Camptothecin structure simplification elaborated new imidazo[2,1-b]quinazoline derivative as a human topoisomerase I inhibitor with efficacy against bone cancer cells and colon adenocarcinoma

Camptothecin is a pentacyclic natural alkaloid that inhibits the hTop1 enzyme involved in DNA transcription and cancer cell growth. Camptothecin structure pitfalls prompted us to design new congeners using a structure simplification strategy to reduce the ring extension number from pentacyclic to tetracyclic while maintaining potential stacking of the new compounds with the DNA base pairs at the Top1-mediated cleavage complex and aqueous solubility, as well as minimizing compound-liver toxicity. The principal axis of this study was the verification of hTop1 inhibiting activity as a possible mechanism of action and the elaboration of new simplified inhibitors with improved pharmacodynamic and pharmacokinetic profiling using three structure panels (A-C) of (isoquinolinoimidazoquinazoline), (imidazoquinazoline), and (imidazoisoquinoline), respectively. DNA relaxation assay identified five compounds as hTop1 inhibitors belonging to the imidazoisoquinolines 3a,b, the imidazoquinazolines 12, and the isoquinolinoimidazoquinazolines 7a,b. In an MTT cytotoxicity assay against different cancer cell lines, compound 12 was the most potent against HOS bone cancer cells (IC50 = 1.47 μM). At the same time, the other inhibitors had no detectable activity against any cancer cell type. Compound (12) demonstrated great penetrating power in the HOS cancer cells' 3D-multicellular tumor spheroid model. Bioinformatics research of the hTop1 gene revealed that the TP53 cell proliferative gene is in the network of hTop1. The finding is confirmed empirically using the gene expression assay that proved the increase in p53 expression. The impact of structure simplification on compound 12 profile, characterized by the absence of acute oral liver toxicity when compared to Doxorubicin as a standard inhibitor, the lethal dose measured on Swiss Albino female mice and reported at LD50 = 250 mg/kg, and therapeutic significance in reducing colon adenocarcinoma tumor volume by 75.36 % after five weeks of treatment with compound 12. The molecular docking solutions of the active CPT-based derivative 12 and the inactive congener 14 into the active site of hTop1 and the activity cliffing of such MMP directed us to recommend the addition of HBD and HBA variables to compound 12 imidazoquinazoline core scaffold to enhance the potency via hydrogen bond formation with the major groove amino acids (Asp533, Lys532) as well as maintaining the hydrogen bond with the minor groove amino acid Arg364.

How clean is clean enough? An observational pilot study to assess central sterilization processing efficacy with adenosine triphosphate levels

BACKGROUND

There is strong evidence showing the need for quantitative assessment of the efficacy of cleaning medical devices. Studies comparing visual and microscopic analysis have demonstrated that visual inspection alone is insufficient to determine cleanliness. OUR OBJECTIVE WAS TO: collect baseline adenosine triphosphate testing data for surgical instruments to inform future quality improvement programs, and to develop a process to comply with standards recommended by the Association for the Advancement of Medical Instrumentation.

METHODS

The central sterilization processing department (CSPD) identified difficult to clean tools in hip, spinal fusion, and colon procedures. Instruments used during the procedures were swabbed at arrival to the CSPD, after manual washing, and after a standard 24-minute machine wash cycle. Each instrument was swabbed in a uniform manner on surface areas including hinged joints and teeth, consistent with manufacturer recommendations. Instruments were tagged to ensure accuracy of tracking.

RESULTS

The mean relative light unit (RLU) readout of all instruments on entry to the CSPD, postmanual wash, and postmachine wash was 240,416, 3,352, and 47, respectively. A total of 97.7% of all instruments had a passable final RLU readout. One Rongeur had a failed final RLU readout of 171.

CONCLUSIONS

This study suggests that the current cleaning process is adequate for the instruments tested. Ongoing quality assessment would be beneficial to validate other instruments.