Improvement of the bioavailability of curcumin by a supersaturatable self nanoemulsifying drug delivery system with incorporation of a hydrophilic polymer: in vitro and in vivo characterisation

Physicochemical Characterization and Oral Bioavailability of Curcumin-Phospholipid Complex Nanosuspensions Prepared Based on Microfluidic System

Background: Curcumin has been proved to have promising prospects in the fields of anti-inflammation, antibacterial, anti-oxidation, and neuroprotection. However, its poor water solubility and stability in strong acid, as well as fast metabolism, lead to low bioavailability, making it difficult to develop further. This study aimed to improve the bioavailability of curcumin by using microfluidic preparation technology. Methods: Using a self-built microfluidic system, polyvinylpyrrolidone K30 and sodium dodecyl sulfate were used as stabilizers to further prepare curcumin-phospholipid complex nanoparticles (CPC-NPs) on the basis of curcumin-phospholipid complex (CPC). The CPC-NPs were characterized and evaluated by X-ray powder diffraction (XRD), differential scanning caborimetry (DSC), dynamic light scattering, and transmission electron microscopy (TEM). Blood samples were collected from rats after oral administration of curcumin, CPC, curcumin nanoparticles (CUR-NPs), and CPC-NPs, respectively. The pharmacokinetics were analyzed by enzymatic digestion and HPLC. Results: The optimized CPC-NPs had a particle size of 71.19 ± 1.37 nm, a PDI of 0.226 ± 0.047, and a zeta potential of -38.23 ± 0.89 mV, which showed a spherical structure under TEM and good stability within 5 days at 4 °C and 25 °C. It was successfully characterized by XRD combined with DSC, indicating the integrational state of curcumin-soy lecithin and conversion to an amorphous form. The results of the pharmacokinetic study showed that the Cmax of curcumin, CUR-NPs, CPC, and CPC-NPs were 133.60 ± 28.10, 270.23 ± 125.42, 1894.43 ± 672.65, and 2163.87 ± 777.36 ng/mL, respectively; the AUC0-t of curcumin, CUR-NPs, CPC, and CPC-NPs were 936.99 ± 201.83, 1155.46 ± 340.38, 5888.79 ± 1073.32, and 9494.28 ± 1863.64 ng/mL/h. Conclusions: CPC-NPs prepared by microfluidic technology had more controllable quality than that of traditional preparation and showed superior bioavailability compared with free drug, CPC, and CUR-NPs. Pharmacodynamic evaluation of anti-inflammatory, anti-oxidation, and neuroprotection needs to be confirmed in follow-up studies.

Innovative Gastrointestinal Drug Delivery Systems: Nanoparticles, Hydrogels, and Microgrippers

Over the past decade, new technologies have emerged to increase intrinsic potency, enhance bioavailability, and improve targeted delivery of drugs. Most pharmaceutical formulations require multiple dosing due to their fast release and short elimination kinetics, increasing the risk of adverse events and patient non-compliance. Due to these limitations, enormous efforts have focused on developing drug delivery systems (DDSs) for sustained release and targeted delivery. Sustained release strategies began with pioneering research using silicone rubber embedding for small molecules and non-inflammatory polymer encapsulation for proteins or DNA. Subsequently, numerous DDSs have been developed as controlled-release formulations to deliver systemic or local therapeutics, such as small molecules, biologics, or live cells. In this review, we discuss the latest developments of DDSs, specifically nanoparticles, hydrogels, and microgrippers for the delivery of systemic or localized drugs to the gastrointestinal (GI) tract. We examine innovative DDS design and delivery strategies tailored to the GI tract's unique characteristics, such as its extensive length and anatomical complexity, varying pH levels and enzymatic activity across different sections, and intrinsic peristalsis. We particularly emphasize those designed for the treatment of inflammatory bowel disease (IBD) with in vivo preclinical studies.

Protective Role and Enhanced Intracellular Uptake of Curcumin in Retinal Cells Using Self-Emulsifying Drug Delivery Systems (SNEDDS)

Background: Sirtuin-1 (SIRT1), a histone deacetylase enzyme expressed in ocular tissues with intracellular localization, plays a critical protective role against various degenerative ocular diseases. The link between reduced SIRT1 levels and diabetic retinopathy (DR) has prompted the exploration of natural therapeutic compounds that act as SIRT1 agonists. Curcumin (CUR), which has been shown to upregulate SIRT1 expression, is one such promising compound. However, effective delivery of CUR to the deeper ocular tissues, particularly the retina, remains a challenge due to its poor solubility and limited ocular penetration following topical administration. Within this context, the development of self-nanoemulsifying drug delivery systems (SNEDDS) for CUR topical ocular delivery represents a novel approach. Methods: In accordance with our prior research, optimized SNEDDS loaded with CUR were developed and characterized post-reconstitution with simulated tear fluid (STF) at a 1:10 ratio, showing suitable physicochemical and technological parameters for ocular delivery. Results: An entrapment efficiency (EE%) of approximately 99% and an absence of drug precipitation were noticed upon resuspension with STF. CUR-SNEDDS resulted in a better stability and release profile than free CUR under simulated ocular conditions. In vitro analysis of mucoadhesive properties revealed that CUR-SNEDDS, modified with a cationic lipid, demonstrated enhanced interactions with mucin, indicating the potential for improved ocular retention. Cytotoxicity tests demonstrated that CUR-SNEDDS did not affect the viability of human corneal epithelial (HCE) cells up to concentrations of 3 μM and displayed superior antioxidant activity compared to free CUR in an oxidative stress model using retinal pigment epithelial (ARPE-19) cells exposed to hydroquinone (HQ). Cell uptake studies confirmed an enhanced accumulation of CUR within the retinal cells following exposure to CUR-SNEDDS compared to neat CUR. CUR-SNEDDS, at lower concentrations, were found to effectively induce SIRT1 expression. Conclusions: The cytocompatibility, antioxidant properties, and enhanced cellular uptake suggest that these developed systems hold promise as formulations for the delivery of CUR to the retina.

Susceptibility of periodontal pathogens to a novel target-specific drug delivery system containing self-nanoemulsifying curcumin: An in vitro study

Background

Long-term use of many classic chemotherapeutic agents as adjuncts in the management of periodontitis has adverse complications, leading to seeking out naturopathic remedies. Although curcumin has been investigated in managing periodontitis, its therapeutic benefits have not been fully explored due to its limited solubility in an aqueous medium. This study aimed to develop a novel target-specific drug delivery system containing 1% self-nanoemulsifying curcumin (SNEC) in a hydroxypropylmethylcellulose (HPMC) matrix and evaluate the susceptibility of periodontal pathogens to this system in vitro.

Methods

Its antibacterial activity against Tannerella forsythia, Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans was evaluated and compared to pure nano-curcumin and SNEC alone by estimating their minimum inhibitory concentrations (MIC).

Results

The antibacterial activity of pure nano-curcumin, SNEC, and SNEC in HPMC against the four periodontal pathogens evaluated in terms of MIC was recorded in the range of 0.2‒0.4, 0.4‒0.8, and 0.2‒0.8 µg/mL, respectively. However, the MIC of all three curcumin formulations against the periodontal pathogens tested was higher than that of the standard moxifloxacin. While both pure nano-curcumin and SNEC showed increasing values of inhibition zones with increasing concentrations on disk diffusion assay, lower concentrations of SNEC in HPMC did not show a zone of inhibition against the tested pathogens.

Conclusion

The novel delivery system containing SNEC in HPMC may be a potential adjunct in managing periodontitis due to its probable sustained antimicrobial activity against the tested periodontal pathogens.

Curcumin-Loaded RH60/F127 Mixed Micelles: Characterization, Biopharmaceutical Characters and Anti-Inflammatory Modulation of Airway Inflammation

Curcumin's ability to impact chronic inflammatory conditions, such as metabolic syndrome and arthritis, has been widely researched; however, its poor bioavailability limits its clinical application. The present study is focused on the development of curcumin-loaded polymeric nanomicelles as a drug delivery system with anti-inflammatory effects. Curcumin was loaded in PEG-60 hydrogenated castor oil and puronic F127 mixed nanomicelles (Cur-RH60/F127-MMs). Cur-RH60/F127-MMs was prepared using the thin film dispersion method. The morphology and releasing characteristics of nanomicelles were evaluated. The uptake and permeability of Cur-RH60/F127-MMs were investigated using RAW264.7 and Caco-2 cells, and their bioavailability and in vivo/vitro anti-inflammatory activity were also evaluated. The results showed that Cur-RH60/F127-MMs have regular sphericity, possess an average diameter smaller than 20 nm, and high encapsulation efficiency for curcumin (89.43%). Cur-RH60/F127-MMs significantly increased the cumulative release of curcumin in vitro and uptake by cells (p < 0.01). The oral bioavailability of Cur-RH60/F127-MMs was much higher than that of curcumin-active pharmaceutical ingredients (Cur-API) (about 9.24-fold). The treatment of cell lines with Cur-RH60/F127-MMs exerted a significantly stronger anti-inflammatory effect compared to Cur-API. In addition, Cur-RH60/F127-MMs significantly reduced OVA-induced airway hyperresponsiveness and inflammation in an in vivo experimental asthma model. In conclusion, this study reveals the possibility of formulating a new drug delivery system for curcumin, in particular nanosized micellar aqueous dispersion, which could be considered a perspective platform for the application of curcumin in inflammatory diseases of the airways.

Curcumin nanocrystals self-stabilized Pickering emulsion freeze-dried powder: Development, characterization, and suppression of airway inflammation

Curcumin, a diketone compound extracted from turmeric's rhizome, is an effective anti-inflammatory drug with multiple pharmacological activities. However, its low oral bioavailability due to its low water solubility and permeability severely limits its clinical applications. Therefore, to enhance the oral bioavailability of curcumin, further enhance its anti-inflammatory effects, and improve its potential in the treatment of airway inflammation, a curcumin nanocrystalline self-stabilizing Pickering emulsion (Cur-NSSPE) was prepared through high-pressure homogenization. Next, Cur-NSSPE was dried using a freeze-drying method to produce Cur-NSSPE-FDP. The prepared Cur-NSSPE and Cur-NSSPE-FDP were physically characterized. The release behavior and transmembrane transport capability of Cur-NSSPE-FDP in vitro were evaluated. Pharmacokinetic study was performed to evaluate its oral bioavailability. The anti-inflammatory effects of Cur-NSSPE-FDP in vivo and in vitro were investigated using RAW 264.7 macrophage inflammation model induced by LPS and IFN-γ and asthma model in BALB/c mice induced by OVA. The average particle size of Cur-NSSPE was (163.66 ± 6.78) nm, and the average drug content was (2.78 ± 0.01) mg/mL. The transmission electron microscopy results showed that the droplets were spherical in shape with a relatively uniform size, and the curcumin nanocrystals formed a spherical core-shell structure wrapped at the interface of the droplets. The scanning electron microscopy showed that Cur-NSSPE-FDP was a neatly arranged, having loose and porous network structure. Furthermore, it can significantly improve the cumulative release of curcumin in vitro and improve oral bioavailability in rats, increase the uptake of RAW264.7 and Caco-2 cells, promote the transport of curcumin across Caco-2 cells, significantly inhibit the expression of inflammatory factors NO, IL-6, TNF-a, MDA, IgE and ICAM-1, and improve the expression of IL-10 and SOD. These results indicated that the curcumin nanocrystalline self-stabilizing Pickering emulsion-freeze dried powder improved the oral bioavailability of curcumin and enhanced its therapeutic effect in airway inflammation.

Enhanced Pharmacokinetics and Anti-inflammatory Activity of Curcumin Using Dry Emulsion as Drug Delivery Vehicle

BACKGROUND AND OBJECTIVE

Many naturally available dietary molecules such as curcumin have not seen the market due to poor solubility, bioavailability, and photodegradability. Successful development of a lipid-based dry emulsion may overcome these issues and help in reaching the markets for natural dietary molecules such as curcumin. The current study aims to develop a dry emulsion formulation of curcumin using natural oil and evaluate its dissolution, photostability, pharmacokinetics, and anti-inflammatory activity.

METHODS

Dry emulsions were prepared using emu oil and corn oil as the lipid phase, Caproyl 90 and Cremophor RH 40 as surfactants, and dextrin as a hydrophilic carrier.

RESULTS

Microscopic studies showed the formation of spherical porous particles, and solid-state characterization using differential scanning calorimetry and powder X-ray diffraction showed the conversion of curcumin to an amorphous form. About 80% drug release was observed from formulation, whereas pure drug showed only 50% drug release in 30 min. In vivo pharmacokinetic studies showed fivefold improvement in the maximum concentration of curcumin in plasma (C_max) and sevenfold improvement in the area under the concentration-time curve of curcumin from emu oil formulation compared with pure curcumin. Significant differences were observed in the anti-inflammatory activity of curcumin dry emulsion and plain curcumin. Emu-oil-based formulations showed synergistic anti-inflammatory activity over corn-oil-based formulations with improved photostability.

CONCLUSION

The present study suggests that the dry emulsion may enhance the bioavailability with synergistic anti-inflammatory activity and photostability of curcumin when given orally.

Research advances of in vivo biological fate of food bioactives delivered by colloidal systems

Food bioactives exhibit various health-promoting effects and are widely used in functional foods to maintain human health. After oral intake, bioactives undergo complex biological processes before reaching the target organs to exert their biological effects. However, several factors may reduce their bioavailability. Colloidal systems have attracted special attention due to their great potential to improve bioavailability and bioefficiency. Herein, we focus on the importance of in vivo studies of the biological fates of bioactives delivered by colloidal systems. Increasing evidence demonstrates that the construction, composition, and physicochemical properties of the delivery systems significantly influence the in vivo biological fates of bioactives. These results demonstrate the great potential to control the in vivo behavior of food bioactives by designing specific delivery systems. We also compare in vivo and in vitro models used for biological studies of the fate of food bioactives delivered by colloidal systems. Meanwhile, the significance of the gut microbiota, targeted delivery, and personalized nutrition should be carefully considered. This review provides new insight for further studies of food bioactives delivered by colloidal systems, as well as scientific guidance for the reasonable design of personalized nutrition.

Solid lipid nanoparticle as an effective drug delivery system of a novel curcumin derivative: formulation, release in vitro and pharmacokinetics in vivo

CONTEXT

Curcumin (Cur) has a short duration of action which limits its therapeutic efficacy. Carbonic acid 17-(1,5-dimethyl-hexyl)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-3-yl ester 4-[7-(4-hydroxy-3-methoxy-phenyl)-3,5-dioxo-hepta-1,6-dienyl]-2-methoxy-phenyl ester (CUD), as a small molecule derivative of Cur with superior stability, has been developed in our laboratory.

OBJECTIVE

CUD-loaded solid lipid nanoparticles (CUD-SLN) were prepared to prolong the duration of the drug action of Cur.

MATERIALS AND METHODS

CUD-SLN were prepared with Poloxamer 188 (F68) and hydrogenated soybean phospholipids (HSPC) as carriers, and the prescription was optimized. The in vitro release of CUD and CUD-SLN was investigated. CUD-SLN (5 mg/kg) was injected into Sprague Dawley (SD) rats to investigate its pharmacokinetic behaviour.

RESULTS

CUD-SLN features high entrapment efficiency (96.8 ± 0.4%), uniform particle size (113.0 ± 0.8 nm), polydispersity index (PDI) (0.177 ± 0.007) and an appropriate drug loading capacity (6.2 ± 0.1%). Optimized CUD-SLN exhibited sustained release of CUD for about 48 h. Moreover, the results of the pharmacokinetic studies showed that, compared to Cur, CUD-SLN had a considerably prolonged half-life of 14.7 h, slowed its metabolism in vivo by 35.6-fold, and had an improved area under the curve (AUC_0-t) of 37.0-fold.

CONCLUSIONS

CUD-SLN is a promising preparation for the development of a small molecule derivative of Cur.

Multivariate Data Analysis and Central Composite Design-Oriented Optimization of Solid Carriers for Formulation of Curcumin-Loaded Solid SNEDDS: Dissolution and Bioavailability Assessment

The study was initiated with two major purposes: investigating the role of isomalt (GIQ9) as a pharmaceutical carrier for solid self-nanoemulsifying drug delivery systems (S-SNEDDSs) and improving the oral bioavailability of lipophilic curcumin (CUN). GIQ9 has never been explored for solidification of liquid lipid-based nanoparticles such as a liquid isotropic mixture of a SNEDDS containing oil, surfactant and co-surfactant. The suitability of GIQ9 as a carrier was assessed by calculating the loading factor, flow and micromeritic properties. The S-SNEDDSs were prepared by surface adsorption technique. The formulation variables were optimized using central composite design (CCD). The optimized S-SNEDDS was evaluated for differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopy, dissolution and pharmacokinetic studies. The S-SNEDDS showed a particle size, zeta potential and PDI of 97 nm, -26.8 mV and 0.354, respectively. The results of DSC, XRD, FTIR and microscopic studies revealed that the isotropic mixture was adsorbed onto the solid carrier. The L-SNEDDS and S-SNEDDS showed no significant difference in drug release, indicating no change upon solidification. The optimized S-SNEDDS showed 5.1-fold and 61.7-fold enhancement in dissolution rate and oral bioavailability as compared to the naïve curcumin. The overall outcomes of the study indicated the suitability of GIQ9 as a solid carrier for SNEDDSs.

Increasing Post-Digestive Solubility of Curcumin Is the Most Successful Strategy to Improve its Oral Bioavailability: A Randomized Cross-Over Trial in Healthy Adults and In Vitro Bioaccessibility Experiments

SCOPE

Different mechanistic approaches to improve the low oral bioavailability of curcumin have been developed, but not yet directly compared in humans.

METHODS AND RESULTS

In a randomized, double-blind, cross-over trial with 12 healthy adults, the 24 h pharmacokinetics of a single dose of 207 mg curcumin is compared from the following formulations: native, liposomes, with turmeric oils, with adjuvants (including piperine), submicron-particles, phytosomes, γ-cyclodextrin complexes, and micelles. No free, but only conjugated curcumin is detected in all subjects. Compared to native curcumin, a significant increase in the area under the plasma concentration-time curve is observed for micellar curcumin (57-fold) and the curcumin-γ-cyclodextrin complex (30-fold) only. In vitro digestive stability, solubility, and micellization efficiency of micellar curcumin (100%, 80%, and 55%) and curcumin-γ-cyclodextrin complex (73%, 33%, and 23%) are higher compared to all other formulations (<72%, <8%, and <4%). The transport efficiencies through Caco-2 cell monolayers of curcumin from the digested mixed-micellar fractions did not differ significantly.

CONCLUSION

The improved oral bioavailability of micellar curcumin, and to a lesser extent of γ-cyclodextrin curcumin complexes, appears to be facilitated by increased post-digestive stability and solubility, whereas strategies targeting post-absorptive processes, including inhibition of biotransformation, appear ineffective.