Changes in the intestinal absorption mechanism of icariin in the nanocavities of cyclodextrins

Binary Nano-inhalant Formulation of Icariin Enhances Cognitive Function in Vascular Dementia via BDNF/TrkB Signaling and Anti-inflammatory Effects

Vascular dementia (VaD) has a serious impact on the patients' quality of life. Icariin (Ica) possesses neuroprotective potential for treating VaD, yet its oral bioavailability and blood-brain barrier (BBB) permeability remain challenges. This research introduced a PEG-PLGA-loaded chitosan hydrogel-based binary formulation tailored for intranasal delivery, enhancing the intracerebral delivery efficacy of neuroprotective agents. The formulation underwent optimization to facilitate BBB crossing, with examinations conducted on its particle size, morphology, drug-loading capacity, in vitro release, and biodistribution. Using the bilateral common carotid artery occlusion (BCCAO) rat model, the therapeutic efficacy of this binary formulation was assessed against chitosan hydrogel and PEG-PLGA nanoparticles loaded with Ica. Post-intranasal administration, enhanced cognitive function was evident in chronic cerebral hypoperfusion (CCH) rats. Further mechanistic evaluations, utilizing immunohistochemistry (IHC), RT-PCR, and ELISA, revealed augmented transcription of synaptic plasticity-associated proteins like SYP and PSD-95, and a marked reduction in hippocampal inflammatory markers such as IL-1β and TNF-α, highlighting the formulation's promise in alleviating cognitive impairment. The brain-derived neurotrophic factor (BDNF)/tropomyosin related kinase B (TrkB) pathway was activated significantly in the binary formulation compared with the other two. Our study demonstrates that the intranasal application of chitosan hydrogel loaded with Ica-encapsulated PEG-PLGA could effectively deliver Ica into the brain and enhance its neuroprotective effect.

Icariin: A Promising Natural Product in Biomedicine and Tissue Engineering

Among scaffolds used in tissue engineering, natural biomaterials such as plant-based materials show a crucial role in cellular function due to their biocompatibility and chemical indicators. Because of environmentally friendly behavior and safety, green methods are so important in designing scaffolds. A key bioactive flavonoid of the Epimedium plant, Icariin (ICRN), has a broad range of applications in improving scaffolds as a constant and non-immunogenic material, and in stimulating the cell growth, differentiation of chondrocytes as well as differentiation of embryonic stem cells towards cardiomyocytes. Moreover, fusion of ICRN into the hydrogel scaffolds or chemical crosslinking can enhance the secretion of the collagen matrix and proteoglycan in bone and cartilage tissue engineering. To scrutinize, in various types of cancer cells, ICRN plays a decisive role through increasing cytochrome c secretion, Bax/Bcl2 ratio, poly (ADP-ribose) polymerase as well as caspase stimulations. Surprisingly, ICRN can induce apoptosis, reduce viability and inhibit proliferation of cancer cells, and repress tumorigenesis as well as metastasis. Moreover, cancer cells no longer grow by halting the cell cycle at two checkpoints, G0/G1 and G2/M, through the inhibition of NF-κB by ICRN. Besides, improving nephrotoxicity occurring due to cisplatin and inhibiting multidrug resistance are the other applications of this biomaterial.

Improvement of solubility and pharmacokinetic profile of hepatoprotector icariin through complexation with HP-γ-cyclodextrin

Icariin as a hepatoprotector from Herba epimedii can expand the cardiovascular and cerebral blood vessels, promote hematopoietic functions, enhance the immune system and show anti-liver tumor activities. However, its low solubility (0.02 mg/mL) limits its clinical applications as food and medical supplements. Through complexation with HP-γ-cyclodextrin by using a trace amount of water-soluble polymer, the water solubility of icariin was increased by 654 times, which is the best result to date for the water solubility study of icariin. In an in vitro pharmacokinetic study, the complexation increased the dissolution rate of icariin by 80 times, and the icariin complex can be 100% released in the first few minutes. Through complexation, in an in vivo dog pharmacokinetic study, the C _max of icariin was increased about 5 times, the AUC_0-120 was increased about 20 times and the clearance of icariin was changed from 11.17 L/h/kg to 0.65 L/h/kg. The half-life time was changed from 0.68 h to 6.38 h and the relative bioavailability was increased by nearly 20 times, indicating that less drug is needed for the same therapeutic effect by using the icariin complex, and the complex can be used as a potential potent hepatoprotector or anti-liver cancer drug.

Stability, Antioxidant Activity and Intestinal Permeation of Oleuropein Inclusion Complexes with Beta-Cyclodextrin and Hydroxypropyl-Beta-Cyclodextrin

Compared to beta-cyclodextrins (beta-CD), hydroxypropyl-beta-cyclodextrins (HP-beta-CD) are a more popular material used to prepare inclusion complexes due to their superior solubility and intestinal absorption. In this study, oleuropein (OL) inclusion complexes with beta-CD (beta-CD:OL) and HP-beta-CD (HP-beta-CD:OL) were prepared and the formation of inclusion complexes was validated by IR, PXRD, and DSC. A phase solubility test showed that the lgK (25 °C) and binding energy of beta-CD:OL and HP-beta-CD:OL was 2.32 versus 1.98, and −6.1 versus −24.66 KJ/mol, respectively. Beta-CD:OL exhibited a more powerful effect than HP-beta-CD:OL in protecting OL from degradation upon exposure to light, high temperature and high humidity. Molecular docking, peak intensity of carbonyls in IR, and ferric reducing power revealed that beta-CD:OL formed more hydrogen bonds with the unstable groups of OL. Both inclusion complexes significantly enhanced the solubility, intestinal permeation and antioxidant activity of OL (p < 0.05). Though HP-beta-CD:OL had higher solubility and intestinal absorption over beta-CD:OL, the difference was not significant (p > 0.05). The study implies that lower binding energy is not always associated with the higher stability of a complex. Beta-CD can protect a multiple-hydroxyl compound more efficiently than HP-beta-CD with the intestinal permeation comparable to HP-beta-CD complex.

Intradermal injection of icariin-HP-β-cyclodextrin improved traumatic brain injury via the trigeminal epineurium-brain dura pathway

The lower bioavailability after oral administration limited icariin applications in Central Nervous System. Icariin/HP-β-cyclodextrin (HP-β-CD) inclusion complex was prepared for acute severe opening traumatic brain injury (TBI) via facial intradermal(i.d.) in mystacial pad. After fluid percussion-induced TBI, icariin/HP-β-CD at 0.4 mg/kg i.d. preserved more neurons and oligodendrocytes than intranasal injection (i.n.) or intravenous injection via tail vein (i.v.) and decreased microglia and astrocyte activation. Icariin/HP-β-CD i.d. reduced apoptosis in cortical penumbra while i.n. and i.v. showed weak or no effects. Icariin/HP-β-CD i.d. reduced Evans blue leakage and altered CD34, ZO-1, Claudin-5 and beta-catenin expression after TBI. Moreover, icariin/HP-β-CD promoted human umbilical vein endothelial cells proliferation. Thus, Icariin/HP-β-CD i.d. improved TBI, including blood brain barrier opening. Fluorescein 5-isothiocyanate (FITC) and 3,3'-Dioctadecyloxacarbocyanine perchlorate (DiOC18(3)) mimic HP-β-CD and icariin respectively. FITC and DiOC18(3) were similarly delivered to trigeminal epineurium, perineurium and perivascular spaces or tissues, caudal dura mater and scattered in trigeminal fasciculus, indicating that icariin/HP-β-CD was delivered to brain via trigeminal nerve-dura mater-brain pathways. In sum, intradermal injection in mystacial pad might delivered icariin/HP-β-CD to brain and icariin/HP-β-CD improved acute severe opening TBI.

Phytochemicals Mediate Autophagy Against Osteoarthritis by Maintaining Cartilage Homeostasis

Osteoarthritis (OA) is a common degenerative joint disease and is a leading cause of disability and reduced quality of life worldwide. There are currently no clinical treatments that can stop or slow down OA. Drugs have pain-relieving effects, but they do not slow down the course of OA and their long-term use can lead to serious side effects. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Autophagy is an intracellular protective mechanism, and targeting autophagy-related pathways has been found to prevent and treat various diseases. Attenuation of the autophagic pathway has now been found to disrupt cartilage homeostasis and plays an important role in the development of OA. Therefore, modulation of autophagic signaling pathways mediating cartilage homeostasis has been considered as a potential therapeutic option for OA. Phytochemicals are active ingredients from plants that have recently been found to reduce inflammatory factor levels in cartilage as well as attenuate chondrocyte apoptosis by modulating autophagy-related signaling pathways, which are not only widely available but also have the potential to alleviate the symptoms of OA. We reviewed preclinical studies and clinical studies of phytochemicals mediating autophagy to regulate cartilage homeostasis for the treatment of OA. The results suggest that phytochemicals derived from plant extracts can target relevant autophagic pathways as complementary and alternative agents for the treatment of OA if subjected to rigorous clinical trials and pharmacological tests.

Bioactive Icariin/β-CD-IC/Bacterial Cellulose with Enhanced Biomedical Potential

A "super" bioactive antibacterial hydrogel, Icariin-β-CD-inclusion complex/Bacterial cellulose and an equally capable counterpart Icariin-Bacterial cellulose (ICBC) were successfully produced with excellent antioxidant properties. The highly porous hydrogels demonstrated very high fluid/liquid absorption capability and were functionally active as Fourier Transform Infrared Spectrometer (FTIR) test confirmed the existence of abundant hydroxyls (-OH stretching), carboxylic acids (-CH₂/C-O stretching), Alkyne/nitrile (C≡C/C≡N stretching with triple bonds) and phenol (C-H/N-O symmetric stretching) functional groups. Scanning electron microscope (SEM) and X-ray diffraction (XRD) tests confirmed a successful β-CD-inclusion complexation with Icariin with a great potential for sustained and controlled drug release. In vitro drug release test results indicated a systemic and controlled release of the drug (Icariin) from the internal cavities of the β-CD inclusion complex incorporated inside the BC matrix with high Icariin (drug) release rates. Impressive inactivation rates against Gram-negative bacteria Escherichia coli ATCC 8099 and gram-positive bacteria Staphylococcus aureus ATCC 6538; >99.19% and >98.89% respectively were recorded, as the materials proved to be non-toxic on L929 cells in the in vitro cytotoxicity test results. The materials with promising versatile multipurpose administration of Icariin for wound dressing (as wound dressers), can also be executed as implants for tissue regeneration, as well as face-mask for cosmetic purposes.

Icariin and Its Metabolites as Potential Protective Phytochemicals Against Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder affecting more than 35 million people worldwide. As the prevalence of AD is dramatically rising, there is an earnest need for the identification of effective therapies. Available drug treatments only target the symptoms and do not halt the progression of this disorder; thus, the use of natural compounds has been proposed as an alternative intervention strategy. Icariin, a prenylated flavonoid, has several therapeutic effects, including osteoporosis prevention, sexual dysfunction amelioration, immune system modulation, and improvement of cardiovascular function. Substantial studies indicate that icariin may be beneficial to AD by reducing the production of extracellular amyloid plaques and intracellular neurofibrillary tangles and inhibiting phosphodiesterase-5 activity. Moreover, increasing evidence has indicated that icariin exerts a protective role in AD also by limiting inflammation, oxidative stress and reducing potential risk factors for AD such as atherosclerosis. This mini-review discusses the multiple potential mechanisms of action of icariin on the pathobiology of AD including explanation regarding its bioavailability, metabolism and pharmacokinetic.

Associated-Extraction Efficiency of Six Cyclodextrins on Various Flavonoids in Puerariae Lobatae Radix

Puerariae Lobatae Radix (PLR), a well-known herbal medicine, is the root of Pueraria lobata (Willd.) Ohwi and has been employed for the treatment and prevention of cardiovascular and cerebrovascular diseases. The purpose of this study was to compare the associated-extraction efficiency of six cyclodextrins (CDs) on five flavonoids in PLR, namely puerarin, daidzein, daidzin, genistein and genistin, which are the major secondary metabolites, and exhibit low water solubility. The six CDs applied were β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), hydroxypropyl-γ-cyclodextrin (HP-γ-CD), carboxymethyl-β-cyclodextrin (CM-β-CD), and sulfobutyl ether β-cyclodextrin (SBE-β-CD). They can be grouped into one of the following three categories: traditional cyclodextrins (β-CD and γ-CD), water-soluble cyclodextrin derivatives (HP-β-CD and HP-γ-CD) and ionic cyclodextrin derivatives (SBE-β-CD and CM-β-CD). High-performance liquid chromatography (HPLC) was used to analyze the five flavonoids in the original aqueous extracts (OAE) in the presence or absence of various CDs. The associated-extraction efficiency of the various CDs followed the ranking: SBE-β-CD > HP-β-CD > CM-β-CD > HP-γ-CD > γ-CD > β-CD. It was clear that SBE-β-CD presented the highest associated-extraction capability, and it was used to extract the four flavonoids from three PLR products, including raw product, stir- fried product, and product simmered with wheat bran. The results showed that SBE-β-CD could improve the extraction capability of flavonoids, both from the raw product and in processed products of PLR. In conclusion, CDs, especially SBE-β-CD, have a promising application for the associated-extraction of flavonoids from PLR.

Multidrug-resistant cancer cells and cancer stem cells hijack cellular systems to circumvent systemic therapies, can natural products reverse this?

Chemotherapy is one of the most effective and broadly used approaches for cancer management and many modern regimes can eliminate the bulk of the cancer cells. However, recurrence and metastasis still remain a major obstacle leading to the failure of systemic cancer treatments. Therefore, to improve the long-term eradication of cancer, the cellular and molecular pathways that provide targets which play crucial roles in drug resistance should be identified and characterised. Multidrug resistance (MDR) and the existence of tumor-initiating cells, also referred to as cancer stem cells (CSCs), are two major contributors to the failure of chemotherapy. MDR describes cancer cells that become resistant to structurally and functionally unrelated anti-cancer agents. CSCs are a small population of cells within cancer cells with the capacity of self-renewal, tumor metastasis, and cell differentiation. CSCs are also believed to be associated with chemoresistance. Thus, MDR and CSCs are the greatest challenges for cancer chemotherapy. A significant effort has been made to identify agents that specifically target MDR cells and CSCs. Consequently, some agents derived from nature have been developed with a view that they may overcome MDR and/or target CSCs. In this review, natural products-targeting MDR cancer cells and CSCs are summarized and clustered by their targets in different signaling pathways.

A promising antitumor activity of evodiamine incorporated in hydroxypropyl-β-cyclodextrin: pro-apoptotic activity in human hepatoma HepG2 cells

BACKGROUND

Evodiamine has gained wide interests recently because of its antitumor activities. However, a superior bioavailability is required to achieve better efficacy due to its poor water solubility. The aim of this study was to enhance the evodiamine's aqueous solubility by preparing evodiamine/hydroxypropyl-β-cyclodextrin (EVO/HP-β-CD) inclusion complex, which is incorporated evodiamine into HP-β-CD, and compare the antitumor activities before and after inclusion with HP-β-CD in human hepatoma HepG2 cells.

RESULTS

The EVO/HP-β-CD inclusion complexes were prepared by the kneading method and structurally characterized. P-glycoprotein ATPase assays firstly demonstrated that evodiamine was a substrate of P-glycoprotein, while HP-β-CD and EVO/HP-β-CD inclusion complexes inhibited P-glycoprotein by blocking P-glycoprotein ATPase activity. The EVO/HP-β-CD inclusion complexes may be a promising anticancer drug candidate without drug resistance. After given evodiamine or EVO/HP-β-CD inclusion complexes intervention, cell viability evaluation indicated that the half inhibition concentration of evodiamine and EVO/HP-β-CD inclusion complexes on HepG2 cells was 8.516 and 0.977 μM, respectively. The caspase-3 enzyme activity analysis and Annexin V/PI double-staining revealed that EVO/HP-β-CD inclusion complexes possessed better antitumor activities than evodiamine. Additionally, Hoechst 33258 staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assay demonstrated that EVO/HP-β-CD inclusion complexes induced HepG2 cell apoptosis more effectively than evodiamine.

CONCLUSIONS

The improved antitumor activities of evodiamine were attributed to the enhanced solubility and P-glycoprotein inhibition by HP-β-CD. These results are promising for the drug administration of EVO/HP-β-CD inclusion complexes to enhance the bioavailability of evodiamine in vivo.

Discovery and Current Status of Evaluation System of Bioavailability and Related Pharmaceutical Technologies for Traditional Chinese Medicines--Flos Lonicerae Japonicae--Fructus Forsythiae Herb Couples as an Example

Traditional Chinese medicines (TCMs) have attracted extensive interest throughout the world due to their long history of health protection and disease control, and the internalization of TCM preparations or patented drugs has been considered a wind vane in the process of TCM modernization. However, multi-target effects, caused by multiple components in TCMs, hinder not only the construction of the quality evaluation system (bioavailability), but also the application of pharmaceutical technologies, which results in the poor efficacy in clinical practice. This review describes the methods in the literature as well as in our thoughts about how to identify the marker components, establish the evaluation system of bioavailability, and improve the bioavailability in TCM preparations. We expect that the current study will be positive and informative.

Oral anticancer drugs: mechanisms of low bioavailability and strategies for improvement

The use of oral anticancer drugs has increased during the last decade, because of patient preference, lower costs, proven efficacy, lack of infusion-related inconveniences, and the opportunity to develop chronic treatment regimens. Oral administration of anticancer drugs is, however, often hampered by limited bioavailability of the drug, which is associated with a wide variability. Since most anticancer drugs have a narrow therapeutic window and are dosed at or close to the maximum tolerated dose, a wide variability in the bioavailability can have a negative impact on treatment outcome. This review discusses mechanisms of low bioavailability of oral anticancer drugs and strategies for improvement. The extent of oral bioavailability depends on many factors, including release of the drug from the pharmaceutical dosage form, a drug's stability in the gastrointestinal tract, factors affecting dissolution, the rate of passage through the gut wall, and the pre-systemic metabolism in the gut wall and liver. These factors are divided into pharmaceutical limitations, physiological endogenous limitations, and patient-specific limitations. There are several strategies to reduce or overcome these limitations. First, pharmaceutical adjustment of the formulation or the physicochemical characteristics of the drug can improve the dissolution rate and absorption. Second, pharmacological interventions by combining the drug with inhibitors of transporter proteins and/or pre-systemic metabolizing enzymes can overcome the physiological endogenous limitations. Third, chemical modification of a drug by synthesis of a derivative, salt form, or prodrug could enhance the bioavailability by improving the absorption and bypassing physiological endogenous limitations. Although the bioavailability can be enhanced by various strategies, the development of novel oral products with low solubility or cell membrane permeability remains cumbersome and is often unsuccessful. The main reasons are unacceptable variation in the bioavailability and high investment costs. Furthermore, novel oral anticancer drugs are frequently associated with toxic effects including unacceptable gastrointestinal adverse effects. Therefore, compliance is often suboptimal, which may negatively influence treatment outcome.