UV can turn Thyroxine (t4) into T3 & t2
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Transforming t4 into t3 (and another active thyroid hormone T2 with similar effects) using a UV device with a filter
Timing & wavelength is key. above 340nm with lower wavelengths filtered t4 is degraded into t3 over 5 minutes. going to 15 minutes gives mainly T2. with wavelengths under 340 included t3 gets turned into t2. If 300+ is included then they will break down too. they said the solvent used is important and changes things , so not sure how useful , but hydrogen donating is important and alcohols might be similar (i was thinking, might be useful for people who get t4 only and dont respond well enough)
The photodegradation of T4, when irradiated with >300-nm light for various periods of time, is shown in Fig. 3. A small amount of T3 has been formed after 1 min while, after 5 min more, T3 and a small amount of 3,5-T2 were present in the reaction mixture. With further irradiation, the stepwise deiodination of T4 continued so that, after 15 min, almost no T4 and only little T3 remained. A small amount of 3,3'-T2 also was present in the 15-min photolysate, but the major reaction products were 3,5-T2 and 3-Ti
The absorption spectrum of rT (not shown) is similar to that of T4. Above 340 nm with filter), nearly all the absorbed light is taken up by T4 (or rT), while T3 receives much less and T2 receives virtually none. This explains why >340-nm light photolyzed T4 much more readily than T3, while 3,5-T2 was resistant to photolysis (see below). In contrast, all three compounds absorb >300-nm lght (without filter) and can therefore be photolyzed.