A 5,7-dimethoxyflavone/hydroxypropyl-β-cyclodextrin inclusion complex with anti-butyrylcholinesterase activity

Insights into the formulation properties, biocompatibility, and permeability of poorly water-soluble methoxyflavones with PEG400 and propylene glycol

Herein, thermal and non-thermal techniques were used to elucidate the putative physical and chemical interactions between poorly water-soluble Kaempferia methoxyflavones and PEG400/propylene glycol. Additionally, the biocompatibility of methoxyflavone-glycol solutions was evaluated using Caco-2 cells whereas the absorptive transport was investigated by measuring the apparent permeability coefficient (P app) of the methoxyflavones and transepithelial electrical resistance (TEER) of the Caco-2 cell monolayer. Data from differential scanning calorimetry, Fourier-transform infrared (FTIR), and proton nuclear magnetic resonance (1H NMR) spectroscopic analysis revealed physico-chemical compatibility between the three methoxyflavones and PEG400/propylene glycol. Furthermore, PEG400 and propylene glycol solutions of the methoxyflavones were shown to be compatible with Caco-2 cells at pharmacologically effective concentrations. In vitro transport studies across the Caco-2 cell monolayer revealed high P app values of 24.07 × 10-6 to 19.63 × 10-6 cm s-1 for PEG400 solutions of the methoxyflavones. The TEER values of the Caco-2 cell monolayers indicated that the increased drug transport was partly due to increased tight junction openings, but without compromising the epithelial barrier integrity. The good pharmaceutical and biocompatibility profiles, as well as improved transport of the methoxyflavones in PEG400 and propylene glycol solutions, are suggestive of the worthiness of this approach for further consideration pertaining to the development of these drugs into oral liquid dosage forms.

Combinations of Piperine with Hydroxypropyl-β-Cyclodextrin as a Multifunctional System

Piperine is an alkaloid that has extensive pharmacological activity and impacts other active substances bioavailability due to inhibition of CYP450 enzymes, stimulation of amino acid transporters and P-glycoprotein inhibition. Low solubility and the associated low bioavailability of piperine limit its potential. The combination of piperine with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) causes a significant increase in its solubility and, consequently, an increase in permeability through gastrointestinal tract membranes and the blood-brain barrier. X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) were used to characterize interactions between piperine and HP-β-CD. The observed physicochemical changes should be combined with the process of piperine and CD system formation. Importantly, with an increase in solubility and permeability of piperine as a result of interaction with CD, it was proven to maintain its biological activity concerning the antioxidant potential (2,2-diphenyl-1-picryl-hydrazyl-hydrate assay), inhibition of enzymes essential for the inflammatory process and for neurodegenerative changes (hyaluronidase, acetylcholinesterase, butyrylcholinesterase).

Kaempferia parviflora and Its Methoxyflavones: Chemistry and Biological Activities

Kaempferia parviflora (KP), a health-promoting herb, has been traditionally used for treating a variety of diseases. Pharmacological studies have claimed the various benefits from KP and its main effective methoxyflavones, including cellular metabolism-regulating activity, anticancer activity, vascular relaxation and cardioprotective activity, sexual enhancing activity, neuroprotective activity, antiallergic, anti-inflammatory, and antioxidative activity, antiosteoarthritis activity, antimicroorganism activity, and transdermal permeable activity. These might be associated with increased mitochondrial functions and activated cGMP-NO signaling pathway. However, the underlying molecular mechanisms of KP and its methoxyflavones are still under investigation. The clinical applications of KP and its methoxyflavones may be limited due to their low bioavailability. But promising strategies are on the way. This review will comprehensively discuss the biological activities of KP and its methoxyflavones.

Tuning the emission of a water-soluble 3-hydroxyflavone derivative by host-guest complexation

3-Hydroxyflavone derivatives have great potential as fluorescent probes for bio-labeling in aqueous medium. They were extensively studied in various organic solvents for the "excited state intramolecular proton transfer" process, but seldom addressed in aqueous solution due to the poor water solubility. Herein, an amphiphilic molecule bearing 3-hydroxyflavone and oligo(ethylene oxide) (denoted as 3HF-EO) was designed and synthesized. Different from the fluorescence in organic solvents, 3HF-EO in aqueous solution showed a remarkable single fluorescence emission, which is ascribed to the fluorescence of its anionic species. We found that the fluorescence intensity could be efficiently tuned via host-guest complexation. α-CD has little effect on the emission, while β-CD and γ-CD lead to enhanced and reduced emissions of 3HF-EO, respectively. The 1H NMR and 2D NOESY NMR spectra indicate that α-CD barely had any interaction with 3HF-EO, while β-CD and γ-CD formed complexes with one and two 3HF-EO molecules, respectively. These results provide a sound explanation for the modulated fluorescence intensity.

Theoretical and Experimental Studies on Inclusion Complexes of Pinostrobin and β-Cyclodextrins

Pinostrobin (PNS) belongs to the flavanone subclass of flavonoids which shows several biological activities such as anti-inflammatory, anti-cancerogenic, anti-viral and anti-oxidative effects. Similar to other flavonoids, PNS has a quite low water solubility. The purpose of this work is to improve the solubility and the biological activities of PNS by forming inclusion complexes with β-cyclodextrin (βCD) and its derivatives, heptakis-(2,6-di-O-methyl)-β-cyclodextrin (2,6-DMβCD) and (2-hydroxypropyl)-β-cyclodextrin (HPβCD). The A_L-type diagram of the phase solubility studies of PNS exhibited the formed inclusion complexes with the 1:1 molar ratio. Inclusion complexes were prepared by the freeze-drying method and were characterized by differential scanning calorimetry (DSC). Two-dimensional nuclear magnetic resonance (2D-NMR) and steered molecular dynamics (SMD) simulation revealed two different binding modes of PNS, i.e., its phenyl- (P-PNS) and chromone- (C-PNS) rings preferably inserted into the cavity of βCD derivatives whilst only one orientation of PNS, where the C-PNS ring is inside the cavity, was detected in the case of the parental βCD. All PNS/βCDs complexes had a higher dissolution rate than free PNS. Both PNS and its complexes significantly exerted a lowering effect on the IL-6 secretion in LPS-stimulated macrophages and showed a moderate cytotoxic effect against MCF-7 and HeLa cancer cell lines in vitro.