Stabilizing Bifurcated Hydrogen Bond in 8-Aminoquinoline Appended Peptides.

The hydrogen bonding interaction between an amide N-H and the amide N of the preceding residue is prevalent in proline-containing proteins and peptides. However, the N-H···N hydrogen bonding interaction is rare in non-prolyl natural peptides due to restricted dihedral angles. Herein, we stabilize this type of interaction in 8-aminoquinoline appended non-prolyl peptides through bifurcated N···H···N hydrogen bond. The 8-aminoquinoline-incorporated model peptides 2a-i were designed, synthesized, and the crystal structures of 2a-c and 2i were solved. Analysis of crystal data reveals that the amide N-H of aminoquinoline is involved in bifurcated hydrogen bonding interaction with the nitrogen of the preceding amino acid residue and the nitrogen in quinoline. Analysis of crystal packing, Hirshfeld surface and fingerprint plots confirms that the intermolecular O···H contacts significantly contribute to stabilizing bifurcated N···H···N hydrogen bonding interaction. Furthermore, NMR experiments and CD spectroscopy were conducted to examine the preferred conformation in solution, and the data corroborate with the crystal structure conformation.

Retrospective application of WHO reporting system for lung cytopathology with assessment of risk of malignancy.

INTRODUCTION: The recently introduced World Health Organization (WHO) Reporting System for Lung Cytopathology presents 5 diagnostic categories with corresponding risk of malignancy (ROM) and management protocols. This study uses the system to categorize our institutional respiratory tract cytology specimens, evaluating ROM and diagnostic accuracy for each category. MATERIALS AND METHODS: In a retrospective analysis (May 2020 to August 2021), the following respiratory cytology specimens were classified based on the WHO categories: bronchoalveolar lavage (BAL), bronchial wash/bronchial brushings (BB/BW), endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), fine-needle aspiration cytology (FNAC), sputum, biopsy imprint (BI), and endotracheal wash. Exclusions comprised pleural effusions and EBUS-TBNA from mediastinal and hilar lymph nodes. Correlation of cytologic and histopathologic diagnoses was performed to assess ROM collectively and individually. RESULTS: A total of 1518 respiratory samples (BAL [968], BW/BB [380], EBUS-TBNA [42], FNAC [32], sputum [80], BI [11] and endotracheal wash [5]) of 1410 patients were screened, of which 522 cases (34.3%) had histopathologic correlation. One hundred forty-one cases (9.3%) were Insufficient/Inadequate/Non-Diagnostic (ND), 1221 (80.4%) were Benign (B), 3 (0.2%) were Atypical (A), 32 (2.1%) were Suspicious for malignancy (SM) and 121 (8.0%) were Malignant (M). The estimated ROM for each category was 49.2% for ND, 13.3% for B, 66.6% for A, 81.5% for SM and 92.7% for M. FNAC and EBUS-TBNA exhibited the highest sensitivity (100%) compared with BW/BB (66.3%). Specificity ranged from 96.8% to 100% across the samples, while diagnostic accuracy varied from 58.8% to 100%. CONCLUSIONS: Application of the WHO reporting system enhances standardized terminology, aiding clinicians in informed decision-making and improving patient care through accurate risk assessment of malignancy.

Metal-free sp2 -C7-H Borylation of Tryptophan Containing Peptides and Late-stage Modification.

The discovery of milder and robust strategies to enable the introduction of organoboronates in peptides remains conspicuously underdeveloped. Herein, we demonstrate an efficient method for the site-selective sp2 -C7-H borylation of tryptophan under metal-free condition using BBr3 directed by pivaloyl group. The versatility of this approach is that gram scale synthesis and C7-borylated N-Phth-Trp(N-Piv)(C7-BPin)-OMe was modified into various C7-substituted derivatives. Moreover, the strategy enables for the peptide elongation and late-stage borylation of peptides, natural product Brevianamide F and drug Oglufanide.

Design and synthesis of N-acyl and dimeric N-Arylpiperazine derivatives as potential antileishmanial agents.

The current regime for leishmaniasis is associated with several adverse effects, expensive, parenteral treatment for longer periods and the emergence of drug resistance. To develop affordable and potent antileishmanial agents, a series of N-acyl and homodimeric aryl piperazines were synthesized with high purity, predicted druggable properties by in silico methods and investigated their antileishmanial activity. The in vitro biological activity of synthesized compounds against clinically validated intracellular amastigote and extracellular promastigote form of Leishmania donovani parasite showed eight compounds inhibited 50% amastigotes growth below 25 µM. The half maximal inhibitory concentration (IC50) and cytotoxicity assessment of eight active compounds, 4a, 4d and 4e demonstrated activity with an IC50 2.0 - 9.1 µM and selectivity index 10 - 42. Compound 4d (IC50 2.0 µM, SI = 42) found to be the best among them with four-folds more potent and eight-folds less toxic than the control drug miltefosine. Overall, results demonstrated that compound 4d is a promising lead candidate for further development as antileishmanial drug.

Design and synthesis of novel halogen rich salicylanilides as potential antileishmanial agents.

The available therapeutic treatment for leishmaniasis is inadequate and toxic due to side effects, expensive and emergence of drug resistance. Affordable and safe antileishmanial agents are urgently needed and toward this objective, we synthesized a series of 32 novel halogen rich salicylanilides including niclosamide and oxyclozanide and investigated their antileishmanial activity against amastigotes of Leishmania donovani. In vitro data showed fifteen compounds inhibited intracellular amastigotes with an IC50 of below 5 µM and selectivity index above 10. Among 15 active compounds, 14 and 24 demonstrated better activity with an IC50 of 2.89 µM and 2.09 µM respectively and selectivity index is 18. Compound 24 exhibited significant in vivo antileishmanial efficacy and reduced 65% of the splenic parasite load on day 28th post-treatment in the experimental visceral leishmaniasis golden hamster model. The data suggest that 24 can be a promising lead candidate possessing potential to be developed into a leishmanial drug candidate.

Influence of Proline Chirality on Neighbouring Azaproline Residue Stereodynamic Nitrogen Preorganization.

We report herein the first systematic crystal structural investigation of azaproline incorporated in homo- and heterochiral diprolyl peptides. The X-ray crystallography data of peptides 1-5 illustrates that stereodynamic nitrogen in azaproline adopted the stereochemistry of neighbouring proline residue without depending on its position in the peptide sequence. Natural bond orbital analysis of crystal structures indicates OazPro -C'Pro of peptides 4 and 5 participating in n→π* interaction with stabilization energy about 1.21-1.33 kcal/mol. Density functional theory calculations suggested that the endo-proline ring puckering favoured over exo-conformation by 6.72-7.64 kcal/mol. NBO and DFT data reveals that the n→π* interactions and proline ring puckering stabilize azaproline chirality with the neighbouring proline stereochemistry. The CD, solvent titration, variable-temperature and 2D NMR experimental results further supported the crystal structures conformation.

Comparison of hematologic abnormalities between hospitalized coronavirus disease 2019 positive and negative patients with correlation to disease severity and outcome.

Peripheral blood smear (PBS) changes in coronavirus disease 2019 (COVID-19) are diverse and have been reported in the literature in the form of case series with relatively smaller sample sizes and with a handful of studies showing the association between PBS and clinical severity. This study aims to highlight the numerical and morphological changes in peripheral blood of COVID-19 patients and to compare the same in intensive care unit (ICU) and non-ICU settings as well as with disease severity and outcome. The study included 80 COVID-19 positive (41 ICU and 39 non-ICU) patients and 32 COVID-19 negative ICU patients. Complete blood counts (CBCs) and PBS findings were studied and scored by two pathologists blindfolded. Absolute lymphocyte count (ALC) and absolute eosinophil count (AEC) were significantly lower in COVID-19 positive cases as compared to the COVID-19 negative group (p = 0.001 and p = 0.001). COVID-19 positive group showed significant left myeloid shift (p = 0.021), Dohle bodies (p = 0.025) with significant prominence of acquired pseudo-Pelger-Huët anomaly, ring-shaped neutrophils, monolobate neutrophils, and plasmacytoid lymphocytes as compared to control group (p = 0.000, p = 0.009, p = 0.046, and p = 0.011, respectively). The overall mean white blood cell (WBC) counts were higher in COVID-19 positive ICU patients as compared to non-ICU COVID patients with significant shift to left, presence of ring-shaped neutrophils, monocyte vacuolation, and large granular lymphocytes (p = 0.017, p = 0.007, p = 0.008, and p = 0.004, respectively). Deceased group showed significantly higher WBC count (p = 0.018) with marked neutrophilia (p = 0.024) and toxic granulation (p = 0.01) with prominence of monocyte vacuolization, ring-shaped neutrophils, large granular lymphocytes, and reactive lymphocytes. Parameters like myeloid left shift, ring-shaped neutrophils, monocyte vacuolation, and large granular lymphocytes emerged as highly sensitive markers of disease severity. Therefore, serial CBC with comprehensive PBS analysis should be done in every newly diagnosed hospitalized COVID-19 patient which potentially predicts the course of the disease.

Serum Levels of Vascular Endothelial Growth Factor and Its Receptor in Newly Diagnosed Paediatric Acute Lymphoblastic Leukemia.

Autocrine and paracrine loop involving vascular endothelial growth factor (VEGF) and its receptor have been described in haematological malignancies. However, scarce literature is present on angiogenesis in paediatric acute lymphoblastic leukemia (ALL) with studies showing controversial results. The aim was to study serum levels of VEGF and its receptors in paediatric ALL at the time of diagnosis and at the end of induction phase and to compare these levels with clinico-haematological parameters in these patients. Serum VEGF, VEGFR-1 and VEGFR-2 levels were measured by enzyme-linked immunoabsorbant assay at diagnosis (day 0) and at the end of induction phase (day 35) in 30 newly diagnosed paediatric ALL patients and in 10 healthy controls. Median s-VEGF was significantly lower at day 0 as compared to day 35 (196.15 vs. 606.75 pg/ml: p < 0.001). s-VEGFR-1 levels were detectable only in 7 patients at day 0 and were below detection level at day 35 in all patients. Median s-VEGFR-2 at day 0 was significantly lower as compared to day 35 (17,577.5 vs. 20,507.5 pg/ml; p = 0.005). Median VEGF-R1 showed an inverse relationship with VEGF-R2 but was statistically insignificant. All patients were in remission at the end of induction. Thus, leukemic infiltration of bone marrow affects angiogenesis and reduces pro-angiogenic markers VEGF and VEGFR-2 in serum possibly due to increased local consumption by blasts. A successful induction leads to clearing of blasts causing restoration of normal hematopoiesis with normalization of VEGF and VEGFR-2 levels.