Preparation and biological evaluation of soluble tetrapeptide epoxyketone proteasome inhibitors

A review on the treatment of multiple myeloma with small molecular agents in the past five years

Multiple myeloma is currently incurable, and the incidence rate is increasing year by year worldwide. Although in recent years the combined treatment plan based on proteasome inhibitors and immunomodulatory drugs has greatly improved the treatment effect of multiple myeloma, most patients still relapse and become resistant to current treatments. To solve this problem, scientists are committed to developing drugs with higher specificity, such as iberdomide, which is highly specific to ikaros and aiolos. This review aims to focus on the small molecular agents that are being researched/clinically used for the treatment of multiple myeloma, including the target mechanism, structure-activity relationship and application prospects of small molecular agents.

Pseudopeptides with aldehyde or vinylsulfone warheads: Synthesis and antiproteasomal activity

The comparative study of new proteasome inhibitors based on salicylic acid-modified pseudo-tripeptides terminated with aldehyde or vinylsulfone is presented. We described the synthesis of 11 pairs of pseudopeptides and their properties related to the proteasome inhibition were determined. The effects of integrated amino acids (combinations of leucine, phenylalanine, tryptophan, proline, cyclohexylalanine or norleucine residues) on the activity of the proteasome were investigated. Compounds preferentially inhibited the chymotrypsin β5-subunit of the proteasome in cell-based assays compared with the β1- and β2-subunits, with IC₅₀ values in mid-nanomolar ranges being obtained for the most active members. Our comparative study demonstrated that aldehydes were able to inhibit the proteasome in cells more effectively than vinylsulfones. These results were corroborated by the accumulation of polyubiquitinated proteins in treated cells, GFP accumulation in a reporter cell line and the ability of new compounds to induce apoptotic cell death.

Synthesis of novel, DNA binding heterocyclic dehydroabietylamine derivatives as potential antiproliferative and apoptosis-inducing agents

Several dehydroabietylamine derivatives containing heterocyclic moieties such as thiophene and pyrazine ring were successfully synthesized. The antiproliferative activities of these thiophene-based Schiff-bases, thiophene amides, and pyrazine amides were investigated in vitro against Hela (cervix), MCF-7 (breast), A549 (lung), HepG2 (liver), and HUVEC (umbilical vein) cells by MTT assay. The toxicity of L1-L10 (IC50 = 5.92- >100 μM) was lower than L0 (1.27 μM) and DOX (4.40 μM) in every case. Compound L1 had higher anti-HepG2 (0.66 μM), anti-MCF-7 (5.33 μM), and anti-A549 (2.11 μM) and compound L3 had higher anti-HepG2 (1.63 μM) and anti-MCF-7 (2.65 μM) activities. Both of these compounds were recognized with high efficiency in apoptosis induction in HepG2 cells and intercalated binding modes with DNA. Moreover, with average IC50 values of 0.66 and 5.98 μM, L1 was nine times more effective at suppressing cultured HepG2 cells viability than normal cells (SI = 9). The relative tumor proliferation rate (T/C) was 38.6%, the tumor inhibition rate was up to 61.2%, which indicated that L1 had no significant toxicity but high anti-HepG2 activity in vivo. Thus, it may be a potential antiproliferation drug with nontoxic side effects.