Effects of Concentrations on the Transdermal Permeation Enhancing Mechanisms of Borneol: A Coarse-Grained Molecular Dynamics Simulation on Mixed-Bilayer Membranes.
ABSTRACT: Borneol is a natural permeation enhancer that is effective in drugs used in traditional clinical practices as well as in modern scientific research. However, its molecular mechanism is not fully understood. In this study, a mixed coarse-grained model of stratum corneum (SC) lipid bilayer comprised of Ceramide-N-sphingosine (CER NS) 24:0, cholesterol (CHOL) and free fatty acids (FFA) 24:0 (2:2:1) was used to examine the permeation enhancing mechanism of borneol on the model drug osthole. We found two different mechanisms that were dependent on concentrations levels of borneol. At low concentrations, the lipid system maintained a bilayer structure. The addition of borneol made the lipid bilayer loosen and improved drug permeation. The "pull" effect of borneol also improved drug permeation. However, for a strongly hydrophobic drug like osthole, the permeation enhancement of borneol was limited. When most borneol molecules permeated into bilayers and were located at the hydrophobic tail region, the spatial competition effect inhibited drug molecules from permeating deeper into the bilayer. At high concentrations, borneol led to the formation of water pores and long-lived reversed micelles. This improved the permeation of osthole and possibly other hydrophobic or hydrophilic drugs through the SC. Our simulation results were supported by Franz diffusion tests and transmission electron microscope (TEM) experiments.
Project description:The influence of temperature on the transdermal permeation enhancing mechanism of borneol (BO) was investigated using a multi-scale method, containing a coarse-grained molecular dynamic (CG-MD) simulation, an in vitro permeation experiment, and a transmission electron microscope (TEM) study. The results showed that BO has the potential to be used as a transdermal penetration enhancer to help osthole (OST) penetrate into the bilayer. With the increasing temperature, the stratum corneum (SC) becomes more flexible, proving to be synergistic with the permeation enhancement of BO, and the lag time (TLag) of BO and OST are shortened. However, when the temperature increased too much, with the effect of BO, the structure of SC was destroyed; for example, a water pore was formed and the micelle reversed. Though there were a number of drugs coming into the SC, the normal bilayer structure was absent. In addition, through comparing the simulation, in vitro experiment, and TEM study, we concluded that the computer simulation provided some visually detailed information, and the method plays an important role in related studies of permeation.
Project description:Borneol and menthol are terpenes that are widely used as penetration enhancers in transdermal drug delivery. To explore their penetration-enhancement effects on hydrophilic drugs, 5-fluorouracil (5-FU) was selected as a model drug. An approach that combined in vitro permeation studies and coarse-grained molecular dynamics was used to investigate their penetration-enhancement effect on 5-FU. The results showed that although both borneol and menthol imparted penetration-enhancement effects on 5-FU, these differed in terms of their mechanism, which may account for the observed variations in penetration-enhancement effects. The main mechanism of action of menthol involves the disruption of the stratum corneum (SC) bilayer, whereas borneol involves multiple mechanisms, including the disruption of the SC bilayer, increasing the diffusion coefficient of 5-FU, and inducing the formation of transient pores. The findings of the present study improve our understanding of the molecular mechanism that is underlying 5-FU penetration-enhancement by borneol and menthol, which may be utilized in future investigations and applications.
Project description:Molecular level understanding of permeation of nanoparticles through human skin establishes the basis for development of novel transdermal drug delivery systems and design and formulation of cosmetics. Recent experiments suggest that surface coated nano-sized gold nanoparticles (AuNPs) can penetrate the rat and human skin. However, the mechanisms by which these AuNPs penetrate are not well understood. In this study, we have carried out coarse grained molecular dynamics simulations to explore the permeation of dodecanethiol coated neutral hydrophobic AuNPs of different sizes (2-5?nm) and surface charges (cationic and anionic) through the model skin lipid membrane. The results indicate that the neutral hydrophobic AuNPs disrupted the bilayer and entered in it with in ~200?ns, while charged AuNPs were adsorbed on the bilayer headgroup. The permeation free energy calculation revealed that at the head group of the bilayer, a very small barrier existed for neutral hydrophobic AuNP while a free energy minimum was observed for charged AuNPs. The permeability was maximum for neutral 2?nm gold nanoparticle (AuNP) and minimum for 3?nm cationic AuNP. The obtained results are aligned with recent experimental findings. This study would be helpful in designing customized nanoparticles for cosmetic and transdermal drug delivery application.
Project description:Borneol is a compound widely used in ophthalmic preparations in China. Little is known about its exact role in treating eye diseases. Here we report that transient receptor potential melastatin 8 (TRPM8) channel is a pharmacological target of borneol and mediates its therapeutic effect in the eyes. Ca2+ measurement and electrophysiological recordings revealed that borneol activated TRPM8 channel in a temperature- and dose-dependent manner, which was similar to but less effective than the action of menthol, an established TRPM8 agonist. Borneol significantly increased tear production in guinea pigs without evoking nociceptive responses at 25°C, but failed to induce tear secretion at 35°C. In contrast, menthol evoked tearing response at both 25 and 35°C. TRPM8 channel blockers N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide hydrochloride (AMTB) and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)piperazine-1-carboxamide (BCTC) abolished borneol- and menthol-induced tear secretion. Borneol at micromolar concentrations did not affect the viability of human corneal epithelial cells. We conclude that borneol can activate the cold-sensing TRPM8 channel and modestly increase ocular surface wetness, which suggests it is an active compound in ophthalmic preparations and particularly useful in treating dry eye syndrome.
Project description:Most plant-produced monoterpenes can be degraded by soil microorganisms. Borneol is a plant terpene that is widely used in traditional Chinese medicine. Neither microbial borneol dehydrogenase (BDH) nor a microbial borneol degradation pathway has been reported previously. One borneol-degrading strain, Pseudomonas sp. strain TCU-HL1, was isolated by our group. Its genome was sequenced and annotated. The genome of TCU-HL1 consists of a 6.2-Mbp circular chromosome and one circular plasmid, pTHL1 (12.6 kbp). Our results suggest that borneol is first converted into camphor by BDH in TCU-HL1 and is further decomposed through a camphor degradation pathway. The recombinant BDH was produced in the form of inclusion bodies. The apparent Km values of refolded recombinant BDH for (+)-borneol and (-)-borneol were 0.20 ± 0.01 and 0.16 ± 0.01 mM, respectively, and the kcat values for (+)-borneol and (-)-borneol were 0.75 ± 0.01 and 0.53 ± 0.01 s-1, respectively. Two plant BDH genes have been reported previously. The kcat and kcat/Km values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. IMPORTANCE:The degradation of borneol in a soil microorganism through a camphor degradation pathway is reported in this study. We also report a microbial borneol dehydrogenase. The kcat and kcat/Km values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. The indigenous borneol- and camphor-degrading strain isolated, Pseudomonas sp. strain TCU-HL1, reminds us of the time 100 years ago when Taiwan was the major producer of natural camphor in the world.
Project description:The serious therapeutic obstacles to glioma treatment include poor penetration across the blood-brain barrier (BBB) and low accumulation of therapeutic drugs at tumor sites. In this study, borneol combined with CGKRK peptide (a ligand of the heparan sulfate which overexpress on the glioma cells) modified paclitaxel prodrug self-assembled redox-responsive nanoparticles (CGKRK-PSNPs) were hypothesized to enhance the BBB penetration ability and active tumor targeting efficiency, respectively. The resulting CGKRK-PSNPs possessed a spherical shape with a small particle size (105.61 ± 1.53 nm) and high drug loading for PTX (54.18 ± 1.13%). The drug release behavior proved that CGKRK-PSNPs were highly sensitive to glutathione (GSH) redox environment. The in vitro cell experiments suggested that CGKRK-PSNPs significantly increased the cellular uptake and cytotoxicity of U87MG cells, meanwhile CGKRK-PSNPs showed the low cytotoxicity against BCEC cells. Combined with borneol, CGKRK-PSNPs exhibited enhanced transportation across in vitro BBB model. In intracranial U87MG glioma-bearing nude mice, the higher accumulation of CGKRK-PSNPs combined with borneol was observed through real-time fluorescence image. Moreover, the in vivo anti-glioma results confirmed that CGKRK-PSNPs combined with borneol could improve the anti-glioma efficacy with the prolonged medium survival time (39 days). In conclusion, the collaborative strategy of CGKRK-PSNPs combined with borneol provided a promising drug delivery routine for glioblastoma therapy.
Project description:Bingpian is a time-honored herb in traditional Chinese medicine (TCM). It is an almost pure chemical with a chemical composition of (+)-borneol and has been historically used as a topical analgesic for millennia. However, the clinical efficacy of topical borneol lacks stringent evidence-based clinical studies and verifiable scientific mechanism. We examined the analgesic efficacy of topical borneol in a randomized, double-blind, placebo-controlled clinical study involving 122 patients with postoperative pain. Topical application of borneol led to significantly greater pain relief than placebo did. Using mouse models of pain, we identified the TRPM8 channel as a molecular target of borneol and showed that topical borneol-induced analgesia was almost exclusively mediated by TRPM8, and involved a downstream glutamatergic mechanism in the spinal cord. Investigation of the actions of topical borneol and menthol revealed mechanistic differences between borneol- and menthol-induced analgesia and indicated that borneol exhibits advantages over menthol as a topical analgesic. Our work demonstrates that borneol, which is currently approved by the US FDA to be used only as a flavoring substance or adjuvant in food, is an effective topical pain reliever in humans and reveals a key part of the molecular mechanism underlying its analgesic effect.
Project description:To achieve sufficient blood-brain barrier (BBB), penetration is one of the biggest challenges in the development of diagnostic and therapeutic for central nervous system (CNS) disorders. Here, we conducted a systematic review and meta-analysis to assess the preclinical evidence and possible mechanisms of borneol for improving co-administration of CNS drug delivery in animal models. The electronic literature search was conducted in six databases. Fifty-eight studies with 63 comparisons involved 1137 animals were included. Among 47 studies reporting the assessments of CNS drug concentration, 45 studies showed the significant effects of borneol for improving CNS drug delivery (p<.05), whereas 2 studies showed no difference (p>.05). Nineteen comparisons showed borneol up-regulated BBB permeability (p<.05) using brain EB content (n?=?8), Rh 123 content (n?=?4), brain imaging agent content (n?=?2), brain water content (n?=?1) and observing ultrastructure of BBB (n?=?4), whereas three studies showed no difference or unclear results. Seven studies reported the safety, in which one study showed borneol was reversible changes in the BBB penetration; six studies showed borneol did not increase co-administration of blood drugs concentration of peripheral tissues (p?>?.05). Effects of borneol are closely associated with inhibition of efflux protein function, releasement of tight junction protein, increasement of vasodilatory neurotransmitters, and inhibition of active transport by ion channels. In conclusion, borneol is a promising candidate for CNS drug delivery, mainly through mediating a multi-targeted BBB permeability.
Project description:Cortisone is an injected anti-inflammatory drug that can cause painful side effects known as "steroid flares" which are caused by cortisone crystallizing at the injection site. We used molecular dynamics simulations and X-ray diffraction to study the interaction of cortisone with model lipid membranes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at drug concentrations from 0?mol% to 50?mol%. Cortisone was found to partition in the lipid bilayer and locate in the hydrophilic to hydrophobic interface of the membranes. Cortisone strongly affects the integrity of the membrane, as quantified by a decreased membrane thickness, increased area per lipid, and decreased lipid tail order parameters. At cortisone concentrations of more than 20?mol%, signals from crystallized cortisone were observed. These crystallites are embedded in the bilayers and orient with the membranes. While the cortisone molecules align parallel to the bilayers at low concentrations, they start to penetrate the hydrophobic core at higher concentrations. Trans-membrane crystallites start to nucleate when the membrane thickness has decreased such that cortisone molecules in the different leaflets can find partners from the opposite leaflet resulting in a non-zero density of cortisone molecules in the bilayer center. We suggest that the lipid bilayer provides a site for cortisone crystallization.
Project description:Background:Dextrorotatory borneol (D-borneol), a cyclic monoterpene, is widely used in traditional Chinese medicine as an efficient topical analgesic drug. Fresh leaves of Cinnamomum trees, e.g., C. burmannii and C. camphor, are the main sources from which D-borneol is extracted by steam distillation, yet with low yields. Insufficient supply of D-borneol has hampered its clinical use and production of patent remedies for a long time. Biological synthesis of D-borneol offers an additional approach; however, mechanisms of D-borneol biosynthesis remain mostly unresolved. Hence, it is important and necessary to elucidate the biosynthetic pathway of D-borneol. Results:Comparative analysis on the gene expression patterns of different D-borneol production C. burmannii samples facilitates elucidation on the underlying biosynthetic pathway of D-borneol. Herein, we collected three different chemotypes of C. burmannii, which harbor different contents of D-borneol.A total of 100,218 unigenes with an N50 of 1,128 bp were assembled de novo using Trinity from a total of 21.21 Gb clean bases. We used BLASTx analysis against several public databases to annotate 45,485 unigenes (45.38%) to at least one database, among which 82 unigenes were assigned to terpenoid biosynthesis pathways by KEGG annotation. In addition, we defined 8,860 unigenes as differentially expressed genes (DEGs), among which 13 DEGs were associated with terpenoid biosynthesis pathways. One 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and two monoterpene synthase, designated as CbDXS9, CbTPS2 and CbTPS3, were up-regulated in the high-borneol group compared to the low-borneol and borneol-free groups, and might be vital to biosynthesis of D-borneol in C. burmannii. In addition, we identified one WRKY, two BHLH, one AP2/ERF and three MYB candidate genes, which exhibited the same expression patterns as CbTPS2 and CbTPS3, suggesting that these transcription factors might potentially regulate D-borneol biosynthesis. Finally, quantitative real-time PCR was conducted to detect the actual expression level of those candidate genes related to the D-borneol biosynthesis pathway, and the result showed that the expression patterns of the candidate genes related to D-borneol biosynthesis were basically consistent with those revealed by transcriptome analysis. Conclusions:We used transcriptome sequencing to analyze three different chemotypes of C. burmannii, identifying three candidate structural genes (one DXS, two monoterpene synthases) and seven potential transcription factor candidates (one WRKY, two BHLH, one AP2/ERF and three MYB) involved in D-borneol biosynthesis. These results provide new insight into our understanding of the production and accumulation of D-borneol in C. burmannii.