Permeation-enhancing effects and mechanisms of borneol and menthol on ligustrazine: A multiscale study using in vitro and coarse-grained molecular dynamics simulation methods

Natural borneol serves as an adjuvant agent to promote the cellular uptake of piperlongumine for improving its antiglioma efficacy

Piperlongumine (PL) can selectively inhibit the proliferation of various cancer cells by increasing reactive oxygen species (ROS) level to cause a redox imbalance in cancer cells rather than in normal cells. However, the clinical application of PL is limited by its poor cellular uptake. Natural borneol (NB) is extracted from the fresh branches and leaves of Cinnamomum camphora (L.) Presl. with the purity of (+)-borneol no less than 96.0%. NB has been often used as an adjuvant agent to promote the cellular uptake of other drugs. This study aims to investigate the effect of NB on the cellular uptake of PL for improving its antiglioma efficacy and underlying mechanism. NB obviously promoted the cellular uptake of PL with a 1.3-fold increase in the maximum peak concentration and an earlier peak time of 30 min in C6 glioma cells. The cellular uptake of PL was enhanced by NB through down-regulating the expression levels of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2). The combination of NB and PL significantly induced higher levels of ROS, which increased apoptosis and enhanced G2/M cycle arrest of C6 glioma cells, compared to PL alone administration. NB-enhanced antiglioma efficacy of PL without side effects was confirmed in tumor-bearing mice, which was attributed to the improved cellular uptake of PL. The distribution of PL in the tumor tissue of combined group increased 2.39 times than that of PL-treated group. We firstly report NB as an adjuvant agent to improve the antiglioma efficacy of PL in a ROS-dependent manner, which is due to the enhanced cellular uptake of PL by NB though down-regulating the expression levels of ABCB1 and ABCG2. This work provides a new strategy to promote the cellular uptake of PL with great potential for the treatment of glioma.

Using molecular simulation to understand the skin barrier

Skin's effectiveness as a barrier to permeation of water and other chemicals rests almost entirely in the outermost layer of the epidermis, the stratum corneum (SC), which consists of layers of corneocytes surrounded by highly organized lipid lamellae. As the only continuous path through the SC, transdermal permeation necessarily involves diffusion through these lipid layers. The role of the SC as a protective barrier is supported by its exceptional lipid composition consisting of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs) and the complete absence of phospholipids, which are present in most biological membranes. Molecular simulation, which provides molecular level detail of lipid configurations that can be connected with barrier function, has become a popular tool for studying SC lipid systems. We review this ever-increasing body of literature with the goals of (1) enabling the experimental skin community to understand, interpret and use the information generated from the simulations, (2) providing simulation experts with a solid background in the chemistry of SC lipids including the composition, structure and organization, and barrier function, and (3) presenting a state of the art picture of the field of SC lipid simulations, highlighting the difficulties and best practices for studying these systems, to encourage the generation of robust reproducible studies in the future. This review describes molecular simulation methodology and then critically examines results derived from simulations using atomistic and then coarse-grained models.

Burn Ointment Promotes Cutaneous Wound Healing by Modulating the PI3K/AKT/mTOR Signaling Pathway

Burn ointment (BO) is a clinically useful medicine for the treatment of burns and scalds. However, there is no enough scientific evidence to report the effect of BO on wound healing and its analgesic and anti-inflammatory efficacy. The aim of this work was to evaluate the anti-inflammatory and analgesic efficacy of BO and to reveal the potential wound healing properties and related mechanisms of BO. In this work, the content of active ingredients of BO was determined by high-performance liquid chromatography (HPLC). Two animal models of inflammation were used to study its anti-inflammatory activity, and a hot plate method was used to evaluate its analgesic effect. In addition, mouse incision and rat burn models were used to investigate the effect of BO on the anti-inflammatory and wound healing mechanisms. The results showed that BO was safe for topical application, and BO could significantly inhibit auricular swelling in mice and paw swelling in rats and significantly prolong the latency period of paw licking in the hot plate experiment in mice. It can also accelerate wound healing and repair scars by promoting the formation of new epithelial tissues in rat burn models. In addition, BO significantly downregulated the serum level of TNF-α and significantly increased the serum levels of VEGF and TGF-β1. Also, BO promoted the expression of collagen I and increased the ratio in p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR pathways. Our results demonstrate the safety and efficacy of BO and suggest that activation of the PI3K/AKT/mTOR signaling pathway may play an important role in the promotion of wound healing by BO.

Borneol-mediated vardenafil hydrochloride patch for pediatric pulmonary arterial hypertension: Preparation, characterization and in vivo study

BACKGROUND

Pediatric pulmonary arterial hypertension (PPAH) is a malignant progressive rare disease characterized by restricted pulmonary artery blood flow and progressively increasing blood pressure, which has shorter survival time of only about 10 months as compared to adults. Previous studies have shown that low-dose vardenafil hydrochloride (Var) could significantly improve the symptoms of PPAH. However, Var is currently available only in tablet form in the market for erectile dysfunction, and no special preparation is available for PPAH.

METHODS

In this study, borneol-mediated vardenafil hydrochloride patch (BO-VarP) with sodium polyacrylate as the skeleton material was prepared by coating method, which was characterized by temperature resistance, formability, adhesive force, skin irritation and in vitro permeation. Blood concentration of optimized BO-VarP was measured by LC-MS/MS using intragastric administration (i.g.) as a control, and pharmacodynamic studies were conducted using a rat model of pulmonary arterial hypertension induced by monocrotaline.

RESULTS AND DISCUSSION

Optimized BO-VarP showed good appearance, with optimal temperature resistance and formability, appropriate adhesive force and low skin irritation, and its cumulative permeation flux was 14.9 times higher than patch without penetration enhancer. The blood concentration within therapeutic window of BO-VarP lasted longer than i.g., and BO-VarP could improve symptoms of PPAH by reducing pulmonary arterial pressure and right heart hypertrophy index.

CONCLUSION

BO-VarP had good therapeutic effect in PPAH rats and suitable compliance in children, which provided a potential industrial transdermal delivery system for the treatment of PPAH.

Finite Element Analysis for Predicting Skin Pharmacokinetics of Nano Transdermal Drug Delivery System Based on the Multilayer Geometry Model

Background

Skin pharmacokinetics is an indispensable indication for studying the drug fate after administration of transdermal drug delivery systems (TDDS). However, the heterogeneity and complex skin structured with stratum corneum, viable epidermis, dermis, and subcutaneous tissue inevitably leads the drug diffusion coefficient (Kp) to vary depending on the skin depth, which seriously limits the development of TDDS pharmacokinetics in full thickness skin.

Methods

A multilayer geometry skin model was established and the Kp of drug in SC, viable epidermis, and dermis was obtained using the technologies of molecular dynamics simulation, in vitro permeation experiments, and in vivo microdialysis, respectively. Besides, finite element analysis (FEA) based on drug Kps in different skin layers was applied to simulate the paeonol nanoemulsion (PAE-NEs) percutaneous dynamic penetration process in two and three dimensions. In addition, PAE-NEs skin pharmacokinetics profile obtained by the simulation was verified by in vivo experiment.

Results

Coarse-grained modeling of molecular dynamic simulation was successfully established and the Kp of PAE in SC was 2.00×10⁻⁶ cm²/h. The Kp of PAE-NE in viable epidermis and in dermis detected using penetration test and microdialysis probe technology, was 1.58×10⁻⁵ cm²/h and 3.20×10⁻⁵ cm²/h, respectively. In addition, the results of verification indicated that PAE-NEs skin pharmacokinetics profile obtained by the simulation was consistent with that by in vivo experiment.

Discussion

This study demonstrated that the FEA combined with the established multilayer geometry skin model could accurately predict the skin pharmacokinetics of TDDS.

Permeation-enhancing effects and mechanisms of O-acylterpineol on isosorbide dinitrate: mechanistic insights based on ATR-FTIR spectroscopy, molecular modeling, and CLSM images

The present study aimed to evaluate the penetration activity of O-acylterpineol derivatives both in vitro and in vivo, and to investigate the enhancing mechanism of O-acylterpineol derivatives which were synthesized by α-terpineol and fatty acid. The promoting activities on the isosorbide dinitrate patch were tested across full thickness rabbit skin both in vitro and in vivo. In order to elucidate the permeation mechanism, attenuated total reflection Fourier transform infrared spectroscopy, molecular modeling, and confocal laser scanning microscopy were introduced to investigate the regulation of enhancers in the skin permeability and biophysical properties. With in vitro cytotoxicity test and in vivo erythema model, the skin irritation of enhancers was also evaluated. Permeation studies showed 2-(4-methylcyclohex-3-en-l-yl) propan-2-yl tetradecanoate produced the obvious enhancement activity for ISDN both in vitro and in vivo from patches. These results were supported by ATR-FTIR, molecular modeling, and CLSM studies which revealed that O-acylterpineol could decrease the order of the alkyl chains in the skin lipids. Additionally, it was found that TER-C14 produced a relatively low skin irritation, compared with the TER which was assumed to be a safe compound. The present research suggested that some newly designed acylterpineol derivatives are shown to be suitable permeation enhancers for transdermal drug delivery, and the chain length of C14 seem to be safe and more favorable for the penetration of ISDN from DIA patches.