Host–guest inclusion complexation of β-cyclodextrin and hecogenin acetate to enhance anti-hyperalgesic effect in an animal model of musculoskeletal pain

Development and characterization of farnesol complexed in β- and hydroxypropyl-β-cyclodextrin and their antibacterial activity

Farnesol (FAR) belongs to terpenes group and is a sesquiterpene alcohol and a hydrophobic compound, which can be extracted from natural sources or obtained by organic chemical or biological synthesis. Recent advances in the field of nanotechnology allow the drawbacks of low drug solubility, which can improve the drug therapeutic index. Therefore, this study aimed to prepare the FAR inclusion complexes with β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) through freeze-drying method, proposing their physicochemical characterization, comparing their toxicity, and evaluating their in vitro antibacterial activity. Initially, physical mixture and freeze-dried inclusion complexes of FAR/β-CD and FAR/HP-β-CD were obtained in the molar ratio (1:1). The samples were characterized by DSC, TG/DTG, FTIR, PXRD, SEM, pHPZC, and the complexation efficiency were performed by HPLC. In vivo toxicity assay was performed using Tenebrio molitor larvae to determine the LD50 and toxic dose of the samples. Also, it was proposed that the evaluation of the fluorescence suppression of Bovine Serum Albumin and the antibacterial activity. The complexation of FAR was evidenced with β-CD and HP-β-CD by the characterization techniques analyzed. The complexation efficiency of FAR/β-CD and FAR/HP-β-CD were 73,53 % and 74.12 %, respectively. The inclusion complexes demonstrated a reduction in toxicity, as evidenced by lower toxic and LD50 doses compared to the free FAR. The inclusion complexes induced conformational changes in BSA, suggesting that they reached the subdomains containing tryptophan residues. In terms of antibacterial activity, FAR/β-CD and FAR/HP-β-CD did not exhibit significant MIC results compared to free FAR, except for FAR/HP-β-CD against S. aureus ATCC 25923.

Nutraceuticals for Fibromyalgia and Neuropathic Pain

Both neuropathic pain and fibromyalgia are horrific painful conditions arising due to impairment in the somatosensory nervous system and the musculoskeletal system, respectively. They share some common symptoms like hyperalgesia, allodynia, insomnia, cognitive deficits, and mood disturbances. It is believed that fibromyalgia is the consequence of dysfunction of the central nervous system, autonomic nervous system, imbalance in neurotransmitters, and psychological and emotional stress. Henceforth, these pain syndromes have become a major challenge for healthcare professionals due to their complex etiology and poor availability and effectiveness of the drugs. Notably, the available synthetic drugs possess serious side effects including physical dependence and tolerance. Therefore, researchers are now seeking natural-based therapy for modulating chronic pain conditions. This chapter has been written with the intention of exploring the beneficial effects of various nutraceuticals including herbal dietary supplements in neuropathic pain and fibromyalgia.

Role of peripheral and central sensitization in the anti-hyperalgesic effect of hecogenin acetate, an acetylated sapogenin, complexed with β-cyclodextrin: Involvement of NFκB and p38 MAPK pathways

Neuropathic pain develops due to injury to the somatosensory system, affecting the patient's quality of life. In view of the ineffectiveness of the current pharmacotherapy, substances obtained from natural products (NPs) are a promising alternative. One NP that has been discussed in the literature is hecogenin acetate (HA), a steroidal sapogenin with anti-inflammatory and antinociceptive activity. However, HA has low water solubility, which affects its bioavailability. Thus, the objective of this study was to evaluate the anti-hyperalgesic activity of pure and complexed hecogenin acetate (HA/βCD) in an animal model of chronic neuropathic and inflammatory pain. The inclusion complex was prepared at a molar ratio of 1:2 (HA:βCD) by the lyophilization method. For the induction of chronic inflammatory pain, the mice received an intraplantar injection of CFA (complete Freund's adjuvant), and were evaluated for mechanical hyperalgesia and for the levels of myeloperoxidase (MPO) in the skin of the paw after eight days of treatment. HA and HA/βCD reduced mechanical hyperalgesia in relation to the vehicle group until the fourth and fifth hours, respectively, in the acute evaluation, with a superior effect of the complexed form over the pure form in the second and third hour after treatment (p < 0.001). In the chronic evaluation, HA and HA/βCD reduced hyperalgesia in relation to the vehicle in the eight days of treatment (p < 0.001). Both pure (p < 0.01) and complexed (p < 0.001) forms reduced myeloperoxidase activity in the skin of the animals' paw. Groups of animals subjected to the same pharmacological protocol were submitted to the partial sciatic nerve ligation (PSNL) model and evaluated for mechanical and thermal hyperalgesia, and cold allodynia. HA and HA/βCD reduced mechanical hyperalgesia until the fourth and sixth hours, respectively, and both reduced hyperalgesia in relation to the vehicle in the chronic evaluation (p < 0.001). HA and HA/βCD also reduced thermal hyperalgesia and cold allodynia (p < 0.05 and p < 0.001, respectively). The analysis of the spinal cord of these animals showed a decrease in the levels of the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 and a reduction in the phosphorylation of NFκB and p38MAPK, as well as a decrease in microglioses compared to the vehicle group. In addition, HA/βCD reduced the nociception induced by intraplantar injection of agonist TRPA1 (p < 0.01) and TRPM8 (p < 0.05). Treatment for eight days with HA and HA/βCD showed no signs of gastric or liver damage. HA and HA/βCD were, therefore, shown to have antinociceptive effects in chronic pain models. Based on our exploration of the mechanisms of the action of HA, these effects are likely to be related to inhibited leukocyte migration, interaction with the TRPA1 and TRPM8 receptors, reduced pro-inflammatory cytokines levels, microglial expression and suppression of NF-κB p65 and p38 MAPK pathway signaling. Therefore, HA/βCD has great potential for use in the treatment of chronic pain.

Characterization of β-cyclodextrin/myrtenol complex and its protective effect against nociceptive behavior and cognitive impairment in a chronic musculoskeletal pain model

Myrtenol has gained wide interest because of its pharmacological profiles, mainly for treatment of chronic diseases. To improve the solubility of myrtenol, the formation of inclusion complexes with β-cyclodextrin was performed by physical mixture, kneading process or slurry complexation (SC) methods and characterized using thermal analysis, XRD, SEM and NMR. From these results, myrtenol complexed by SC was successfully complexed into β-cyclodextrin cavity. The interaction between myrtenol and β-cyclodextrin was confirmed by molecular docking. Hence, the SC β-cyclodextrin-myrtenol complex was evaluate for its anti-hyperalgesic, anxiolytic and antioxidant activity in a fibromyalgia model. Results show that myrtenol and β-cyclodextrin form a stable complex and have anti-hyperalgesic effect, improve the cognitive impairment caused and have an anxiolytic-like effect. Furthermore, the β-cyclodextrin/myrtenol complex decrease lipoperoxidation, increased catalase activity and a reduce SOD/CAT ratio. Therefore, β-cyclodextrin/myrtenol complex reduce painful behavior, improves motor skills and emotional behavior and decreases oxidative stress in a fibromyalgia model.

Development and Evaluation of Antimicrobial and Modulatory Activity of Inclusion Complex of Euterpe oleracea Mart Oil and β-Cyclodextrin or HP-β-Cyclodextrin

The development of inclusion complexes is used to encapsulate nonpolar compounds and improve their physicochemical characteristics. This study aims to develop complexes made up of Euterpe oleracea Mart oil (EOO) and β-cyclodextrin (β-CD) or hydroxypropyl-β-cyclodextrin (HP-β-CD) by either kneading (KND) or slurry (SL). Complexes were analyzed by molecular modeling, Fourier-transform infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction, thermogravimetry analysis and differential scanning calorimetry. The antibacterial activity was expressed as Minimum Inhibitory Concentration (MIC), and the antibiotic resistance modulatory activity as subinhibitory concentration (MIC/8) against Escherichia coli, Streptomyces aureus, Pseudomonas aeruginosa and Enterococcus faecalis. Inclusion complexes with β-CD and HP-β-CD were confirmed, and efficiency was proven by an interaction energy between oleic acid and β-CD of -41.28 ± 0.57 kJ/mol. MIC values revealed higher antibacterial activity of complexes compared to the isolated oil. The modulatory response of EOO and EOO-β-CD prepared by KND as well as of EOO-β-CD and EOO-HP-β-CD prepared by SL showed a synergistic effect with ampicillin against E. coli, whereas it was not significant with the other drugs tested, maintaining the biological response of antibiotics. The antimicrobial response exhibited by the complexes is of great significance because it subsidizes studies for the development of new pharmaceutical forms.

Evaluation of the molecular inclusion process of β-hexachlorocyclohexane in cyclodextrins

The present work aimed to study the guest-host complexes of β-hexachlorocyclohexane (β-HCH), a pesticide with high environmental stability that can cause severe health problems, with the most common cyclodextrins (α-, β-, and γ-CDs). The formation reactions of these molecular inclusion complexes were addressed in this research. The multiple minima hypersurface methodology, quantum calculations based on density functional theory and a topological exploration of the electron density based on the quantum theory of atoms in molecules approach were used to characterize the interaction spaces of the pollutant with the three CDs. Additionally, charge distribution, charge transfer and dual descriptor analyses were employed to elucidate the driving forces involved in the formation of these molecular inclusion complexes. Three types of fundamental interactions were observed: total occlusion, partial occlusion and external interaction (non-occlusion). Finally, experiments were performed to confirm the formation of the studied complexes. The most stable complexes were obtained when γ-CD was the host molecule. The interactions between the pesticide and CDs have fundamentally dispersive natures, as was confirmed experimentally by spectroscopic results. All the obtained results suggest the possibility of using CDs for the purification and treatment of water polluted with β-HCH.

Inclusion Complexes of β and HPβ-Cyclodextrin with α, β Amyrin and In Vitro Anti-Inflammatory Activity

α, β amyrin (ABAM) is a natural mixture of pentacyclic triterpenes that has a wide range of biological activities. ABAM is isolated from the species of the Burseraceae family, in which the species Protium is commonly found in the Amazon region of Brazil. The aim of this work was to develop inclusion complexes (ICs) of ABAM and β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPβCD) by physical mixing (PM) and kneading (KN) methods. Interactions between ABAM and the CD’s as well as the formation of ICs were confirmed by physicochemical characterization in the solid state by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Physicochemical characterization indicated the formation of ICs with both βCD and HPβCD. Such ICs were able to induce changes in the physicochemical properties of ABAM. In addition, the formation of ICs with cyclodextrins showed to be an effective and promising alternative to enhance the anti-inflammatory activity and safety of ABAM.

Cyclodextrin⁻Drug Inclusion Complexes: In Vivo and In Vitro Approaches

This review aims to provide a critical review of the biological performance of natural and synthetic substances complexed with cyclodextrins, highlighting: (i) inclusion complexes with cyclodextrins and their biological studies in vitro and in vivo; (ii) Evaluation and comparison of the bioactive efficacy of complexed and non-complexed substances; (iii) Chemical and biological performance tests of inclusion complexes, aimed at the development of new pharmaceutical products. Based on the evidence presented in the review, it is clear that cyclodextrins play a vital role in the development of inclusion complexes which promote improvements in the chemical and biological properties of the complexed active principles, as well as providing improved solubility and aqueous stability. Although the literature shows the importance of their ability to help produce innovative biotechnological substances, we still need more studies to develop and expand their therapeutic properties. It is, therefore, very important to gather together evidence of the effectiveness of inclusion complexes with cyclodextrins in order to facilitate a better understanding of research on this topic and encourage further studies.

Anti-hyperalgesic effect of Lippia grata leaf essential oil complexed with β-cyclodextrin in a chronic musculoskeletal pain animal model: Complemented with a molecular docking and antioxidant screening

BACKGROUND

Due to its unclear pathophysiology, the pharmacological treatment of fibromyalgia is a challenge for researchers. Studies using medicinal plants, such as those from the genus Lippia, complexed with cyclodextrins (CDs) have shown innovative results.

OBJECTIVE

The present research intended to evaluate the effect of an inclusion complex containing β-cyclodextrin (βCD) inclusion complex with Lippia grata (LG) essential oil in a chronic musculoskeletal pain model, its central activity and its possible interaction with neurotransmitters involved in pain.

METHODS

After acid saline-induced chronic muscle pain, male mice were evaluated for primary and secondary hyperalgesia and muscle strength. Moreover, an antagonist assay was performed to assess the possible involvement of the opioidergic, serotonergic and noradrenergic pathways. In addition, Fos protein in the spinal cord was assessed, and a docking study and antioxidant assays were performed.

RESULTS

The treatment with LG-βCD, especially in the dose of 24mg/kg, was able to significantly decrease (p<0.05) the paw withdrawal and muscle threshold. Furthermore, LG-βCD was shown to affect the opioidergic and serotonergic pathways. There were no significant changes in muscle strength. Fos protein immunofluorescence showed a significant decrease in expression in the dorsal horn of the spinal cord. The main compounds of LG showed through the docking study interaction energies with the alpha-adrenergic and μOpioid receptors. In all antioxidant assays, LG exhibited stronger antioxidant activities than LG-βCD.

CONCLUSION

This study suggested that LG-βCD could be considered as a valuable source for designing new drugs in the treatment of chronic pain, especially musculoskeletal pain.