Rhamnolipids enhance epithelial permeability in Caco-2 monolayers

Absorption enhancement of peach kernel oil on hydroxysafflor yellow A in safflower extracts and its mechanisms

Carthamus tinctorius L. (Safflower) is extensively used as a functional food and herbal medicine, with its application closely associated with hydroxysafflor yellow A (HSYA). However, the low oral bioavailability of HSYA in safflower extract (SFE) limits its health benefits and application. Our study found that co-administration of 250, 330, and 400 mg/kg peach kernel oil (PKO) increased the oral bioavailability of HSYA in SFE by 1.99-, 2.11-, and 2.49-fold, respectively. The enhanced bioavailability is attributed to improved lipid solubility and intestinal permeability of HSYA in SFE due to PKO. PKO is believed to modify membrane fluidity and tight junctions, increase paracellular penetration, and inhibit the expression and function of P-glycoprotein, enhancing the transcellular transport of substrates. These mechanisms suggest that PKO is an effective absorption enhancer. Our findings provide valuable insights for developing functional foods with improved bioavailability.

Rhamnolipids: A biosurfactant for the development of lipid-based nanosystems for food applications

Biosurfactants (surfactants synthesized by microorganisms) are produced by microorganisms and are suitable for use in different areas. Among biosurfactants, rhamnolipids are the most studied and popular, attracting scientists, and industries' interest. Due to their unique characteristics, the rhamnolipids have been used as synthetic surfactants' alternatives and explored in food applications. Besides the production challenges that need to be tackled to guarantee efficient production and low cost, their properties need to be adjusted to the final application, where the pH instability needs to be considered. Moreover, regulatory approval is needed to start being used in commercial applications. One characteristic of interest is their capacity to form oil-in-water nanosystems. Some of the most explored have been nanoemulsions, solid-lipid nanoparticles and nanostructured lipid carriers. This review presents an overview of the main properties of rhamnolipids, asserts the potential and efficiency of rhamnolipids to replace the synthetic surfactants in the development of nanosystems, and describes the rhamnolipids-based nanosystems used in food applications. It also discusses the main characteristics and methodologies used for their characterization and in the end, some of the main challenges are highlighted.

Intestinal epithelium penetration of liraglutide via cholic acid pre-complexation and zein/rhamnolipids nanocomposite delivery

BACKGROUND

Oral administration offered a painless way and improved compliance for diabetics. However, the emerging GLP-1 analog peptide drugs for diabetes primarily rely on the injection route, and the development of oral dosage forms was hampered by the low oral bioavailability due to the structural vulnerability to digestive enzymes and molecule impermeability in the gastrointestinal tract.

RESULTS

In this study, the non-covalent interaction between cholic acid (CA) and liraglutide (LIRA) was found and theoretically explained by molecular docking simulation. Formation of this physical complex of liraglutide and cholic acid (LIRA/CA Complex) reduced the self-aggregation of LIRA and accelerated intestinal epithelium penetration. By the anti-solvent method, LIRA/CA Complex was loaded into zein/rhamnolipids nanoparticles (LIRA/CA@Zein/RLs) with a loading efficiency of 76.8%. LIRA was protected from fast enzymatic degradation by the hydrophobic zein component. Meanwhile, Rhamnolipids, a glycolipid with surface activity, promoted endocytosis while also stabilizing the nanoparticles. The two components worked synergistically to ensure the delivery of LIRA/CA Complex to intestinal villi and improved oral absorption without disrupting tight junctions. LIRA/CA@Zein/RLs demonstrated a considerable intestinal epithelium absorption in mouse gastrointestinal section and a retention in vivo over 24 h, resulting in a significant and long-lasting hypoglycemic effect in Type 2 diabetes mice.

CONCLUSION

This study provided a promising oral delivery approach for LIRA and exhibited the potential for further translation into clinical application.

Elucidating a Potential Mechanism of Permeability Enhancer Sodium N-[8-(2-hydroxybenzoyl) amino] Caprylate in Rats: Evidence of Lymphatic Absorption of Cyanocobalamin using the Mesenteric Lymph Duct Cannulated Rat

Oral administration is the most popular and convenient route for drug delivery, yet the success of oral drug delivery is dependent on the ADME properties of the drug. Among those ADME properties, permeability is considered one of the key attributes for successful oral drug absorption. Hence, the utilization of permeability enhancers to improve drug oral absorption is an important area of research in drug delivery. A multitude of data suggests that sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC) is an effective permeability enhancer. Despite its success, the mechanism of how SNAC works to enhance the oral absorption of compounds is poorly understood. To better understand how SNAC worked, we investigated the hypothesis of SNAC promotes lymphatic absorption of target compounds. In this study, cyanocobalamin was used as the model compound and mesenteric lymph duct cannulated rats were used to investigate its absorption with or without SNAC. The present study demonstrated that SNAC enhanced the lymphatic absorption of cyanocobalamin when the two were co-dosed in rats. Furthermore, levels of SNAC in lymph fluid and the systemic circulation were higher when co-dosed with cyanocobalamin.

Long-term daily oral administration of intestinal permeation enhancers is safe and effective in mice

Although protein drugs are powerful biologic therapeutics, they cannot be delivered orally because their large size and hydrophilicity limit their absorption across the intestinal epithelium. One potential solution is the incorporation of permeation enhancers into oral protein formulations; however, few have advanced clinically due to toxicity concerns surrounding chronic use. To better understand these concerns, we conducted a 30-day longitudinal study of daily oral permeation enhancer use in mice and resultant effects on intestinal health. Specifically, we investigated three permeation enhancers: sodium caprate (C₁₀), an industry standard, as well as 1-phenylpiperazine (PPZ) and sodium deoxycholate (SDC). Over 30 days of treatment, all mice gained weight, and none required removal from the study due to poor health. Furthermore, intestinal permeability did not increase following chronic use. We also quantified the gene expression of four tight junction proteins (claudin 2, claudin 3, ZO-1, and JAM-A). Significant differences in gene expression between untreated and permeation enhancer-treated mice were found, but these varied between treatment groups, with most differences resolving after a 1-week washout period. Immunofluorescence microscopy revealed no observable differences in protein localization or villus architecture between treated and untreated mice. Overall, PPZ and SDC performed comparably to C₁₀, one of the most clinically advanced enhancers, and results suggest that the chronic use of some permeation enhancers may be therapeutically viable from a safety standpoint.

In Vitro Evaluation of P-gp-Mediated Drug-Drug Interactions Using the RPTEC/TERT1 Human Renal Cell Model

BACKGROUND AND OBJECTIVES

In vitro evaluation of the P-glycoprotein (P-gp) inhibitory potential is an important issue when predicting clinically relevant drug-drug interactions (DDIs). Located within all physiological barriers, including intestine, liver, and kidneys, P-gp plays a major role in the pharmacokinetics of various therapeutic classes. However, few data are available about DDIs involving renal transporters during the active tubular secretion of drugs. In this context, the present study was designed to investigate the application of the human renal cell line RPTEC/TERT1 to study drug interactions mediated by P-gp.

METHODS

The P-gp inhibitory potentials of a panel of drugs were first determined by measuring the intracellular accumulation of rhodamine 123 in RPTEC/TERT1 cells. Then four drugs were selected to assess the half-maximal inhibitor concentration (IC50) values by measuring the intracellular accumulation of two P-gp-substrate drugs, apixaban and rivaroxaban. Finally, according to the FDA guidelines, the [I₁]/IC50 ratio was calculated for each combination of drugs to assess the clinical relevance of the DDIs.

RESULTS

The data showed that drugs which are known P-gp inhibitors, including cyclosporin A, ketoconazole, and verapamil, caused great increases in rhodamine 123 retention, whereas noninhibitors did not affect the intracellular accumulation of the P-gp substrate. The determined IC50 values were in accordance with the inhibition profiles observed in the rhodamine 123 accumulation assays, confirming the reliability of the RPTEC/TERT1 model.

CONCLUSIONS

Taken together, the data demonstrate the feasibility of the application of the RPTEC/TERT1 model for evaluating the P-gp inhibitory potentials of drugs and consequently predicting renal drug interactions.

Nanoemulsions for Enhancement of Curcumin Bioavailability and Their Safety Evaluation: Effect of Emulsifier Type

This work aimed at evaluating the effects of different emulsifiers on curcumin-loaded nanoemulsions’ behavior during digestion, its safety and absorption, to develop nanoemulsions that provide safety and improved curcumin functionality. Nanoemulsions (NEs) were produced using two bio-based (lecithin (LEC) and rhamnolipids (RHAM)) and one synthetic (Tween^®80 (TWE)) emulsifier at similar concentrations. Different NEs were subjected to in vitro digestion. The cytotoxicity and permeability tests were performed in Caco-2 cells. NE_TWE were stable during all phases of in vitro digestion, whereas NE_LEC and NE_RHAM were found to be unstable from the gastric phase. NE_TWE showed 100% of free fatty acids released, followed by NE_RHAM and NE_LEC. Curcumin’s bioaccessibility and stability increased in the following order: NE_LEC > NE_RHAM > NE_TWE. NE_LEC and NE_TWE did not show cytotoxic effects in any of the concentrations tested, while NE_RHAM presented high cytotoxicity in all concentrations tested. The apparent permeability coefficients were determined for NE_LEC and NE_TWE; however, the results were not statistically different. These results showed that the emulsifier used has a high impact on nanoemulsions’ behavior under the digestion process and on their cytotoxicity. This work contributed to the state-of-the-art’s progress on the development of safer curcumin delivery systems with improved functionality, particularly regarding the proper selection of ingredients to produce said systems.

Biosurfactants as a Novel Additive in Pharmaceutical Formulations: Current Trends and Future Implications

BACKGROUND

Surfactants are an important category of additives that are used widely in most of the formulations as solubilizers, stabilizers, and emulsifiers. Current drug delivery systems comprise of numerous synthetic surfactants (such as Cremophor EL, polysorbate 80, Transcutol-P), which are associated with several side effects though used in many formulations. Therefore, to attenuate the problems associated with conventional surfactants, a new generation of surface-active agents is obtained from the metabolites of fungi, yeast, and bacteria, which are termed as biosurfactants.

OBJECTIVES

In this article, we critically analyze the different types of biosurfactants, their origin along with their chemical and physical properties, advantages, drawbacks, regulatory status, and detailed pharmaceutical applications.

METHODS

243 papers were reviewed and included in this review.

RESULTS

Briefly, Biosurfactants are classified as glycolipids, rhamnolipids, sophorolipids, trehalolipids, surfactin, lipopeptides & lipoproteins, lichenysin, fatty acids, phospholipids, and polymeric biosurfactants. These are amphiphilic biomolecules with lipophilic and hydrophilic ends and are used as drug delivery vehicles (foaming, solubilizer, detergent, and emulsifier) in the pharmaceutical industry. Despite additives, they have some biological activity as well (anti-cancer, anti-viral, anti-microbial, P-gp inhibition, etc.). These biomolecules possess better safety profiles and are biocompatible, biodegradable, and specific at different temperatures.

CONCLUSION

Biosurfactants exhibit good biomedicine and additive properties that can be used in developing novel drug delivery systems. However, more research should be driven due to the lack of comprehensive toxicity testing and high production cost which limits their use.

Evaluating the Pharmacokinetics and Systemic Effects of a Permeability Enhancer Sodium N-[8-(2-hydroxybenzoyl)amino] Caprylate in Rats

Oral administration is the preferred route for drug delivery and its success is highly dependent on a compound's ADME properties, of which, permeability plays a major role. Therefore, permeability enhancers are an attractive area of research in the pharmaceutical industry. Recent data suggest that sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC) is an effective permeability enhancer, yet the pharmacokinetic (PK) and systemic effects of SNAC are poorly understood, specifically its oral bioavailability and systemic effects on distribution, which could influence the safety of certain drugs. To answer these questions, both in vitro and in vivo studies were conducted. Of 3 permeability enhancers (SNAC, 4-CNAB, and 5-CNAC), SNAC was found to have the greatest effect on the absorption of cyanocobalamin in rats. It was also found that SNAC is orally bioavailable (almost 40%) when dosed to rats. Based on these findings, tool compounds were co-dosed in rats to further evaluate the systemic effects of SNAC. Oral co-dosing of SNAC with an intravenous infusion of 2 poorly brain penetrant compounds, quinidine, and gabapentin, did not increase brain ISF: plasma ratio or total brain:plasma ratio for either of these compounds, implying that SNAC is effective only in the intestine at pharmacologically relevant concentrations.

Hydroxytyrosol encapsulated in biocompatible water-in-oil microemulsions: How the structure affects in vitro absorption

Over the last years, the incorporation of natural antioxidants in food and pharmaceutical formulations has gained attention, delaying or preventing oxidation phenomena in the final products. In order to take full advantage of their properties, protection in special microenvironments is of great importance. The unique features of the natural phenolic compound hydroxytyrosol (HT) - including antioxidant, anti-inflammatory, antiproliferative and cardioprotective properties - have been studied to clarify its mechanism of action. In the present study novel biocompatible water-in-oil (W/O) microemulsions were developed as hosts for HT and subsequently examined for their absorption profile following their oral uptake. The absorption of HT in solution was compared with the encapsulated one in vitro, using a coculture model (Caco-2/TC7 and HT29-MTX cell lines). The systems were structurally characterized by means of Dynamic Light Scattering (DLS) and Electron Paramagnetic Resonance (EPR) techniques. The diameter of the micelles remained unaltered after the incorporation of 678 ppm of HT but the interfacial properties were slightly affected, indicating the involvement of the HT molecules in the surfactant monolayer. EPR was used towards a lipophilic stable free radial, namely galvinoxyl, indicating a high scavenging activity of the systems and encapsulated HT. Finally, after the biocompatibility study of the microemulsions the intestinal absorption of the encapsulated HT was compared with its aqueous solution in vitro. The higher the surfactants' concentration in the system the lower the HT concentration that penetrated the constructed epithelium, indicating the involvement of the amphiphiles in the antioxidant's absorption and its entrapment in the mucus layer.

Physicochemical and colloidal aspects of food matrix effects on gastrointestinal fate of ingested inorganic nanoparticles

Inorganic nanoparticles, such as titanium dioxide, silicon dioxide, iron oxide, zinc oxide, or silver nanoparticles, are added to some food products and food packaging materials to obtain specific functional attributes, such as lightening, powder flow, nutrition, or antimicrobial properties. These engineered nanomaterials (ENMs) all have dimensions below 100nm, but may still vary considerably in composition, morphology, charge, surface properties and aggregation state, which effects their gastrointestinal fate and potential toxicity. In addition to their intrinsic physicochemical and morphological properties, the extrinsic properties of the media they are suspended in also affects their biotransformation, gastrointestinal fate and bioactivity. For instance, inorganic nanoparticles are usually consumed as part of a food or meal that contains numerous other components, such as lipids, proteins, carbohydrates, surfactants, minerals, and water, which may alter their gastrointestinal fate. This review article provides an overview of the potential effects of food components on the behavior of ENMs in the gastrointestinal tract (GIT), and highlights some important physicochemical and colloidal mechanisms by which the food matrix may alter the properties of inorganic nanoparticles. This information is essential for developing appropriate test methods to establish the potential toxicity and biokinetics of inorganic nanoparticles in foods.

Rhamnolipids as epithelial permeability enhancers for macromolecular therapeutics

The use of surfactants as drug permeability enhancers across epithelial barriers remains a challenge. Although many studies have been performed in this field using synthetic surfactants, the possibility of employing surfactants produced by bacteria (the so called biosurfactants") has not been completely explored. Among them, one of the most well characterized class of biosurfactants are rhamnolipids. The aim of the study was to investigate the effect of rhamnolipids on the epithelial permeability of fluorescein isothiocyanate-labelled dextrans 4kDa and 10kDa (named FD4 and FD10, respectively) as model for macromolecular drugs, across Caco-2 and Calu-3monolayers. These cell lines were selected as an in vitro model for the oral and respiratory administration of drugs. Before performing permeability studies, rhamnolipids mixture was analysed in terms of chemical composition and quantification through mass analysis and HPLC. Cytotoxicity and transepithelial electrical resistance (TEER) studies were also conducted using Caco-2 and Calu-3 cell lines. A dose-dependent effect of rhamnolipids on TEER and FD4 or FD10 permeability across both cell lines was observed at relatively safe concentrations. Overall, results suggest the possibility of using rhamnolipids as absorption enhancers for macromolecular drugs through a reversible tight junction opening (paracellular route), despite more investigations are required to confirm their mechanism of action in term of permeability.

Intestinal permeation enhancers for oral peptide delivery

Intestinal permeation enhancers (PEs) are one of the most widely tested strategies to improve oral delivery of therapeutic peptides. This article assesses the intestinal permeation enhancement action of over 250 PEs that have been tested in intestinal delivery models. In depth analysis of pre-clinical data is presented for PEs as components of proprietary delivery systems that have progressed to clinical trials. Given the importance of co-presentation of sufficiently high concentrations of PE and peptide at the small intestinal epithelium, there is an emphasis on studies where PEs have been formulated with poorly permeable molecules in solid dosage forms and lipoidal dispersions.

Foliar penetration enhanced by biosurfactant rhamnolipid

With recent environmental and health concerns, biosurfactants have obtained increasing interest in replacing conventional surfactants for diverse applications. In agriculture, the use of surfactant in stimulating foliar uptake is mainly for wetting leaf surface, resisting deposition/evaporation, enhancing penetration across cuticular membrane (CM) and translocation. This paper aimed to address the improved foliar uptake by rhamnolipid (RL) in comparison with the currently used alkyl polyglucoside (APG). As found, compared with APG at 900mg/L (1×critical micellar concentration, CMC), RL at a much lower concentration of 50mg/L (1×CMC) showed much better wettability and surface activity, indicative of its high effectiveness as surfactants. Its performance on resistance to deposition and evaporation was at least as same as APG. Moreover, RL could significantly improve the penetration of herbicide glyphosate and other two small water-soluble molecules (phenol red and Fe(2+)) across CM at an equivalent efficiency as APG at 1×CMC. Finally, the greatly enhanced herbicidal actitivity of glyphosate on greenhouse plants confirmed that RL and APG could both enhance the foliar uptake including translocation. Overall, RL should be more applicable than APG in agriculture due to its more promising properties on health/environmental friendliness.

Excipient Nanoemulsions for Improving Oral Bioavailability of Bioactives

The oral bioavailability of many hydrophobic bioactive compounds found in natural food products (such as vitamins and nutraceuticals in fruits and vegetables) is relatively low due to their low bioaccessibility, chemical instability, or poor absorption. Most previous research has therefore focused on the design of delivery systems to incorporate isolated bioactive compounds into food products. However, a more sustainable and cost-effect approach to enhancing the functionality of bioactive compounds is to leave them within their natural environment, but specifically design excipient foods that enhance their bioavailability. Excipient foods typically do not have functionality themselves but they have the capacity to enhance the functionality of nutrients present in natural foods by altering their bioaccessibility, absorption, and/or chemical transformation. In this review article we present the use of excipient nanoemulsions for increasing the bioavailability of bioactive components from fruits and vegetables. Nanoemulsions present several advantages over other food systems for this application, such as the ability to incorporate hydrophilic, amphiphilic, and lipophilic excipient ingredients, high physical stability, and rapid gastrointestinal digestibility. The design, fabrication, and application of nanoemulsions as excipient foods will therefore be described in this article.

Reduced ABCB1 Expression and Activity in the Presence of Acrylic Copolymers

PURPOSE

P-glycoprotein (P-gp; ABCB1), an integral membrane protein in the apical surface of human intestinal epithelial cells, plays a crucial role in the intestinal transport and efflux leading to changes in the bioavailability of oral pharmaceutical compounds. This study was set to examine the potential effects of three Eudragits RL100, S100 and L100 on the intestinal epithelial membrane transport of rhodammine-123 (Rho-123), a substrate of P-gp using a monolayer of human colon cancer cell line (Caco-2).

METHODS

The least non-cytotoxic concentrations of the excipients were assessed in Caco-2 cells by the MTT assay. Then the transepithelial transport of Rho-123 across Caco-2 monolayers was determined with a fluorescence spectrophotometer. Besides, the expression of the P-gp in cells exposed to the polymers was demonstrated using Western-blotting analysis.

RESULTS

Treatment of cells with Eudragit RL100 and L100 led to a very slight change while Eudragit S100 showed 61% increase in Rho-123 accumulation (P<0.001) and also reduced transporter expression.

CONCLUSION

Our studies suggest that using proper concentrations of the Eudragit S100 in drug formulation would improve intestinal permeability and absorption of p-gp substrate drugs.

Excipient foods: designing food matrices that improve the oral bioavailability of pharmaceuticals and nutraceuticals

The oral bioavailability of many lipophilic bioactive agents (pharmaceuticals and nutraceuticals) is limited due to various physicochemical and physiological processes. Excipient foods can be designed to improve the oral bioavailability of these bioactive agents.