Caffeine represents a useful scaffold for the design of monoamine oxidase (MAO) type B inhibitors. Specifically, substitution on the C8 position yields structures which are high-potency MAO-B inhibitors. To explore the structure–activity relationships of MAO-B inhibition by caffeine-derived compounds, this study examines the MAO inhibitory properties of a series of phenylalkylcaffeine analogues.
Employing the recombinant human enzymes, the potencies (IC50 values) by which the caffeine analogues inhibit MAO-A and MAO-B were measured. The reversibility of inhibition of a selected inhibitor was determined by measuring the recovery of enzyme activity after dilution and dialysis of enzyme-inhibitor mixtures.
The results document that the phenylalkylcaffeine analogues are reversible and selective MAO-B inhibitors with a competitive mode of inhibition. The most potent analogue, 8-(7-phenylheptyl)caffeine, exhibits IC50 values for the inhibition of MAO-A and MAO-B of 3.01 μm and 0.086 μm, respectively. Increasing the length of the alkyl side chain leads to enhanced MAO-A and MAO-B inhibitory potency while introduction of a carbonyl group reduces MAO-B inhibitory potency.
Phenylalkylcaffeines represent a new class of high-potency MAO-B inhibitors with the longer alkyl side chains yielding enhanced inhibitory activity. Such compounds may represent useful leads for the development of anti-parkinsonian therapies.
咖啡因是设计单胺氧化酶(MAO)B型抑制剂的有用支架。特别是,C8位上的取代产生的高效MAO-B抑制剂的结构。为了探索咖啡因衍生物对MAO-B抑制的结构-活性关系,本研究检查了一系列苯基烷基咖啡因类似物的MAO抑制特性。
使用重组人酶,测量咖啡因类似物抑制MAO-A和MAO-B的效力(IC50值)。通过测量酶-抑制剂混合物的稀释和透析后酶活性的恢复,确定了一种选定抑制剂的抑制可逆性。
结果表明,苯基烷基咖啡因类似物是具有竞争性抑制模式的可逆和选择性MAO-B抑制剂。最有效的类似物,8-(7-苯基庚基)咖啡因,对MAO-A和MAO-B的抑制的IC50值分别为3.01 μm和0.086 μm。增加烷基侧链的长度可增强MAO-A和MAO-B的抑制效力,而引入羰基则降低MAO-B的抑制效力。
苯基烷基咖啡因代表了一类新的高效MAO-B抑制剂,较长的烷基侧链可提高抑制活性。这类化合物可能成为开发抗帕金森疗法的有用先导。