Three compounds were found to have been illegally added to dietary supplements marketed for erectile dysfunction. The structures of these compounds were identified with NMR, HRMS, IR, UV and LC/MS/MS, after comparison with the structure of sildenafil, data showed that the oxygen atom of the carbonyl group in the heterocyclic ring had been replaced with a sulfur atom, these thio-sildenafil analogues were identified as thiosildenafil, thiohomosildenafil and hydroxythiohomosildenafil. Since their structures were similar to that of sildenafil, according to structure-activity relationship, the side effects of these analogues might also associate with that of sildenafil. In accordance with this finding, thio-sildenafil analogues have been included in the inspection list of illegal adulterants in Taiwan. From January to October 2009, thiosildenafil was detected in 6 samples, thiohomosildenafil was detected in 4 samples and hydroxythiohomosildenafil was detected in 3 samples.
Lai, K.-C.; Liu, Y.-C.; Liao, Y.-C.; Lin, Y.-L.; Tsai, L.-Y.; Lin, J.-H.; and Lo, C.-F.
"Isolation and identification of three thio-sildenafil analogues in dietary supplements,"
Journal of Food and Drug Analysis: Vol. 18
, Article 1.
Available at: https://doi.org/10.38212/2224-6614.2226