The serine protease urokinase-type plasminogen activator (uPA) interacts with a specific receptor (uPAR) on the surface of various cell types, including tumor cells, and plays a crucial role in pericellular proteolysis. High levels of uPA and uPAR often correlate with poor prognosis of cancer patients. Therefore, the specific inhibition of uPA with small molecule active-site inhibitors is one strategy to decrease the invasive and metastatic activity of tumor cells. We have developed a series of highly potent and selective uPA inhibitors with a C-terminal 4-amidinobenzylamide residue. Optimization was directed toward reducing the fast elimination from circulation that was observed with initial analogues. The x-ray structures of three inhibitor/uPA complexes have been solved and were used to improve the inhibition efficacy. One of the most potent and selective derivatives, benzylsulfonyl-d-Ser-Ser-4-amidinobenzylamide (inhibitor 26), inhibits uPA with a K_i of 20 nm. This inhibitor was used in a fibrosarcoma model in nude mice using lacZ-tagged human HT1080 cells, to prevent experimental lung metastasis formation. Compared with control (100%), an inhibitor dose of 2 × 1.5 mg/kg/day reduced the number of experimental metastases to 4.6 ± 1%. Under these conditions inhibitor 26 also significantly prolonged survival. All mice from the control group died within 43 days after tumor cell inoculation, whereas 50% of mice from the inhibitor-treated group survived more than 117 days. This study demonstrates that the specific inhibition of uPA by these inhibitors may be a useful strategy for the treatment of cancer to prevent metastasis.

An efficient microwave-assisted synthesis of rhodanine and 2-thiohydantoin derivatives, and the correlation between their chemical structure and biological properties is reported.

Selenocyanates represent an interesting class of organic selenium compounds. Due to their similarity with better known natural (iso-)thiocyanates, they promise high biological activity and may also be metabolized to other Reactive Selenium Species (RSeS), such as selenols, diselenides and seleninic acids. Thirteen arylmethyl selenocyanates (1–13) have been synthesized and evaluated for potential antimicrobial, nematicidal and cytotoxic activity. The compounds exhibit pronounced antimicrobial activity against various strains of Gram-positive and Gram-negative bacteria and yeasts, including multidrug resistant strains. The results obtained so far demonstrate that these arylmethyl selenocyanates are also non-mutagenic and have limited cytotoxicity against human cells. Here, benzyl selenocyanate (1) represents the most active anti-ESKAPE agent, with potent activity against multidrug resistant MRSA strains (HEMSA 5) – with a competitive MIC value of just 0.76 μg mL⁻¹ (3.88 μM), whereas it exhibits low(er) cytotoxicity (IC₅₀ = 31 μM) and no mutagenicity against mammalian cells. Due to this selective antimicrobial activity, aromatic selenocyanates may provide an interesting lead in the development of antimicrobial agents, particularly in the context of drug resistance.