Evidence of the protective role of Carvacrol in a retinal degeneration animal model.

Neurodegenerative pathologies affecting the posterior segment of the eye, are characterized by being devastating and responsible for the majority of visual dysfunctions worldwide. These diseases are primarily degenerative, progressing chronically, and can inflict gradual harm to the optic nerve, retinal ganglion cells (RGC), photoreceptors, and other retinal cells. This retinal damage leads to a progressive loss of vision, marking these conditions as a significant health concern worldwide. The intravitreal administration of the phytochemical Carvacrol (CAR) is expected to demonstrate a neuroprotective and antiapoptotic effect on retinal cells, with a specific focus on RGC. This effect will be observed in a retinal degeneration model (RDM) in rabbits induced by cytotoxic and oxidative agents, namely glutamate (GLUT) and L-buthionine-S, R-sulfoximine (BSO). An in vivo study was conducted using New Zealand rabbits in which retinal damage was created to evaluate the effectiveness of CAR. The effectiveness of CAR on the functionality of retinal neuronal cells in RDM was evaluated using pupillary light reflection (PLR). Furthermore, the phytotherapeutic's influence on cell viability was determined through flow cytometry analysis. Finally, the neuroprotective and antiapoptotic capabilities of CAR were specifically scrutinized in RGC through histological studies, quantifying cell survival, and employing immunohistochemical assays to detect the apoptotic index (%) using the TUNEL technique. Our results demonstrated that CAR promoted the recovery of the pupillary contraction profile over time, maintaining the functionality of retinal cells as healthy controls. Additionally, it showed increased cell viability under oxidative and cytotoxic conditions given by GLUT-BSO agents. Finally, we found that CAR protects the survival of RGC and decreases the percentage of apoptotic cells when compared to RDM. CAR demonstrated to have positive effects on the functionality of photoreceptive nerve cells by restoring pupillary contraction. Likewise, it was shown to have neuroprotective and antiapoptotic effects when evaluated in a general and specific way on retinal nerve cells.

Piperine, quercetin, and curcumin identified as promising natural products for topical treatment of cutaneous leishmaniasis.

Leishmania braziliensis (L. braziliensis) causes cutaneous leishmaniasis (CL) in the New World. The costs and the side effects of current treatments render imperative the development of new therapies that are affordable and easy to administer. Topical treatment would be the ideal option for the treatment of CL. This underscores the urgent need for affordable and effective treatments, with natural compounds being explored as potential solutions. The alkaloid piperine (PIP), the polyphenol curcumin (CUR), and the flavonoid quercetin (QUE), known for their diverse biological properties, are promising candidates to address these parasitic diseases. Initially, the in vitro cytotoxicity activity of the compounds was evaluated using U-937 cells, followed by the assessment of the leishmanicidal activity of these compounds against amastigotes of L. braziliensis. Subsequently, a golden hamster model with stationary-phase L. braziliensis promastigote infections was employed. Once the ulcer appeared, hamsters were treated with QUE, PIP, or CUR formulations and compared to the control group treated with meglumine antimoniate administered intralesionally. We observed that the three organic compounds showed high in vitro leishmanicidal activity with effective concentrations of less than 50 mM, with PIP having the highest activity at a concentration of 8 mM. None of the compounds showed cytotoxic activity for U937 macrophages with values between 500 and 700 mM. In vivo, topical treatment with QUE daily for 15 days produced cured in 100% of hamsters while the effectiveness of CUR and PIP was 83% and 67%, respectively. No failures were observed with QUE. Collectively, our data suggest that topical formulations mainly for QUE but also for CUR and PIP could be a promising topical treatment for CL. Not only the ease of obtaining or synthesizing the organic compounds evaluated in this work but also their commercial availability eliminates one of the most important barriers or bottlenecks in drug development, thus facilitating the roadmap for the development of a topical drug for the management of CL caused by L. braziliensis.

Enhancing the Functional Properties of Tea Tree Oil: In Vitro Antimicrobial Activity and Microencapsulation Strategy.

In the context of addressing antimicrobial drug resistance in periocular infections, Tea Tree Oil (TTO) has emerged as a promising therapeutic option. This study aimed to assess the efficacy of TTO against bacterial strains isolated from ocular infections, with a particular focus on its ability to inhibit biofilm formation. Additionally, we designed and analyzed microcapsules containing TTO to overcome certain unfavorable physicochemical properties and enhance its inherent biological attributes. The quality of TTO was confirmed through rigorous analysis using GC-MS and UV-Vis techniques. Our agar diffusion assay demonstrated the effectiveness of Tea Tree Oil (TTO) against ocular bacterial strains, including Corynebacterium spp., coagulase-negative Staphylococcus spp., and Staphylococcus aureus, as well as a reference strain of Staphylococcus aureus (ATCC 25923). Notably, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for all tested microorganisms were found to be 0.2% and 0.4%, respectively, with the exception of Corynebacterium spp., which exhibited resistance to TTO. Furthermore, TTO exhibited a substantial reduction in biofilm biomass, ranging from 30% to 70%, as determined by the MTT method. Through the spray-drying technique, we successfully prepared two TTO-containing formulations with high encapsulation yields (80-85%), microencapsulation efficiency (90-95%), and embedding rates (approximately 40%). These formulations yielded microcapsules with diameters of 6-12 µm, as determined by laser scattering particle size distribution analysis, and exhibited regular, spherical morphologies under scanning electron microscopy. Importantly, UV-Vis analysis post-encapsulation confirmed the presence of TTO within the capsules, with preserved antioxidant and antimicrobial activities. In summary, our findings underscore the substantial therapeutic potential of TTO and its microcapsules for treating ocular infections.

Naringin: Nanotechnological Strategies for Potential Pharmaceutical Applications.

Polyphenols comprise a number of natural substances, such as flavonoids, that show interesting biological effects. Among these substances is naringin, a naturally occurring flavanone glycoside found in citrus fruits and Chinese medicinal herbs. Several studies have shown that naringin has numerous biological properties, including cardioprotective, cholesterol-lowering, anti-Alzheimer's, nephroprotective, antiageing, antihyperglycemic, antiosteoporotic and gastroprotective, anti-inflammatory, antioxidant, antiapoptotic, anticancer and antiulcer effects. Despite its multiple benefits, the clinical application of naringin is severely restricted due to its susceptibility to oxidation, poor water solubility, and dissolution rate. In addition, naringin shows instability at acidic pH, is enzymatically metabolized by ß-glycosidase in the stomach and is degraded in the bloodstream when administered intravenously. These limitations, however, have been overcome thanks to the development of naringin nanoformulations. This review summarizes recent research carried out on strategies designed to improve naringin's bioactivity for potential therapeutic applications.

Menthol carbonates as potent antiparasitic agents: synthesis and in vitro studies along with computer-aided approaches.

INTRODUCTION: Despite the number of deaths and the significant economic and social costs associated with Chagas, Leishmaniasis and Malaria diseases worldwide, available drugs are limited and have serious side effects and high toxicity for the patient. Therefore, there is an urgent need for safe, low-cost, and effective treatments. Natural products are an important source of bioactive compounds and there is current interest in finding natural bioactive molecules that can be used for treating these parasitic diseases. In the present study we proposed to evaluate the in vitro antiparasitic activity of new menthol derivatives against Trypanosoma cruzi, Leishmania braziliensis and Plasmodium falciparum; moreover, we propose to explore their mode of action through in silico approaches. MATERIAL AND METHODS: A series of carbonate prodrugs (1-9) were synthesized from menthol with different aliphatic alcohols. Spectroscopic techniques were used to confirm the structures of the synthesized compounds. The cytotoxicity of the compounds was assessed using U-937 cells. In vitro trypanocidal, leishmanicidal and antiplasmodial activity were evaluated using a T. cruzi, L. braziliensis and P. falciparum organism, respectively. In addition, in silico studies were also performed through molecular dynamics simulations and MM-PBSA analysis. RESULTS: The assay revealed that most of the compounds were highly active against intracellular amastigotes of T. cruzi and L. braziliensis, and had moderate activity against the total forms of P. falciparum. Compound 2 was one of the drugs that showed a high selectivity index (SI) for the three organisms evaluated. The prediction of the ADME properties suggests that all the compounds have drug-like molecular properties and the probability to be lead candidates. Finally, molecular dynamics simulations, and MM-PBSA studies indicate that menthol at the substrate binding site of TcDHODH, LbDHODH and PfDHODH is structurally stable in the same order as the natural substrate; also, interactions of menthol with residues involved in the inhibition of TcDHODH and PfDHODH proteins were predicted. CONCLUSIONS: The present study demonstrates that menthol prodrugs are promising antiparasitic agents; however, the mechanisms of action proposed in this study need to be experimentally verified by future enzymatic assays.

Eugenol carbonate activity against Plasmodium falciparum, Leishmania braziliensis, and Trypanosoma cruzi.

Neglected tropical diseases are a major health problem throughout the world, and there are few effective and safe drugs. In this study, we report the design and synthesis of a novel series of carbonates of eugenol using different aliphatic alcohols and N,N-carbonyldiimidazole. Spectroscopic techniques, including 1 H nuclear magnetic resonance (NMR), 13 C NMR, Fourier transform infrared, and high-resolution mass spectrometry, were used to confirm the structures of the synthesized compounds. In vitro and in silico studies of prodrugs of eugenol were performed to determine their antiplasmodial, trypanocidal, and leishmanicidal activities, and also their cytotoxicity. Compounds were highly active against Leishmania braziliensis and Plasmodium falciparum, whereas the activity shown for Trypanosoma cruzi was moderate. Molecular docking was used to determine a possible mode of action of eugenol against the dihydroorotate dehydrogenase of the three parasites (TcDHODH, LbDHODH, and PfDHODH). Notably, the docking results showed that eugenol not only has binding energy similar to that of the natural substrate (-7.2 and -7.1, respectively) but also has interactions with relevant biological residues of PfDHODH. This result indicates that eugenol could act as a substrate for PfDHODH in the pyrimidine biosynthesis pathway of P. falciparum. In conclusion, the combination of certain aliphatic alcohols and eugenol through a carbonate bond could significantly increase the antiparasitic activity of this class of compounds, which merits further studies.

Anti-echinococcal activity of menthol and a novel prodrug, menthol-pentanol, against Echinococcus multilocularis.

Alveolar echinococcosis is one of the most dangerous parasitic zoonoses. This disease, widely distributed in the northern hemisphere, is caused by the metacestode stage of the tapeworm Echinococcus multilocularis. All surgical and non-surgical patients should perform chemotherapy with benzimidazoles, mainly with albendazole. However, the efficacy of albendazole is variable due to its deficient pharmacokinetic properties. Therefore, the need to find new therapeutic alternatives for the treatment of alveolar echinococcosis is evident. Menthol is a natural compound of low toxicity, used in industries such as cosmetics and gastronomy and generally recognized as safe by the Food and Drug Administration. In addition, menthol has important pharmacological effects and is effective against a wide variety of organisms. The development of prodrugs allows improving the pharmacokinetic properties of the parental drug. To improve lipophilicity and therefore the bioavailability of menthol, a novel prodrug called menthol-pentanol was developed by masking the functional polar group of menthol by linking n-pentanol by a carbonate bond. The aim of the current work was to evaluate the in vitro and in vivo efficacy of menthol and menthol-pentanol against E. multilocularis. Menthol-pentanol had a greater protoscolicidal effect than menthol. In addition, the prodrug demonstrated a similar clinical efficacy to albendazole. The increase in lipophilicity of the prodrug with respect to menthol was reflected in an increase in its antiparasitic activity against E. multilocularis. Thus, menthol-pentanol appears as a promising candidate for further evaluation as a potential alternative for the treatment of alveolar echinococcosis.

Validation of Ultraviolet-visible and High-performance Liquid Chromatographic Methods for the Determination of Sodium p-Aminosalicylate and m-Aminophenol in a New Pharmaceutical Formulation.

Sodium p-aminosalycilate is an orphan drug used in patients affected with Multidrug-resistant Tuberculosis. Two methods, high-performance liquid chromatographic and ultraviolet spectrophotometric for the quantitative determination of sodium p-aminosalycilate and its degradation product m-aminophenol in a new pharmaceutical formulation, powder for extemporaneous reconstitution, were developed in the present work. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection, and limit of quantification were also studied. Chromatography was carried out by reverse-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic/dibasic phosphate buffer and methanol (42.5:42.5:15 v/v/v) with 1.9 g of hidroxytetrabutylammonium ionic pare adjusted to pH 7.0 with orthophosphoric acid. The ultraviolet spectrophotometric method was performed at 254 nm and 280 nm for quantification of sodium p-aminosalycilate and m-aminophenol, respectively. The proposed methods are highly sensitive, precise, and accurate and can be used for the reliable quantification of sodium p-aminosalycilate in the new alternative formulation. High-performance liquid chromatographic approach demonstrated to be a stability-indicating method, therefore suitable for the investigation of the chemical stability of sodium p-aminosalycilate.

Preformulation studies of novel 5'-O-carbonates of lamivudine with biological activity: solubility and stability assays.

As a part of preformulation studies, the aim of this work was to examine the solubility and stability of a series of 5'-O-carbonates of lamivudine with proven antihuman immunodeficiency virus activity. Solubility studies were carried out using pure solvents (water, ethanol and polyethylene glycol 400 [PEG 400]), as well as cosolvents in binary mixture systems (water-ethanol and water-PEG 400). These ionizable compounds showed that their aqueous solubility is decreasing as the carbon length of the substituent moiety increases, but being enhanced as the pH was reduced from 7.4 to 1.2. Thus, 3TC-Metha an active compound of the series, with an intrinsic solubility at 25 °C of 17 mg/mL, was about 70 times more soluble than 3TC-Octa (0.24 mg/mL), and at pHs of 1.2, 5.8 and 7.4 had intrinsic solubilities of 36.48, 19.20 and 15.40 mg/mL, respectively. In addition, the solubility was enhanced significantly by using ethanol and PEG 400 as cosolvents. A stability study was conducted in buffer solutions at pH 1.2, 5.8, 7.4 and 13.0 and in human plasma at 37 °C. Stability-indicating high-performance liquid chromatography procedure was found to be selective, sensitive and accurate for these compounds and good recovery, linearity and precision were also observed.

Antiviral activity of 5'-O-carbonate-2',3'-dideoxy-3'-thiacytidine prodrugs against hepatitis B virus in HepG2 2.2.15 cells.

The antiviral activities of lamivudine (3TC; 2',3'-dideoxy-3'-thiacytidine) and six 5'-O-carbonates of 3TC were determined by inhibition of hepatitis B virus (HBV) replication in HepG2 2.2.15 cells. HBV DNA in cell supernatants was quantified by real-time polymerase chain reaction (PCR). The results showed that 3TC-Etha was six times more active than 3TC and that 3TC-Buta, 3TC-Hexa and 3TC-Octa were approximately three times more active than 3TC. In contrast, 3TC-Penta and 3TC-Metha showed anti-HBV activity similar to that of the parent compound 3TC. In conclusion, 5'-O-carbonates of 3TC appear to be promising candidates as anti-HBV compounds. This modification could optimise the use of 3TC, a well-tolerated, effective and inexpensive drug, in monotherapy or combined therapy for chronic HBV infections as well as human immunodeficiency virus (HIV)/HBV co-infections.

Synthesis and anti-HIV activity of novel 2',3'-dideoxy-3'-thiacytidine prodrugs.

We report here the synthesis of a novel series of 5'-O-carbonates of 3TC, using different aliphatic alcohols and N,N-carbonyldiimidazol. Its antiviral activity was determined in peripheral blood mononuclear cells (PBMCs) showing some carbonate derivatives with an activity similar to or better than 3TC, except 3TC-Metha and 3TC-2Pro with less activity. In vitro assays in PBMCs have demonstrated that cytotoxicity increases as the carbon chain length of the alcohol moiety increases, showing compounds with a normal chain length of n=2-5 good selective index, compared to the parent drug. Thus, this work is an important contribution leading to the suppression of HIV replication.