Presence Of Lipase Research Articles

Triclosan loaded polyurethane micelles with pH and lipase sensitive properties for antibacterial applications and treatment of biofilms

Three different kinds of polyurethane (PU) micelles, i.e. PEG-c-PU, PEG-g-PU and PEG-b-PU, with hydrophobic PCL core and hydrophilic PEG corona were prepared by self-assembly method. DLS studies illustrated that PEG-g-PU micelles showed pH dependent surface charge switching properties while no obvious surface charge switching activities were found for PEG-b-PU and PEG-c-PU micelles. Triclosan was loaded into PCL core by dialysis method with pretty high encapsulate content and efficiency and the payloads were released at an accelerate rate in the presence of lipase. MIC and MBC studies demonstrated an enhanced antibacterial activity of encapsulated Triclosan against planktonic bacteria than free Triclosan. CLSM images of S. aureus biofilms treated with Nile red loaded PU micelles illustrated the penetration and accumulation of PEG-g-PU micelles inside the bacterial biofilms at an acidic environment. In addition, Triclosan loaded into PEG-g-PU micelles showed more potent antibiofilm activities than that loaded into PEG-c-PEG and PEG-b-PU micelles. Therefore, the PEG-g-PU micelles can be potentially used as hydrophobic antibiotic carriers to treat bacterial infections and biofilms.

Lipase‐Catalyzed Butanolysis of Echium Oil for the Selective Enrichment in Gamma‐Linolenic and Stearidonic Acids

Enzymatic butanolysis of Echium oil in the presence of lipases from Candida rugosa and Rhizopus oryzae has been studied. The effects of lipase immobilization, hydration of the reaction mixture and oil oxidation degree on lipase catalytic activity, fatty acid selectivity, and inactivation degree are evaluated. The utilization of butanol containing 2.5% (w/w) of water produces the highest catalytic activity of lipases in both powder and immobilized form; particularly of immobilized lipase from Rhizopus oryzae, which led to the complete conversion of triacylglycerols. The presence of 2.5% water also improves the biocatalyst stability, as the rate of immobilized lipase from Rhizopus oryzae inactivation (Kd = 0.0084 h−1) is much lower than in the absence of water (Kd = 0.0285 h−1). Stability of immobilized lipase from Rhizopus oryzae further increases when bleached oil is used (Kd = 0.0008 h−1). Then, fatty acid selectivity of immobilized lipase from Rhizopus oryzae is investigated by determining competitive factors for each fatty acid from Echium oil. Results indicates a very good activity, stability, and very important discrimination of this lipase against stearidonic and gamma‐linolenic acids which can be utilized for the efficient and selective oil enrichment in polyunsaturated fatty acids.Practical Applications: This study describes an interesting methodology for the selective enrichment in polyunsaturated fatty acid from Echium oil utilizing intact triacylglycerols as starting material. This study also evaluates the lipase inactivation as a crucial tool for industrial application of this bioprocess. Finally the study describes the production of lower glycerides that can be used as precursors of structured bioactive lipids enriched in stearidonic and gamma‐linoleic acids.Schematic representation of the simultaneous reactions that occur in the butanolysis reaction carried out. SAFA saturated fatty acid, MUFA monounsaturated fatty acid, PUFA polyunsaturated fatty acid, FABE fatty acid butyl ester, BUTOH Butanol.

Fatty Acids Effect on Lipase and Biosurfactant Induction in Rhodotorula Glutinis CMGB-RG5

Abstract Fatty acids represent important substrates for obtaining microbial lipases and biosurfactants. The yeast strain CMGBRG5 was identified as Rhodotorula glutinis using the BIOLOG MicroLog System. The opacity screening tests showed that R. glutinis CMGB-RG5 was able to produce lipases in presence of 1% Tween 80 after three days of incubation. Lipase induction was estimated as cell growth in presence of Tween 80, Tween 20, olive oil and tributyrin. After 48 hours, best results were obtained in presence of butyric acid, respectively, oleic acid: 2.2 × 107 cells/ml on tributyrin and 1.0 × 107 cells/ml on olive oil. Biosurfactant production was evaluated as emulsification index (E24%). After one week, high E24 values were obtained on fried sunflower oil (53%) and olive oil (35%). Crude and concentrated biosurfactants were tested against nine Candida strains. Best antimicrobial activity was observed for [20X] biosurfactants against C. tropicalis, C. guilliermondii and C. krusei. In conclusion, R. glutinis CGB-RG5 shows high potential for using fatty acids from various sources as unique carbon substrates for synthesis of biocompounds with high economic and biotechnological value.

Modulating the Tg of Poly(alkylene succinate)s by Inserting Bio-Based Aromatic Units via Ring-Opening Copolymerization.

Two series of aliphatic-aromatic copolyesters derived from succinic and 2,5-furandicarboxylic acids, and di-O-2-(hydroxyethyl) resorcinol as diol substituent of either 1,4-butanediol or ethylene glycol, respectively, were obtained by ring opening polymerization(ROP) performed in bulk and catalyzed by Sn(Oct)2. Cyclic oligomers of furandicarboxylate of di-O-2-(hydroxyethyl) resorcinol were successfully synthesized by high-dilution condensation, and then copolymerized with cyclic oligomers of either butylene or ethylene succinate. The synthesized resorcinol-containing succinate-furanoatecopolyesters had Mw oscillating between 50,000 and 30,000 g·mol−1 depending on composition, and they all displayed a nearly random microstructure. They showed an excellent thermal stability with onset decomposition temperatures near 300 °C. They are amorphous with Tg increasing monotonically with the content in resorcinol in both series with values ranging from −30 or −13 °C for butylene and ethylene-based copolyesters, respectively, up to around 45 °C. The resorcinol-containing succinate-furanoate copolyesters showed appreciable hydrolytic degradation when incubated for a few weeks in water under physiological conditions, a behavior that was notably enhanced in the presence of lipases.

Controlling insulin release from reverse hexagonal (HII) liquid crystalline mesophase by enzymatic lipolysis

In the present study we aimed to control insulin release from the reverse hexagonal (HII) mesophase using Thermomyces lanuginosa lipase (TLL) in the environment (outer TLL) or within the HII cylinders (inner TLL). Two insulin-loaded systems differing by the presence (or absence) of phosphatidylcholine (PC) were examined.In general, incorporation of PC into the HII interface (without TLL) increased insulin release, as a more cooperative system was formed.Addition of TLL to the systems’ environments resulted in lipolysis of the HII structure. In the absence of PC, the lipolysis was more dominant and led to a significant increase in insulin release (50% after 8h). However, the presence of PC stabilized the interface, hindering the lipolysis, and therefore no impact on the release profile was detected during the first 8h.Entrapment of TLL within the HII cylinders (with and without PC) drastically increased insulin release in both systems up to 100%. In the presence of PC insulin released faster and the structure was more stable.Consequently, the presence of lipases (inner or outer) both enhanced the destruction of the carrier, and provided sustained release of the entrapped insulin.

Bioremediation of cooking oil waste using lipases from wastes.

Cooking oil waste leads to well-known environmental impacts and its bioremediation by lipase-based enzymatic activity can minimize the high cytotoxic potential. In addition, they are among the biocatalysts most commercialized worldwide due to the versatility of reactions and substrates. However, although lipases are able to process cooking oil wastes, the products generated from this process do not necessarily become less toxic. Thus, the aim of the current study is to analyze the bioremediation of lipase-catalyzed cooking oil wastes, as well as their effect on the cytotoxicity of both the oil and its waste before and after enzymatic treatment. Thus, assessed the post-frying modification in soybean oil and in its waste, which was caused by hydrolysis reaction catalyzed by commercial and home-made lipases. The presence of lipases in the extracts obtained from orange wastes was identified by zymography. The profile of the fatty acid esters formed after these reactions was detected and quantified through gas chromatography and fatty acids profile compared through multivariate statistical analyses. Finally, the soybean oil and its waste, with and without enzymatic treatment, were assessed for toxicity in cytotoxicity assays conducted in vitro using fibroblast cell culture. The soybean oil wastes treated with core and frit lipases through transesterification reaction were less toxic than the untreated oils, thus confirming that cooking oil wastes can be bioremediated using orange lipases.

Impact of lipases with different substrate specificity in wheat flour separation on the properties of the resultant gluten

Wheat gluten was isolated in a laboratory dough-batter flour separation process in the presence or absence of lipases differing in hydrolysis specificity. The obtained gluten was blended with wheat starch to obtain gluten-starch (GS) blends of which the water and oil binding capacities were investigated. Furthermore, GS blends were mixed into dough and processed into model breads, of which dough extensibility and loaf volume were measured, respectively. In comparison to GS blends prepared with control gluten, oil binding capacity was higher when GS blends contained gluten isolated with Lecitase Ultra (at 5.0 mg enzyme protein/kg flour), a lipase hydrolyzing both non-polar and polar lipids. Additionally, dough extensibility and total work needed for fracture were lower for dough prepared from GS blends containing gluten isolated with Lipolase (at 5.0 mg enzyme protein/kg flour), a lipase selectively degrading non-polar lipids. In GS blend bread making, this resulted in inferior loaf volumes. Comparable GS blend properties were measured when using control gluten and gluten isolated with YieldMAX, a lipase mainly degrading N-acyl phosphatidylethanolamine. In conclusion, properties of GS blend model systems are altered when gluten prepared in the presence of lipases is used to a degree which depends on lipase specificity and concentration.

ISOLATION OF LIPOLYTIC BACTERIA FROM COLOMBIAN ANDEAN SOILS: A TARGET FOR BIOPROSPECTING

Microbial enrichments with a substrate of interest could enhance the possibility of finding certain desired metabolic activities. As lipases are one of the most important enzymes in industrial applications, the Colombian Andean soils were explored as a source of lipolytic microorganisms. Two Andean soils under low temperatures were sampled: paramo and glacier soils from “Los Nevados” National Natural Park. Both soils were enriched through a fed-batch fermentation using olive oil as the inductor substrate. Forty-three lipolytic isolates were obtained and their taxonomic assignments were performed on the basis of 16S rDNA gene sequencing. In both cases, the phylum Proteobacteria represented the majority of the isolates. Qualitative assays to measure the lipolytic activity were performed by using tributyrin, triolein or olive oil (1%). Two isolates identified as Pseudomonas psychrophila and Stenotrophomonas rhizophila produced the largest hydrolysis halos, with an optimal activity at pH 8 and 50°C. Only the S. rhizophila extracellular fraction hydrolyzed short and long chain pNP-esters, including pNP-palmitate. The broader substrate specificity of this isolate is probably due to the simultaneous presence of lipase and esterase activity in the crude extract. This is the first report of lipolytic activity in S. rhizophila, and the first preliminary characterization of the novel lipolytic activity in S. rhizophila and P. psychrophila. Further work is needed to purify and completely characterize the esterases and lipases produced by both species.

Silver nanoparticles decorated lipase-sensitive polyurethane micelles for on-demand release of silver nanoparticles

In order to improve the antibacterial activities while decrease the cytotoxity of silver nanoparticles, we prepared a novel nanocomposites composed of silver nanoparticles decorated lipase-sensitive polyurethane micelles (PUM-Ag) with MPEG brush on the surface. The nanocomposite was characterized by UV–vis, TEM and DLS. UV–vis and TEM demonstrated the formation of silver nanoparticles on PU micelles and the nanoassembly remained intact without the presence of lipase. The silver nanoparticles were protected by the polymer matrix and PEG brush which show good cytocompatibility to HUVEC cells and low hemolysis. Moreover, at the presence of lipase, the polymer matrix of nanocomposites is subject to degradation and the small silver nanoparticles were released as is shown by DLS and TEM. The MIC and MBC studies showed an enhanced toxicity of the nanocomposites to both gram negative and gram positive bacteria, i.e. E. coli and S. aureus, as the result of the degradation of polymer matrix by bacterial lipase. Therefore, the nanocomposites are biocompatible to mammalian cells cells which can also lead to activated smaller silver nanoparticles release at the presence of bacteria and subsequently enhanced inhibition of bacteria growth. The satisfactory selectivity for bacteria compared to HUVEC and RBCs make PUM-Ag a promising antibacterial nanomedicine in biomedical field.

L-dopa co-drugs in nanostructured lipid carriers: A comparative study

This paper describes the production and characterization of nanostructured lipid carriers (NLC) containing four different levodopa (LD) co-drugs (PD), named PDA (3,4-diacetyloxy-LD-caffeic acid co-drug), PDB (lipoic acid-dopamine co-drug), PDC (lipoic acid-3,4-diacetoxy-dopamine co-drug), and PDD (dimeric LD co-drug containing an alkyl linker), with therapeutic potential in Parkinson's disease. These co-drugs were produced with the aim of prolonging the pharmacological activity of LD, enhancing its absorption and protecting it from metabolism. These compounds were characterized by very low water solubility that limits their systemic administration. To improve the solubility of these LDPD, NLC were considered.The obtained NLC showed acceptable particle size and a good stability up to two months from preparation. Cryo-TEM morphological characterization revealed no substantial differences between unloaded and co-drug loaded NLC. In vitro studies showed that the LDPD loaded NLC provided a controlled drug release. Moreover, the enhancement of LDPD stability on the hydrolysis catalysed by foetal calf serum (FCS) esterases or in the presence of lipases was evaluated as compared to a labrasol solution. In presence of esterases PDA-NLC and PDD-NLC showed half-lives higher >3-fold as compared to the corresponding aqueous micellar solution. In the case of PDB-NLC it was found that the stability exceeds the 19h. It can be concluded that NLC represent good strategies to encapsulate lipophilic LD co-drugs, although further studies aimed to deeply evaluate anti-parkinsonian effects in vivo have to be carried on.

Effects of aroma compounds and lipid composition on release of functional substances encapsulated in nanostructured lipid carriers lipolyzed by lipase

Nanostructured lipid carriers (NLC) are a delivery system for drugs or functional substances to control their release and protect them from harmful environmental stresses. The aims of this research were to investigate the effects of chemical structure of aroma compounds, type and composition of lipids as well inhibitors on the lipolysis of NLC in the presence of lipase, and to study the release rate of a functional substance, curcumin, encapsulated in the NLC by a kinetic study. The amount of free fatty acids released from the lipid digestion of NLC was determined by a pH-stat method. Franz diffusion cells were used to study the release rate of curcumin from the digestion of NLC by the lipase in the presence or absence of an inhibitor. The results indicate that the chemical structures of the tested aroma compounds have a marked effect on the inhibition of lipase activity. In addition, the release rate of functional substances such as curcumin encapsulated in the NLC can be controlled by manipulating the lipid type and composition, and using a lipase inhibitor.

The interactions between lipase and pyridinium ligands investigated by electrochemical and spectrophotometric methods

<p class="PaperAbstract"><span lang="EN-GB">The interaction between pyridinium ligands derived from 4,4’-bipyridine (N,N’-bis(p-bromophenacyl)-4,4’-bipyridinium dibromide – Lr) and (N,N’-bis(p-bromophenacyl)-1,2-bis (4-pyridyl) ethane dibromide – Lm) with lipase enzyme was evaluated. The stability of the pyridinium ligands, having an essential role in biological systems, in 0.1 M KNO<sub>3</sub> as supporting electrolyte is influenced by the lipase concentration added. The pH and conductometry measurements in aqueous solution suggest a rapid ionic exchange process. The behavior of pyridinium ligands in the presence of lipase is investigated by cyclic voltammetry and UV/Vis spectroscopy, which indicated bindings and changes from the interaction between them. The voltammograms recorded on the glassy carbon electrode showed a more intense electronic transfer for the Lr interaction with lipase compared to Lm, which is due to the absence of mobile ethylene groups from Lr structure.</span></p>

Study of the factors influencing the bioaccessibility of 10 elements from chocolate drink powder

A risk/benefit assessment of chocolate drink powder has been conducted by evaluating the total contents and the bioaccessibilities of Al, Ba, Cd, Cr, Cu, Fe, Mg, Mn, P and Zn. The bioaccessibility was studied considering the type of sample (traditional, light, diet and organic) and the different factors that may affect it, including physical-chemical parameters of the human digestive process (gastric pH, concentration of bile salts and presence of lipase) and the presence of dietary components (phytate, pectin, cellulose and tannin). The bioaccessibility varied greatly according to the sample type, being greater in the diet and organic samples, and on the element being considered (5–12% for Al, 74–120% for Ba, 3–11% for Cd, 5–19% for Cr, 22–74% for Cu, 1–30% for Fe, 47–98% for Mg, 19–59% for Mn, 19–115% for P and 15–31% for Zn). Bile salts concentrations and the presence of dietary components also modify the bioaccessibilities of some of these elements. In addition, consideration of the bioaccessible fractions instead of the total contents in the product reduces significantly the contribution of chocolate drink consumption to the Recommended Daily Intake of essential elements, but has also a positive effect, reducing the contributions to tolerable intakes of Al and Cd.

Production of Antilisterial Bacteriocins from Lactic Acid Bacteria in Dairy-Based Media: A Comparative Study.

One hundred and eight strains of lactic acid bacteria (LAB) were screened for bacteriocin production by the modified deferred antagonism and agar well diffusion methods. When the modified deferred antagonism method was employed, 82 LAB strains showed inhibitory action against Listeria monocytogenes v7 ½a, whereas 26 LAB strains expressed no inhibition. Only 12 LAB strains exhibited inhibitory activity when the agar well diffusion method was used, 11 of which had been previously recognized as bacteriocin production positive (Bac(+)). Lactobacillus viridescens NRRL B-1951 was determined, for the first time, to produce an inhibitory compound with a proteinaceous nature. The inhibitory activity was observed in the presence of lipase, α-chymotrypsin, and trypsin, but no inhibition zone could be detected in the presence of proteinase K, indicating the proteinaceous nature of the inhibitory compound. The inhibitory compound was active against Lact. sake ATCC 15521 and Lact. plantarum NCDO 995. Bacteriocin production by the Bac(+) LAB strains was assessed in Lactobacillus MRS Broth as well as in dairy-based media such as nonfat milk, demineralized whey powder, and cheddar cheese whey supplemented with complex nutrient sources that are rich in nitrogen. Lact. sake ATCC 15521 and L. monocytogenes CWD 1002, CWD 1092, CWD 1157, CWD 1198, and v7 ½a were used as indicators. The inhibitory activities of the bacteriocins varied depending on the indicator strains and the growth media used. The LAB indicator strains were found to be more sensitive to inhibition by bacteriocins when compared to the listerial indicator strains. Among the listerial indicators, L. monocytogenes CWD 1002 and CWD 1198 were the most sensitive strains to the bacteriocins investigated in this study. Media composition had a significant influence on bacteriocin production and activity. When compared to demineralized whey powder medium and cheddar cheese whey medium supplemented with whey protein concentrate, cheddar cheese whey medium supplemented with complex nutrient sources such as yeast extract, polypeptone, proteose peptone nr. 3, or soytone appeared to be more supportive of bacteriocin production.

SCREENING, OPTIMIZATION AND CHARACTERIZATION OF EXTRACELLULAR LIPASE OF Aspergillus niger ATCC 1015

This study focused on screening, production and characterization of strains of microorganisms isolated from groundnut cake wastes capable of producing lipolytic enzyme. Over one hundred isolates were screened on Bromocresol green medium to detect the presence of lipase producing organisms by a colour change of the medium from green to yellow around the colonies at pH 3.8 – 5.6. Two of the isolates with NCBI Accession number ACJE01000015.1 and NT-166520.1 were identified as Aspergillus niger ATCC 1015 and A.niger CBS 513.88 respectively based on the nucleotide sequence of the domain of DNA gene. Other lipase producers include A. niger (B-05, B-17, B-33), A. oryzae (G -47, G- 51), and yeast, Candida sp. (H-06, H-11). Lipase activities of A. niger ATCC 1015 were evaluated at temperature (25 – 60 °C), pH 5 - 9 and enzyme loading (10 -35 %, v/v) for optimization.The effect of inducers on lipase production was also carried out by using coconut oil, physic nut oil, groundnut oil and olive oil.A. niger ATCC 1015 gave the largest halo on the medium with 102.4 U/g activity. Zones of hydrolysis also increased with time and ranged from 3 mm to 10 mm at 30 ºC for 96 h. The ability of cells to maintain sharp contrast between green medium and its clear zone without prior replication permits direct visualization and isolation of positive strains. Optimum production of the enzyme (specific activity 216.7 Umg-1)was attained at temperature 45°C, pH 7, and enzyme loading (25% v/v) with physic nut oil (2%) inducer. Hence A. niger ATCC 1015 strain can be commercially exploited as a potential lipase producing strain for industrial application.

Hydrolytic and enzymatic degradation of flexible polymer networks comprising fatty acid derivatives

In this study a degradation process of flexible polymer networks fabricated from telechelic macromonomers comprising methacrylic functionalities and dimer fatty acid derivatives were discussed. Hydrolytic degradation in simulated body fluid (SBF) as well as enzymatic degradation with a lipase of six different systems comprising ester, anhydride and urethane bonds was investigated. In parallel, in order to make a comparison with other analogous polymeric systems, reference materials were also considered. The degradation process was monitored by determining the weight loss and water uptake, FT-IR analysis and changes in pH of degradation medium as a function of time. A rapid progress of degradation of the network containing anhydride bonds was observed. Furthermore, polymer networks showed low water absorption from 10 to 2 wt.%. Polymer networks did not release acidic degradation products in an amount that causes acidification of the medium except the anhydride network. The IR analysis of characteristic bands showed degradation of specific bonds leading to formation of possible hydrolysis products of these networks such as poly(methacrylic acid), macromonomer precursor molecules and derivatives of the macromonomers having terminal carboxylic and hydroxyl groups. We demonstrated that the referred polymeric networks undergo a controlled gradual degradation in the presence of lipase. This study provides an example of how the susceptibility of cross-linked polymers to degradation can be tailored by varying their molecular structure, depending on the needs.

Oral self-nanoemulsifying peptide drug delivery systems: impact of lipase on drug release

It was the aim of this study to evaluate the impact of lipases on the release behaviour of a peptide drug from oral self-nanoemulsifying drug delivery systems. Octreotide was ion paired with the anionic surfactants deoxycholate, decanoate, oleate and dodecylsulphate. The lipophilic character of these complexes was characterised by determining the n-octanol/buffer pH 7.4 partition coefficient. In the following the most hydrophilic complex was incorporated in a likely lipase degradable self-nanoemulsifying drug delivery systems (SNEDDS) formulation containing a triglyceride (olive oil; Pharm.Eur.) and in a likely not lipase degradable SNEDDS containing lipids and surfactants without any ester bonds. After 1:100 dilutions in artificial intestinal fluid (AIF), the lipid droplets were characterised regarding size distribution. With these SNEDDS, drug release studies were performed in AIF with and without lipase. Results showed that the most hydrophobic complex can be formed with deoxycholate in an octreotide:anionic surfactant ratio of 1:5. Even 73.1 ± 8.1% of it could be quantified in the n-octanol phase. SNEDDS containing octreotide | olive oil | cremophor EL | propylene glycol (2|57|38|3) and octreotide | liquid paraffin | Brij 35 | propylene glycol | ethanol (2|66.5|25|5|1.5) showed after dilution in AIF, a mean droplet size of 232 ± 53 nm and 235 ± 50 nm, respectively. Drug release studies showed a sustained release of octreotide out of these formulations for at least 24 h, whereas > 80% of the drug was released within 2 h in the presence of lipase in the case of the triglyceride containing SNEEDS. In contrast the release profile from ester-free SNEDDS was not significantly altered (p < 0.05) due to the addition of lipase providing evidence for the stability of this formulation towards lipases. According to these results, SNEDDS could be identified as a useful tool for sustained oral peptide delivery taking an enzymatic degradation by intestinal lipases into considerations.

Enzymatic degradation of polycaprolactone–gelatin blend

Blends of polycaprolactone (PCL), a synthetic polymer and gelatin, natural polymer offer a optimal combination of strength, water wettability and cytocompatibility for use as a resorbable biomaterial. The enzymatic degradation of PCL, gelatin and PCL–gelatin blended films was studied in the presence of lipase (Novozym 435, immobilized) and lysozyme. Novozym 435 degraded the PCL films whereas lysozyme degraded the gelatin. Though Novozym 435 and lysozyme individually could degrade PCL–gelatin blended films, the combination of these enzymes showed the highest degradation of these blended films. Moreover, the enzymatic degradation was much faster when fresh enzymes were added at regular intervals. The changes in physico-chemical properties of polymer films due to degradation were studied by scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. These results have important implications for designing resorbable biomedical implants.

Formulation and development of bicontinuous nanostructured liquid crystalline particles of efavirenz

Efavirenz is a lipophilic non-nucleoside reverse transcriptase inhibitor used in the first-line pediatric therapeutic cocktail. Due to its high lipophilicity (logP=5.4) and poor aqueous solubility (intrinsic water solubility=8.3μg/mL) efavirenz has low bioavailability. A 30mg/mL solution in a medium-chain triglyceride vehicle is the only pediatric formulation available with an oral bioavailability 20% lower than the solid form. The current work was aimed at formulating and characterizing liquid crystal nanoparticles for oral delivery of efavirenz to improve oral bioavailability, provide sustained release, minimize side effects and drug resistance. Formulation of cubosomes was done by two methods; sonication and spray drying. Sonication gave highest entrapment efficiency and least particle size. Further, monoolein was substituted with phytantriol as monoolein gets degraded in the presence of lipase when administered orally with consequent loss of liquid crystalline structure. It was confirmed that there was no difference in particle size, entrapment efficiency and nature of product formed by using monoolein or phytantriol. The best formulation was found to be F9, having particle size 104.19±0.21nm and entrapment efficiency 91.40±0.10%. In vitro release at the end of 12h was found to be 56.45% and zeta potential to be −23.14mV which stabilized the cubic phase dispersions. It was further characterized for TEM, small angle X-ray scattering (SAXS), DSC and stability studies. SAXS revealed Pn3m space group, indicating a diamond cubic phase which was further confirmed by TEM. Pharmacokinetics of EFV was studied in male Wistar rats. EFV-loaded cubosome dispersions exhibited 1.93 and 1.62-fold increase in peak plasma concentration (Cmax) and 1.48 and 1.42-fold increase in AUC in comparison to that of a suspension prepared with the contents of EFV capsules suspended in 1.5% carboxymethylcellulose PBS solution (pH 5.0), and an EFV solution in medium-chain triglyceride respectively. Thus, stable cubosomes of efavirenz with increased bioavailability providing sustained release effect could be prepared successfully using phytantriol and poloxamer 407.

Evaluating the bioaccessibility of flame retardants in house dust using an in vitro Tenax bead-assisted sorptive physiologically based method.

Exposure to house dust is a significant source of exposure to flame retardant chemicals (FRs), particularly in the US. Given the high exposure there is a need to understand the bioaccessibility of FRs from dust. In this study, Tenax beads (TA) encapsulated within a stainless steel insert were used as an adsorption sink to estimate the dynamic absorption of a suite of FRs commonly detected in indoor dust samples (n = 17), and from a few polyurethane foam samples for comparison. Organophosphate flame retardants (OPFRs) had the highest estimated bioaccessibility (∼80%) compared to brominated compounds (e.g., PBDEs), and values generally decreased with increasing Log Kow, with <30% bioaccessibility measured for BDE209. These measurements were in very close agreement with reported PBDE bioavailability measures from an in vivo rat exposure study using indoor dust. The bioaccessibility of very hydrophobic FRs (Log Kow > 6) in foam was much less than that in house dust, and increasing bioaccessibility was observed with decreasing particle size. In addition, we examined the stability of more labile FRs containing ester groups (e.g., OPFRs and 2-ethylhexyl-tetrabromo-benzoate (EH-TBB)) in a mock-digestive fluid matrix. No significant changes in the OPFR concentrations were observed in this fluid; however, EH-TBB was found to readily hydrolyze to tetrabromobenzoic acid (TBBA) in the intestinal fluid in the presence of lipases. In conclusion, our study demonstrates that the bioaccessibility and stability of FRs following ingestion varies by chemical and sample matrix and thus should be considered in exposure assessments.