Physicochemical Properties of a Combination of 5-Hydroxy-L-tryptophan with β-Aminoethylisothiuronium Bromide Hydrobromide

Radiation Biology Department, Institute of Nuclear Medicine & Allied Sciences, l.ucknow Road, Delhi-110 054

Manuscript received 22 November 1991, revised 21 December 1992, accepted 29 January 1993

A combination of 5-hydroxy-L-tryptophan (HT) and 2-aminoethylisothi u ron i um bromide hydrobromide (AET) increases radioprotection to a significant extent in biological systems. In the present report some physicochemical nature or the combination has been probed. It has been shown that HT lot^-ms a complex with AET in the concentration ratio of 90.82 : 14.23 (μM) by different analytical techniques. Probable structure has also been assigned for the complex. The inference is based on uv spectrophotometry, spectrophotofluorimetry, conductance measurement and infrared spectros­copy. The complex is stable for 6 days at room temperature. With gamma irradiation, there is consistent decrease in pH for HT and AET but for HT + AET the change in pH is biphasic. Possible explanations for these observations have been given.