Effect of borneol as a penetration enhancer on brain targeting of nanoliposomes: facilitate direct delivery to neurons

Advances and perspectives on pharmacological activities and mechanisms of the monoterpene borneol

BACKGROUND

Borneol, a highly lipid-soluble bicyclic terpene mainly extracted from plants, is representative of monoterpenoids. Modern medicine has established that borneol exhibits a range of pharmacological activities and used in the treatment of many diseases, particularly Cardio-cerebrovascular diseases (CVDs). The crucial role in enhancing drug delivery and improving bioavailability has attracted much attention. In addition, borneol is also widely utilized in food, daily chemicals, fragrances, and flavors industries.

PURPOSE

This review systematically summarized the sources, pharmacological activities and mechanisms, clinical trial, pharmacokinetics, toxicity, and application of borneol. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial. This review will provide a valuable resource for those pursuing researches on borneol inspiring the pharmacological applications in the medicine, food and daily chemical products, and developing of new drugs containing borneol or its derivatives.

METHODS

This review searched the keywords ("borneol" or "bornyl esters") and ("pharmacology" or "Traditional Chinese medicine" or "Cardio-cerebrovascular diseases" or "blood-brain barrier" or "ischemic stroke" or "nanomaterials" or "neurodegenerative diseases" or "diabetes" or "toxicity") in Web of Science, PubMed, Google Scholar and China National Knowledge Infrastructure (CNKI) from January 1990 to May 2024. The search was limited to articles published in English and Chinese.

RESULTS

Borneol exhibits extensive pharmacological activities including anti-inflammatory effects, analgesia, antioxidation, and has the property of crossing biological barriers and treating CVDs. The intrinsic molecular mechanisms are involved in multiple components, such as regulation of various key factors (including Tumor necrosis factor-α, Nuclear factor kappa-B, Interleukin-1β, Malondialdehyde), inhibiting transporter protein function, regulating biochemical levels, and altering physical structural changes. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial.

CONCLUSION

The pharmacological properties and applications of borneol are promising, including anti-inflammatory, analgesic, antimicrobial, and antioxidant properties, as well as enhancing drug delivery and treating CVDs. However, its clinical application is hindered by the limited research on safety, efficacy, and pharmacokinetics. Therefore, this review systemically summarized the advances on pharmacological activities and mechanisms of the borneol. Standardized clinical trials and exploration of synergistic effects with other drugs were also are outlined.

A Sustainable Retinal Drug Co-Delivery for Boosting Therapeutic Efficacy in wAMD: Unveiling Multifaceted Evidence and Synergistic Mechanisms

Sustainable retinal codelivery poses significant challenges technically, although it is imperative for synergistic treatment of wet age-related macular degeneration (wAMD). Here, a microemulsion-doped hydrogel (Bor/PT-M@TRG) is engineered as an intravitreal depot composing of temperature-responsive hydrogel (TRG) and borneol-decorated paeoniflorin (PF) & tetramethylpyrazine (TMP)-coloaded microemulsions (Bor/PT-M). Bor/PT-M@TRG, functioning as the "ammunition depot", resides in the vitreous and continuously releases Bor/PT-M as the therapeutic "bullet", enabling deep penetration into the retina for 21 days. A single intravitreal injection of Bor/PT-M@TRG yields substantial reductions in choroidal neovascularization (CNV, a hallmark feature of wAMD) progression and mitigates oxidative stress-induced damage in vivo. Combinational PF&TMP regulates the "reactive oxygen species/nuclear factor erythroid-2-related factor 2/heme oxygenase-1" pathway and blocks the "hypoxia inducible factor-1α/vascular endothelial growth factor" signaling in retina, synergistically cutting off the loop of CNV formation. Utilizing fluorescence resonance energy transfer and liquid chromatography-mass spectrometry techniques, they present compelling multifaceted evidence of sustainable retinal codelivery spanning formulations, ARPE-19 cells, in vivo eye balls, and ex vivo section/retina-choroid complex cell levels. Such codelivery approach is elucidated as the key driving force behind the exceptional therapeutic outcomes of Bor/PT-M@TRG. These findings highlight the significance of sustainable retinal drug codelivery and rational combination for effective treatment of wAMD.

Functionalized lipid nanoparticles modulate the blood-brain barrier and eliminate α-synuclein to repair dopamine neurons

The challenge in the clinical treatment of Parkinson's disease lies in the lack of disease-modifying therapies that can halt or slow down the progression. Peptide drugs, such as exenatide (Exe), with potential disease-modifying efficacy, have difficulty in crossing the blood-brain barrier (BBB) due to their large molecular weight. Herein, we fabricate multi-functionalized lipid nanoparticles (LNP) Lpc-BoSA/CSO with BBB targeting, permeability-increasing and responsive release functions. Borneol is chemically bonded with stearic acid and, as one of the components of Lpc-BoSA/CSO, is used to increase BBB permeability. Immunofluorescence results of brain tissue of 15-month-old C57BL/6 mice show that Lpc-BoSA/CSO disperses across the BBB into brain parenchyma, and the amount is 4.21 times greater than that of conventional LNP. Motor symptoms of mice in Lpc-BoSA/CSO-Exe group are significantly improved, and the content of dopamine is 1.85 times (substantia nigra compacta) and 1.49 times (striatum) that of PD mice. α-Synuclein expression and Lewy bodies deposition are reduced to 51.85% and 44.72% of PD mice, respectively. Immunohistochemical mechanism studies show AKT expression in Lpc-BoSA/CSO-Exe is 4.23 times that of PD mice and GSK-3β expression is reduced to 18.41%. Lpc-BoSA/CSO-Exe could reduce the production of α-synuclein and Lewy bodies through AKT/GSK-3β pathway, and effectively prevent the progressive deterioration of Parkinson's disease. In summary, Lpc-BoSA/CSO-Exe increases the entry of exenatide into brain and promotes its clinical application for Parkinson's disease therapy.

Borneol-Modified Schisandrin B Micelles Cross the Blood-Brain Barrier To Treat Alzheimer's Disease in Aged Mice

Objective: Schisandrin B (Sch B) is a bioactive dibenzocyclooctadiene derizative that is prevalent in the fruit of Schisandra chinensis. Numerous studies have demonstrated that Sch B has a neuroprotective action by reducing oxidative stress and effectively preventing inflammation. It follows that Sch B is a potential treatment for Alzheimer's disease (AD). However, the drug's solubility, bioavailability, and lower permeability of the blood-brain barrier (BBB) can all reduce its efficacy during the therapy process. Therefore, this study constructed borneol-modified schisandrin B micelles (Bor-Sch B-Ms), which increase brain targeting by accurately delivering medications to the brain, effectively improving bioavailability. High therapeutic efficacy has been achieved at the pathological site. Methods: Bor-Sch B-Ms were prepared using the thin film dispersion approach in this article. On the one hand, to observe the targeting effect of borneol, we constructed a blood-brain barrier (BBB) model in vitro and studied the ability of micelles to cross the BBB. On the other hand, the distribution of micelle drugs and their related pharmacological effects on neuroinflammation, oxidative stress, and neuronal damage were studied through in vivo administration in mice. Results: In vitro studies have demonstrated that the drug uptake of bEnd.3 cells was increased by the borneol alteration on the surface of the nano micelles, implying that Bor-Sch B-Ms can promote the therapeutic effect of N2a cells. This could result in more medicines entering the BBB. In addition, in vivo studies revealed that the distribution and circulation time of medications in the brain tissue were significantly higher than those in other groups, making it more suitable for the treatment of central nervous system diseases. Conclusion: As a novel nanodrug delivery system, borneol modified schisandrin B micelles have promising research prospects in the treatment of Alzheimer's disease.

Recent Progress on the Synergistic Antitumor Effect of a Borneol-Modified Nanocarrier Drug Delivery System

Borneol, a traditional Chinese medicine, can enhance therapeutic efficacy by guiding the active ingredients to the target site. Reportedly, borneol improves the penetration capacity of the nasal, cornea, transdermal, intestinal, and blood-brain barriers. Although nanotechnology dramatically changed the face of oncology by targeting tumor sites, the efficiency of nanoparticles delivered to tumor sites is very low, with only 0.7% of the total particles delivered. Thus, based on the penetration ability and the inhibition drug efflux of borneol, it was expected to increase the targeting and detention efficacy of drugs into tumor sites in nanocarriers with borneol modification. Borneol modified nanocarriers used to improve drug-targeting has become a research focus in recent years, but few studies in this area, especially in the antitumor application. Hence, this review summarizes the recent development of nanocarriers with borneol modification. We focus on the updated works of improving therapeutic efficacy, reducing toxicity, inhibiting tumor metastasis, reversing multidrug resistance, and enhancing brain targeting to expand their application and provide a reference for further exploration of targeting drug delivery systems for solid tumor treatment.

Multiple regulation and targeting effects of borneol in the neurovascular unit in neurodegenerative diseases

Efficient delivery of brain-targeted drugs is highly important for the success of therapies in neurodegenerative diseases. Borneol has several biological activities, such as anti-inflammatory and cell penetration enhancing effect, and can regulate processes in the neurovascular unit (NVU), such as protein toxic stress, autophagosome/lysosomal system, oxidative stress, programmed cell death and neuroinflammation. However, the influence of borneol on NVU in neurodegenerative diseases has not been fully explained. This study searched the keywords 'borneol', 'neurovascular unit', 'endothelial cell', 'astrocyte', 'neuron', 'blood-brain barrier', 'neurodegenerative diseases' and 'brain disease', in PubMed, BioMed Central, China National Knowledge Infrastructure (CNKI), and Bing search engines to explore the influence of borneol on NVU. In addition to the principle and mechanism of penetration of borneol in the brain, this study also showed its multiple regulation effects on NVU. Borneol was able to penetrate the blood-brain barrier (BBB), affecting the signal transmission between BBB and the microenvironment of the brain, down-regulating the expression of inflammatory and oxidative stress proteins in NVU, especially in microglia and astrocytes. In summary, borneol is a potential drug delivery agent for drugs against neurodegenerative diseases.

Borneol: a Promising Monoterpenoid in Enhancing Drug Delivery Across Various Physiological Barriers

Incorporation of permeation enhancers is one of the most widely employed approaches for delivering drugs across biological membranes. Permeation enhancers aid in delivering drugs across various physiological barriers such as brain capillary endothelium, stratum corneum, corneal epithelium, and mucosal membranes that pose resistance to the entry of a majority of drugs. Borneol is a natural, plant-derived, lipophilic, volatile, bicyclic monoterpenoid belonging to the class of camphene. It has been used under the names "Bing Pian" or "Long Nao" in Traditional Chinese Medicine for more than 1000 years. Borneol has been incorporated predominantly as an adjuvant in the traditional Chinese formulations of centrally acting drugs to improve drug delivery to the brain. This background knowledge and anecdotal evidence have led to extensive research in establishing borneol as a permeation enhancer across the blood-brain barrier. Alteration in cell membrane lipid structures and modulation of multiple ATP binding cassette transporters as well as tight junction proteins are the major contributing factors to blood-brain barrier opening functions of borneol. Owing to these mechanisms of altering membrane properties, borneol has also shown promising potential to improve drug delivery across other physiological barriers as well. The current review focuses on the role of borneol as a permeation enhancer across the blood-brain barrier, mucosal barriers including nasal and gastrointestinal linings, transdermal, transcorneal, and blood optic nerve barrier.

Preparation, Characterization and in vivo Study of Borneol-Baicalin-Liposomes for Treatment of Cerebral Ischemia-Reperfusion Injury

Purpose

Baicalin (BA) has a good neuroprotective effect, but it is eliminated quickly in the body and does not easily reach the brain. In this experiment, borneol (BO) was used as an auxiliary drug to prepare borneol-baicalin-liposomes (BO-BA-LP) to prolong the efficacy time of BA, synergistically synergize, introduce drugs into the brain, and better exert the therapeutic effect on cerebral ischemia-reperfusion (I/R) injury.

Methods

Through single-factor inspection and response surface optimization analysis, obtained the best preparation process of BO-BA-LP and characterized by various analytical techniques. Validated the long-term effectiveness of BA-BO-LP through pharmacokinetic studies and conducted pharmacodynamic studies on the middle cerebral artery occlusion (MCAO) rat model to verify the therapeutic effect of BO-BA-LP on cerebral I/R injury.

Results

The optimum preparation conditions of BO-BA-LP were as follows: the dosage of BO was 9.55 mg, the ratio of phospholipid to drug was 4.02:1, the ratio of phospholipid to cholesterol was 7.25:1, the entrapment efficiency (EE) was 41.49%, and the drug loading (DL) was 4.29%. The particle size range of the liposomes was 167.1 nm, and the polydispersity index (PDI) range was 0.113. The results of pharmacokinetic experiments showed that the combination of BA and BO liposomes effectively improved the pharmacokinetic parameters of BA and prolonged the half-life of BA. Pharmacodynamic studies have found that, compared with BA-LP, BO-BA-LP can significantly improve neurological deficits, cerebral infarction volume, and brain pathological states on MCAO rats.

Conclusion

These results demonstrated that BO-BA-LP can improve the circulation of drugs in the blood, and the addition of BO can enhance the therapeutic effect of BA and effectively improve cerebral I/R.

An overview of nanomedicines for neuron targeting

Medical treatments of neuron-related disorders are limited due to the difficulty of targeting brain cells. Major drawbacks are the presence of the blood-brain barrier and the lack of specificity of the drugs for the diseased cells. Nanomedicine-based approaches provide promising opportunities for overcoming these limitations. Although many previous reviews are focused on brain targeting with nanomedicines in general, none of those are concerned explicitly on the neurons, while targeting neuronal cells in central nervous diseases is now one of the biggest challenges in nanomedicine and neuroscience. We review the most relevant advances in nanomedicine design and strategies for neuronal drug delivery that might successfully bridge the gap between laboratory and bedside treatment in neurology.

Increased microneedle-mediated transdermal delivery of tetramethylpyrazine to the brain, combined with borneol and iontophoresis, for MCAO prevention

The aim of this research was to improve transdermal delivery and distribution of tetramethylpyrazine (TMP) in the brain, by adding borneol (BN) and iontophoresis (ITP), and using microneedles (MN), to prevent middle cerebral artery occlusion (MCAO). BN was encapsulated into sulfobutylated-β-cyclodextrin (BN-SBE-β-CD), and then dispersed together with TMP. Four delivery groups were tested: passive (with no ITP and MN), ITP, MN, and MN combined with ITP (MN-ITP). In vitro transdermal fluxes of the drugs in those groups and in that corresponding order were 79.12 ± 14.5, 395.43 ± 12.37, 319.16 ± 29.99, and 1018.07 ± 108.92 μg/cm² (for TMP), and 39.34 ± 1.31, 202.81 ± 53.56, 715.47 ± 75.52, and 1088.60 ± 53.90 μg/cm² (for BN), respectively, which indicated that the use of MN-ITP greatly enhanced transdermal TMP and BN delivery compared to the other groups. The AUC_0-t for the combined use of TMP and BN drugs was measured using two in vivo studies, cutaneous microdialysis and pharmacodynamic, yielding increased folds of 3.69 and 1.98 in ITP, 6.05 and 2.73 in MN, and 12.43 and 7.47 in MN-ITP groups, respectively, as compared to those in the passive group. In addition, the combined use of TMP and BN increased TMP distribution in the heart and the brain, indicated by TMP C_max of 1.76- and 1.59-fold higher (p < 0.05), and TMP AUC_0-t of 1.50 times and 1.19-fold higher (p < 0.01), than with administration of TMP in absence of BN, respectively. The brain infarction area and IL-β expression in the MCAO rat were significantly decreased in the MN-ITP group, compared with the control group (p < 0.05). In conclusion, combination of MN and ITP resulted in a synergistic enhancement of transdermal delivery and distribution of TMP in the brain, when in combination with BN, thereby significantly decreasing the infarct volumes and improving the neurological scores of MCAO.