Preparation and characterization of solidified oleanolic acid–phospholipid complex aiming to improve the dissolution of oleanolic acid

Unlocking the Potential of Oleanolic Acid: Integrating Pharmacological Insights and Advancements in Delivery Systems

The growing interest in oleanolic acid (OA) as a triterpenoid with remarkable health benefits prompts an emphasis on its efficient use in pharmaceutical research. OA exhibits a range of pharmacological effects, including antidiabetic, anti-inflammatory, immune-enhancing, gastroprotective, hepatoprotective, antitumor, and antiviral properties. While OA demonstrates diverse pharmacological effects, optimizing its therapeutic potential requires overcoming significant challenges. In the field of pharmaceutical research, the exploration of efficient drug delivery systems is essential to maximizing the therapeutic potential of bioactive compounds. Efficiently delivering OA faces challenges, such as poor aqueous solubility and restricted bioavailability, and to unlock its full therapeutic efficacy, novel formulation strategies are imperative. This discussion thoroughly investigates different approaches and advancements in OA drug delivery systems with the aim of enhancing the biopharmaceutical features and overall efficacy in diverse therapeutic contexts.

EGFR targeted albumin nanoparticles of oleanolic acid: In silico screening of nanocarrier, cytotoxicity and pharmacokinetics for lung cancer therapy

This study aimed to develop cetuximab (CTX) functionalized albumin nanoparticles (ALB-NPs) of oleanolic acid for EGFR targeted lung cancer therapy. The molecular docking methodology has been applied for a selection of suitable nanocarrier. Various physicochemical parameters like particle size, polydispersity, zeta potential, morphology, entrapment efficiency, and in-vitro drug release of all the ALB-NPs were analyzed. Furthermore, the in-vitro qualitative and quantitative cellular uptake study revealed that higher uptake of CTX conjugated ALB-NPs than nontargeted ALB-NPs in A549 cells. The in-vitro MTT assay revealed that the IC50 value of CTX-OLA-ALB-NPs (4.34 ± 1.90 μg/mL) was significantly reduced (p < 0.001) than OLA-ALB-NPs (13.87 ± 1.28 μg/mL) in A-549 cells. CTX-OLA-ALB-NPs caused apoptosis in A-549 cells at concentrations equivalent to its IC50 value and blocked the cell cycle in the G0/G1 phases. The hemocompatibility, histopathology and lung safety study confirmed the biocompatibility of the developed NPs. In vivo ultrasound and photoacoustic imaging confirmed the targeted delivery of the NPs to lung cancer. The findings demonstrated that CTX-OLA-ALB-NPs have potential for site-specific delivery of OLA for effective and targeted therapy of lung carcinoma.

Chrysin-phospholipid complex-based solid dispersion for improved anti-aging and neuroprotective effects in mice

The present study aimed to improve the neuroprotective effect of chrysin (CHR) by combining two formulation techniques, phospholipid (PL) complexation and solid dispersion (SD). CHR-phospholipid complex (CHR-PLC) was prepared through solvent evaporation. The molar ratio CHR/PL (1:3), which exhibited the highest complexation efficiency, was selected for the preparation of CHR-PLC loaded SD (CHR-PLC-SD) with 2-hydroxypropyl β cyclodextrin (2-HPβCD) and polyvinylpyrrolidone 8000. CHR-PLC/2-HPβCD (1:2, w/w) displayed the highest aqueous solubility of CHR (5.86 times more than that of plain CHR). CHR-SD was also prepared using 2-HPβCD for comparison. The in vitro dissolution of CHR-PLC-SD4 revealed an enhancement in the dissolution rate over CHR-PLC (1:3), CHR-SD, and plain CHR by six times. The optimum formulations and plain CHR were evaluated for their neuroprotective effect on brain aging induced by D-galactose in mice. The results demonstrated a behavioral activity elevation, an increase of AMPK, LKB1, and PGC1α brain contents as well as a reduction of AGEs, GFAP, NT-3, TNF-α, and NF-κβ brain contents when compared with those of the D-galactose control group. Thus, the developed formulations stimulated neurogenesis and mitochondrial biogenesis as well as suppressed neuroinflammation and neurodegeneration. The order of activity was as follows: CHR-PLC-SD4 > CHR-PLC (1:3) > CHR-SD > plain CHR.

Novel rhein-phospholipid complex targeting skin diseases: development, in vitro, ex vivo, and in vivo studies

Rhein (RH), an anthraquinone derivative, has proven to be a promising molecule for treating several skin disorders thanks to its pleiotropic pharmacological activities like antimicrobial, antifungal, antioxidant, and anticancer. However, RH's low water and oil solubility and poor skin permeability halted its topical delivery. This is the first work to investigate the expediency of tailoring a rhein-phospholipid complex (RH-PLC) to improve RH challenging physicochemical and skin permeability properties. The phospholipid complex was prepared by employing different methods and different RH/PL molar ratios. RH-PLC was successfully developed at a stoichiometric ratio of 1:1 using a novel pH-dependent method where at a certain pH, it exhibits the highest complexation efficiency (95%). RH-PLC formation was confirmed using FTIR, DSC, and XRPD analysis. RH-PLC showed a significant increase in water and n-octanol solubility. RH-PLC was self-assembled upon dispersion into water forming nano-sized particles (196.6 ± 1.6 nm) with high negatively charged surface (- 29.7 ± 2.45 mV). RH-PLC exhibited a significant 3.3- and 2.46-fold increase in ex vivo and in vivo skin permeability when compared with RH suspension, respectively. Confocal microscopy study confirmed the ability of RH-PLC to penetrate deeply into rat skin. Besides, skin irritation test on healthy rats indicated compatibility and safety of RH-PLC. Conclusively, phospholipid complex might be a suitable approach to improve permeability of RH and other promising abandoned poor-permeable drugs. The proposed RH-PLC is expected to be a major progressive step toward the development of a topical RH formulation. Graphical abstract.

Fabrication and assessment of milk phospholipid-complexed antioxidant phytosomes with vitamin C and E: A comparison with liposomes

Evidences have shown that phytosome assemblies are novel drug delivery system. However, studies of phytosomes in food applications are scarce. The characteristics of milk phospholipid assemblies and their functionality in terms of in vitro digestibility and bioavailability of encapsulated nutrients (ascorbic acid and α-tocopherol) were studied. The phytosomes were fabricated using ethanolic evaporation technique. Spectral analysis revealed that polar parts of phospholipids formed hydrogen bonds with ascorbic acid hydroxyl groups, further, incorporating ascorbic acid or α-tocopherol into the phospholipid assembly changed the chemical conformation of the complexes. Phospholipid-ascorbic acid phytosomes yielded an optimal complexing index of 98.52 ± 0.03% at a molar ratio of 1:1. Phytosomes exhibited good biocompatibility on intestinal epithelial cells. The cellular uptake of ascorbic acid was 29.06 ± 1.18% for phytosomes. It was higher than that for liposomes (24.14 ± 0.60%) and for ascorbic acid aqueous solution (1.17 ± 0.70%).

Physicochemical Characterization of Oleanolic Acid-Human Serum Albumin Complexes for Pharmaceutical and Biosensing Applications

Among numerous compounds found in marine organisms, triterpenes have attracted considerable research interest due to a beneficial impact on health including anti-inflammatory, antitumor, antiviral, and antioxidation effects. Specifically, new functionalities of oleanolic acid (OLA) have been revealed recently, indicating possible applications in nutrition and pharmaceuticals. However, this bioactive material has limited value due to low water solubility and stability. Therefore, oleanolic acid needs a carrier that protects it and enables controlled release in the human body. Innovative drug delivery systems provide a promising strategy for overcoming these problems. However, the development of those systems requires a comprehensive understanding of the physicochemical properties of triterpenes and their carriers as well as the interactions between them. Among numerous substances, human serum albumin (HSA) has been widely studied as a drug carrier. In addition, human serum albumin is the main blood plasma protein responsible for the transport of drugs and metabolites; therefore, the interactions between that protein and other substances are of physiological and pharmaceutical importance. Moreover, sensing the HSA level in blood plasma is an important challenge that requires binding studies on a molecular scale. The aim of this study was to investigate the properties of oleanolic acid in the presence of human serum albumin in terms of thermodynamics, morphology, and viscoelasticity at the air/water interface. Moreover, the wettability, surface free energy, and topography of the films after deposition on the solid substrate were determined. The results have been discussed in terms of providing physicochemical insight into the interfacial behavior of the OLA-HSA complex, which is crucial for pharmaceutical and bioanalytical applications.

A matrix dispersion based on phospholipid complex system: preparation, lymphatic transport, and pharmacokinetics

Raloxifene hydrochloride (RH) suffers from low oral bioavailability due to its low water-solubility and first-pass metabolism. Therefore, a novel phospholipid complex of RH (RHPC) and a matrix dispersion based on phospholipid complex (RHPC-MD) were successfully prepared and optimized. Several methods were used to validate the formation of RHPC and RHPC-MD, such as differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, particle size, and zeta potential, meanwhile, their octanol-water partition coefficient, solubility, and dissolution in vitro were also evaluated. To investigate the absorption mechanism of RHPC in vivo, the RHPC was administered to the chylomicron flow blockage rat model. Interestingly, as we expected, a significant reduction in RHPC absorption (67%) (**p< .01) in presence of cycloheximide (CXI) inhibitor was observed, thus confirming the RHPC could be absorbed by lymphatic transport in vivo. Pharmacokinetic studies revealed that the relative oral bioavailability of RHPC as well as RHPC-MD was 223% and 329%, respectively, when comparing with the commercial RH tablets. These outcomes suggested that the current study provided an attractive formulation to enhance the oral bioavailability of RH and stimulated to further research the absorption mechanism of RHPC in vivo.

Polymer/lipid interplay in altering in vitro supersaturation and plasma concentration of a model poorly soluble drug

Supersaturation drug delivery system (SDDS) based on amorphous solid dispersion (ASD) is a widely used strategy to improve oral absorption of poorly water-soluble drugs by achieving a supersaturated state where drug concentration is significantly higher than drug solubility. However, dissolved drugs tend to recrystallize in gastrointestinal (GI) tract if without effective stabilizing excipients. In this paper, well-recognized polymer (polyvinylpyrrolidone, PVP) and lipid (phosphatidylcholine, PC) excipients are combined as ASD carrier, aiming at investigating the effects on evolution of in vitro supersaturation and in vivo plasma concentration of a model poorly soluble drug indomethacin (IND). Fundamental aspects including polymer/lipid composition ratio, drug loading (DL) degree and administration dose were investigated. The in vitro dissolution profiles of ASDs were assessed by supersaturation degree, duration, maximum achievable drug concentration and dose-normalized efficiency, and correlated with in vivo pharmacokinetic data. Results showed that both in vitro and in vivo concentration-time profiles of IND were significantly varying with abovementioned factors. Solution viscosity, solid-state properties and morphology of ASDs were related to the results. This study revealed fundamental mechanisms of PVP/PC mixture effect on IND supersaturation and oral bioavailability, demonstrating that polymer/lipid mixture could be used as a promising carrier to alter supersaturation profile and oral bioavailability of SDDS products.

Preparation of ursolic acid-phospholipid complex by solvent-assisted grinding method to improve dissolution and oral bioavailability

To improve the aqueous solubility and the oral bioavailability of a poorly water-soluble biologically active pentacyclic triterpenoid, ursolic acid (UA), ursolic acid-phospholipid complex (UA-PC) was prepared using solvent-assisted grinding method which is green and simple. The phospholipid complex was characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), scanning electron microscope (SEM), and transmission electron microscope (TEM), which confirmed the formation of the phospholipid complex. Specifically, compared with free UA, the formulation demonstrated over 276-fold higher aqueous solubility of UA and exhibited faster dissolution rate and higher cumulative dissolution percentages. Finally, the oral bioavailability of the prepared UA-PC was evaluated using Sprague-Dawley (SD) rats. Compared with free UA, the UA-PC exhibited considerable enhancement in the bioavailability with an increase in Cmax (183.80 vs 68.26 μg/l) and AUC 0-24 h (878.0 vs 212.1 μg·h/l), which was consistent with the in vitro results. This enhancement was attributed to the improvement of solubility and dissolution in vitro. Therefore, the method of solvent-assisted grinding appears to be an efficient approach for the preparation of UA-PC, and the prepared UA-PC showed a promising potential to overcome the limitation of poor oral bioavailability associated with low water solubility.

Effect of Metamorphed Keratolytic Agent on the Behavior of Imiquimod Loaded Hybrid Vesicles Containing Gel

The cost, side effects, and patient compliance-related issues of topically effective imiquimod have prevented its widespread acceptance. The present work intends to evaluate the feasibility of overcoming the shortcomings of poorly soluble and skin-penetrating immunomodulator by using biocompatible keratolytic agent with drug-loaded hybrid vesicles. Salicylic acid was complexed with phospholipid through simple mixing and incorporated into carbopol 940 gel containing drug-loaded vesicles, prepared by thin-film hydration method. The morphology, physicochemical properties, rheological behavior, release profile, and dermatokinetics of developed gel were compared with control gel (developed gel without keratolytic agent). In ex vivo drug release studies across the rat skin, there was significant increase in the steady-state permeation flux (J_ss) and skin retention of drug from developed gel in comparison with control. There was favorable change in almost every evaluated dermatokinetic parameter. The innocuous nature of control gel had not changed on addition of skin structure-altering agent. The developed gel was found to be stable at room temperature and humidity for 1 year.

Preparation of a nanoscale dihydromyricetin-phospholipid complex to improve the bioavailability: in vitro and in vivo evaluations

Dihydromyricetin (DMY), a flavanonol compound found as the most abundant and bioactive constituent in Ampelopsis grossedentata (Hand-Mazz) W.T. Wang, possesses numerous pharmacological activities, such as antioxidant, anti-inflammation, anticancer, anti-microbial, hypoglycemic and hypolipidemic effects, and so on. Recently, DMY shows a promising potential to develop as an agent for the prevention and treatment of Type 2 diabetes mellitus (T2DM). However, the low oral bioavailability of DMY was one of the special concerns to be resolved for its clinical applications. In this study, DMY phospholipid complex (DMY-HSPC COM) was prepared by the solvent evaporation technique and optimized with DMY combination ratio. Scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier transform infrared spectrophotometry (FT-IR) were carried to characterize the formation of DMY-HSPC COM. The particle size, zeta potential, drug loading and solubility of DMY-HSPC COM were further investigated. The phospholipid complex technology could significantly improve the solubility of DMY. Pharmacokinetic study results of DMY-HSPC COM in healthy SD rats and T2DM rats demonstrated that the oral bioavailability was significantly increased when compared with pure DMY as well, which could be attributed to the improvement of the aqueous solubility of the complex, absorption promotion and a probable decrease in intestinal and hepatic metabolism. In addition, when compared with healthy SD rats, pharmacokinetic parameters of pure DMY and DMY-HSPC COM showed significant difference in T2DM rats. Thus, phospholipid complex technology holds a promising potential for increasing the oral bioavailability of DMY.

Enhanced bioavailability and hepatoprotectivity of optimized ursolic acid-phospholipid complex

OBJECTIVE

To prepare and characterize an optimized phospholipid complex of Ursolic acid (UA) to overcome the poor pharmacokinetic properties and to investigate the impact of the complex on hepatoprotective activity and bioavailability in animal model.

SIGNIFICANCE

UA is a potential phytoconstituent obtained from several plant sources, which has been explored for its diverse pharmacological activities including hepatoprotection. Its major limitation is poor absorption, rapid elimination, and hence low bioavailability after administration.

METHODS

Response surface methodology was adopted to formulate an optimized (UA) complex. The complex was characterized by differential thermal analysis (DTA), Fourier transform-Infrared Spectroscopy, Powder X ray Diffraction, molecular docking, etc. The physico-chemical profile (solubility, oil/water partition coefficient) and in vitro dissolution profile was estimated. The formulation was then used to study hepatoprotective activity and bioavailability in animal models.

RESULTS

Results showed that the phospholipid complex of UA has enhanced the hepatoprotective potential as compared to pure UA at the same dose level. The complex restored the levels of serum hepatic marker enzymes with respect to untreated group and increased the relative bioavailability of UA in rat plasma by 8.49-fold in comparison with pure compound at the same dose level. It enhanced the elimination half-life (t1/2 el) from 0.69 ± 1.76 to 8.28 ± 1.98 h.

CONCLUSION

Complexation of UA with phospholipid markedly enhanced the hepatoprotective potential of UA by improving its bioavailability and pharmacokinetic parameters. Novelty statement The present article deals with rational optimization of the formulation parameters for phospholipid complex of ursolic acid by Response Surface Methodology analysis, characterizing the formulation by in silico approach apart from conventional instrumental techniques, and evaluating the in vitro dissolution, pharmacokinetics, and hepatoprotective activity of the complex in animals. Novelty statement The present article deals with rational optimization of the formulation parameters for phospholipid complex of ursolic acid by Response Surface Methodology analysis, characterizing the formulation by in silico approach apart from conventional instrumental techniques, and evaluating the in vitro dissolution, pharmacokinetics, and hepatoprotective activity of the complex in animals.

Evaluation of Intestinal Absorption and Bioavailability of a Bergenin-Phospholipid Complex Solid Dispersion in Rats

Bergenin (BN) is a Biopharmaceutics Classification System class IV (BCS IV) drug with poor hydrophilicity and lipophilicity and is potentially eliminated by the efflux function of P-glycoprotein (P-gp). These factors may explain its low oral bioavailability. In the present study, a BN-phospholipid complex solid dispersion (BNPC-SD) was prepared by solvent evaporation and characterized based on differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, infrared diffraction, solubility, octanol-water partition coefficient, and in vitro dissolution. To investigate how P-gp can inhibit BN absorption in vivo, the P-gp inhibitor verapamil was co-administered with BNPC-SD to Sprague Dawley rats. By in situ single-pass intestinal perfusion, the membrane permeability of BN from BNPC-SD was higher than that of BN given alone and was improved further by co-administered verapamil. A pharmacokinetics study was done in Sprague Dawley rats, with plasma BN levels estimated by high-performance liquid chromatography. C_max and AUC_0 → t values for BN were significantly higher for BNPC-SD than for BN given alone and were increased further by verapamil. Thus, the relative oral bioavailability of BNPC-SD as well as BNPC-SD co-administered with verapamil was 156.33 and 202.46%, respectively, compared with the value for BN given alone. These results showed that BNPC-SD can increase the oral bioavailability of BCS IV drugs.

Polymeric nanoparticles developed by vitamin E-modified aliphatic polycarbonate polymer to promote oral absorption of oleanolic acid

Oleanolic acid (OA) exhibited good pharmacological activities in the clinical treatment of hypoglycemia, immune regulation, acute jaundice and chronic toxic hepatitis. However, the oral delivery of OA is greatly limited by its inferior water solubility and poor intestinal mucosa permeability. Herein, we developed a novel polymeric nanoparticle (NP) delivery system based on vitamin E modified aliphatic polycarbonate (mPEG-PCC-VE) to facilitate oral absorption of OA. OA encapsulated mPEG-PCC-VE NPs (OA/mPEG-PCC-VE NPs) showed uniform particle size of about 170 nm with high drug loading capability (8.9%). Furthermore, the polymeric mPEG-PCC-VE NPs, with good colloidal stability and pH-sensitive drug release characteristics, significantly enhanced the in vitro dissolution of OA in the alkaline medium. The in situ single pass intestinal perfusion (SPIP) studies performed on rats demonstrated that the OA/mPEG-PCC-VE NPs showed significantly improved permeability in the whole intestinal tract when compared to OA solution, especially for duodenum and colon. As a result, the in vivo pharmacokinetics study indicated that the bioavailability of OA/mPEG-PCC-VE NPs showed 1.5-fold higher than commercially available OA tablets. These results suggest that mPEG-PCC-VE NPs are a promising platform to facilitate the oral delivery of OA.