Inclusion Complexation of Novocaine by β-Cyclodextrin in Aqueous Solutions

Enhancing ketoprofen's solubility and anti-inflammatory efficacy with safe methyl-β-cyclodextrin complexation

Improved solubility and anti-inflammatory (AI) properties are imperative for enhancing the effectiveness of poorly water-soluble drugs, particularly non-steroidal anti-inflammatory drugs (NSAIDs). To address these critical issues, our focus is on obtaining NSAID materials in the form of inclusion complexes (IC) with methyl-beta-cyclodextrin (MCD). Ketoprofen (KTP) is selected as the NSAID for this study due to its potency in treating various types of pain, inflammation, and arthritis. Our objective is to tackle the solubility challenge followed by enhancing the AI activity. Confirmation of complexation is achieved through observing changes in the absorbance and fluorescence intensities of KTP upon the addition of MCD, indicating a 1:1 stoichiometric ratio. Phase solubility studies demonstrated improved dissolution rates after the formation of ICs. Further analysis of the optimized IC is conducted using FT-IR, NMR, FE-SEM, and TG/DTA techniques. Notable shifts in chemical shift values and morphological alterations on the surface of the ICs are observed compared to their free form. Most significantly, the IC exhibited superior AI and anti-arthritic (AA) activity compared to KTP alone. These findings highlight the potential of ICs in expanding the application of KTP, particularly in pharmaceuticals, where enhanced stability and efficacy of natural AIs and AAs are paramount.

A novel and water-soluble material for coronavirus inactivation from oseltamivir in the cavity of methyl and sulfated-β-cyclodextrins through inclusion complexation

A potentially active water-soluble anti-viral with lesser toxic material from the Oseltamivir (OTV) has been produced by the sonication method. The formed material has been further characterized by UV–visible, FT-IR, powder XRD, SEM, TGA/DTA, ROESY, XPS, AFM and etc., The results of DFT calculation have proven that inclusion complexes (ICs) are theoretically and energetically more advantageous models and structures have also been proposed based on the results. Analysis of drug release has been carried out at three pH levels, and it is revealed the analysis is most helpful at acidic pH levels for the ICs with S-CD over H-CD. Over OTV without CDs, OTV:S-CD-ICs exhibited a very less cytotoxic ability on cancer cell lines than ICs with M-CD. ICs enhanced the coronavirus inactivation nature of OTV. This study provides for the first time a full characterization of ICs of OTV with CDs and highlights the impact of complexation on pharmacological activity.

Inclusion of fluorophores in cyclodextrins: a closer look at the fluorometric determination of association constants by linear and nonlinear fitting procedures

The author discusses methods for the fluorometric determination of affinity constants by linear and nonlinear fitting methods. This is outlined in particular for the interaction between cyclodextrins and several anesthetic drugs including benzocaine. Special emphasis is given to the limitations of certain fits, and the impact of such studies on enzyme-substrate interactions are demonstrated. Both the experimental part and methods of analysis are well suited for students in an advanced lab.

Effects of cyclodextrins on the chemical stability of drugs

Cyclodextrins (CDs) are enabling pharmaceutical excipients that can enhance both solubility and stability of wide variety of drugs in aqueous solutions through formation of drug/CD inclusion complexes where apolar moieties of the drug molecules are located inside the CD cavity. In properly designed pharmaceutical formulations CDs will improve physiochemical properties of lipophilic drugs without affecting their intrinsic ability to permeate biological membranes. Here the effect of CD complexes on the chemical stability of drugs is reviewed. Numerous studies shown that in aqueous solutions CD complexation can hamper hydrolysis, oxidation, photodegradation, isomerization and enzyme catalyzed degradation of dissolved drugs. However, some drugs, such as β-lactam antibiotics, can under certain conditions undergo CD catalyzed degradation in aqueous solutions. Also, some drugs that are stabilized by CDs in aqueous solutions are destabilized by the same CDs in solid dosage forms. Thus, the effects of CDs on drug stability have to be tested and verified in the final drug formulation and under the recommended storage conditions.

Molecular recognition of organic ammonium ions in solution using synthetic receptors

Ammonium ions are ubiquitous in chemistry and molecular biology. Considerable efforts have been undertaken to develop synthetic receptors for their selective molecular recognition. The type of host compounds for organic ammonium ion binding span a wide range from crown ethers to calixarenes to metal complexes. Typical intermolecular interactions are hydrogen bonds, electrostatic and cation-π interactions, hydrophobic interactions or reversible covalent bond formation. In this review we discuss the different classes of synthetic receptors for organic ammonium ion recognition and illustrate the scope and limitations of each class with selected examples from the recent literature. The molecular recognition of ammonium ions in amino acids is included and the enantioselective binding of chiral ammonium ions by synthetic receptors is also covered. In our conclusion we compare the strengths and weaknesses of the different types of ammonium ion receptors which may help to select the best approach for specific applications.

Host-guest complexations of local anaesthetics by cucurbit[7]uril in aqueous solution

The cucurbit[7]uril (CB[7]) host molecule forms very stable host-guest complexes with the local anaesthetics procaine (K(CB[7]) = (3.5 +/- 0.7) x 10(4) dm(3) mol(-1)), tetracaine (K(CB[7]) = (1.5 +/- 0.4) x 10(4) dm(3) mol(-1)), procainamide (K(CB[7]) = (7.8 +/- 1.6) x 10(4) dm(3) mol(-1)), dibucaine (K(CB[7]) = (1.8 +/- 0.4) x 10(5) dm(3) mol(-1)) and prilocaine (K(CB[7]) = (2.6 +/- 0.6) x 10(4) dm(3) mol(-1)) in aqueous solution (pD = 4.75). The stability constants are 2-3 orders of magnitude greater than the values reported for binding by the comparably sized beta-cyclodextrin host molecule. The inclusion by CB[7] raises the first pK(a) values of the anaesthetics by 0.5-1.9 pK units, as the protonated forms are bound more strongly in acidic solution. The complexation-induced chemical shift changes in the guest proton resonances provide an indication of the site(s) of binding and the effects of protonation on the location of the binding sites.

Characterization of cyclodextrin inclusion complexes of the anti-HIV non-nucleoside reverse transcriptase inhibitor UC781

The highly potent anti-HIV agent UC781 is being evaluated for use in topical microbicides to prevent HIV transmission. However, UC781 is extremely hydrophobic with poor water solubility, a property that may complicate appropriate formulation of the drug. In this study, we examined the ability of several cyclodextrins, beta-cyclodextrin (beta CD), methyl-beta-cyclodextrin (M beta CD), and 2-hydroxylpropyl-beta-cyclodextrin (HP beta CD), to enhance the aqueous solubility of UC781. Each of the cyclodextrins provided dramatic increases in UC781 aqueous solubility, the order being M beta CD>HP beta CD>beta CD. The complexation constants (K (1:1)) of the inclusion complexes were determined via a phase solubility technique using high-performance liquid chromatography and showed that UC781 solubility increased linearly as a function of cyclodextrin concentration. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and 2D (1)H ROESY NMR spectroscopy were used to further characterize these UC781/cyclodextrin complexes. The inhibitory potency of UC781 and its HP beta CD inclusion complex were evaluated using an in vitro HIV-1 reverse transcriptase inhibition assay The inhibitory potency of the UC781/HP beta CD complex was 30-fold greater than that of UC781 alone, showing that the complexed drug is able to provide substantial inhibition of its target. The enhancement of UC781 aqueous solubility is essential for the development of a useful vaginal microbicide dosage form, and our data suggest that UC781/cyclodextrin inclusion complexes may be useful in this context.

Preparation and characterization of the inclusion complex of chlorpyrifos in cyclodextrins to improve insecticide formulations

The chemical control of crops by organophosphate insecticide treatment is usually limited because the insecticides do not maintain their efficiency for long periods for several reasons, including environmental conditions or rapid degradation of the active ingredient. Chlorpyrifos is an organophosphate insecticide used worldwide to control a variety of soil insects and arthropods in a wide range of crops. It is easily soluble in organic solvents but shows poor water solubility. The inclusion of chrorpyrifos in cyclodextrins (CDs) improves its water solubility, bioavailability, and insecticidal activity and helps prevent overdosing, leading to more cost-effective and more environmentally friendly agricultural practices. Solubility studies of chlorpyrifos in the presence of different types of CDs show G2-beta-CDs to be the most effective CDs in the complexation process, giving 1:2 complexes, with complexation constant (Kc) values of 12.34 +/- 3.1 M(-1) for K1 and 3895 +/- 183 M(-1) for K2. These complexation constant values were corroborated by applying a fluorimetric method.

Cyclodextrin/imatinib complexation: Binding mode and charge dependent stabilities

Host-guest interactions in various protonation forms of the anticancer drug imatinib with beta-cyclodextrin (CD) and randomly methylated beta-CD (RAMEB) have been investigated using techniques of proton magnetic resonance spectroscopy ((1)H NMR), phase solubility, pH-potentiometry and electrospray ionization mass spectrometry (ESI-MS). Phase-solubility analysis showed A(L)-type diagram with beta-CD, which suggested the formation of 1:1 inclusion complexes. The 1:1 stoichiometry was confirmed by potentiometry in aqueous solution and by ESI-MS in the gas phase. Charge-specific stability constants of the neutral, mono-, di-, and tricationic forms of imatinib were determined for both the beta-CD and RAMEB. Stability of the beta-CD complexes shows an unexpected minimum at the monoprotonated form, while a stepwise decrease with increasing guest charge was observed for RAMEB. The 1:1 complex stoichiometry and stability constants of selected imatinib protonation species were verified by (1)H NMR titrations. Two-dimensional rotating frame nuclear Overhauser effect spectroscopy (ROESY) experiments were carried out to identify the interacting host-guest moieties. The observed ROESY cross-peaks indicated spatial proximities between several aromatic hydrogens of imatinib and beta-CD protons, revealing that the inclusion occurs by accommodation of the benzamide ring of imatinib.