Antirheumatic agents. II. Novel methotrexate derivatives bearing an alkyl-substituted benzene ring

Novel methotrexate (MTX) derivatives with either a mono- or dialkyl-substituted benzene ring were synthesized and initially tested for in vitro anti-proliferative activities using human peripheral blood mononuclear cells (hPBMC) derived from healthy volunteers and synovial cells (hSC) derived from patients with rheumatoid arthritis (RA). Compounds with potent activities were further evaluated in an in vivo adjuvant arthritis model. In comparison with MTX, a glutamate derivative 3a was more potent as a suppressor of the in vitro cell proliferation and the in vivo experimental arthritis, and a homoglutamate derivative, 3e, exhibited fairly good activities in vitro and considerable activity in vivo in a dose-dependent manner. As expected, 3e did not act as a substrate of folylpolyglutamate synthetase (FPGS), and thus did not undergo polyglutamation, which is thought to be responsible for side-effects that occur during MTX therapy.