ABSTRACT
Cathepsin L is a cysteine protease that is upregulated in a variety of malignant tumors and plays a significant role in cancer cell invasion and migration. It is an attractive target for the development of small-molecule inhibitors, which may prove beneficial as treatment agents to limit or arrest cancer metastasis. We have previously identified a structurally diverse series of thiosemicarbazone-based inhibitors that incorporate the benzophenone and thiochromanone molecular scaffolds. Herein we report an important extension of this work designed to explore fused aryl-alkyl ring molecular systems that feature nitrogen atom incorporation (dihydroquinoline-based) and carbon atom exclusivity (tetrahydronaphthalene-based). In addition, analogues that contain oxygen (chromanone-based), sulfur (thiochroman-based), sulfoxide, and sulfone functionalization have been prepared in order to further investigate the structure-activity relationship aspects associated with these compounds and their ability to inhibit cathepsins L and B. From this small-library of 30 compounds, five were found to be strongly inhibitory (IC50 <500 nM) against cathepsin L with the most active compound (7-bromodihydroquinoline thiosemicarbazone 48) demonstrating an IC50=164 nM. All of the compounds evaluated were inactive (IC50 >10,000 nM) as inhibitors of cathepsin B, thus establishing a high degree (>20-fold) of selectivity (cathepsin L vs. cathepsin B) for the most active cathepsin L inhibitors in this series.
Subject(s)
Cathepsin L/antagonists & inhibitors , Protease Inhibitors/chemistry , Small Molecule Libraries/chemistry , Cathepsin B/antagonists & inhibitors , Cathepsin B/metabolism , Cathepsin L/metabolism , Chromans/chemistry , Protease Inhibitors/chemical synthesis , Protease Inhibitors/metabolism , Protein Binding , Quinolines/chemistry , Safrole/analogs & derivatives , Safrole/chemistry , Small Molecule Libraries/chemical synthesis , Small Molecule Libraries/metabolism , Structure-Activity Relationship , Sulfones/chemistry , Tetrahydronaphthalenes/chemistryABSTRACT
BACKGROUND: A combination capsule of bismuth, metronidazole, and tetracycline plus omeprazole given as 10-day therapy has an overall effectiveness of 92-93% in per-protocol analysis (Grade B) with eradication of 86-91% of metronidazole-resistant Helicobacter pylori. This study aimed to explore whether extending the duration to 14 days would improve overall effectiveness per protocol to ≥95% (Grade A) in a population in which metronidazole resistance was anticipated to exist. METHODS: A one-arm, open-label pilot study of H. pylori-infected, asymptomatic/mildly dyspeptic adults, Hispanic residents of El Paso, Texas, received a 14-day course of omeprazole, plus the combination capsule. We cultured and Gram-stained specimens obtained using a minimally invasive orogastric brush. Helicobacter pylori status was determined by (13)C-urea breath test at 4 or more weeks post-therapy. RESULTS: Forty-seven subjects (7 men and 40 women, average age 42 years) were entered. The per-protocol effectiveness was 97.1% (33/34) (95% mid-P CI: 86.3, 99.9); 100% of metronidazole-resistant strains were eradicated. Side effects were mild and self-limited but contributed to nonadherence. Therapy taken for <10 days was more likely to result in eradication failure (p < .001). Office-based orogastric brushing was well tolerated; positive cultures were obtained in 95%. Gram staining showed H. pylori-like forms in all specimens. CONCLUSIONS: This pilot study supports the concept that 14-day OBMT therapy is likely to be more efficacious for H. pylori eradication (Grade A, PP basis) than a 10-day course where metronidazole resistance is suspected. If confirmed, 14 days should be recommended in populations where metronidazole resistance is common.
