Challenges and Opportunities for Drug Discovery in Developing Countries: The Example of Cutaneous Leishmaniasis

The global prevalence of antibiotic self-medication among the adult population: systematic review and meta-analysis

BACKGROUND

Antibiotic self-medication (ASM) is when a person takes antibiotics without a prescription or consulting a healthcare professional. These practices contribute to the misuse of medicines and antibiotic resistance which is a growing global health threat that can lead to longer hospital stays, higher healthcare costs, and increased mortality rates. Though various studies have been conducted on ASM in different countries, there has not yet been a systematic review that comprehensively assesses the problem in the entire globe. Hence, this systematic review and meta-analysis aimed to evaluate the global pooled prevalence of antibiotic self-medication and the reasons for its practice.

METHOD

A systematic search of electronic registers and databases was conducted on PubMed, Medline, Embase, Scopus, Web of Science, Google Scholar, and gray literature including institutional repositories, and national health databases. It used carefully selected keywords and indexing terms in the past ten years. The Joanna Briggs Institute's critical checklist extracted relevant data after appraisal. Narrative analysis was used for descriptive data while Comprehensive Meta-Analysis (CMA) Software was used to analyze quantitative data. Statistics were used to look for heterogeneity, publication bias, and correlations. Sensitivity tests and sub-group analysis were employed to compare outcomes. A p-value < 0.05 was considered significant in all cases.

RESULTS

Seventy-one studies were included in this systematic review and meta-analysis. The total number of participants was 63,251 with sample sizes ranging from 110 to 15,526. In primary outcomes, ASM ranged from 0.65 to 92.2%. The pooled prevalence of ASM globally was 43.0% (95% CI: 38.0, 48.1%). A high degree of heterogeneity across studies was shown with I2 = 99.2%, p < 0.001 assuming a random effect model. In subgroup analysis, the highest ASM pooled prevalence was 55.2% (95% CI: 47.2, 63.2) in sub-Saharan Africa followed by the Middle East, North Africa, and Greater Arabia at 48.3% (95% CI: 38.3, 58.4), Europe at 34.7% (95% CI:18.0, 56.4), and Asia at 25.8% (95% CI: 18.6, 34.6). Students have been identified as the major users of ASM at 62.1% (95% CI: 53.7, 69.7). The meta-regression showed a coefficient of 0.0365, -0.0117, and -0.0001 for a year of publication, recall time, and total sample size, respectively. Publication bias was demonstrated from the asymmetrical distribution of the funnel plot, and the Eggers regression p-value was greater than 0.05 (0.264). Moreover, knowledge of antibiotics (46.19% (95% CI: 27.99, 65.46)), previous successful experiences (39.13% (95% CI: 30.13, 48.93)), and perceiving illness as minor (38.10% (95% CI: 27.19, 50.37)) were the top three reasons pooled proportion for practicing ASM.

CONCLUSION

ASM practice was higher among African and student users. The previous successful experience was the most frequent reason reported. Educational level, gender, and age were often mentioned as predictor factors. Hence, designing interventional approaches that consider the different burdens among the target population and tackle the reasons for the practices might benefit averting antimicrobial resistance.

In Vitro and In Silico Assessment of Antileishmanial Potential of Novel Tri- and Penta-Valent Antimony Complexes With Phenolic Ligands

Leishmaniasis, caused by protozoan parasites of the genus Leishmania, affects nearly 12 million people annually worldwide, and has limited, highly toxic therapeutic options. This study reports the synthesis, in vitro and in silico evaluations of four novel antimony complexes (3a-3d) as potent and safe antileishmanial agents. The complexes were synthesized using Sb-salts with different phenolic ligands and characterized by elemental analysis, FT-IR and NMR spectroscopic techniques. Structural parameters were further evaluated via DFT studies. The antileishmanial activity of these complexes (3a-3d) was assessed in vitro against promastigote and axenic amastigote forms of Leishmania tropica, showing promising potential as antileishmanial agents. Complex 3a and 3c were particularly active, with IC50 values of 10.8 ± 2.1 and 11.0 ± 2.0 μmol/L against promastigotes, and 20.14 ± 6.11 and 27.72 ± 0.13 μmol/L against amastigotes, respectively. Molecular docking analysis against receptor protein (PDB ID: 8FI6) from genus Leishmania revealed high binding conformations of synthesized molecules within the active cavity of the target protein. With the lowest Ki value of 1.25 and a pattern of hydrophobic π-interactions and strong conventional hydrogen bonds, complex 3d demonstrated excellent binding affinities within the active pocket. Notably, these complexes exhibited low cytotoxicity, compared to the standard antileishmanial drugs, TA (potassium antimonyl tartrate) and AmB (Amphotericin B), with hemolysis rates of < 12% for all complexes. Our findings suggest that these complexes (3a-3d) are promising candidates for the development of new, safer antileishmanial therapies, combining potent activity against L. tropica with significantly lower cytotoxicity compared to existing treatments.

AI-powered drug discovery for neglected diseases: accelerating public health solutions in the developing world

The emergence of artificial intelligence (AI) in drug discovery represents a transformative development in addressing neglected diseases, particularly in the context of the developing world. Neglected diseases, often overlooked by traditional pharmaceutical research due to limited commercial profitability, pose significant public health challenges in low- and middle-income countries. AI-powered drug discovery offers a promising solution by accelerating the identification of potential drug candidates, optimising the drug development process, and reducing the time and cost associated with bringing new treatments to market. However, while AI shows promise, many of its applications are still in their early stages and require human validation to ensure the accuracy and reliability of predictions. Additionally, AI models are limited by the availability of high-quality data, which is often sparse in regions where neglected diseases are most prevalent. This viewpoint explores the application of AI in drug discovery for neglected diseases, examining its current impact, related ethical considerations, and the broader implications for public health in the developing world. It also highlights the challenges and opportunities presented by AI in this context, emphasising the need for ongoing research, ethical oversight, and collaboration between public health stakeholders to fully realise its potential in transforming global health outcomes.

Fexinidazole optimization: enhancing anti-leishmanial profile, metabolic stability and hERG safety

The lack of adequate anti-leishmanial therapies has led to the continued suffering of millions of people from developing nations. Moreover, optimism for a therapeutic intervention by fexinidazole was dashed due to the inability to maintain cures and control unwanted side effects. To solve these shortcomings, the structural elements of fexinidazole responsible for anti-leishmanial activity and toxicities were explored. Accordingly, a systematic analog design approach was taken for the synthesis of 24 novel analogs. We established the structural features important for activity and identified modifications that improved the hERG receptor safety and liver microsomal metabolic stability. Compared to fexinidazole, the S-configured imidazolooxazole analog 51 exhibited 25-fold greater potency against miltefosine resistant L. donovani amastigotes, greater metabolic stability and little hERG receptor inhibition. Replacement of the toxicophore nitro group for a cyano group resulted in a complete loss of anti-leishmanial activity. The SAR findings should be useful in the further development of this important class of anti-leishmanial agents.

Souza AB, Levita DP, Mello CC, da Silva AFM, dos Santos TC, Ronconi CM. Innovating Leishmaniasis Treatment: A Critical Chemist's Review of Inorganic Nanomaterials

Leishmaniasis, a critical Neglected Tropical Disease caused by Leishmania protozoa, represents a significant global health risk, particularly in resource-limited regions. Conventional treatments are effective but suffer from serious limitations, such as toxicity, prolonged treatment courses, and rising drug resistance. Herein, we highlight the potential of inorganic nanomaterials as an innovative approach to enhance Leishmaniasis therapy, aligning with the One Health concept by considering these treatments' environmental, veterinary, and public health impacts. By leveraging the adjustable properties of these nanomaterials─including size, shape, and surface charge, tailored treatments for various diseases can be developed that are less harmful to the environment and nontarget species. We review recent advances in metal-, oxide-, and carbon-based nanomaterials for combating Leishmaniasis, examining their mechanisms of action and their dual use as standalone treatments or drug delivery systems. Our analysis highlights a promising yet underexplored frontier in employing these materials for more holistic and effective disease management.

Techniques and Strategies in Drug Design and Discovery

The process of drug discovery constitutes a highly intricate and formidable undertaking, encompassing the identification and advancement of novel therapeutic entities [...].

Nitazoxanide and quercetin co-loaded nanotransfersomal gel for topical treatment of cutaneous leishmaniasis with macrophage targeting and enhanced anti-leishmanial effect

Purpose

Anti-leishmanial medications administered by oral and parenteral routes are less effective for treatment of cutaneous leishmaniasis (CL) and cause toxicity, hence targeted drug delivery is an efficient way to improve drug availability for CL with reduced toxicity. This study aimed to develop, characterize and evaluate nitazoxanide and quercetin co-loaded nanotransfersomal gel (NTZ-QUR-NTG) for the treatment of CL.

Methods

NTZ-QUR-NT were prepared by thin film hydration method and were statistically optimized using Box-Behnken design. To ease the topical delivery and enhance the retention time, the NTZ-QUR-NT were dispersed in 2 % chitosan gel. Moreover, in-vitro drug release, ex-vivo permeation, macrophage uptake, cytotoxicity and anti-leishmanial assays were performed.

Results

The optimized formulation indicated mean particle size 210 nm, poly dispersity index (PDI) 0.16, zeta potential (ZP) -15.1 mV and entrapment efficiency (EE) of NTZ and QUR was 88 % and 85 %, respectively. NTZ-QUR-NT and NTZ-QUR-NTG showed sustained release of the incorporated drugs as compared to the drug dispersions. Skin permeation of NTZ and QUR in NTZ-QUR-NTG was 4 times higher in comparison to the plain gels. The NTZ-QUR-NT cell internalization was almost 10-folds higher than NTZ-QUR dispersion. The cytotoxicity potential (CC50) of NTZ-QUR-NT (71.95 ± 3.32 μg/mL) was reduced as compared to NTZ-QUR dispersion (49.77 ± 2.15 μg/mL. A synergistic interaction was found between NTZ and QUR. Moreover, in-vitro anti-leishmanial assay presented a lower IC50 value of NTZ-QUR-NT as compared to NTZ-QUR dispersion. Additionally, a significantly reduced lesion size was observed in NTZ-QUR-NTG treated BALB/c mice, indicating its antileishmanial potential.

Conclusion

It can be concluded that nanotransfersomal gel has the capability to retain and permeate the incorporated drugs through stratum corneum and induce synergetic anti-leishmanial effect of NTZ and QUR against cutaneous leishmaniasis.

Burden of neglected tropical diseases and access to medicine and diagnostics in Ethiopia: a scoping review

BACKGROUND

More than 1.7 billion people are affected by neglected tropical diseases (NTDs) worldwide. Forty percent of the NTD-affected people live in Africa with the poorest, most vulnerable, and hard to reach geographical areas. The NTDs cause significant social and economic burden and deepen marginalization and stigmatization. The World Health Organization's current roadmap for NTD aims to prevent, control, eliminate, or eradicate 20 tropical diseases. Ethiopia experiences a high burden of these diseases, but current access to diagnostics, medicine, and/or care has been little explored to inform the country's NTD strategic plan. The overall purpose of the scoping review was to map and characterize the burden of NTDs and challenges in access to diagnostics, medicine, and/or care in Ethiopia.

METHODS

A systematic search of evidence was conducted in PubMed, Cochrane Library, and Google Scholar from January 2000 until May 2022, without restrictions of language or study design. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Review was followed for screening of studies. Key findings were extracted and narrated qualitatively.

RESULTS

The search resulted in 4532 articles, of which 105 met the inclusion criteria and were included in the scoping review under three themes: burden of NTDs, access to diagnostics, medicine and/or care, and key barriers. Although gains have been made in the prevention and control of NTDs in Ethiopia, the burden remains high, and progress in access to diagnostics, medicine/drugs, and/or care is very slow. Poverty, poor quality of life, and underfunding of NTD programs decelerate the process of NTD elimination program in the country.

CONCLUSIONS

The scoping review identified a considerable number of studies on the burden of NTDs in Ethiopia and strategies for diagnosis, treatment, and/or care; however, there is a paucity of evidence on the suitability and potential benefits of novel diagnostic technologies and medicines in the country. A regular review and analysis of such country-level evidence is important to inform the country NTDs roadmap and local implementation strategies.

Antileishmanial Activity of Clinanthus milagroanthus S. Leiva & Meerow (Amaryllidaceae) Collected in Peru

Leishmaniasis is a worldwide infectious parasitic disease caused by different species of protozoa of the genus Leishmania, which are transmitted to animals and humans through the bite of insects of the Psychodidae family. In the present work, the antileishmanial activity of an alkaloid extract of the bulbs of Clinanthus milagroanthus S. Leiva & Meerow (Amaryllidaceae) was evaluated in vitro, in vivo, and in silico against the parasite Leishmania braziliensis, and the chemical profile of the sample was determined by GC-MS analysis. At concentrations of 1, 10, and 100 µg·mL−1, the alkaloid extract presented inhibition percentages of 8.7%, 23.1%, and 98.8%, respectively, against L. braziliensis with a p < 0.05, and IC50 values of 18.5 ± 0.3 µg·mL−1. Furthermore, at a dose of 1.0 mg·kg−1, a greater decrease in lesion size was observed (90%) for in vivo assays, as well as a decrease in infection (96%), finding no significant differences (p > 0.05) in comparison with amphotericin B (92% and 98%, respectively). Eleven alkaloids were identified in C. milagroanthus bulbs: galanthamine, vittatine/crinine, 8-O-demethylmaritidine, anhydrolycorine, 11,12-dehydroanhydrolycorine, hippamine, lycorine, 2-hydroxyanhydrolycorine, 7-hydroxyclivonine, 2α-hydroxyhomolycorine, and 7-hydroxyclivonine isomer. A molecular model of Leishmania braziliensis trypanothione reductase (TRLb) was built using computational experiments to evaluate in silico the potential of the Amaryllidaceae alkaloid identified in C. milagroanthus toward this enzyme. The structures galanthamine, 7-hydroxyclivonine isomer, and crinine showed better estimated free energy of binding than the reference compound, amphotericin B. In conclusion, this is the first in vitro, in vivo, and in silico report about the antileishmanial potential and alkaloid profiling of the extract of C. milagroanthus bulbs, which could become an interesting source of bioactive molecules.

The effects of medicinal herbs and marine natural products on wound healing of cutaneous leishmaniasis: A systematic review

This study aimed to investigate the effects of medicinal herbs and marine natural products on wound healing of cutaneous leishmaniasis. To carry out this literature review, the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) instructions were used. Articles on the potential of medicinal plants and natural substances of marine origin against wound healing of cutaneous leishmaniasis were explored. The scientific databases considered were PubMed, Science Direct, Google Scholar, Web of Science, Scopus, and SpringerLink. The scientific documents collected were mainly scientific articles, books, book chapters, and doctoral thesis. The research considered 73 manuscripts published in the period from 1990 to 2020. From all the data collected, it appears that the scientific literature is rich in medicinal herbs and marine products to be valorized in the wound healing of cutaneous leishmaniasis. We have identified 15 medicinal plants traditionally used in the management of healing or ulcer of cutaneous leishmaniasis, 32 medicinal plants whose efficacy has been demonstrated in vitro or in vivo against cutaneous leishmaniasis, 5 marine products active against cutaneous leishmaniasis. It is also clear that the option of medicinal herbs/marine products in the management of cutaneous leishmaniasis is less expensive and allows to avoid the side effects of conventional products. It is necessary to encourage the development of dermatological topicals for the management of cutaneous leishmaniasis based on the data collected. In vivo research should be intensified on medicinal herbs traditionally used in wound healing of cutaneous leishmaniasis.

Green Approach: ''A Forwarding Step for Curing Leishmaniasis-A Neglected Tropical Disease''

The present review focuses on a dreaded vector-mediated leishmaniasis, with the existing therapeutic approaches including a variety of drugs along with their limitations, the treatment with natural compounds, and different types of metal/metal oxide nanoparticles (NPs). As evidenced, various metallic NPs, comprising silver, silver oxide, gold, zinc oxide, titanium, lead oxide, etc., played a curative role to treat leishmaniasis, are also presented. Keeping in view the advance success of vaccines against the prevalent dreaded diseases in the past and the present scenario, efforts are also being made to develop vaccines based on these NP formulations.

Colombian Contributions Fighting Leishmaniasis: A Systematic Review on Antileishmanials Combined with Chemoinformatics Analysis

Leishmaniasis is a parasitic morbid/fatal disease caused by Leishmania protozoa. Twelve million people worldwide are appraised to be currently infected, including ca. two million infections each year, and 350 million people in 88 countries are at risk of becoming infected. In Colombia, cutaneous leishmaniasis (CL) is a public health problem in some tropical areas. Therapeutics is based on traditional antileishmanial drugs, but this practice has several drawbacks for patients. Thus, the search for new antileishmanial agents is a serious need, but the lack of adequately funded research programs on drug discovery has hampered its progress. Some Colombian researchers have conducted different research projects focused on the assessment of the antileishmanial activity of naturally occurring and synthetic compounds against promastigotes and/or amastigotes. Results of such studies have separately demonstrated important hits and reasonable potential, but a holistic view of them is lacking. Hence, we present the outcome from a systematic review of the literature (under PRISMA guidelines) on those Colombian studies investigating antileishmanials during the last thirty-two years. In order to combine the general efforts aiming at finding a lead against Leishmania panamensis (one of the most studied and incident parasites in Colombia causing CL) and to recognize structural features of representative compounds, fingerprint-based analyses using conventional machine learning algorithms and clustering methods are shown. Abstraction from such a meta-description led to describe some function-determining molecular features and simplify the clustering of plausible isofunctional hits. This systematic review indicated that the Colombian efforts for the antileishmanials discovery are increasingly intensified, though improvements in the followed pathways must be definitively pursued. In this context, a brief discussion about scope, strengths and limitations of such advances and relationships is addressed.

Indole: The After Next Scaffold of Antiplasmodial Agents?

Malaria remains a global public health problem due to the uphill fight against the causative Plasmodium parasites that are relentless in developing resistance. Indole-based antiplasmodial compounds are endowed with multiple modes of action, of which inhibition of hemozoin formation is the major mechanism of action reported for compounds such as cryptolepine, flinderoles, and isosungucine. Indole-based compounds exert their potent activity against chloroquine-resistant Plasmodium strains by inhibiting hemozoin formation in a mode of action different from that of chloroquine or through a novel mechanism of action. For example, dysregulating the sodium and osmotic homeostasis of Plasmodium through inhibition of PfATP4 is the novel mechanism of cipargamin. The potential of developing multi-targeted compounds through molecular hybridization ensures the existence of indole-based compounds in the antimalarial pipeline.