments separated from the radioactivity. Two main peaks appeared for the 14C seeds ex- tracts. Peak I was essentially unaltered when it was co-cromatographed with the standard 14C - TIBA, Peak II was indis- tinguishable from the TIBA peak.

Although the work did not reach the final stage of caracterization, postulation was made for a conjugate nature of the ester type for peak I and the correspondence of peak II with free TIBA or TIBA in mixture with related compounds, such as 2,5 DIBA and 3,5 DIBA, products of its deiodination.