Direct Oral FXa Inhibitors Binding to Human Serum Albumin: Spectroscopic, Calorimetric, and Computational Studies

Direct FXa inhibitors are an important class of bioactive molecules (rivaroxaban, apixaban, edoxaban, and betrixaban) applied for thromboprophylaxis in diverse cardiovascular pathologies. The interaction of active compounds with human serum albumin (HSA), the most abundant protein in blood plasma, is a key research area and provides crucial information about drugs' pharmacokinetics and pharmacodynamic properties. This research focuses on the study of the interactions between HSA and four commercially available direct oral FXa inhibitors, applying methodologies including steady-state and time-resolved fluorescence, isothermal titration calorimetry (ITC), and molecular dynamics. The HSA complexation of FXa inhibitors was found to occur via static quenching, and the complex formation in the ground states affects the fluorescence of HSA, with a moderate binding constant of 10⁴ M^-1. However, the ITC studies reported significantly different binding constants (10³ M^-1) compared with the results obtained through spectrophotometric methods. The suspected binding mode is supported by molecular dynamics simulations, where the predominant interactions were hydrogen bonds and hydrophobic interactions (mainly π-π stacking interactions between the phenyl ring of FXa inhibitors and the indole moiety of Trp214). Finally, the possible implications of the obtained results regarding pathologies such as hypoalbuminemia are briefly discussed.

Synthesis, and spectroscopic and structural characterization of three new styrylquinoline–benzimidazole hybrids

Three new 4-styrylquinoline–benzimidazole hybrids have been synthesized using a reaction sequence in which 2-methylquinoline precursors first undergo selective oxidation by selenium dioxide to form the corresponding 2-formylquinoline intermediates, followed by oxidative cyclocondensation reactions with benzene-1,2-diamine to yield the hybrid products. The formyl intermediates and the hybrid products have all been fully characterized using a combination of IR, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry, and the structures of the three hybrid products have been determined using single-crystal X-ray diffraction. Ethyl (E)-2-(1H-benzo[d]imidazol-2-yl)-4-(4-chlorostyryl)quinoline-3-carboxylate, C27H20ClN3O2, (IIIa), and ethyl (E)-2-(1H-benzo[d]imidazol-2-yl)-4-(2-methoxystyryl)quinoline-3-carboxylate, C28H23N3O3, (IIIb), both crystallize in the solvent-free form with Z′ = 1, but ethyl (E)-2-(1H-benzo[d]imidazol-2-yl)-4-(4-methylstyryl)quinoline-3-carboxylate, C28H23N3O2, (IIIc), crystallizes as a partial hexane solvate with Z′ = 3, and the ester group in one of the independent molecules is disordered over two sets of atomic sites having occupancies of 0.765 (7) and 0.235 (7). The molecules of (IIIc) enclose continuous channels which are occupied by disordered solvent molecules having partial occupancy. In all of the molecules of (IIIa)–(IIIc), the styrylquinoline fragment is markedly nonplanar. Different combinations of N—H...O and C—H...π hydrogen bonds generate supramolecular assemblies which are two-dimensional in (IIIb) and (IIIc), but three-dimensional in (IIIa). Comparisons are made with the structures of some related compounds.

Bio-click chemistry: a bridge between biocatalysis and click chemistry

The fields of click chemistry and biocatalysis have rapidly grown over the last two decades. The development of robust and active biocatalysts and the widespread use of straightforward click reactions led to significant interactions between these two fields. Therefore the name bio-click chemistry seems to be an accurate definition of chemoenzymatic reactions cooperating with click transformations. Bio-click chemistry can be understood as the approach towards molecules of high-value using a green and sustainable approach by exploiting the potential of biocatalytic enzyme activity combined with the reliable nature of click reactions. This review summarizes the principal bio-click chemistry reactions reported over the last two decades, with a special emphasis on small molecules. Contributions to the field of bio-click chemistry are manifold, but the synthesis of chiral molecules with applications in medicinal chemistry and sustainable syntheses will be especially highlighted.

Green by Design: Convergent Synthesis, Computational Analyses, and Activity Evaluation of New FXa Inhibitors Bearing Peptide Triazole Linking Units

Green chemistry implementation has led to promising results in waste reduction in the pharmaceutical industry. However, the early sustainable development of pharmaceutically active compounds and ingredients remains a considerable challenge. Herein, we wish to report a green synthesis of new pharmaceutically active peptide triazoles as potent factor Xa inhibitors, an important drug target associated with the treatment of diverse cardiovascular diseases. The new inhibitors were synthesized in three steps, featuring cycloaddition reactions (high atom economy), microwave-assisted organic synthesis (energy efficiency), and copper nanoparticle catalysis, thus featuring Earth-abundant metals. The molecules obtained showed FXa inhibition, with IC50-values as low as 17.2 μM and no associated cytotoxicity in HEK293 and HeLa cells. These results showcase the environmental potential and chemical implications of the applied methodologies for the development of new molecules with pharmacological potential.

Prognostic factors in patients with locally advanced rectal adenocarcinoma treated with preoperative radiotherapy and surgery

Preoperative radiation therapy (PRT) prior to potential curative resection for rectal adenocarcinoma is not widely accepted. This report evaluates the prognostic factors affecting local recurrence and 5-year survival. This is a retrospective study of 214 patients with primary rectal adenocarcinoma treated from January 1986 to December 1994. A PRT dosage of 45 Gy in 20 fractions was administered to patients with clinically tethered or fixed tumors, and 4 to 8 weeks later surgery was performed (group I). Patients with clinically mobile tumors were treated by surgery alone (group II). There were 130 men and 84 women. The median age was 58 years (range 19-85 years). There were 111 patients in group I: 7 patients had no microscopic residual tumor, 80 had Dukes' A and B, and 24 had Dukes' C. There were 103 patients in group II: 70 patients were classified as Dukes' A and B and 33 as Dukes' C. The mean follow-up of the entire cohort was 62 months (range 2-132 months). Local recurrence was seen in 17% of patients in group I and 35% in group II (p = 0.002). Distant recurrence in patients with metastatic lymph nodes was seen in 79% of group I and in 34% of group II (p = 0.001). The favorable prognostic factors for local control were the administration of PRT and well differentiated cancer. The favorable prognostic factors for survival were age < 50 years and the absence of lymph node metastasis. The administration of PRT diminishes the risk of local recurrence. The presence of metastatic lymph nodes in the postirradiated specimen is an ominous prognostic factor for survival. Therefore such patients should be considered for adjuvant chemotherapy.

Colorectal sarcoma: analysis of failure patterns

BACKGROUND AND OBJECTIVES

Colorectal sarcomas (CRS) are rare and their treatment remains controversial, especially for those located in the rectum. The aim of this paper is to evaluate our experience, with special emphasis on the failure pattern after surgical therapy alone or combined with postoperative radiotherapy.

MATERIALS AND METHODS

The medical records and histological slides of 13 CRS patients treated between 1986 and 1996 were reviewed retrospectively.

RESULTS

The patients included eight males and five females, with a median age of 54 years; nine of their primary tumors were located in the rectum, and four in the colon. The histologies were leiomyosarcoma in nine cases and malignant fibrous histiocytoma in four cases. Surgical treatment consisted of anatomical colectomy (four); local excision (three); abdominoperineal resection (APR)(two); low anterior resection (LAR)(two); LAR en bloc with the prostate (one), and total pelvic exenteration (one). One operative death occurred. The median size of the tumors was 8 cm (range, 5-40). The tumors were graded as low, three, and high, ten. The median follow-up was 24 months. Eight patients in the overall group developed recurrences as follows: local, three; local and distant, three, and distant, two. Five out of nine patients with rectal sarcoma received adjuvant postoperative radiotherapy (PRT). Local recurrence occurred in 20% (1/5) of those who received PRT, and in 100% (3/3) of those who did not. The overall 5-year survival was 40%, and the 5-year survival for patients with low-grade tumors was 66%, as compared with 22% for those with high-grade tumors.

CONCLUSIONS

The patterns of failure in CRS are combined in both local and distant sites. However, our results suggest that in rectal sarcoma, the use of surgery + PRT may reduce the local recurrence rate; in selected patients, it may allow for anal sphincter preservation.