Abstract
Phenylethylamine’s acute toxic effects in a population of adult (10 to 12 weeks old; ∼30 g) Swiss male albino mice are significantly increased by para-position aromatic ring halogenation. LDLO, LD50, and LD100 values (mg/kg; x ± SEM) for p-F- (116.7 ± 3.3, 136.7 ± 1.7, and 160.0 ± 2.9), p-Br- (126.7 ± 3.3, 145.0 ± 2.9, and 163.3 ± 3.3), p-Cl- (133.3 ± 3.3, 146.7 ± 1.7, and 165.0 ± 2.9), and p-I-PEA (133.3 ± 3.3, 153.3 ± 1.7, and 168.3 ± 1.7), compared to PEA 203.3 ± 3.3, 226.7 ± 4.4, and 258.3 ± 8.8). Like PEA, the difference between LDLO and LD50, and LD50 and LD100 for individual amines were similar and in the range (10 to 20%). Toxicity variation between the various p-halogenatedPEAs also fell within a relatively narrow range (as a group: LDLO 116.7 ± 3.3 to 133.3 ± 3.3, LD50 136.7 ± 1.7 to 153.3 ± 1.7, and LD100 160.0 ± 2.9 to 168.3 ± 1.7 mg/kg). PEA methylation, (exception of its α-methyl derivative), results in relatively modest changes in acute toxicity. LDLO, LD50, and LD100 values (mg/kg; x ± SEM) for N-Me- (176.6 ± 3.3, 200.0 ± 2.9, and 221.7 ± 3.3), p-Me- (183.3 ± 3.3, 206.7 ± 3.3, and 225.0 ± 2.9), o-Me- (210.0 ± 5.8, 233.3 ± 3.3, and 258.3 ± 1.7), and β-MePEA (220.0 ± 5.8, 243.3 ± 4.4, and 278.3 ± 44). Similar to PEA, and the p-HPEAs, the difference between LDLO and LD50 and LD50 and LD100 values for individual amines fell within a relatively narrow range (10 to 20%). Variation in toxicity among the methylatedPEAs also fell within a limited range (as a group: LDLO 176 ± 3.3 to 220 ± 5.8, LD50 200.0 ± 2.9 to 243.3 ± 4.4 and LD100 221.7 ± 3.3 to 278.3 ± 4.4 mg/kg). With the exception of PEA’s methyl derivative (amphetamine) all the amines studied are rapidly metabolized by monoamine oxidase. This pharmacokinetics difference would help to explain the markedly higher amphetamine toxicity [(LDLO, LD50 and LD100 (mg/kg; x ± SEM) of 21.3 ± 0.9, 25.0 ± 0.6, and 29.3 ± 0.7, respectively)].
Acknowledgments
The authors thank the late Professor E.A. Zeller for his invaluable input to this work. They greatly appreciate the skillful technical assistance of Dr. S. Huprikar and Mr. S. Myles. This research was supported, in part, by The National Migraine Foundation, Chicago, IL.
Disclosure statement
The authors declare that they have no conflict of interest related to this research.