The synthesis of boronic-imine structured compounds and identification of their anticancer, antimicrobial and antioxidant activities

Cream production and biological in vivo/in vitro activity assessment of a novel boron-based compound derived from quercetin and phenyl boronic acid

Boronic acids constitute an important class of synthetic intermediates due to their high chemical stability, ease of use, moderate organic Lewis acid properties, reduced reactivity profiles and numerous biological activities such as antibacterial and antioxidant. The present study documents the synthesis and characterization of a novel boronic ester compound (3,5,7-trihydroxy-2- (2-phenyl benzo [d] [1,3,2] dioxaborol-5-yl) -4H-chromen-4-a) which was derived from phenyl boronic acid and quercetin. The new boron-based compound was used in the cream formulation after evaluating its antioxidant, antibacterial, anti-enzyme, anticancer activities and electrochemical oxidation behaviour. Furthermore, the cream has been dermatologically and microbiologically tested. Also, histological evaluation of the agent was estimated on multiple rat organs by hematoxylin-eosin staining method. Antioxidant potential of the new compound was tested by ABTS cation radical (IC₅₀: 0.11 ± 0.01 µg/mL), DPPH free radical scavenging (IC₅₀: 0.14 ± 0.01 µg/mL), and CUPRAC (A_0.5: 1.73 ± 0.16 µg/mL) methods, respectively. The compound determined to have a dominant antioxidant activity. In addition, the synthesized compound had no toxic effect on the healthy cell line (PDF), while having a very high (IC₅₀: 18.76 ± 0.62 µg/mL) cytotoxic effect on the cancerous cell line (MCF-7). In general, the compound showed moderate acetylcholinesterase enzyme activity (IC₅₀: 115.63 ± 1.16 µg/mL), high butyrylcholinesterase (IC₅₀: 3.12 ± 0.04 µg/mL), antiurease (IC₅₀: 1.10 ± 0.06 µg/mL), and antithyrosinase (IC₅₀: 11.52 ± 0.46 µg/mL) enzyme activities. In addition, the compound was found to be effective against Escherichia coli (ATCC 25922) bacteria studied at concentrations of 6.50 mg/mL. Moreover, the test results of the boronic ester compound used in the cream formulation demonstrated that it was microbiologically and dermatologically appropriate. Histologic analysis showed that the control group and experimental group were at similar properties without significant change. The phenyl boronic acid derivative compound synthesized from quercetin may have higher biological activity potential than quercetin. Due to the high biological activity potential of the synthesized compound, it has the potential to be used in food, feed, pharmaceutical and cosmetic industries.

Smart Supra- and Macro-Molecular Tools for Biomedical Applications

Stimuli-responsive, “smart” polymeric materials used in the biomedical field function in a bio-mimicking manner by providing a non-linear response to triggers coming from a physiological microenvironment or other external source. They are built based on various chemical, physical, and biological tools that enable pH and/or temperature-stimulated changes in structural or physicochemical attributes, like shape, volume, solubility, supramolecular arrangement, and others. This review touches on some particular developments on the topic of stimuli-sensitive molecular tools for biomedical applications. Design and mechanistic details are provided concerning the smart synthetic instruments that are employed to prepare supra- and macro-molecular architectures with specific responses to external stimuli. Five major themes are approached: (i) temperature- and pH-responsive systems for controlled drug delivery; (ii) glycodynameric hydrogels for drug delivery; (iii) polymeric non-viral vectors for gene delivery; (iv) metallic nanoconjugates for biomedical applications; and, (v) smart organic tools for biomedical imaging.

3-Pyridinylboronic acid normalizes the effects of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine exposure in zebrafish embryos

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that damages dopaminergic neurons. Zebrafish has been shown to be a suitable model organism to investigate the molecular pathways in the pathogenesis of Parkinson's disease and also for potential therapeutic agent research. Boron has been shown to play an important role in the neural activity of the brain. Boronic acids are used in combinatorial approaches in drug design and discovery. The effect of 3-pyridinylboronic acid which is an important sub-class of heterocyclic boronic acids has not been evaluated in case of MPTP exposure in zebrafish embryos. Accordingly, this study was designed to investigate the effects of 3-pyridinylboronic acid on MPTP exposed zebrafish embryos focusing on the molecular pathways related to neurodegeneration and apoptosis by RT-PCR. Zebrafish embryos were exposed to MPTP (800 μM); MPTP + Low Dose 3-Pyridinylboronic acid (50 μM) (MPTP + LB) and MPTP + High Dose 3-Pyridinylboronic acid (100 μM) (MPTP + HB) in well plates for 72 hours post fertilization. Results of our study showed that MPTP induced a P53 dependent and Bax mediated apoptosis in zebrafish embryos and 3-pyridinylboronic acid restored the locomotor activity and gene expressions related to mitochondrial dysfunction and oxidative stress due to the deleterious effects of MPTP, in a dose-dependent manner.

Boronic Acid-Functionalized Two-Dimensional MoS2 at Biointerfaces

While noncovalent interactions at two-dimensional nanobiointerfaces are extensively investigated, less knowledge about covalent interactions at this interface is available. In this work, boronic acid-functionalized 2D MoS₂ was synthesized and its covalent multivalent interactions with bacteria and nematodes were investigated. Polymerization of glycidol by freshly exfoliated MoS₂ and condensation of 2,5-thiophenediylbisboronic acid on the produced platform resulted in boronic acid-functionalized 2D MoS₂. The destructive interactions between 2D MoS₂ and bacteria as well as nematodes were significantly amplified by boronic acid functional groups. Because of the high antibacterial and antinematodal activities of boronic acid-functionalized 2D MoS₂, its therapeutic efficacy for diabetic wound healing was investigated. The infected diabetic wounds were completely healed 10 days after treatment with boronic acid-functionalized 2D MoS₂, and a normal structure for recovered tissues including different layers of skin, collagen, and blood vessels was detected.

Synthesis and Evaluation of C15 Triene Urushiol Derivatives as Potential Anticancer Agents and HDAC2 Inhibitor

A series of C15 triene urushiol derivatives were synthesized and evaluated for their anti-HepG2 aggregation in vitro. The results indicated that all compounds had an effective anti-HepG2 vitality. Compound 1 was a potent inhibitor of HepG2 with IC₅₀ of 7.886 μM and 150 μM against LO2. Moreover, compound 1 increased the apoptosis of HepG2. Compound 1’s thiol sulfur formed hydrogen bonding interactions with Gly154 and Tyr308, respectively, and made it bound more closely to HDAC2. In addition, it also formed hydrophobic interactions with the residues His33, Pro106, Val107, Gly154, Phe155, and His183, and was provided with a strong van der Waals force by the hydrophobic action.

Synthesis and Characterization of the Hemi-Salen Ligands and Their Triboron Complexes: Spectroscopy and Examination of Anticancer Properties

The synthesis, spectroscopic properties, and in vitro cytotoxicity activity of a series of various salen-based triboron complexes have been designed and prepared from hemi-salen (L₁ H₃  - L₄ H₃ ) ligands and BF₃ ·Et₂ O or BPh₃ under simple reaction conditions. The hemi-salen (L₁ H₃  - L₄ H₃ ) ligands and their BF₂ or BPh₂ chelating triboron complexes were characterized by means of NMR (¹ H, ¹³ C, ¹⁹ F, and ¹¹ B) spectra, FT-IR spectra, UV/VIS spectra, fluorescence spectra, mass spectra, melting point, as well as elemental analysis. The triboron [L_(1 - 4) (BF₂ )₃ ] and [L_(1 - 4) (BPh₂ )₃ ] complexes were investigated for their absorption and emission properties, and these complexes are also good chelates towards boron(III) fragments such as BF₂ or BPh₂ quantum yield in solution reaching up to 38%. The hemi-salen (L₁ H₃  - L₄ H₃ ) ligands and their BF₂ or BPh₂ chelating triboron complexes were tested for the in vitro anticancer activity against various cancer and normal cells (HeLa, DLD-1, ECC-1, PC-3, PNT-1A, and CRL-4010), and it was found that the cell viability of cancer cells was decreased while most of the healthy cells could still be viable. Also, the cytotoxicity studies showed that anticancer activity of hemi-salen (L₁ H₃  - L₄ H₃ ) ligands is higher than that of triboron [L_(1 - 4) (BF₂ )₃ ] and [L_(1 - 4) (BPh₂ )₃ ] complexes. The hemi-salen (L₁ H₃  - L₄ H₃ ) ligands showing the strongest cytotoxic effect in PC-3 cells were found to exhibit anticancer activity with apoptosis by increasing the level of ROS in the PC-3 cells.

Dual crosslinked iminoboronate-chitosan hydrogels with strong antifungal activity against Candida planktonic yeasts and biofilms

Chitosan based hydrogels are a class of cross-linked materials intensely studied for their biomedical, industrial and environmental application, but their biomedical use is limited because of the toxicity of different organic crosslinkers. To overcome this disadvantage, a new strategy to produce supramolecular chitosan hydrogels using low molecular weight compounds able to form covalent linkages and H-bonds to give a dual crosslinking is proposed. For this purpose we used 2-formylphenylboronic acid, which brings the advantage of imine stabilization via iminoboronate formation and potential antifungal activity due to the presence of boric acid residue. FTIR and NMR spectroscopy indicated that the gelling process took place by chemo-physical crosslinking forming a dual iminoboronate-chitosan network. Further, X-ray diffraction demonstrated a three-dimensional nanostructuring of the iminoboronate network with consequences on the micrometer-scale morphology and on the improvement of mechanical properties, as demonstrated by SEM and rheological investigation. The hydrogels proved strong antifungal activity against Candida planktonic yeasts and biofilms, promising to be a friendly treatment of the recurrent vulvovaginitis infections.