Weak complexation of 5-fluorouracil with ß-cyclodextrin, carbonate, and dianhydride crosslinked ß-cyclodextrin: in vitro and in silico studies.

Background and purpose: Several pharmaceutical formulations were investigated to improve the solubility of 5-fluorouracil to enhance bioavailability and therapeutic efficacy. This study aimed to examine the potential use of cyclodextrin-based nanosponges for the incorporation of 5-fluorouracil and to investigate the use of different crosslinking agents on the properties of the resulting drug carrier. 5-Fluorouracil complexation with ß-cyclodextrin was also studied to explain the unexpected results of weak 5-fluorouracil incorporation in nanosponge. Experimental approach: Nanosponges were synthesized by crosslinking ß-cyclodextrin with two different crosslinkers; diphenyl carbonate and ethylenediaminetetraacetic dianhydride. The incorporation of 5-fluorouracil into ß-cyclodextrin and the prepared nanosponges were assessed by NMR, FTIR, PXRD, DSC, and TGA. In addition, an in vitro release study was carried out to evaluate the potential use of ß-cyclodextrin- based nanosponges as pharmaceutical formulations for 5-fluorouracil. Findings / Results: Physicochemical characterization of the dried formulations indicated the complexation of 5-fluorouracil with the ß-cyclodextrin polymer. Despite that, no clear manifestation of 5-fluorouracil encapsulation in the prepared ß-cyclodextrin-based nanosponge was detected. Furthermore, no significant differences were observed in the release profiles of 5-fluorouracil, ß-cyclodextrin complex, and ß- cyclodextrin-based nanosponge, suggesting weak complexation and instability in aqueous solutions. EDTA- crosslinked ß-cyclodextrin-based nanosponge showed a slight improvement in 5-fluorouracil solubility with a faster initial rate of 5-fluorouracil release. Conclusion and implications: This study suggested weak complexation between 5-fluorouracil and the ß- cyclodextrin polymer or nanosponges. Crosslinking of ß-cyclodextrin with EDTA dianhydride crosslinker showed an enhancement in 5-fluorouracil saturation solubility combined with a faster initial rate of drug release.

High Performance Liquid Chromatography (HPLC) with Fluorescence Detection for Quantification of Steroids in Clinical, Pharmaceutical, and Environmental Samples: A Review.

Steroids are compounds widely available in nature and synthesized for therapeutic and medical purposes. Although several analytical techniques are available for the quantification of steroids, their analysis is challenging due to their low levels and complex matrices of the samples. The efficiency and quick separation of the HPLC combined with the sensitivity, selectivity, simplicity, and cost-efficiency of fluorescence, make HPLC coupled to fluorescence detection (HPLC-FLD) an ideal tool for routine measurement and detection of steroids. In this review, we covered HPLC-FLD methods reported in the literature for the steroids quantification in clinical, pharmaceutical, and environmental applications, focusing on the various approaches of fluorescent derivatization. The aspects related to analytical methodology including sample preparation, derivatization reagents, and chromatographic conditions will be discussed.

Coumarins, dihydroisocoumarins, a dibenzo-α-pyrone, a meroterpenoid, and a merodrimane from Talaromyces amestolkiae.

Chemical investigation of an organic extract of a fungus isolated from submerged wood collected from fresh water (strain G173), identified as a Talaromyces amestolkiae (Eurotiales; Trichocomaceae), led to the isolation of three coumarins, three dihydroisocoumarins, a dibenzo-α-pyrone, a meroterpenoid, and a merodrimane. Three of the isolated compounds, namely 7-chloropestalasin A (3), 4-hydroxyaspergillumarin (6), and ent-thailandolide B (9) were new. The structures were elucidated using a combination of spectroscopic and spectrometric techniques. The absolute configurations of 2, 3, 5, and 6 were established via a modified Mosher's ester method, whereas for 9 a combination of TDDFT ECD and ORD calculations were employed. Compounds 1-9 were evaluated for antimicrobial activity against a group of bacteria and fungi.

Pim kinase inhibitors in cancer: medicinal chemistry insights into their activity and selectivity.

The oncogenic Pim kinase proteins (Pim-1/2/3) regulate tumorigenesis through phosphorylating essential proteins that control cell cycle and proliferation. Pim kinase is a potential chemotherapeutic target in cancer and its inhibition is currently the focus of intensive drug design and development efforts. The distinctive presence of proline amino acids in the hinge region provides an opportunity to inhibit Pim kinase while conserving the physiological functions of other kinases and reducing the toxicity profiles of the inhibitors. Various Pim kinase inhibitors have been clinically evaluated for the treatment of hematological cancers, yet none has reached the clinic. In this review, we discuss the design and development of selective and potent Pim inhibitors with novel chemotypes focusing on structural features essential for high potency and selectivity.

Amino-carboxamide benzothiazoles as potential LSD1 hit inhibitors. Part I: Computational fragment-based drug design.

The lysine specific demethylase enzyme LSD1 regulates the function of histone proteins in cells through the demethylation of specific lysine amino acid residues. Being overexpressed in various cancers, LSD1 is considered as a validated target for cancer treatment. In this study, we describe the discovery of novel LSD1 inhibitors using computational fragment-based drug design approach. Structure-based screening of the Maybridge Ro3 2000 Diversity Fragment Library had identified two sets of fragments that bind to two different regions within the LSD1 active site. De Novo and Multiple Copy Simultaneous search (MCSS) docking, ligand efficiency (LE), and binding energy calculations (BE) had assisted the selection of the best scoring fragments that were grown to produce lead-like compounds. The final grown compounds were docked into the active site of the enzyme using flexible docking and their total binding energies were calculated in order to aid the selection of potential LSD1 inhibitors that will be synthesized and biologically evaluated. Six compounds were synthesized and biologically tested, of which two had showed a promising activity against LSD1. Compound 37, with an amino-carboxamide benzothiazole scaffold, showed the best inhibitory activity with an IC50 value of 18.4 µM. Compound 37 was chosen as an LSD1 hit inhibitor worthy of further optimization.

Hit identification of SMYD3 enzyme inhibitors using structure-based pharmacophore modeling.

Aim: SMYD3 enzyme is overexpressed in many types of cancer and its role in the methylation of cytoplasmic mitogen-activated protein kinase, kinase kinase 2 (MAP3K2), has been linked to promotion of Kras-driven cancer in pancreatic ductal and lung adenocarcinoma. Materials & methods: A hybrid 3D structure-based pharmacophore model was generated using crystal structures of SMYD3 complexed with sinefungin and was used to search for potential SMYD3 inhibitors through virtual screening of the Maybridge database. The retrieved hits from screening were further docked into the binding site of SMYD3 using CDOCKER docking algorithms. The top-ranked hits were selected and their inhibitory activity was evaluated. Results & conclusion: The results obtained helped us to find an SMYD3 small molecule hit inhibitor scaffold.

Evaluation of analogues of furan-amidines as inhibitors of NQO2.

Inhibitors of the enzyme NQO2 (NRH: quinone oxidoreductase 2) are of potential use in cancer chemotherapy and malaria. We have previously reported that non-symmetrical furan amidines are potent inhibitors of NQO2 and here novel analogues are evaluated. The furan ring has been changed to other heterocycles (imidazole, N-methylimidazole, oxazole, thiophene) and the amidine group has been replaced with imidate, reversed amidine, N-arylamide and amidoxime to probe NQO2 activity, improve solubility and decrease basicity of the lead furan amidine. All compounds were fully characterised spectroscopically and the structure of the unexpected product N-hydroxy-4-(5-methyl-4-phenylfuran-2-yl)benzamidine was established by X-ray crystallography. The analogues were evaluated for inhibition of NQO2, which showed lower activity than the lead furan amidine. The observed structure-activity relationship for the furan-amidine series with NQO2 was rationalized by preliminary molecular docking and binding mode analysis. In addition, the oxazole-amidine analogue inhibited the growth of Plasmodium falciparum with an IC50 value of 0.3 µM.

Explaining the autoinhibition of the SMYD enzyme family: A theoretical study.

The SMYD enzymes (SMYD1-5) are lysine methyltransferases that have diverse biological functions including gene expression and regulation of skeletal and cardiac muscle development and function. Recently, they have gained more attention as potential drug targets because of their involvement in cardiovascular diseases and in the progression of different cancer types. Their activity has been suggested to be regulated by a posttranslational mechanism and by autoinhibition. The later relies on a hinge-like movement of the N- and C-lobes to adopt an open or closed conformation, consequently, determining the accessibility of the active site and substrate specificity. In this study we aim to investigate and explain the possibility of the regulatory autoinhibition process of the SMYD enzymes by a thorough computational exploration of their dynamic, energetic, and structural changes by using extended molecular dynamics simulations; normal mode analysis (NMA); and energy correlations. Three SMYD models (SMYD1-3) were used in this study. Our results showed an obvious hinge-like motion between the N- and C-lobes. Also, we identified interaction energy pathways within the 3D structures of the proteins, and hot spots on their surfaces that could be of particular importance for the regulation of their activities via allosteric means. These results can help in a better understanding of the nature of these promising drug targets; and in designing selective drugs that can interfere with (inhibit) the function of a specific SMYD member by disrupting its dynamical and conformational behaviour without disrupting the function of the entire SMYD proteins.

Non-symmetrical furan-amidines as novel leads for the treatment of cancer and malaria.

NRH:quinone oxidoreductase 2 enzyme (NQO2) is a potential therapeutic target in cancer and neurodegenerative diseases, with roles in either chemoprevention or chemotherapy. Here we report the design, synthesis and evaluation of non-symmetrical furan-amidines and their analogues as novel selective NQO2 inhibitors with reduced adverse off-target effects, such as binding to DNA. A pathway for the synthesis of the non-symmetrical furan-amidines was established from the corresponding 1,4-diketones. The synthesized non-symmetrical furan-amidines and their analogues showed potent NQO2 inhibition activity with nano-molar IC50 values. The most active compounds were non-symmetrical furan-amidines with meta- and para-nitro substitution on the aromatic ring, with IC50 values of 15 nM. In contrast to the symmetric furan-amidines, which showed potent intercalation in the minor grooves of DNA, the synthesized non-symmetrical furan-amidines showed no affinity towards DNA, as demonstrated by DNA melting temperature experiments. In addition, Plasmodium parasites, which possess their own quinone oxidoreductase PfNDH2, were inhibited by the non-symmetrical furan-amidines, the most active possessing a para-fluoro substituent (IC50 9.6 nM). The high NQO2 inhibition activity and nanomolar antimalarial effect of some of these analogues suggest the lead compounds are worthy of further development and optimization as potential drugs for novel anti-cancer and antimalarial strategies.