Enhanced Oral Bioavailability of the Pharmacologically Active Lignin Magnolol via Zr-Based Metal Organic Framework Impregnation

Evaluation of the Antibacterial, Anti-Inflammatory, And Bone-Promoting Capacity of UiO-66 Loaded with Thymol or Carvacrol

Oral infectious diseases have a significant impact on the health of oral and maxillofacial regions, as well as the overall well-being of individuals. Carvacrol and thymol, two isomers known for their effective antibacterial and anti-inflammatory properties, have gained considerable attention in the treatment of oral infectious diseases. However, their application as topical drugs for oral use is limited due to their poor physical and chemical stability. UiO-66, a metal-organic framework based on zirconium ion (Zr4+), exhibits high drug loading capability. Carvacrol and thymol were efficiently loaded onto UiO-66 with loading rates of 79.60 ± 0.71% and 79.65 ± 0.76%, respectively. The release rates of carvacrol and thymol were 77.82 ± 0.87% and 76.51 ± 0.58%, respectively, after a period of 72 h. Moreover, Car@UiO-66 and Thy@UiO-66 demonstrated excellent antibacterial properties against Candida albicans, Escherichia coli, and Staphylococcus aureus with minimum bactericidal concentrations (MBC) of 0.313 mg/mL, 0.313 mg/mL, and 1.25 mg/mL, respectively. Furthermore, based on the results of the CCK8 cytotoxicity assay, even at concentrations as high as 1.25 mg/mL, Car@UiO-66 and Thy@UiO-66 exhibited excellent biocompatibility with a relative cell survival rate above 50%. These findings suggest that Car@UiO-66 and Thy@UiO-66 possess favorable biocompatibility properties without significant toxicity towards periodontal membrane cells. Additionally, in vivo studies confirmed the efficacy of Car@UiO-66and Thy@UiO-66 in reducing inflammation, promoting bone formation through inhibition of TNF-a and IL6 expression, enhancement of IL10 expression, and acceleration of bone defect healing. Therefore, the unique combination of antibacterial, anti-inflammatory, and osteogenic properties make Car@UiO-66 and Thy@Ui O-66 promising candidates for the treatment of oral infectious diseases and repairing bone defects.

Honokiol and magnolol: A review of structure-activity relationships of their derivatives

Honokiol (HK) and magnolol (MAG) are typical representatives of neolignans possessing a wide range of biological activities and are employed as traditional medicines in Asia. In the past few decades, HK and MAG have been proven to be promising chemical scaffolds for the development of novel neolignan drugs. This review focuses on recent advances in the medicinal chemistry of HK and MAG derivatives, especially their structure-activity relationships. In addition, it also presents a comprehensive summary of the pharmacology, biosynthetic pathways, and metabolic characteristics of HK and MAG. This review can provide pharmaceutical chemists deeper insights into medicinal research on HK and MAG, and a reference for the rational design of HK and MAG derivatives.

Improving cellular uptake and synergetic anti-tumor effects of magnolol and Brucea javanica oil through self-microemulsion

OBJECTIVE

Magnolol (MG) and Brucea javanica (L.) Merr. oil (BJO) possess synergetic anti-tumor effects, but have poor water solubility and stability, which results in low oral bioavailability.

SIGNIFICANCE

The MG loaded self-microemulsion drug delivery system (MG-SMDDS) with BJO as oil phase component was utilized to improve the cellular uptake and synergetic anti-tumor effects.

METHODS

Compatibility study and pseudoternary phase diagram (PTPD) were respectively employed to screen for the composition and proportion of oil phase in the formulation. Central composite design-effect surface method was applied to optimize proportion of each formulation condition. The droplet size, ζ-potential, colloid stability, encapsulation rate (ER) and in vitro dissolution rate of MG-SMDDS were evaluated. Furthermore, cellular uptake and cytotoxicity of the microemulsion on HepG2 cells were assessed.

RESULTS

The optimal composition of MG-SMDDS was: MG (9.09%), castor oil (7.40%), BJO (2.47%), Cremophor EL 35 (54.04%) and 1, 2-propanediol (27.01%). The MG-SMDDS exhibited satisfactory droplet size, ζ-potential, colloid stability and ER, as well as faster dissolution rate than free MG. More importantly, SMEDDS containing BJO could enhance the cellular uptake and cytotoxicity of free BJO and free MG on tumor cells.

CONCLUSIONS

The BJO self-microemulsion delivery technique can provide an idea for design of oral delivery vehicles based on BJO.

Bacteria-targeted magnolol-loaded multifunctional nanocomplexes for antibacterial and anti-inflammatory treatment

Natural plant-derived small molecules have shown great potential for their antimicrobial and anti-inflammatory properties. In this study, we successfully developed a nanocomplex consisting of magnolol (Mag), a surfactant with an 18 carbon hydrocarbon chain and multi-amine head groups (C18N3), and a peptide (cyclic 9-amino acid peptide (CARG)) with targeting capabilities forStaphylococcus aureus(S. aureus). The obtained Mag/C18N3/CARG nanocomplexes exhibited strong antibacterial activity againstS. aureus. Furthermore, they demonstrated anti-inflammatory effects by reducing the secretion of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-1βfrom macrophage inflammatory cells. This was achieved through downregulating the activation of NF-κB, KEAP1, and NRF2 signaling pathways. In a murine skin infection model, the Mag/C18N3/CARG nanocomplexes effectively suppressed the growth ofS. aureusin the infected area and promoted wound healing. Additionally, in a mouse model of acute kidney injury (AKI), the nanocomplexes significantly reduced the levels of blood urea nitrogen and creatinine, leading to a decrease in mortality rate. These findings demonstrate the potential of combining natural plant-derived small molecules with C18N3/CARG assemblies as a novel approach for the development of effective and safe antibacterial agents.

Mechanosynthesis of magnolol multicomponent crystalline solids for improved natural antibiotics and customizable release profiles

Antibiotic is one of the most important discoveries in human and animal medicine. However, the inefficient use of antibiotics has caused widespread and persistent contamination of ecosystems, setting off microbial resistance storms. Magnolol is a botanical antibiotic, but poor physicochemical properties result in low bioavailability. Increasing solubility of magnolol can help to reduce the doses of medications to patients, minimize bothersome side effects. In this work, three novel multicomponent crystalline solids were synthesized from magnolol and isomeric coformers by mechanochemistry. It was found that the multicomponent crystalline solids achieved the customizable release profile of magnolol by manipulating the substituent positions of the isomers and complexation. Antibacterial activity test showed that bioactivity on two bacteria was considerably improved by designed MGN multicomponent crystals. In addition, the coformers controlled the dissolution behavior and further stabilized the improvement according to the variable statistical analysis. In conclusion, the properties of antibiotic multicomponent solids can be manipulated through the coformers. This provides an effective strategy for managing the release of drugs to meet individual biological differences and diverse therapeutic needs.

Metal-Organic Frameworks and Their Biodegradable Composites for Controlled Delivery of Antimicrobial Drugs

Antimicrobial resistance (AMR) is a growing global crisis with an increasing number of untreatable or exceedingly difficult-to-treat bacterial infections, due to their growing resistance to existing drugs. It is predicted that AMR will be the leading cause of death by 2050. In addition to ongoing efforts on preventive strategies and infection control, there is ongoing research towards the development of novel vaccines, antimicrobial agents, and optimised diagnostic practices to address AMR. However, developing new therapeutic agents and medicines can be a lengthy process. Therefore, there is a parallel ongoing worldwide effort to develop materials for optimised drug delivery to improve efficacy and minimise AMR. Examples of such materials include functionalisation of surfaces so that they can become self-disinfecting or non-fouling, and the development of nanoparticles with promising antimicrobial properties attributed to their ability to damage numerous essential components of pathogens. A relatively new class of materials, metal-organic frameworks (MOFs), is also being investigated for their ability to act as carriers of antimicrobial agents, because of their ultrahigh porosity and modular structures, which can be engineered to control the delivery mechanism of loaded drugs. Biodegradable polymers have also been found to show promising applications as antimicrobial carriers; and, recently, several studies have been reported on delivery of antimicrobial drugs using composites of MOF and biodegradable polymers. This review article reflects on MOFs and polymer-MOF composites, as carriers and delivery agents of antimicrobial drugs, that have been studied recently, and provides an overview of the state of the art in this highly topical area of research.

Pushing the Limits on the Intestinal Crossing of Metal-Organic Frameworks: An Ex Vivo and In Vivo Detailed Study

Biocompatible nanoscaled metal-organic frameworks (nanoMOFs) have been widely studied as drug delivery systems (DDSs), through different administration routes, with rare examples in the convenient and commonly used oral administration. So far, the main objective of nanoMOFs as oral DDSs was to increase the bioavailability of the cargo, without considering the MOF intestinal crossing with potential advantages (e.g., increasing drug availability, direct transport to systemic circulation). Thus, we propose to address the direct quantification and visualization of MOFs' intestinal bypass. For that purpose, we select the microporous Fe-based nanoMOF, MIL-127, exhibiting interesting properties as a nanocarrier (great biocompatibility, large porosity accessible to different drugs, green and multigram scale synthesis, outstanding stability along the gastrointestinal tract). Additionally, the outer surface of MIL-127 was engineered with the biopolymer chitosan (CS@MIL-127) to improve the nanoMOF intestinal permeation. The biocompatibility and intestinal crossing of nanoMOFs is confirmed using a simple and relevant in vivo model, Caenorhabditis elegans; these worms are able to ingest enormous amounts of nanoMOFs (up to 35 g per kg of body weight). Finally, an ex vivo intestinal model (rat) is used to further support the nanoMOFs' bypass across the intestinal barrier, demonstrating a fast crossing (only 2 h). To the best of our knowledge, this report on the intestinal crossing of intact nanoMOFs sheds light on the safe and efficient application of MOFs as oral DDSs.

Enhanced Oral NO Delivery through Bioinorganic Engineering of Acid-Sensitive Prodrug into a Transformer-like DNIC@MOF Microrod

Nitric oxide (NO) is an endogenous gasotransmitter regulating alternative physiological processes in the cardiovascular system. To achieve translational application of NO, continued efforts are made on the development of orally active NO prodrugs for long-term treatment of chronic cardiovascular diseases. Herein, immobilization of NO-delivery [Fe₂(μ-SCH₂CH₂COOH)₂(NO)₄] (DNIC-2) onto MIL-88B, a metal-organic framework (MOF) consisting of biocompatible Fe³⁺ and 1,4-benzenedicarboxylate (BDC), was performed to prepare a DNIC@MOF microrod for enhanced oral delivery of NO. In simulated gastric fluid, protonation of the BDC linker in DNIC@MOF initiates its transformation into a DNIC@tMOF microrod, which consisted of DNIC-2 well dispersed and confined within the BDC-based framework. Moreover, subsequent deprotonation of the BDC-based framework in DNIC@tMOF under simulated intestinal conditions promotes the release of DNIC-2 and NO. Of importance, this discovery of transformer-like DNIC@MOF provides a parallel insight into its stepwise transformation into DNIC@tMOF in the stomach followed by subsequent conversion into molecular DNIC-2 in the small intestine and release of NO in the bloodstream of mice. In comparison with acid-sensitive DNIC-2, oral administration of DNIC@MOF results in a 2.2-fold increase in the oral bioavailability of NO to 65.7% in mice and an effective reduction of systolic blood pressure (SBP) to a ΔSBP of 60.9 ± 4.7 mmHg in spontaneously hypertensive rats for 12 h.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Convenient synthesis of zwitterionic calcium(II)-carboxylate metal organic frameworks with efficient activities for the treatment of osteoporosis

Calcium supplementation is effective in alleviating the process of osteoporosis and the occurrence of osteoporotic fractures for people with long-term calcium deficiency. Herein, five water-stable calcium carboxylate compounds, that is, mononuclear coordination compound [Ca(Cbdcp)(H₂O)₆]·0.5H₂O (1, H₃CbdcpBr = N-(4-carboxybenzyl)-(3,5-dicarboxyl)pyridinium bromide), and metal organic frameworks (MOFs) {[Ca₃(Dcbdcp)₂(H₂O)₁₂]·2H₂O}_n (2, H₄DcbdcpBr = N-(3,5-dicarboxybenzyl)-(3,5-dicarboxyl)pyridinium bromide), {[Ca(Cmdcp)(H₂O)₄]·3H₂O}_n (3, H₃CmdcpBr = N-carboxymethyl-(3,5-dicarboxyl)pyridinium bromide), {[Ca(Cdcbp)]·2H₂O}_n (4, H₃CdcbpBr = 3-carboxyl-(3,5-dicarboxybenzyl)-pyridinium bromide) and {[Ca_0.5(Cmcp)]·2H₂O}_n (5, H₂CmcpBr = N-carboxymethyl-(3-carboxyl)pyridinium bromide), were synthesized from the reaction of CaCl₂ with five different kinds of zwitterionic carboxylate ligands in the presence of NaOH, respectively. Compounds 1-5 were characterized by Fourier-transform infrared (FTIR) spectroscopy, elemental analyses, single-crystal X-ray crystallography, and inductively coupled plasma mass spectrometry (ICP-MS). Compound 1 features a mononuclear structure and MOF 2 with a one-dimensional (1D) structure while MOFs 3 and 5 with 2D layer structures and MOF 4 showing a 3D structure. Compounds 1-5 exhibited good water stability and possessed considerable biocompatibility with primary mice osteoblasts. The in vitro ability of compounds 1-5 in regulating osteoblastic differentiation was studied via alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, and quantitative real-time polymerase chain reaction (qPCR). Among these 5 compounds, MOF 4 showed the overall best in vitro osteogenic effects. Then, we administrated MOF 4 intragastrically to bilaterally ovariectomized mice for 8 weeks and found that bone loss caused by ovariectomy (OVX) was significantly alleviated. Besides, MOF 4 administration showed no toxic effects in the main organs of the mice. Altogether, zwitterionic carboxylate ligands-based calcium compounds provide a new strategy for calcium agents development.

Computational and Experimental Assessments of Magnolol as a Neuroprotective Agent and Utilization of UiO-66(Zr) as Its Drug Delivery System

The phenolic natural product magnolol exhibits neuroprotective properties through β-amyloid toxicity in PC-12 cells and ameliorative effects against cognitive deficits in a TgCRND8 transgenic mice model. Its bioavailability and blood-brain barrier crossing ability have been significantly improved using the metal-organic framework (MOF) UiO-66(Zr) as a drug delivery system (DDS). To investigate the neuroprotective effects of the Zr-based DDS, magnolol and magnolol-loaded-UiO-66(Zr) (Mag@UiO-66(Zr)) were evaluated for inhibitory activity against β-secretase and AlCl₃-induced neurotoxicity. Due to the moderate inhibition observed for magnolol in vitro, in silico binding studies were explored against β-secretase along with 11 enzymes known to affect Alzheimer's disease (AD). Favorable binding energies against CDK2, CKD5, MARK, and phosphodiesterase 3B (PDE3B) and dynamically stable complexes were noted through molecular docking and molecular dynamic simulation experiments, respectively. The magnolol-loaded DDS UiO-66(Zr) also showed enhanced neuroprotective activity against two pathological indices, namely, neutrophil infiltration and apoptotic neurons, in addition to damage reversal compared to magnolol. Thus, MOFs are promising drug delivery platforms for poorly bioavailable drugs.

Improving the genistein oral bioavailability via its formulation into the metal-organic framework MIL-100(Fe)

Despite the interesting chemopreventive, antioxidant and antiangiogenic effects of the natural bioflavonoid genistein (GEN), its low aqueous solubility and bioavailability make it necessary to administer it using a suitable drug carrier system. Nanometric porous metal-organic frameworks (nanoMOFs) are appealing systems for drug delivery. Particularly, mesoporous MIL-100(Fe) possesses a variety of interesting features related to its composition and structure, which make it an excellent candidate to be used as a drug nanocarrier (highly porous, biocompatible, can be synthesized as homogenous and stable nanoparticles (NPs), etc.). In this study, GEN was entrapped via simple impregnation in MIL-100 NPs achieving remarkable drug loading (27.1 wt%). A combination of experimental and computing techniques was used to achieve a deep understanding of the encapsulation of GEN in MIL-100 nanoMOF. Subsequently, GEN delivery studies were carried out under simulated physiological conditions, showing on the whole a sustained GEN release for 3 days. Initial pharmacokinetic and biodistribution studies were also carried out upon the oral administration of the GEN@MIL-100 NPs in a mouse model, evidencing a higher bioavailability and showing that this oral nanoformulation appears to be very promising. To the best of our knowledge, the GEN-loaded MIL-100 will be the first antitumor oral formulation based on nanoMOFs studied in vivo, and paves the way to the efficient delivery of nontoxic antitumorals via a convenient oral route.

Anti-inflammatory and antioxidant effects of nanoformulations composed of metal-organic frameworks delivering rutin and/or piperine natural agents

Plant-derived natural medicines have been extensively studied for anti-inflammatory or antioxidant properties, but challenges to their clinical use include low bioavailability, poor solubility in water, and difficult-to-control release kinetics. Nanomedicine may offer innovative solutions that can enhance the therapeutic activity and control release kinetics of these agents, opening the way to translating them into the clinic. Two agents of particular interest are rutin (Ru), a flavonoid, and piperine (Pip), an alkaloid, which exhibit a range of pharmacological activities that include antioxidant and anti-inflammatory effects. In this work, nanoformulations were developed consisting of two metal–organic frameworks (MOFs) with surface modifications, Ti-MOF and Zr-MOF, each of them loaded with Ru and/or Pip. Both MOFs and nanoformulations were characterized and evaluated in vivo for anti-inflammatory and antioxidant effects. Loadings of ∼17 wt.% for a single pro-drug and ∼27 wt.% for dual loading were achieved. The release patterns for Ru and or Pip followed two stages: a zero-order for the first 12-hour stage, and a second stage of stable sustained release. At pH 7.4, the release patterns best fit to zero-order and Korsmeyer–Peppas kinetic models. The nanoformulations had enhanced anti-inflammatory and antioxidant effects than any of their elements singly, and those with Ru or Pip alone showed stronger effects than those with both agents. Results of assays using a paw edema model, leukocyte migration, and plasma antioxidant capacity were in agreement. Our preliminary findings indicate that nanoformulations with these agents exert better anti-inflammatory and antioxidant effects than the agents in their free form.

Pharmacology, Toxicity, Bioavailability, and Formulation of Magnolol: An Update

Magnolol (MG) is one of the primary active components of Magnoliae officinalis cortex, which has been widely used in traditional Chinese and Japanese herbal medicine and possesses a wide range of pharmacological activities. In recent years, attention has been drawn to this component due to its potential as an anti-inflammatory and antitumor drug. To summarize the new biological and pharmacological data on MG, we screened the literature from January 2011 to October 2020. In this review, we provide an actualization of already known anti-inflammatory, cardiovascular protection, antiangiogenesis, antidiabetes, hypoglycemic, antioxidation, neuroprotection, gastrointestinal protection, and antibacterial activities of MG. Besides, results from studies on antitumor activity are presented. We also summarized the molecular mechanisms, toxicity, bioavailability, and formulations of MG. Therefore, we provide a valid cognition of MG.