Structure-Aided Identification and Optimization of Tetrahydro-isoquinolines as Novel PDE4 Inhibitors Leading to Discovery of an Effective Antipsoriasis Agent.

Psoriasis is a common, chronic inflammatory disease characterized by abnormal skin plaques, and the effectiveness of phosphodiesterase 4 (PDE4) inhibitor to lessen the symptoms of psoriasis has been proved. Aiming to find a novel PDE4 inhibitor acting as an effective, safe, and convenient therapeutic agent, we constructed a library consisting of berberine analogues, and compound 2 with a tetrahydroisoquinoline scaffold was identified as a novel and potent hit. The structure-aided and cell-based structure-activity relationship studies on a series of tetrahydro-isoquinolines lead to efficient discovery of a qualified lead compound (16) with the high potency and selectivity, well-characterized binding mechanism, high cell permeability, good safety and pharmacokinetic profile, and impressive in vivo efficacy on antipsoriasis, in particular with a topical application. Thus, our study presents a prime example for efficient discovery of novel, potent lead compounds derived from natural products using a combination of medicinal chemistry, biochemical, biophysical, and pharmacological approaches.

Pharmacological inhibition of dihydroorotate dehydrogenase induces apoptosis and differentiation in acute myeloid leukemia cells.

Acute myeloid leukemia is a disorder characterized by abnormal differentiation of myeloid cells and a clonal proliferation derived from primitive hematopoietic stem cells. Interventions that overcome myeloid differentiation have been shown to be a promising therapeutic strategy for acute myeloid leukemia. In this study, we demonstrate that CRISPR/Cas9-mediated knockout of dihydroorotate dehydrogenase leads to apoptosis and normal differentiation of acute myeloid leukemia cells, indicating that dihydroorotate dehydrogenase is a potential differentiation regulator and a therapeutic target in acute myeloid leukemia. By screening a library of natural products, we identified a novel dihydroorotate dehydrogenase inhibitor, isobavachalcone, derived from the traditional Chinese medicine Psoralea corylifolia Using enzymatic analysis, thermal shift assay, pull down, nuclear magnetic resonance, and isothermal titration calorimetry experiments, we demonstrate that isobavachalcone inhibits human dihydroorotate dehydrogenase directly, and triggers apoptosis and differentiation of acute myeloid leukemia cells. Oral administration of isobavachalcone suppresses subcutaneous HL60 xenograft tumor growth without obvious toxicity. Importantly, our results suggest that a combination of isobavachalcone and adriamycin prolonged survival in an intravenous HL60 leukemia model. In summary, this study demonstrates that isobavachalcone triggers apoptosis and differentiation of acute myeloid leukemia cells via pharmacological inhibition of human dihydroorotate dehydrogenase, offering a potential therapeutic strategy for acute myeloid leukemia.