New pyrazolylindolin-2-one based coumarin derivatives as anti-melanoma agents: design, synthesis, dual BRAF^V600E/VEGFR-2 inhibition, and computational studies

Abstract

Malignant melanoma is the most invasive skin cancer with the highest risk of death. The inhibition of BRAF^V600E appears relevant for overcoming secondary resistance developed during melanoma treatment. BRAF^V600E triggers angiogenesis <i>via</i> modification of the expression of angiogenic inducers, which play a crucial role in the metastasis of melanoma. Accordingly, the dual inhibition of the BRAF^V600E/VEGFR-2 signaling pathway is considered a rational approach in the design of anti-melanoma candidates. In this study, a new class of pyrazolylindolin-2-one linked coumarin derivatives as dual BRAF^V600E/VEGFR-2 inhibitors targeting A375 melanoma cells was designed. Target compounds were tailored to occupy the pockets of BRAF^V600E and VEGFR-2. Most of the synthesized compounds demonstrated potent mean growth inhibitory activity against A375 cells. Compound 4j was the most active cytotoxic derivative, displaying an IC₅₀ value at a low micromolar concentration of 0.96 μM with a significant safety profile. Moreover, 4j showed dual potent inhibitory activity against BRAF^V600E and VEGFR-2 (IC₅₀ = 1.033 and 0.64 μM, respectively) and was more active than the reference drug sorafenib. Furthermore, derivative 4j caused significant G0/G1 cell cycle arrest, induced apoptosis, and inhibited the migration of melanoma cells. Molecular docking showed that compound 4j achieved the highest Δ<i>G</i> value of -9.5 kcal mol^-1 against BRAF^V600E and significant Δ<i>G</i> of -8.47 kcal mol^-1 against VEGFR-2. Furthermore, the structure-activity relationship study revealed that TPSA directly contributed to the anticancer activity of the tested compounds.