Active pharmaceutical ingredients (APIs) in ionic liquids: An effective approach for API physiochemical parameter optimization

Extraction and Processing of Bioactive Phytoconstituents from Widely Used South African Medicinal Plants for the Preparation of Effective Traditional Herbal Medicine Products: A Narrative Review

Medicinal plants are sources of crude traditional herbal medicines that are utilized to reduce the risk of, treat, or manage diseases in most indigenous communities. This is due to their potent antioxidant and anti-inflammatory effects. It is estimated that about 80% of the population in developing countries rely on herbal traditional medicines for healthcare. This signifies the need for traditional herbal medicines, which are polyherbal formulations prepared by traditional health practitioners. This review examines preparatory steps to extract bioactive phytoconstituents and post-extraction processes to increase the potency of the extracted bioactive phytoconstituents. Achieving this will allow for the reduced use of plant materials and promote the sustainable use of the limited resource of medicinal plants, especially in our South African context. Electronic ethnobotanical books and online databases were used to find studies that focus on phytoconstituent extraction and post-extraction processing to enhance the potency of the extracted bioactive phytoconstituents. Modification of the extracted bioactive phytoconstituents to synthesize daughter compounds facilitates an enhancement in their potency and bioavailability. Based on the data collected through this review, the importance of understanding the properties of the targeted phytoconstituents is essential in selecting the required extraction method. This determines the quality and yield of extracted bioactive phytoconstituents.

New Ionic Liquid Forms of Antituberculosis Drug Combinations for Optimized Stability and Dissolution

Isoniazid (INH) and rifampicin (RIF) are the two main drugs used for the management of tuberculosis. They are often used as a fixed drug combination, but their delivery is challenged by suboptimal solubility and physical instability. This study explores the potential of active pharmaceutical ingredient-ionic liquids (API-ILs) to improve the physicochemical and pharmaceutical properties of INH and RIF. Antitubercular drugs, INH, or RIF, were paired with different counter ions (ascorbic acid (AsA), citric acid (CA), tartaric acid (TA), benzoic acid (BA), salicylic acid (SA), and p-amino salicylic acid (PAS)) using the solvent evaporation method. INH and RIF API-ILs were formed successfully using AsA and CA counter ions. IL formation was examined and analyzed using Fourier transform infrared (FTIR) spectroscopy, x-ray powder diffraction (XRPD), and polarized optical microscopy (POM). XRPD and POM confirmed their amorphous nature, while FTIR analysis demonstrated the contribution of hydrogen bonding to IL formation. IL formation enhanced the storage stability of the INH + RIF mixture in the presence of CA. Moreover, RIF-CA IL significantly increased the rate and extent of RIF dissolution. An effect that is unattainable with the RIF/CA physical mixture. Thus, API-IL formation not only enhances RIF dissolution but also facilitates the preparation of stable, compatible INH-RIF combinations.

Piperine solubility enhancement via DES formation: Elucidation of intermolecular interactions and impact of counterpart structure via computational and spectroscopic approaches

The development of new forms of existing APIs with enhanced physicochemical properties is critical for improving their therapeutic potential. In this context, ionic liquids (ILs) and deep eutectic solvents (DESs) have gained significant attention in recent years due to their unique properties and potential for solubility enhancement. In this study, we explore the role of different counterparts in the formation of IL/DESs with piperine (PI), a poorly water-soluble drug. After screening a library of fourteen counterpart molecules, ten liquid PI-counterpart systems were developed and investigated. Thermal analysis confirmed the formation of IL/DES, while computational and spectroscopic studies revealed that hydrogen bonding played a crucial role in the interaction between PI and the counterparts, confirming DES formation. The solubility enhancement of PI in these systems ranged from ∼ 36 % to 294 %, with PI-Oxalic acid (OA) exhibiting the highest saturation solubility (49.71 μg/mL) and PI-Ibuprofen (IB) the lowest (17.23 μg/mL). The presence of hydrogen bonding groups in counterparts was key to successful DES formation. A negative correlation was observed between solubility and logP (r =  - 0.75, p* = 0.0129), while a positive correlation was found between solubility and normalized polar surface area (PSA) (r = 0.68, p* = 0.029). PI-OA and PI-IB were located at the extreme ends of these regression lines, further validating the relationship between these properties and solubility enhancement. These findings highlight essential aspects of rational IL/DES design, optimizing their properties for broader applications.

Design, synthesis, analgesic, antibacterial and docking studies of novel 8-piperazinylcaffeine carboxylate ionic liquids

This paper presents a comprehensive evaluation of novel 8-piperazinylcaffeine carboxylate ionic liquids, including their design, synthesis, characterization, analgesic and antibacterial properties, as well as docking studies. These unique salts were produced by combining 8-piperazinyl caffeine (8-PC) with various carboxylic acids, some of which are commonly used nonsteroidal anti-inflammatory drugs (NSAIDs). Through in vivo experiments on female mice using the formalin test, the analgesic efficacy of different 8-PC salts with various NSAIDs was assessed. Results demonstrated that a majority of these salts exhibited significant analgesic activity when compared to NaIBP, a standard reference drug. Particularly noteworthy was the enhanced analgesic effect of the 8-PC's NSAIDs salts (11a, 11c-e, and 11k) compared to their corresponding sodium salts, which was attributed to the presence of the 8-PC cation (synergistic effect). Furthermore, all synthesized salts were subjected to in vitro testing against Gram-positive Staphylococcus aureus (PTCC 1133), Gram-negative Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (PTCC 1330) bacteria. Among them, salt 11k displayed notable antibacterial activity, especially against P. aeruginosa, a dangerous opportunistic pathogen. Additionally, docking analysis revealed strong binding of the synthesized 8-PC and NSAID salts to the active site of the COX-2 enzyme.

Ionic liquid-based formulation approaches for enhanced transmucosal drug delivery

The utilization of ionic liquids (ILs) in pharmaceutical drug delivery applications has seen significant expansion in recent years, owing to their distinctive characteristics and inherent adjustability. These innovative compounds can be used to tackle challenges associated with traditional dosage forms, such as polymorphism, inadequate solubility, permeability, and efficacy in topical drug delivery systems. Here, we provide a brief classification of ILs, and their effectiveness in augmenting transmucosal drug delivery approaches by improving the solubility and permeability of active pharmaceutical ingredients (APIs) by temporary mucus modulation aiding the paracellular transport of APIs, prolonging drug retention, and, thus, aiding controlled drug release across various mucosal surfaces. We also highlight potential advances in, and future perspectives of, IL-based formulations in mucosal drug delivery.

Review of ionic liquid and ionogel-based biomaterials for advanced drug delivery

Ionic liquids (ILs) play a crucial role in the design of novel materials. The ionic nature of ILs provides numerous advantages in drug delivery, acting as a green solvent or active ingredient to enhance the solubility, permeability, and binding efficiency of drugs. They could also function as a structuring agent in the development of nano/micro particles for drug delivery, including micelles, vesicles, gels, emulsion, and more. This review summarize the ILs and IL-based gel structures with their advanced drug delivery applications. The first part of review focuses on the role of ILs in drug formulation and the applications of ILs in drug delivery. The second part of review offers a comprehensive overview of recent drug delivery applications of IL-based gel. It aims to offer new perspectives and attract more attention to open up new avenues in the biomedical applications of ILs and IL-based gels.

Mechanisms of Biological Effects of Ionic Liquids: From Single Cells to Multicellular Organisms

The review presents a detailed discussion of the evolving field studying interactions between ionic liquids (ILs) and biological systems. Originating from molten salt electrolytes to present multiapplication substances, ILs have found usage across various fields due to their exceptional physicochemical properties, including excellent tunability. However, their interactions with biological systems and potential influence on living organisms remain largely unexplored. This review examines the cytotoxic effects of ILs on cell cultures, biomolecules, and vertebrate and invertebrate organisms. Our understanding of IL toxicity, while growing in recent years, is yet nascent. The established findings include correlations between harmful effects of ILs and their ability to disturb cellular membranes, their potential to trigger oxidative stress in cells, and their ability to cause cell death via apoptosis. Future research directions proposed in the review include studying the distribution of various ILs within cellular compartments and organelles, investigating metabolic transformations of ILs in cells and organisms, detailed analysis of IL effects on proteins involved in oxidative stress and apoptosis, correlation studies between IL doses, exposure times and resulting adverse effects, and examination of effects of subtoxic concentrations of ILs on various biological objects. This review aims to serve as a critical analysis of the current body of knowledge on IL-related toxicity mechanisms. Furthermore, it can guide researchers toward the design of less toxic ILs and the informed use of ILs in drug development and medicine.

Tuning of the Anti-Breast Cancer Activity of Betulinic Acid via Its Conversion to Ionic Liquids

Betulinic acid (BA) is a natural pentacyclic triterpene with diverse biological activities. However, its low water solubility limits its pharmaceutical application. The conversion of pharmaceutically active molecules into ionic liquids (ILs) is a promising strategy to improve their physicochemical properties, stability, and/or potency. Here, we report the synthesis and characterization of 15 novel ILs containing a cation ethyl ester of a polar, non-polar, or charged amino acid [AAOEt] and an anion BA. Except for [ValOEt][BA], we observed preserved or up to 2-fold enhanced cytotoxicity toward hormone-dependent breast cancer cells MCF-7. The estimated IC50 (72 h) values within the series varied between 4.8 and 25.7 µM. We found that the most cytotoxic IL, [LysOEt][BA]2, reduced clonogenic efficiency to 20% compared to that of BA. In addition, we evaluated the effect of a 72 h treatment with BA or [LysOEt][BA]2, the most cytotoxic compound, on the thermodynamic behavior of MCF-7 cells. Based on our data, we suggest that the charged amino acid lysine included in the novel ILs provokes cytotoxicity by a mechanism involving alteration in membrane lipid organization, which could be accompanied by modulation of the visco-elastic properties of the cytoplasm.

Active pharmaceutical ingredient-ionic liquids assisted follicular co-delivery of ferulic acid and finasteride for enhancing targeted anti-alopecia

Androgenetic alopecia (AGA) is the primary hair loss with impairing patients' quality of life. Finasteride (FIN) is an SRD5A2 inhibitor for AGA treatment, but oral FIN causes systemic adverse effects. Topical FIN delivery is anticipated to overcome this problem. Ferulic acid (FA) is a natural phenolic acid with vascular remodeling and anti-inflammatory effects. Herein, an active pharmaceutical ingredient ionic liquid (API IL) based on choline and FA (CF-IL) is for the first time constructed to load FIN for fabricating FIN CF-IL. CF-IL aims to act as carriers and cargos and enhance hair follicle (HF) co-delivery of FA and FIN for synergistic anti-alopecia. Thermal and spectroscopic analysis combined with quantum chemistry calculations and molecular dynamics confirm the formation of CF-IL. The CF-IL simultaneously increases the solubility of FA (∼648-fold) and FIN (∼686-fold), enhances the permeation and retention of FIN and FA through the follicular pathway, and promotes cellular uptake. FIN CFIL regulates the abnormal mRNA expressions in dihydrotestosterone-irritated hDPCs, and promotes hair regrowth in AGA mice in a combined manner with FIN and FA. These findings suggest that FA-based API IL is a promising approach for percutaneously co-delivering FA and FIN to HF, providing an enhanced targeting treatment for AGA.

Enhanced photocatalytic degradation of levofloxacin over heterostructured C3N4/Nb2O5 system under visible light

The growing usage of antibiotics and their subsequent release in water bodies have become a serious environmental concern. In this study, heterostructured photocatalysts C3N4/Nb2O5 have been synthesized using a simple hydrothermal method and applied to facilitate the degradation of the widely used antibiotic levofloxacin. The structural, morphological, and optical properties of the photocatalysts were characterized using XRD, SEM, TEM, UV-Vis and PL to establish the structure-property relationship. The type-II heterojunctions C3N4/Nb2O5 show remarkable activity under visible light irradiation, where Nb2O5 facilitates preferential adsorption of levofloxacin at the catalyst surface while C3N4 extends visible light absorption. This synergy resulted in superior catalytic performance (91%) in the optimized system, exceeding that of individual materials (Nb2O5 30% and C3N4 56%). The effect of catalyst dosage, pH, oxygen and point of zero is also investigated. The process is mainly photo-driven, and the trapping experiments reveal superoxide radicals as key species responsible for the degradation. Additionally, the adsorption behaviour, reformation of the degraded pollutant and reusability factors are evaluated to assess the practical feasibility of the photocatalytic system.

Development of mabuterol transdermal patch: Molecular mechanism study of ion-pair improving patch stability

This paper aimed to prepare a Mabuterol (MAB) patch for treating asthma by ion-pair strategy to overcome the drug's thermal instability and elucidate the molecular mechanisms of the stabilization effect. The formulation factor, including counter-ion and pressure-sensitive adhesive (PSA), was optimized by the stability and in vitro skin permeation studies. The molecular mechanism of ion-pair stability was characterized using TGA, Raman, FT-IR, NMR, XPS, and molecular modeling. The optimized patch comprised MAB-Lactic acid (MAB-LA) and hydroxyl adhesive (AAOH) as the matrix, with Q = 126.47 ± 9.75 μg/cm2 and Fabs = 75.27%. The increased TGA (213.11 °C), disproportionation energy (ΔG = 97.44 KJ), and ion-pair lifetime (Tlife = 2.21 × 103) indicated that the counter-ion improved MAB stability through strong ionic and hydrogen bonds with LA. The remaining drug content in the MAB-LA patch was 15% higher than that of the pure MAB patch after storage for 12 months at room temperature, which was visualized by Raman imaging. The interaction between MAB-LA and AAOH PSA via hydrogen bond decreased the diffusion rate and increased the drug stability further. This study successfully developed the MAB patch, which provided a reference for applying ion-pairing strategies to improve the stability of transdermal patches.

Ionic Levothyroxine Formulations: Synthesis, Bioavailability, and Cytotoxicity Studies

Thyroid diseases affect a considerable portion of the population, with hypothyroidism being one of the most commonly reported thyroid diseases. Levothyroxine (T4) is clinically used to treat hypothyroidism and suppress thyroid stimulating hormone secretion in other thyroid diseases. In this work, an attempt to improve T4 solubility is made through the synthesis of ionic liquids (ILs) based on this drug. In this context, [Na][T4] was combined with choline [Ch]+ and 1-(2-hydroxyethyl)-3-methylimidazolium [C2OHMiM] + cations in order to prepare the desired T4-ILs. All compounds were characterized by NMR, ATR-FTIR, elemental analysis, and DSC, aiming to check their chemical structure, purities, and thermal properties. The serum, water, and PBS solubilities of the T4-ILs were compared to [Na][T4], as well as the permeability assays. It is important to note an improved adsorption capacity, in which no significant cytotoxicity was observed against L929 cells. [C2OHMiM][T4] seems to be a good alternative to the commercial levothyroxine sodium salt with promising bioavailability.

Deep Eutectic Solvents Comprising Organic Acids and Their Application in (Bio)Medicine

Over the last years, we observed a significant increase in the number of published studies that focus on the synthesis and characterization of deep eutectic solvents (DESs). These materials are of particular interest mainly due to their physical and chemical stability, low vapor pressure, ease of synthesis, and the possibility of tailoring their properties through dilution or change of the ratio of parent substances (PS). DESs, considered as one of the greenest families of solvents, are used in many fields, such as organic synthesis, (bio)catalysis, electrochemistry, and (bio)medicine. DESs applications have already been reported in various review articles. However, these reports mainly described these components' basics and general properties without focusing on the particular, PS-wise, group of DESs. Many DESs investigated for potential (bio)medical applications comprise organic acids. However, due to the different aims of the reported studies, many of these substances have not yet been investigated thoroughly, which makes it challenging for the field to move forward. Herein, we propose distinguishing DESs comprising organic acids (OA-DESs) as a specific group derived from natural deep eutectic solvents (NADESs). This review aims to highlight and compare the applications of OA-DESs as antimicrobial agents and drug delivery enhancers-two essential fields in (bio)medical studies where DESs have already been implemented and proven their potential. From the survey of the literature data, it is evident that OA-DESs represent an excellent type of DESs for specific biomedical applications, owing to their negligible cytotoxicity, fulfilling the rules of green chemistry and being generally effective as drug delivery enhancers and antimicrobial agents. The main focus is on the most intriguing examples and (where possible) application-based comparison of particular groups of OA-DESs. This should highlight the importance of OA-DESs and give valuable clues on the direction the field can take.

Role and Recent Advancements of Ionic Liquids in Drug Delivery Systems

Advancements in the fields of ionic liquids (ILs) broaden its applications not only in traditional use but also in different pharmaceutical and biomedical fields. Ionic liquids "Solutions for Your Success" have received a lot of interest from scientists due to a myriad of applications in the pharmaceutical industry for drug delivery systems as well as targeting different diseases. Solubility is a critical physicochemical property that determines the drug's fate at the target site. Many promising drug candidates fail in various phases of drug research due to poor solubility. In this context, ionic liquids are regarded as effective drug delivery systems for poorly soluble medicines. ILs are also able to combine different anions/cations with other cations/anions to produce salts that satisfy the concept behind the ILs. The important characteristics of ionic liquids are the modularity of their physicochemical properties depending on the application. The review highlights the recent advancement and further applications of ionic liquids to deliver drugs in the pharmaceutical and biomedical fields.

Isopropyl Amino Acid Esters Ionic Liquids as Vehicles for Non-Steroidal Anti-Inflammatory Drugs in Potential Topical Drug Delivery Systems with Antimicrobial Activity

New derivatives of non-steroidal anti-inflammatory drugs were synthesized via conjugation with L-amino acid isopropyl esters. The characteristics of the physicochemical properties of the obtained pharmaceutically active ionic liquids were determined. It has been shown how the incorporation of various L-amino acid esters as an ion pair affects the properties of the parent drug. Moreover, the antimicrobial activity of the obtained compounds was evaluated. The proposed structural modifications of commonly used drugs indicate great potential for use in topical and transdermal preparations.