Drug development inhibitory potency

With the development of (-)-l-phenyl-2-propylaminopentane, (-)-PPAP, the (-)-deprenyl analogue free of the MAO-B inhibitory potency, we already furnished direct evidence that the enhanced dopaminergic activity following administration of (-)-deprenyl was unrelated to the inhibition of MAO-B. Because (-)-PPAP, like (-)-deprenyl, inhibited the uptake of tyramine in isolated smooth muscle tests, we first assumed that the drug-induced enhanced dopaminergic activity was due to an uptake inhibitory effect. Further studies revealed that this interpretation was false. 

The tyrosinase inhibitory potency of these compounds was also evaluated by the authors and attempts were made to justify their structure-activity relationships [52], Their inhibitory potential is shown in Table 3. Compound 58 was foimd to be the most potent (IC50 = 3.21 [jlM), while other compounds demonstrated moderate to potent inhibitions [52]. It was reported that the substitution of functional group(s) at the C-2 and C-3 positions and the presence of the - CH2OH group play a vital role in the potency of these compounds. Compound 58 can act as a potential lead molecule to develop new drugs for the treatment of hyperpigmentation associated with the high production of melanocytes [52]. 

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