Parallel Artificial Membrane Permeability Assay Research Articles

Cyclodextrin Derivatives as Promising Solubilizers to Enhance the Biological Activity of Rosmarinic Acid.

Rosmarinic acid (RA) is a natural antioxidant with neuroprotective properties; however, its preventive and therapeutic use is limited due to its slight solubility and poor permeability. This study aimed to improve RA physicochemical properties by systems formation with cyclodextrins (CDs): hydroxypropyl-α-CD (HP-α-CD), HP-β-CD, and HP-γ-CD, which were prepared by the solvent evaporation (s.e.) method. The interactions between components were determined by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and Fourier Transform infrared spectroscopy (FTIR). The sites of interaction between RA and CDs were suggested as a result of in silico studies focused on assessing the interaction between molecules. The impact of amorphous systems formation on water solubility, dissolution rate, gastrointestinal (GIT) permeability, and biological activity was studied. RA solubility was increased from 5.869 mg/mL to 113.027 mg/mL, 179.840 mg/mL, and 194.354 mg/mL by systems formation with HP-α-CD, HP-β-CD, and HP-γ-CD, respectively. During apparent solubility studies, the systems provided an acceleration of RA dissolution. Poor RA GIT permeability at pH 4.5 and 5.8, determined by parallel artificial membrane permeability assay (PAMPA system), was increased; RA–HP-γ-CD s.e. indicated the greatest improvement (at pH 4.5 from Papp 6.901 × 10−7 cm/s to 1.085 × 10−6 cm/s and at pH 5.8 from 5.019 × 10−7 cm/s to 9.680 × 10−7 cm/s). Antioxidant activity, which was determined by DPPH, ABTS, CUPRAC, and FRAP methods, was ameliorated by systems; the greatest results were obtained for RA–HP-γ-CD s.e. The inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) was increased from 36.876% for AChE and 13.68% for BChE to a maximum inhibition of the enzyme (plateau), and enabled reaching IC50 values for both enzymes by all systems. CDs are efficient excipients for improving RA physicochemical and biological properties. HP-γ-CD was the greatest one with potential for future food or dietary supplement applications.

Novel TRKB agonists activate TRKB and downstream ERK and AKT signaling to protect Aβ-GFP SH-SY5Y cells against Aβ toxicity.

Decreased BDNF and impaired TRKB signaling contribute to neurodegeneration in Alzheimer’s disease (AD). We have shown previously that coumarin derivative LM-031 enhanced CREB/BDNF/BCL2 pathway. In this study we explored if LM-031 analogs LMDS-1 to -4 may act as TRKB agonists to protect SH-SY5Y cells against Aβ toxicity. By docking computation for binding with TRKB using 7,8-DHF as a control, all four LMDS compounds displayed potential of binding to domain d5 of TRKB. In addition, all four LMDS compounds exhibited anti-aggregation and neuroprotective efficacy on SH-SY5Y cells with induced Aβ-GFP expression. Knock-down of TRKB significantly attenuated TRKB downstream signaling and the neurite outgrowth-promoting effects of these LMDS compounds. Among them, LMDS-1 and -2 were further examined for TRKB signaling. Treatment of ERK inhibitor U0126 or PI3K inhibitor wortmannin decreased p-CREB, BDNF and BCL2 in Aβ-GFP cells, implicating the neuroprotective effects are via activating TRKB downstream ERK, PI3K-AKT and CREB signaling. LMDS-1 and -2 are blood–brain barrier permeable as shown by parallel artificial membrane permeability assay. Our results demonstrate how LMDS-1 and -2 are likely to work as TRKB agonists to exert neuroprotection in Aβ cells, which may shed light on the potential application in therapeutics of AD.

Влияние простатических пептидов на трансмембранный перенос ломефлоксацина.

Introduction. The use of peptides that penetrate the cell without the participation of membrane proteins and are capable of intracellular transport of low molecular weight substances associated with them opens up a new stage in the development of targeted drug delivery to therapeutic targets. Aim. Evaluation of the effect of prostatic peptides of Vitaprost® (prostate extract) on the transmembrane transport of the antimicrobial drug lomefloxacin. Material and methods. In the first series, the effects of prostatic peptides on the ability of lomefloxacin to pass through artificial membranes by passive diffusion (PAMPA method – parallel artificial membrane permeability assay) were studied. In the second series, the effects of prostatic peptides on the cell permeability of lomefloxacin were studied in the Caco-2 model. Results. Comparative study of effective membrane permeability (logPe). for lomefloxacin in the absence (control group) and presence of prostatic peptides (a mixture of prostate extract at a concentration of 10 mg/ml) showed that the combined use of lomefloxacin and prostatic peptides leads to a significant increase in the logPe value, an increase of 29% on average. The specific nature of the identified interaction was confirmed: the addition of beta-mercaptoethanol (BME) to the donor compartment did not affect the permeability of pure lomefloxacin, but suppressed the cargo effect of prostatic peptides. The permeability coefficient (Papp) calculated on the Caco-2 model for lomefloxacin in combination with peptides was 13.04±1.80×10-6 cm/s, while for lomefloxacin it was 10.31±0.76×10-6 cm/s. Conclusion. Comparison of the obtained data of two series of experiments indicates the presence of a direct cargo effect of prostatic peptides on the transmembrane transport of lomefloxacin in vitro.

Stability Study of Alpinia galanga Constituents and Investigation of Their Membrane Permeability by ChemGPS-NP and the Parallel Artificial Membrane Permeability Assay.

Alpinia galanga Willd., greater galangal, has been used for thousands of years as a spice as well as in traditional medicine. Its central nervous system (CNS) stimulant activity and neuroprotective effects have been proved both in animal models and human trials. However, the compounds responsible for these effects have not been identified yet. Therefore, the main constituents (p-OH-benzaldehyde (1), trans-p-coumaryl-alcohol (2), p-coumaryl-aldehyde (4), galanganol A (5), galanganol B (6), trans-p-acetoxycinnamyl alcohol (7), 1′S-1′-acetoxychavicol acetate (ACA, 9), and 1′S-1′-acetoxyeugenol acetate (AEA, 10)) were isolated to investigate their aqueous stability and passive diffusion across the gastro-intestinal tract (GIT) membrane and the blood–brain barrier (BBB) by the parallel artificial membrane permeability assay (PAMPA). Our positive results for compounds 1, 2, 4, 7, 9, and 10 suggest good permeability, thus potential contribution to the effects of greater galangal in the CNS. The results of the PAMPA-BBB were corroborated by in silico chemography-based ChemGPS-NP framework experiments. In addition, examination of the chemical space position of galangal compounds in relation to known psychostimulants revealed that all the molecules in proximity are NET/SERT inhibitors. As ACA and AEA did not show much proximity to either compound, the importance of further investigation of their degradation products becomes more pronounced.

Blood-brain barrier permeable benzylpiperidin-4-yl-linked benzylamino benzamides as dual cholinesterase inhibitors.

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder involving various pathological events. The existing options for managing the disease utterly rely on cholinesterase (ChE) inhibitors. In recent years, the dual inhibition of ChEs as a potential AD therapeutics has substantially attracted the attention of medicinal chemists. Recently, we reported benzyl piperidinyl-linked methoxy-naphthamides as dual ChE inhibitors. Herein, we investigated the peripheralanionic binding site-binding methoxy-naphthamide fragment that yielded benzyl piperidinyl-linked benzyl aminobenzamide as another class of dual ChE inhibitors. The 3,5-dimethoxy benzyl aminobenzamide, 8c1, exhibits inhibition of acetylcholinesterase(AChE) and butyrylcholinesterase (BChE)with half-maximal inhibitory concentration valuesof 0.61 and 2.04 µM, respectively. The enzyme kinetics and molecular modeling study indicated the noncompetitive and mixed-type mode of inhibition for AChE and BChE with ki values of 0.14 and 0.46 µM, respectively. The derivative 8c1 crosses the blood-brain barrier as indicated by the Pe value of 14.34 × 10-6 cm/s in the parallel artificial membrane permeability assay. Besides this, it also inhibits the self-aggregation of amyloid-β. The results presented herein indicate the potential of benzamide 8c1 for further investigation in preclinical models of AD.

Evaluation of the In Vitro Wound-Healing Potential of Ayahuasca.

Ayahuasca is an Amazonian drink, which contains β-carboline alkaloids and N,N-dimethyltryptamine. The aim of this study was to evaluate the healing potential of decoctions of a commercial mixture, four individual plants and four mixtures of two plants used in the ayahuasca preparation. Thus, the cytotoxic potential of the samples was evaluated and a wound-healing assay was performed with a NHDF cell line. Subsequently, a parallel artificial membrane permeability assay was also performed, to verify if any psychoactive compound could be absorbed by skin fibroblasts. The integrity and permeability of the cell layer were also evaluated, using the transepithelial electrical resistance assay and Lucifer yellow permeability assay, respectively. The compounds absorbed by the cell layer were quantified by high-performance liquid chromatography coupled to a diode array detector. The results showed that only one sample showed cytotoxicity and all the others promoted the migration of skin fibroblasts. Additionally, it was also verified that β-carbolynic alkaloids and N,N-dimethyltriptamine were not absorbed by the cell layer, and in general, did not interfere with its permeability and integrity. To the best of our knowledge, this is the first study where ayahuasca’s wound-healing potential was evaluated.

N-substituted arylhydroxamic acids as acetylcholinesterase reactivators

The problem of the efficient treatment of acute organophosphorus (OP) poisoning needs more efforts in the development of a versatile antidote, applicable for treatment of the injuries of both peripheral and central nervous systems. A series of N–H, N-methyl, N-butyl, and N-phenyl derivatives of benzhydroxamic (1a-1d), 3-methoxybenzhydroxamic (2a-2d), 4-methoxybenzhydroxamic (3a-3d) acids, and corresponding salycilhydroxamates (4a-4d) was prepared. Their predicted hydrophobicity (log P) was evaluated as regards to ВВВ score by the open access cheminformatics tools; prediction of the passive transport across the BBB was found by means on the parallel artificial membrane permeability assay (PAMPA). The data on reactivation capacity of human acetylcholinesterase (HssAChE) inhibited by GB, VX, and paraoxon was supported by molecular docking study on binding to the active site of the AChE, viability study against mammalian cells (Chinese hamster ovary CHO–K1), and biodegradability (Closed Bottle test OECD 301D). Among the studied compounds, N-butyl derivatives have better balanced combination of properties; among them, N-butylsalicylhydroxamic acid is most promising. The studied compounds demonstrate modest reactivation capacity; change of N–H by N–Me ensures the reactivation capacity in studied concentrations on all studied OP substrates; among N-butyl derivatives, the N-butylsalicylhydroxamic acid demonstrates most promising results within the series. The found regularities may lead to selection of perspective structures to complement current formulations for medical countermeasures against poisoning by organophosphorus toxicants.

Synthesis and evaluation of carbamate derivatives as fatty acid amide hydrolase and monoacylglycerol lipase inhibitors.

Fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) are the primary catabolic enzymes for endocannabinoids, anandamide (AEA), and 2-arachidonoyl glycerol. Numerous studies have shown that FAAH and MAGL play an important role in modulating various central nervous system activities; hence, the development of small molecule FAAH/MAGL inhibitors is an active area of research. Several small molecules possessing the carbamate scaffold are documented as potential FAAH/MAGL inhibitors. Here, we designed and synthesized a series of open chain and cyclic carbamates and evaluated their dual FAAH-MAGL inhibition properties. Phenyl [4-(piperidin-1-ylmethyl)phenyl]carbamate (2e) emerged as the most potent MAGL inhibitor (IC50 = 19 nM), benzyl (1H-benzo[d]imidazol-2-yl)carbamate (3h) was the most potent FAAH inhibitor (IC50 = 55 nM), and phenyl (6-fluorobenzo[d]thiazol-2-yl)carbamate (2i) egressed as a nonselective dual FAAH-MAGL inhibitor (FAAH: 82 nM, MAGL: 72 nM). The enzyme kinetics experiments revealed that the compounds inhibit FAAH/MAGL in a covalent-reversible manner, with a mixed binding mode of action. Moreover, the lead compounds were found suitable for blood-brain permeation in the parallel artificial membrane permeation assay. Furthermore, docking simulation experiments suggested that the potency of the lead compounds was governed by hydrogen bonds and hydrophobic interactions with the enzyme active sites. In silico drug-likeness and ADMETox prediction studies provided useful information on the compounds' oral absorption, metabolism, and toxicity profiles. In summary, this study afforded potent multifunctional carbamates with appreciable pharmacokinetic profiles meriting further investigation.

Aliskiren Hemifumarate Proliposomes for Improved Oral Drug Delivery: Formulation Development, In Vitro and In Vivo Permeability Testing.

The objective of this study was to develop proliposomal formulations for a poorly bioavailable drug, aliskiren hemifumarate (AKH). A solvent evaporation method was used to prepare proliposomes using different lipids. The lipids of selection were soy phosphatidylcholine (SPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoylphosphatidylglycerol sodium (DMPG Na), stearylamine, and cholesterol in various ratios. Proliposomes were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics upon hydration with aqueous phase. In vitro drug release studies were conducted in 0.01 N hydrochloric acid using USP type II dissolution apparatus. Parallel artificial membrane permeation assay (PAMPA) and Caco-2 cell line models were used to study the in vitro drug permeation. Male Sprague-Dawley (SD) rats were used to conduct in vivo pharmacokinetic studies. Among different formulations, proliposomes with drug/DMPC/cholesterol/stearylamine in the ratio of 1:5:0.025:0.050 (w/w/w/w) demonstrated the desired particle size, higher zeta potential, and higher encapsulation efficiency. The PAMPA and Caco-2 cell line experiments showed a significantly higher permeability of AKH with proliposomes as compared to pure AKH. In animal studies, the optimized formulation of proliposomes showed significant improvement in the rate and extent of absorption of AKH. Specifically, following a single oral administration, the relative bioavailability of AKH proliposome formulation was 230% when compared to pure AKH suspension.

Systematic Exploration of Passive Permeability in Tetrapeptides with Hydrogen-Bond-Accepting Amino Acid Side Chains.

We synthesized and experimentally tested the passive permeability of more than thirty tetrapeptides mimicking the N-terminus of the pro-apoptotic protein Smac (Second mitochondria-derived activator of caspases). Each peptide bore one or two unnatural Hydrogen Bond Acceptor-bearing Amino Acid (HBA-AA) residues, such that intramolecular hydrogen bonding with proximal backbone amide N-H donors is feasible. Passive permeability of the synthetic peptides was determined using the parallel artificial membrane permeability assay (PAMPA). Experimental permeability values were found to span three orders of magnitude, providing useful empirical guidance for the design of more permeable Smac mimetics specifically, and peptidic ligands generally.

Blood-Brain Barrier Permeability Study of Potential Neuroprotective Compounds Recovered From Plants and Agri-Food by-Products.

Plants and agri-food by-products represent a wide and renewable source of bioactive compounds with neuroprotective properties. In this research, various green extraction techniques were employed to recover bioactive molecules from Kalanchoe daigremontiana (kalanchoe), epicarp of Cyphomandra betacea (tamarillo), and cooperage woods from Robinia pseudoacacia (acacia) and Nothofagus pumilio (lenga), as well as a reference extract (positive control) from Rosmarinus officinalis L. (rosemary). The neuroprotective capacity of these plant extracts was evaluated in a set of in vitro assays, including enzymatic [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and lipoxygenase (LOX)] and antioxidant [ABTS, and reactive oxygen and nitrogen species (ROS and RNS)] bioactivity tests. Extracts were also submitted to a parallel artificial membrane permeability assay mimicking the blood–brain barrier (PAMPA-BBB) and to two cell viability assays in HK-2 and SH-SY5Y cell lines. Comprehensive phytochemical profiling based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS) analysis showed enriched content of phenolic and terpenoid compounds in the target extracts. Moreover, in vitro bioactivity tests showed promising neuroprotective capacity, particularly for supercritical-fluid extraction (SFE) extract from acacia (ABTS IC50 = 0.11 μg ml−1; ROS IC50 = 1.56 μg ml−1; AChE IC50 = 4.23 μg ml−1; BChE IC50 = 1.20 μg ml−1; and LOX IC50 = 4.37 μg ml−1), whereas PAMPA-BBB assays revealed high perfusion capacity of some representative compounds, such as phenolic acids or flavonoids. Regarding cytotoxic assays, tamarillo and rosemary SFE extracts can be considered as non-toxic, acacia SFE extract and lenga pressurized liquid extraction (PLE) extract as mild-cytotoxic, and kalanchoe as highly toxic extracts. The obtained results demonstrate the great potential of the studied biomass extracts to be transformed into valuable food additives, food supplements, or nutraceuticals with promising neuroprotective properties.

Membrane Permeability and Aqueous Stability Study of Linear and Cyclic Diarylheptanoids from Corylus maxima.

Seven diarylheptanoids were isolated from Corylus maxima by flash chromatography and semipreparative high-performance liquid chromatography (HPLC) and identified by Orbitrap® mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy as linear diarylheptanoids: hirsutanonol-5-O-β-D-glucopyranoside (1), platyphyllonol-5-O-β-D-xylopyranoside (4), platyphyllenone (5); and cyclic derivatives: alnusonol-11-O-β-D-glucopyranoside (6), alnusone (7), giffonin F (8), carpinontriol B (9). Cyclic diarylheptanoids are reported in C. maxima for the first time. The aqueous stability of the isolated compounds and other characteristic constituents of C. maxima, oregonin (2), hirsutenone (3), quercitrin (10) and myricitrin (11) was evaluated at pH 1.2, 6.8 and 7.4. The passive diffusion of the constituents across biological membranes was investigated by parallel artificial membrane permeability assay for the gastrointestinal tract (PAMPA-GI) and the blood–brain barrier (PAMPA-BBB) methods. The cyclic diarylheptanoid aglycones and quercitrin were stable at all investigated pH values, while a pH-dependent degradation of the other compounds was observed. A validated ultrahigh-performance liquid chromatography-diode-array detection (UHPLC-DAD) method was utilized for the determination of compound concentrations. The structures of the degradation products were characterized by UHPLC-Orbitrap® MS. Platyphyllenone and alnusone possessed log Pe values greater than −5.0 and −6.0 in the PAMPA-GI and PAMPA-BBB studies, respectively, indicating their ability to cross the membranes via passive diffusion. However, only alnusone can be considered to have both good aqueous stability and satisfactory membrane penetration ability.

2-Aminopyridines with a shortened amino sidechain as potent, selective, and highly permeable human neuronal nitric oxide synthase inhibitors

A series of potent, selective, and highly permeable human neuronal nitric oxide synthase inhibitors (hnNOS) based on the 2-aminopyridine scaffold with a shortened amino sidechain is reported. A rapid and simple protocol was developed to access these inhibitors in excellent yields. Neuronal nitric oxide synthase (nNOS) is a novel therapeutic target for the treatment of various neurological disorders. The major challenges in designing nNOS inhibitors in humans focus on potency, selectivity over other isoforms of nitric oxide synthases (NOSs), and blood–brain barrier permeability. In this context, we discovered a promising inhibitor, 6-(3-(4,4-difluoropiperidin-1-yl)propyl)-4-methylpyridin-2-amine dihydrochloride, that exhibits excellent potency for rat (Ki = 46 nM) and human nNOS (Ki = 48 nM), respectively, with 388-fold human eNOS and 135-fold human iNOS selectivity. It also displayed excellent permeability (Pe = 17.3 × 10-6 cm s-1) through a parallel artificial membrane permeability assay, a model for blood–brain permeability. We found that increasing lipophilicity by incorporation of fluorine atoms on the backbone of the inhibitors significantly increased potential blood–brain barrier permeability. In addition to measuring potency, isoform selectivity, and permeability of NOS inhibitors, we also explored structure–activity relationships via structures of key inhibitors complexed to various isoforms of nitric oxide synthases.

In silico-in vitro estimation of lipophilicity and permeability association for succinimide derivatives using chromatographic anisotropic systems and parallel artificial membrane permeability assay.

Passive permeability is one of the key features that determine absorbability and one of the most studied properties in the early phases of drug development. Newly synthesized succinimide derivatives from two different series (1-aryl-3-methylsuccinimides and 1-aryl-3-ethyl-3-methylsuccinimides) with high biological potential have been subjected to estimation of their passive permeability and their association with (a) experimentally obtained anisotropic lipophilicity, (b) in silico-calculated lipophilicity and (c) in silico-predicted permeability and absorbability. Non-cellular-based parallel artificial membrane permeability assay was applied for quantifying their passive permeation, expressed as logPapp . Passive permeation was governed by the lipophilicity of the analysed compounds, and anisotropic lipophilicity was related with statistically significant passive transcellular diffusion (r2 = 0.614, P < 0.001). Moreover, experimentally determined passive permeability, logPapp , was statistically significantly associated with both in silico-predicted absorption constant, ka (r2 = 0.7886, P < 0.001), and human intestinal absorption (HIA) in percentage (r2 = 0.484, P < 0.001), respectively. However, there was no statistically significant relationship between experimentally obtained permeability on non-cellular-based model and in silico-predicted Caco-2 permeability based on the predictions conducted on two different software. Based on the obtained results, anisotropic systems are promising surrogates for determining lipophilicity, except for compounds with acidic functional groups that are completely ionized under (pH = 7.4).

Antinociceptive and modulatory effect of pathoplastic changes in spinal glia of a TLR4/CD14 blocking molecule in two models of pain in rat.

The role of spinal glia in the development and maintenance of chronic pain has become over the last years a subject of increasing interest. In this regard, toll-like receptor 4 (TLR4) signaling has been proposed as a major trigger mechanism. Hence, in this study we explored the implications of TLR4 inhibition in the periphery and primarily in the CNS, focusing on the impact this inhibition renders in pain development and glia activation in the dorsal horn in two models of pain. Making use of a synthetic cluster of differentiation 14 (CD14)/TLR4 antagonist, the effect of TLR4 blockade on tactile allodynia and heat hyperalgesia was evaluated in osteoarthritic and postoperative rat models. An in vitro parallel artificial membrane permeation assay was performed to determine the proneness of the drug to permeate the blood-brain barrier prior to systemic and central administration. Findings suggest a dominant role of peripheral TLR4 in the model of incisional pain, whilst both peripheral and central TLR4 seem to be responsible for osteoarthritic pain. That is, central and peripheral TLR4 may be differently involved in the etiopathology of diverse types of pain what potentially seems a promising approach in the management of pain.

Formulation and Characterization of Raloxifene Nanostructured Lipid Carriers for Permeability and Uptake Enhancement Applications.

Raloxifene (RLX), a biopharmaceutical classification system (BCS) class II drug, is a selective estrogen receptor modulator (SERM) having an estrogenic effect on the bone and an antiestrogenic effect on the endometrium and breast. Low solubility, high permeability, high metabolism, and low bioavailability are the characteristics of raloxifene. Although 60% is absorbed orally, raloxifene shows extremely poor bioavailability (2%) owing to its low solubility and extensive (>90%) intestinal/hepatic first-pass metabolism. Hence, it becomes important to increase the solubility of raloxifene to enhance its bioavailability. In this study, raloxifene nanostructured lipid carriers (RNLCs) were prepared using the melt dispersion ultrasonication method. The prepared RNLCs were characterized, and the in vitro studies were carried out in the human epithelial breast cancer cell line (MCF-7). The RNLCs had a size of 114.8 ± 0.98 nm and a zeta potential of +9.21 ± 0.58 mV. Transmission electron microscopy (TEM) images showed particle size ranging from 65 to 120 nm. With an entrapment efficiency of 75.04% ± 2.75%, the RNLCs showed sustained release over 7 days compared with the raloxifene drug solution. The prepared RNLCs were successfully taken up by the MCF-7 cells in a time-dependent manner, and the RNLCs showed increased cell cytotoxicity compared with the raloxifene drug. Using the parallel artificial membrane permeability assay (PAMPA), the permeability rate for raloxifene solution was calculated to be 8 × 10-6 cm/s, and for the RNLCs, it was calculated to be 17.8 × 10-6 cm/s. Hence, from the permeability rate calculated, we could conclude that raloxifene, when formulated as nanostructured lipid carriers, showed increased permeability. Overall, the prepared RNLCs were found to be superior to the raloxifene drug as such.

Solubility and Permeability Enhancement of Oleanolic Acid by Solid Dispersion in Poloxamers and γ-CD.

Oleanolic acid (OA) is a pentacyclic triterpenoid widely found in the Oleaceae family, and it represents 3.5% of the dry weight of olive leaves. OA has many pharmacological activities, such as hepatoprotection, anti-inflammatory, anti-oxidant, anti-diabetic, anti-tumor, and anti-microbic activities. Its therapeutic application is limited by its poor water solubility, bioavailability, and permeability. In this study, solid dispersions (SDs) were developed to overcome these OA limitations. Solubility studies were conducted to evaluate different hydrophilic polymers, drug-to-polymer ratios, and preparation methods. Poloxamer 188, Poloxamer 407, and γ-CD exhibited the highest increases in terms of OA solubility, regardless of the method of preparation. Binary systems were characterized using differential scanning calorimetry (DSC), X-ray diffraction (XRPD), and Fourier transform infrared spectroscopy (FTIR). In addition, pure compounds and SDs were analyzed using scanning electron microscopy (SEM) in order to observe both the morphology and the particle surface. In vitro dissolution studies were performed for P407, P188, and γ-CD SDs. Preparation using the solvent evaporation method (SEM) produced the highest increase in the dissolution profiles of all three polymers with respect to the OA solution. Finally, the effect of SDs on OA permeability was evaluated with an in vitro parallel artificial membrane permeability assay (PAMPA). The formulation improved passive permeation across the simulated barrier due to OA increased solubility. The dissolution and PAMPA results indicate that the amorphization of OA by SD preparation could be a useful method to enhance its oral absorption, and it is also applicable on an industrial scale.

Biopharmaceutics studies applied to goyazensolide: a drug candidate from Lychnophora species.

To predict the substance's behaviour in vivo and determine the viability of the bioactive substance to become a drug, this work aimed to evaluate the biopharmaceutics characteristics of goyazensolide. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were applied for the characterization of goyazensolide. The biopharmaceutics characteristics were evaluated using in-silico and in-vitro (shake-flask and Parallel Artificial Membrane Permeability Assay) methods. DSC curve showed a single endothermic peak. According to the TG curve, goyazensolide has thermal stability close to 221.0°C and 210.0°C, under a nitrogen and oxygen atmosphere, respectively. In-silico data indicated that goyazensolide has high solubility and low permeability. The high solubility was confirmed by equilibrium solubility studies determined by the shake-flask method. The dose/solubility ratio values were 175.16 ml (pH 1.2), 194.99 ml (pH 4.5) and 222.07 ml (pH 6.8). The effective permeability of 0.03 × 10-6 cm/s was obtained for goyazensolide. This value is lower than furosemide (1.03 × 10-6 cm/s), confirming the low permeability of goyazensolide. Biopharmaceutics characteristics of goyazensolide are similar to drugs available on the market and attest to the feasibility of starting the process of developing a formulation containing this substance.

Mechanistic bottom-up estimation of passive drug absorption from the gastrointestinal tract: Comparison among primary cultured human intestinal cells, Caco-2 cells, artificial membrane, and animal scale-up.

The fraction of drug absorbed (Fa) from the intestine is an important parameter to characterize the pharmacokinetics of a drug. We aimed to search for an experimental system that provides the best parameters for estimating the effective permeability (Peff) used for the bottom-up prediction of Fa. The absorption kinetics of 12 passively absorbed drugs were simulated by a compartment absorption transit (CAT) model using absorption parameters from four different experimental systems: human intestinal epithelial cell (HIEC) monolayer, Caco-2 monolayer, parallel artificial membrane permeability assay (PAMPA), and in situ rat intestinal perfusion. All absorption parameters were obtained from the literature. The in vitro apparent permeability coefficient (Papp) and rat in situ Peff were converted to human Peff using a bottom-up approach for each region, based on the morphological features of the human intestine. The simulated Fa values were compared to the respective observed values. Furthermore, plasma concentration profiles of the drugs were simulated by convolution using the time-course of the absorption rate simulated using the Peff values calculated from the HIEC Papp. The Fa values were best predicted by using the Peff values calculated from HEIC, within a 1.3-fold range of observed Fa in 11 out of 12 drugs. The simulated Cmax values of pharmacokinetic simulation using HIEC Papp fell within a 1.5-fold range of observed values for all the drugs examined. The HIEC monolayer was identified as the most suitable permeation parameter for estimating Fa and Cmax using a morphological feature-based bottom-up approach.

Impact of Cyclization and Methylation on Peptide Penetration through Droplet Interface Bilayers.

Cell-penetrating peptides enter cells via diverse mechanisms, such as endocytosis, active transport, or direct translocation. For the design of orally delivered cell-penetrating peptides, it is crucial to know the contribution of these different mechanisms. In particular, the ability of a peptide to translocate through a lipid bilayer remains a key parameter for the delivery of cargos. However, existing approaches used to assess translocation often provide discrepant results probably because they have different sensitivities to the distinct translocation mechanisms. Here, we focus on the passive permeation of a range of hydrophobic cyclic peptides inspired by somatostatin, a somatotropin release-inhibiting factor. Using droplet interface bilayers (DIB), we assess the passive membrane permeability of these peptides and study the impact of the peptide cyclization and backbone methylation on translocation rates. Cyclization systematically improved the permeability of the tested peptides while methylation did not. By studying the interaction of the peptides with the DIB interfaces, we found membrane insertion and peptide intrinsic diffusion to be two independent factors of permeability. Compared to the industrial gold standard Caco-2 and parallel artificial membrane permeability assay (PAMPA) models, DIBs provide intermediate membrane permeability values, closer to Caco-2. Even for conditions where Caco-2 and PAMPA are discrepant, the DIB approach also gives results closer to Caco-2. Thereupon, DIBs represent a robust alternative to the PAMPA approach for predicting the permeability of peptides, even if the latter present extremely small structural differences.