Usefulness of liquid-crystal oral formulations to enhance the bioavailability and skin tissue targeting of p-amino benzoic acid as a model compound

The immunomodulatory effects of vitamins in cancer

Nutrition may affect animal health due to the strong link between them. Also, diets improve the healing process in various disease states. Cancer is a disease, where the harmful consequences of tumors severely impair the body. The information regarding the evolution of this disease is extrapolated from human to animal because there are few specific studies regarding nutritional needs in animals with cancer. Thus, this paper aims to review the literature regarding the immunomodulatory effects of vitamins in mammal cancer. An adequate understanding of the metabolism and requirements of nutrients for mammals is essential to ensuring their optimal growth, development, and health, regardless of their food sources. According to these: 1) Some species are highly dependent on vitamin D from food, so special attention must be paid to this aspect. Calcitriol/VDR signaling can activate pro-apoptotic proteins and suppress anti-apoptotic ones. 2) Nitric oxide (NO) production is modulated by vitamin E through inhibiting transcription nuclear factor kappa B (NF-κB) activation. 3) Thiamine supplementation could be responsible for the stimulation of tumor cell proliferation, survival, and resistance to chemotherapy. 4) Also, it was found that the treatment with NO-Cbl in dogs is a viable anti-cancer therapy that capitalizes on the tumor-specific properties of the vitamin B12 receptor. Therefore, diets should contain the appropriate class of compounds in adequate proportions. Also, the limitations of this paper are that some vitamins are intensively studied and at the same time regarding others, there is a lack of information, especially in animals. Therefore, some subsections are longer and more heavily debated than others.

An efficient synthesis of O- and N- alkyl derivatives of 4-aminobenzoic acid and evaluation of their anticancer properties

A series of twenty alkyl derivatives (2-21) of 4-amino benzoic acid (1, PABA) have been prepared using potassium carbonate and opportune alkylating agents under simple and mild reaction conditions. Compounds (16-21) are reported for the first time. Electron impact mass spectrometry (EIMS), Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (1H-NMR) spectroscopic techniques were adopted for the characterization of these analogues. In the present study, the cytotoxic screening of sixteen compounds (3, 5-11, 13 and 15-21) was also achieved against lung (NCI-H460) and oral squamous carcinoma (CAL-27) cell lines. Compound 20 has shown magnificent inhibitory properties against NCI-H460 cell line (IC50 15.59 and 20.04 µM, respectively) at a lower dose than that of the control (cisplatin; IC50 21.00 µM). One-way analysis of variance (ANOVA), t-test and Pearson correlation coefficient (PCC) have been performed to determine the reliability of current data through statistical package for the social sciences (SPSS).

Lyotropic liquid crystalline phases: Drug delivery and biomedical applications

Liquid crystal (LC)-based nanoformulations may efficiently deliver drugs and therapeutics to targeted biological sites. Lyotropic liquid crystalline phases (LLCPs) have received much interest in recent years due to their unique structural characteristics of both isotropic liquids and crystalline solids. These LLCPs can be utilized as promising drug delivery systems to deliver drugs, proteins, peptides and vaccines because of their improved drug loading, stabilization, and controlled drug release. The effects of molecule shape, microsegregation, and chirality are very important in the formation of liquid crystalline phases (LCPs). Homogenization of self-assembled amphiphilic lipids, water and stabilizers produces LLCPs with different types of mesophases, bicontinuous cubic (cubosomes) and inverse hexagonal (hexosomes). Moreover, many studies have also shown higher bioadhesivity and biocompatibility of LCs due to their structural resemblance to biological membranes, thus making them more efficient for targeted drug delivery. In this review, an outline of the engineering aspects of LLCPs and polymer-based LLCPs is summarized. Moreover, it covers parenteral, oral, transdermal delivery and medical imaging of LC in targeting various tissues and is discussed with a scope to design more efficient next-generation novel nanosystems. In addition, a detailed overview of advanced liquid crystal-based drug delivery for vaccines and biomedical applications is reviewed.

Design, synthesis and molecular modeling of isatin-aminobenzoic acid hybrids as antibacterial and antibiofilm agents

Number of factors, including newly emerging infectious diseases and an increase in multi-drug resistant microbial pathogens with particular relevance for Gram-positive bacteria, make the treatment of infectious diseases in hospital-based healthcare a major challenge in the medical community. 4-Aminobenzoic acid (PABA), has demonstrated a variety of biological actions particularly, antimicrobial activity. In our study we coupled this vitamin-like molecule with different isatin derivatives. We investigated the antibacterial activity of the synthesized Schiff's bases. The compounds showed high selective activity against Gram-positive bacteria and showed weak or no activity against both Gram-negative bacteria and fungi. Compound 2a showed highest activity against S. aureus and B. subtilis (MIC 0.09 mmol/L). Additionally, these substances exhibit strong anti-B. Subtilis biofilm formation. We were able to shed insight on the binding mode of these new inhibitors using in silico docking of the compounds in the binding sites of a 3D structure of B. subtilis histidine kinase/Walk. The binding free energy of the compound 2a to the catalytic domain walk, of histidine kinase enzyme of B. subtilis bacteria, was calculated using molecular mechanics/generalized born surface area scoring. The key residues for macromolecule-ligand binding were postulated. The optimized 3D protein-ligand binding modes shed light on the B. subtilis HK/Walk-ligand interactions that afford a means to assess binding affinity to design new HK/Walk inhibitor as antibacterial agents.

Recent Advances in the Development of Liquid Crystalline Nanoparticles as Drug Delivery Systems

Due to their distinctive structural features, lyotropic nonlamellar liquid crystalline nanoparticles (LCNPs), such as cubosomes and hexosomes, are considered effective drug delivery systems. Cubosomes have a lipid bilayer that makes a membrane lattice with two water channels that are intertwined. Hexosomes are inverse hexagonal phases made of an infinite number of hexagonal lattices that are tightly connected with water channels. These nanostructures are often stabilized by surfactants. The structure's membrane has a much larger surface area than that of other lipid nanoparticles, which makes it possible to load therapeutic molecules. In addition, the composition of mesophases can be modified by pore diameters, thus influencing drug release. Much research has been conducted in recent years to improve their preparation and characterization, as well as to control drug release and improve the efficacy of loaded bioactive chemicals. This article reviews current advances in LCNP technology that permit their application, as well as design ideas for revolutionary biomedical applications. Furthermore, we have provided a summary of the application of LCNPs based on the administration routes, including the pharmacokinetic modulation property.

Recent advances in versatile inverse lyotropic liquid crystals

Owing to the rapid and significant progress in advanced materials and life sciences, nanotechnology is increasingly gaining in popularity. Among numerous bio-mimicking carriers, inverse lyotropic liquid crystals are known for their unique properties. These carriers make accommodation of molecules with varied characteristics achievable due to their complicated topologies. Besides, versatile symmetries of inverse LCNPs (lyotropic crystalline nanoparticles) and their aggregating bulk phases allow them to be applied in a wide range of fields including drug delivery, food, cosmetics, material sciences etc. In this review, in-depth summary, discussion and outlook for inverse lyotropic liquid crystals are provided.

Development and Evaluation of Biocompatible Topical Petrolatum-liquid Crystal Formulations with Enhanced Skin Permeation Properties

Transdermal administration represents a major advancement over traditional pharmaceutical dosing methods. However, a frequent issue is inadequate penetration of the active medicinal component through the skin. As a result, in the current research, we assessed the utility of newly developed petrolatum-liquid crystal (LC) ointment formulations and characterized their biocompatibility and function in the transdermal drug delivery system. To begin, we made petrolatum-LC formulations using p-aminobenzoic acid (PABA) as a hydrophilic model molecule. The viscosity, small-angle X-ray scattering (SAXS), particle diameters, and z-potential were measured to assess the physicochemical properties of the formulations. A dialysis release technique was used to evaluate medication release from petrolatum-LC formulations. In vitro testing was performed to determine the potential to enhance skin penetration. The biocompatibility of the produced formulations was further tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and single-cell gel electrophoresis. According to the results, the novel petrolatum-LC formulations are biocompatible and effective in forming hexosomes. PABA skin penetration was significantly enhanced by the new petrolatum-LC formulations. According to this study, petroleum-LC formulations are more efficient than commercial petrolatum in terms of skin permeability improvement and PABA skin concentration.

Ketoconazole-p aminobenzoic cocrystal, an improved antimycotic drug formulation, does not induce skin sensitization on the skin of BALBc mice

Fungal infections are a growing global health problem. Therefore, our group has synthetized and characterized an improved antimycotic by co-crystallization of ketoconazole and para-amino benzoic acid, named KET-PABA. The aim was to increase bioavailability, biocompatibility, and efficiency of the parent drug-ketoconazole. Based on our previous results showing the cocrystal improved physical properties, such as stability in suspension, solubility, as well as antimycotic efficiency compared to ketoconazole, the current study investigated the local possible side effects induced on the skin of BALBc mice by the application of KET-PABA cocrystal, in view of a further use as a topically applied antimycotic drug. A specific test (mouse ear-swelling test) was used, combined with the histopathological examination and the measurement of pro and anti-inflammatory cytokines and inflammation mediators. KET-PABA application was safe, without signs of skin sensitization shown by the mouse ear sensitization test, or histopathology. KET-PABA strongly inhibited proinflammatory cytokines such as IL1 α, IL1 β, IL6 and TNF α, and other proinflammatory inducers such as NRF2, compared to vehicle. KET-PABA had no effect on the levels of the anti-inflammatory cytokine IL10, or proinflammatory enzyme COX2 and had minimal effects on the activation of the NF-κB pathway. Overall, KET-PABA application induced no sensitization, moreover, it decreased the skin levels of proinflammatory molecules. The lack of skin sensitization effects on BALBc mice skin along with the inhibition of the proinflammatory markers show a good safety profile for topical applications of KET-PABA and show promise for a further clinical use in the treatment of cutaneous mycosis.

Liquid Crystalline Phases for Enhancement of Oral Bioavailability

Liquid crystalline phases (LCPs) are generated upon lipolysis of ingested lipids in the gastrointestinal tract. The breaking off and subsequent evolution of LCPs produce more advanced vesicular and micellar structures which facilitate oral absorption of lipids, as well as co-loaded drug entities. Owing to sustained or controlled drug release, bioadhesiveness, and capability of loading drugs of different properties, LCPs are promising vehicles to implement for enhancement of oral bioavailability. This review aims to provide an overview on the classification, preparation and characterization, in vivo generation and transformation, absorption mechanisms, and encouraging applications of LCPs in enhancement of oral bioavailability. In addition, we comment on the merits of LCPs as oral drug delivery carriers, as well as solutions to industrialization utilizing liquid crystalline precursor and preconcentrate formulations.

Vibrational spectroscopy of the cryogenically cooled O- and N-protomers of 4-Aminobenzoic acid: Tag effects, isotopic labels, and identification of the E,Z isomer of the O-protomer

4-Aminobenzoic acid (4ABA) is a biologically relevant, small organic molecule with two protonation sites: the amino group (N-protomer) and the carboxyl group (O-protomer). The O-protomer is energetically preferred in the gas-phase, while the higher energy N-protomer can be trapped using aprotic solvents such as acetonitrile during electrospray ionization. Here, we focus on the structure of the O-protomer, which can occur in three low-lying isomeric forms that result from different orientations of the OH groups relative to the benzene ring. We report the vibrational spectra of both N- and O-protomers of the cryogenically cooled ions in the gas phase over the spectral range 800-4000 cm-1. The bands arising from the OH stretches are isolated from the nearby NH stretching fundamentals using isotopic labeling as well as by analysis of the shifts in these fundamentals upon attachment of D2 and N2 molecules to the OH groups of the O-protomer. The spectra of isomers derived from the different locations of the adducts were isolated using two-color, IR-IR photofragmentation spectroscopy. The docking motifs by which the O-protomer binds to another 4ABA molecule is also explored and found to feature a bifurcated arrangement involving attachment of both OH groups of the protonated head group to the carbonyl group of the neutral partner.

4-Aminobenzoic Acid Derivatives: Converting Folate Precursor to Antimicrobial and Cytotoxic Agents

4-aminobenzoic acid (PABA), an essential nutrient for many human pathogens, but dispensable for humans, and its derivatives have exhibited various biological activities. In this study, we combined two pharmacophores using a molecular hybridization approach: this vitamin-like molecule and various aromatic aldehydes, including salicylaldehydes and 5-nitrofurfural, via imine bond in one-step reaction. Resulting Schiff bases were screened as potential antimicrobial and cytotoxic agents. The simple chemical modification of non-toxic PABA resulted in constitution of antibacterial activity including inhibition of methicillin-resistant Staphylococcus aureus (minimum inhibitory concentrations, MIC, from 15.62 µM), moderate antimycobacterial activity (MIC ≥ 62.5 µM) and potent broad-spectrum antifungal properties (MIC of ≥ 7.81 µM). Some of the Schiff bases also exhibited notable cytotoxicity for cancer HepG2 cell line (IC50 ≥ 15.0 µM). Regarding aldehyde used for the derivatization of PABA, it is possible to tune up the particular activities and obtain derivatives with promising bioactivities.

Cubic and hexagonal liquid crystals as drug carriers for the transdermal delivery of triptolide

The purpose of this study was to develop and evaluate triptolide-loaded cubic and hexagonal liquid crystals for transdermal drug delivery systems (TDDSs). We prepared and characterized triptolide-loaded lyotropic liquid crystals and evaluated for their percutaneous permeation properties in vitro and in vivo. We then used the adjuvant arthritic rat model and HaCaT cells to analyze the pharmacodynamics and conduct cell-stimulating studies of these liquid crystals. The optimized preparations were identified as cubic and hexagonal phase structures, respectively. Moreover, the in vitro percutaneous penetration studies demonstrated that compared to the homemade triptolide gel, cubic and hexagonal liquid crystals could significantly increase the percutaneous cumulative penetration of drugs within 48 h. Besides, the results of skin-blood synchronous microdialysis showed that the triptolide concentration in skin was higher than that in blood, and the cubic and hexagonal liquid crystals significantly increased the bioavailability of triptolide. Triptolide-loaded cubic and hexagonal liquid crystals presented excellent anti-arthritic effects, alleviating paw swelling and inhibiting inflammation by downregulating the levels of TNF-α and IL-1β. In vitro cell-stimulating studies displayed that triptolide-loaded cubic and hexagonal liquid crystals exhibited no obvious toxicity, which exhibited that triptolide-loaded cubic and hexagonal liquid crystals were remarkable biocompatibility. Collectively, triptolide-loaded cubic and hexagonal liquid crystals represented a promising candidate for rheumatoid arthritis therapy.

Non-Lamellar Lyotropic Liquid Crystalline Lipid Nanoparticles for the Next Generation of Nanomedicine

Nonlamellar lyotropic liquid crystalline (LLC) lipid nanomaterials have emerged as a promising class of advanced materials for the next generation of nanomedicine, comprising mainly of amphiphilic lipids and functional additives self-assembling into two- and three-dimensional, inverse hexagonal, and cubic nanostructures. In particular, the lyotropic liquid crystalline lipid nanoparticles (LCNPs) have received great interest as nanocarriers for a variety of hydrophobic and hydrophilic small molecule drugs, peptides, proteins, siRNAs, DNAs, and imaging agents. Within this space, there has been a tremendous amount of effort over the last two decades elucidating the self-assembly behavior and structure-function relationship of natural and synthetic lipid-based drug delivery vehicles in vitro, yet successful clinical translation remains sparse due to the lack of understanding of these materials in biological bodies. This review provides an overview of (1) the benefits and advantages of using LCNPs as drug delivery nanocarriers, (2) design principles for making LCNPs with desirable functionalities for drug delivery applications, (3) current understanding of the LLC material-biology interface illustrated by more than 50 in vivo, preclinical studies, and (4) current patenting and translation activities in a pharmaceutical context. Together with our perspectives and expert opinions, we anticipate that this review will guide future studies in developing LCNP-based drug delivery nanocarriers with the objective of translating them into a key player among nanoparticle platforms comprising the next generation of nanomedicine for disease therapy and diagnosis.

Antiadhesion effect of the C17 glycerin ester of isoprenoid-type lipid forming a nonlamellar liquid crystal

Postoperative adhesion is a relevant clinical problem that causes a variety of clinical complications after abdominal surgery. The objective of this study is to develop a liquid-type antiadhesion agent and evaluate its efficacy in preventing tissue adhesion in a rat peritoneal adhesion model. The liquid-type agent was prepared by submicron-sized emulsification of C17 glycerin ester (C17GE), squalene, pluronic F127, ethanol, and water with a high-pressure homogenizer. The primary component was C17GE, which is an amphiphilic lipid of one isoprenoid-type hydrophobic chain and can form two phases of self-assembly nonlamellar liquid crystals. The C17GE agent consisted of nanoparticles with an internal inverted hexagonal phase when evaluated by small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM). Upon contact with the biological tissue, this agent formed a thin membrane with a bioadhesive property. After this agent was applied to a sidewall injury of rats, it showed a percentage average of adhesion significantly less than that obtained with the Seprafilm® antiadhesion membrane in a rat model. Additionally, the retention of the agent prolonged at the applied site in the peritoneal cavity of rats. In conclusion, the C17GE agent is promising as an antiadhesion material. STATEMENT OF SIGNIFICANCE: Postoperative adhesion remains a common adverse effect. Although various materials have been investigated, there are few products commercially available to prevent adhesion. For the sheet-type agent, it is inconvenient to be applied through small laparotomy, especially in laparoscopic surgery. Additionally, the liquid-type agent currently used requires a complicated procedure to spray at the targeted site. Our liquid-type antiadhesion agent can form liquid crystals and act as a thin membrane-like physical barrier between the peritoneum and tissues to prevent adhesion. Indeed, the antiadhesion agent used in our present study significantly prevents adhesion compared with the antiadhesion membrane most used clinically. Moreover, our agent is highly stable by itself and easy to use in laparoscopic surgery, thus leading to a promising new candidate as an antiadhesion material.

Self-Assembled Lipid Cubic Phase and Cubosomes for the Delivery of Aspirin as a Model Drug

Three-dimensionally organized lipid cubic self-assemblies and derived oil-in-water emulsions called "cubosomes" are attractive for various biotechnological applications due to their ability to be loaded with functional molecules and their associated sustained release properties. Here, we employed both of these lipid-based systems for the delivery of a model drug, aspirin, under comparable conditions. Studies were performed by varying drug-to-lipid ratio and the type of release medium, water and phosphate buffer saline (PBS). Release rates were determined using UV-vis spectroscopy, and small-angle X-ray scattering was used to confirm the type of self-assembled nanostructures formed in these lipid systems. The release from the bulk lipid cubic phase was sustained as compared to that of dispersed cubosomes, and the release in PBS was more efficient than in water. The tortuosity of the architecture, length of the diffusion pathway, type of nanostructure, and physicochemical interaction with the release media evidently contribute to these observations. This work is particularly important as it is the first report where both of these nanostructured lipid systems have been studied together under similar conditions. This work provides important insights into understanding and therefore controlling the release behavior of lipid-based drug nanocarriers.

Spotlight on Biomimetic Systems Based on Lyotropic Liquid Crystal

The behavior of lyotropic biomimetic systems in drug delivery was reviewed. These behaviors are influenced by drug properties, the initial water content, type of lyotropic liquid crystals (LLC), swell ability, drug loading rate, the presence of ions with higher or less kosmotropic or chaotropic force, and the electrostatic interaction between the drug and the lipid bilayers. The in vivo interaction between LCC-drugs, and the impact on the bioavailability of drugs, was reviewed. The LLC with a different architecture can be formed by the self-assembly of lipids in aqueous medium, and can be tuned by the structures and physical properties of the emulsion. These LLC lamellar phase, cubic phase, and hexagonal phase, possess fascinating viscoelastic properties, which make them useful as a dispersion technology, and a highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix for drug delivery. In addition, the biodegradable and biocompatible nature of lipids demonstrates a minimum toxicity and thus, they are used for various routes of administration. This review is not intended to provide a comprehensive overview, but focuses on the advantages over non modified conventional materials and LLC biomimetic properties.