Trypanocidal Mechanism of Action and in silico Studies of p-Coumaric Acid Derivatives

Synthesis, antimicrobial activity, and toxicological evaluation of a p-coumaric acid derivative as a potential new antibacterial agent

AIMS

Bacterial infections have a profound impact on human health and require continuous development of medical treatments. They remain an important area of research due to their ability to adapt and develop resistance to available therapies. This research aims to identify an additional molecule as a potential future option for the treatment of bacterial infections.

METHODS AND RESULTS

4-Chlorobenzyl p-coumarate was tested to evaluate its activity against bacterial strains in both planktonic and biofilm forms, its possible mode of action, and its toxicity through in silico, in vitro, and in vivo approaches. The molecule exhibited significant activity against Gram-positive bacteria leading to their elimination within 24 h. It induced morphological alterations on the surface and within the cells, ultimately causing cell lysis. The compound reduced bacterial biofilm, penetrated the extracellular matrix, and reached cells within the biofilm, disrupting its architecture. Toxicological assessments in predictive models were promising, showing low cytotoxic effects on human cells and no systemic toxicity.

CONCLUSIONS

4-Chlorobenzyl p-coumarate proved to be a promising compound for proposing new investigative hypotheses considering its effect on multidrug-resistant and non-resistant Gram-positive bacteria.

Semisynthetic Ecdysteroid Cinnamate Esters and tert-Butyl Oxime Ether Derivatives with Trypanocidal Activity

The parasite Trypanosoma cruzi is the causative agent of Chagas disease, a neglected tropical disease that affects the lives of millions of indigenous people in Latin America. As medications to treat Chagas disease are limited to the application of benznidazole and nifurtimox, which are not ideal treatments for the chronic stage of the disease, the search for new antichagasic drug candidates is an important need. Ecdysone has previously been shown to interfere with the life cycle of T. cruzi. Here, we report the biological profiling and subsequent semisynthetic structure optimization of 47 ecdysteroids against T. cruzi with the aim of identifying selective trypanocidal ecdysteroids. Two moderately trypanocidal pharmacophores were identified: ecdysteroids containing a 6-tert-butyl oxime ether and a cinnamic ester moiety. These functional groups were combined into the structures of four new semisynthetic ecdysteroids (44-47), among which 44 exerted potent and selective trypanocidal activity (IC50 < 2 μM). Cellular infection assays showed that ecdysteroid 44 potently and efficiently inhibited amastigote replication as determined by trypomastigote release after cellular infection with an IC50 of 2.7 ± 0.1 μM. The compound was similarly potent to benznidazole (IC50 = 3.8 ± 0.7 μM) and more than 5-fold more cytotoxic toward T. cruzi over RAW264.7 host macrophages. Overall, the ecdysteroid cinnamate ester 44 is a novel trypanocidal lead structure that needs to be further characterized in follow-up studies.

Molecular Insights on Coffee Components as Chemical Antioxidants

Coffee is not only a delicious beverage but also an important dietary source of natural antioxidants. We live in a world where it is impossible to avoid pollution, stress, food additives, radiation, and other sources of oxidants that eventually lead to severe health disorders. Fortunately, there are chemicals in our diet that counteract the hazards posed by the reactive species that trigger oxidative stress. They are usually referred to as antioxidants; some of them can be versatile compounds that exert such a role in many ways. This review summarizes, from a chemical point of view, the antioxidant effects of relevant molecules found in coffee. Their mechanisms of action, trends in activity, and the influence of media and pH in aqueous solutions, are analyzed. Structure-activity relationships are discussed, and the protective roles of these compounds are examined. A particular section is devoted to derivatives of some coffee components, and another one to their bioactivity. The data used in the analysis come from theoretical and computational protocols, which have been proven to be very useful in this context. Hopefully, the information provided here will pro-mote further investigations into the amazing chemistry contained in our morning coffee cup.   Resumen. El café no solo es una bebida deliciosa, sino también una importante fuente dietética de antioxidantes naturales. Vivimos en un mundo donde es imposible evitar la contaminación, el estrés, los aditivos alimentarios, la radiación y otras fuentes de oxidantes que eventualmente conducen a trastornos de salud graves. Afortunadamente, existen sustancias químicas en nuestra dieta que contrarrestan los peligros planteados por las especies reactivas que desencadenan el estrés oxidativo. Por lo general, se les denomina antioxidantes; algunos de ellos pueden ser compuestos versátiles que ejercen dicho papel de muchas maneras. Este artículo de revisión resume, desde un punto de vista químico, los efectos antioxidantes de moléculas relevantes encontradas en el café. Se analizan sus mecanismos de acción, tendencias en la actividad y la influencia del medio y el pH en soluciones acuosas. Se discuten las relaciones estructura-actividad, y se examinan los roles protectores de estos compuestos. Se dedica una sección particular a los derivados de algunos componentes del café, y otra a su bioactividad. Los datos utilizados en el análisis provienen de protocolos teóricos y computacionales, que han demostrado ser muy útiles en este contexto. Se espera que la información proporcionada aquí promueva investigaciones futuras sobre la química contenida en nuestra taza de café matutina.

Synergistic Interactions between Selected β-Lactam Antibiotics and Cinnamic Acid and Its Chosen Derivatives

Staphylococcus epidermidis, a component of human microbiota, may also cause life-threatening opportunistic infections. These are becoming increasingly common infections associated with the implantation of various implants. Due to the exhaustion of antibiotic resources, new substances with antimicrobial activity are being sought. The present study examined the antibacterial effect of cinnamic acid and its derivatives and their combinations with β-lactam antibiotics on the growth of Staphylococcus epidermidis strains isolated from vascular infections. The data obtained during the research indicated that cinnamic acid and its derivatives, sinapic acid, ferulic acid, and p-coumaric acid, have weak antibacterial activity (MIC values at the level of 2048 and 4096 mg/L). The combination of cinnamic acid and its derivatives with β-lactam antibiotics increases the effectiveness of their action and may demonstrate various pharmacological effects depending on the established cutoff.

Antifungal Activity, Mode of Action, and Cytotoxicity of 4-Chlorobenzyl p-Coumarate: A Promising New Molecule

Fungal infections represent a serious health problem worldwide. The study evaluated the antifungal activity of 4-chlorobenzyl p-coumarate, an unprecedented semi-synthetic molecule. Docking molecular and assay experiments were conducted to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC), mode of action, effect on growth, fungal death kinetics, drug association, effects on biofilm, micromorphology, and against human keratinocytes. The investigation included 16 strains of Candida spp, including C. albicans, C. krusei, C. glabrata, C. tropicalis, C. dubliniensis, C. lusitaniae, C. utilis, C. rugosa, C. guilhermondi, and C. parapsilosis. Docking analysis predicted affinity between the molecule and all tested targets. MIC and MFC values ranged from 3.9 μg/mL (13.54 μM) to 62.5 μg/mL (217.01 μM), indicating a probable effect on the plasma membrane. The molecule inhibited growth from the first hour of testing. Association with nystatin proved to be indifferent. All concentrations of the molecule reduced fungal biofilm. The compound altered fungal micromorphology. The tested compound exhibited an IC50 of 7.90±0.40 μg/mL (27.45±1.42 μM) for keratinocytes. 4-chlorobenzyl p-coumarate showed strong fungicidal effects, likely through its action on the plasma membrane and alteration of fungal micromorphology, and mildly cytotoxic to human keratinocytes.

Antifungal activity against Candida albicans of methyl 3,5-dinitrobenzoate loaded nanoemulsion

The objective of this study was to evaluate the antifungal activity of free methyl 3,5 dinitrobenzoate (MDNB) and its nanoemulsion (MDNB-NE) against strains of Candida albicans. Additionally, a molecular modeling study was also carried out to propose the mechanism of action and toxicity of MDNB. These results demonstrated the MDNB-NE presented a droplet size of 181.16 ± 3.20 nm and polydispersity index of 0.30 ± 0.03. MDNB and MDNB-NE inhibited the growth of all strains with minimum inhibitory concentrations of 0.27-1.10 mM. The biological results corroborated the molecular model, which pointed to a multi-target antifungal mechanism of action for MDNB in C. albicans. The study could serve as a basis for further research involving compounds with nitro groups with antifungal.

Molecular Docking and Molecular Dynamics Simulations in Related to Leishmania donovani: An Update and Literature Review

Leishmaniasis, a disease caused by Leishmania parasites and transmitted via sandflies, presents in two main forms: cutaneous and visceral, the latter being more severe. With 0.7 to 1 million new cases each year, primarily in Brazil, diagnosing remains challenging due to diverse disease manifestations. Traditionally, the identification of Leishmania species is inferred from clinical and epidemiological data. Advances in disease management depend on technological progress and the improvement of parasite identification programs. Current treatments, despite the high incidence, show limited efficacy due to factors like cost, toxicity, and lengthy regimens causing poor adherence and resistance development. Diagnostic techniques have improved but a significant gap remains between scientific progress and application in endemic areas. Complete genomic sequence knowledge of Leishmania allows for the identification of therapeutic targets. With the aid of computational tools, testing, searching, and detecting affinity in molecular docking are optimized, and strategies that assess advantages among different options are developed. The review focuses on the use of molecular docking and molecular dynamics (MD) simulation for drug development. It also discusses the limitations and advancements of current treatments, emphasizing the importance of new techniques in improving disease management.

Piplartine-Inspired 3,4,5-Trimethoxycinnamates: Trypanocidal, Mechanism of Action, and In Silico Evaluation

Chagas disease (CD) is one of the main neglected tropical diseases that promote relevant socioeconomic impacts in several countries. The therapeutic options for the treatment of CD are limited, and parasite resistance has been reported. Piplartine is a phenylpropanoid imide that has diverse biological activities, including trypanocidal action. Thus, the objective of the present work was to prepare a collection of thirteen esters analogous to piplartine (1-13) and evaluate their trypanocidal activity against Trypanosoma cruzi. Of the tested analogues, compound 11 ((E)-furan-2-ylmethyl 3-(3,4,5-trimethoxyphenyl)acrylate) showed good activity with IC₅₀ values = 28.21 ± 5.34 μM and 47.02 ± 8.70 μM, against the epimastigote and trypomastigote forms, respectively. In addition, it showed a high rate of selectivity to the parasite. The trypanocidal mechanism of action occurs through the induction of oxidative stress and mitochondrial damage. In addition, scanning electron microscopy showed the formation of pores and leakage of cytoplasmic content. Molecular docking indicated that 11 probably produces a trypanocidal effect through a multi-target mechanism, including affinity with proteins CRK1, MPK13, GSK3B, AKR, UCE-1, and UCE-2, which are important for the survival of the parasite. Therefore, the results suggest chemical characteristics that can serve for the development of new trypanocidal prototypes for researching drugs against Chagas disease.

Degradation of PET Bottles by an Engineered Ideonella sakaiensis PETase

Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. In recent years, enzymatic degradation of PET by Ideonella sakaiensis PETase (IsPETase), a cutinase-like enzyme, has emerged as a promising strategy to completely depolymerize this polymer into its building blocks. Here, inspired by the architecture of cutinases and lipases homologous to IsPETase and using 3D structure information of the enzyme, we rationally designed three mutations in IsPETase active site for enhancing its PET-degrading activity. In particular, the S238Y mutant, located nearby the catalytic triad, showed a degradation activity increased by 3.3-fold in comparison to the wild-type enzyme. Importantly, this structural modification favoured the function of the enzyme in breaking down highly crystallized (~31%) PET, which is found in commercial soft drink bottles. In addition, microscopical analysis of enzyme-treated PET samples showed that IsPETase acts better when the smooth surface of highly crystalline PET is altered by mechanical stress. These results represent important progress in the accomplishment of a sustainable and complete degradation of PET pollution.

Antileishmanial Activity of Cinnamic Acid Derivatives against Leishmania infantum

Leishmania infantum is the etiological agent of visceral leishmaniasis (VL) in South America, the Mediterranean basin, and West and Central Asia. The most affected country, Brazil, reported 4297 VL cases in 2017. L. infantum is transmitted by female phlebotomine sand flies during successive blood meals. There are no validated vaccines to prevent the infection and the treatment relies on drugs that often present severe side effects, which justify the efforts to find new antileishmanial drugs. Cinnamic acid derivatives have shown several pharmacological activities, including antiparasitic action. Therefore, in the present study, the biological evaluation of cinnamic acid and thirty-four derivatives against L. infantum is reported. The compounds were prepared by several synthesis methods and characterized by spectroscopic techniques and high-resolution mass spectrometry. The results revealed that compound 32 (N-(4-isopropylbenzyl)cinnamamide) was the most potent antileishmanial agent (IC₅₀ = 33.71 μM) with the highest selectivity index (SI > 42.46), followed by compound 15 (piperonyl cinnamate) with an IC₅₀ = 42.80 μM and SI > 32.86. Compound 32 was slightly less potent and nineteen times more selective for the parasite than amphotericin B (MIC = 3.14 uM; SI = 2.24). In the molecular docking study, the most likely target for the compound in L. infantum was aspartyl aminopeptidase, followed by aldehyde dehydrogenase, mitochondrial. The data obtained show the antileishmanial potential of this class of compounds and may be used in the search for new drug candidates against Leishmania species.

Synthetic Cinnamides and Cinnamates: Antimicrobial Activity, Mechanism of Action, and In Silico Study

The severity of infectious diseases associated with the resistance of microorganisms to drugs highlights the importance of investigating bioactive compounds with antimicrobial potential. Therefore, nineteen synthetic cinnamides and cinnamates having a cinnamoyl nucleus were prepared and submitted for the evaluation of antimicrobial activity against pathogenic fungi and bacteria in this study. To determine the minimum inhibitory concentration (MIC) of the compounds, possible mechanisms of antifungal action, and synergistic effects, microdilution testing in broth was used. The structures of the synthesized products were characterized with FTIR spectroscopy, ¹ H-NMR, ¹³ C-NMR, and HRMS. Derivative 6 presented the best antifungal profile, suggesting that the presence of the butyl substituent potentiates its biological response (MIC = 626.62 μM), followed by compound 4 (672.83 μM) and compound 3 (726.36 μM). All three compounds were fungicidal, with MFC/MIC ≤ 4. For mechanism of action, compounds 4 and 6 directly interacted with the ergosterol present in the fungal plasmatic membrane and with the cell wall. Compound 18 presented the best antibacterial profile (MIC = 458.15 μM), followed by compound 9 (550.96 μM) and compound 6 (626.62 μM), which suggested that the presence of an isopropyl group is important for antibacterial activity. The compounds were bactericidal, with MBC/MIC ≤ 4. Association tests were performed using the Checkerboard method to evaluate potential synergistic effects with nystatin (fungi) and amoxicillin (bacteria). Derivatives 6 and 18 presented additive effects. Molecular docking simulations suggested that the most likely targets of compound 6 in C. albicans were caHOS2 and caRPD3, while the most likely target of compound 18 in S. aureus was saFABH. Our results suggest that these compounds could be used as prototypes to obtain new antimicrobial drugs.

Molecular Modeling and In Vitro Evaluation of Piplartine Analogs against Oral Squamous Cell Carcinoma

Cancer is a principal cause of death in the world, and providing a better quality of life and reducing mortality through effective pharmacological treatment remains a challenge. Among malignant tumor types, squamous cell carcinoma-esophageal cancer (EC) is usually located in the mouth, with approximately 90% located mainly on the tongue and floor of the mouth. Piplartine is an alkamide found in certain species of the genus Piper and presents many pharmacological properties including antitumor activity. In the present study, the cytotoxic potential of a collection of piplartine analogs against human oral SCC9 carcinoma cells was evaluated. The analogs were prepared via Fischer esterification reactions, alkyl and aryl halide esterification, and a coupling reaction with PyBOP using the natural compound 3,4,5-trimethoxybenzoic acid as a starting material. The products were structurally characterized using 1H and 13C nuclear magnetic resonance, infrared spectroscopy, and high-resolution mass spectrometry for the unpublished compounds. The compound 4-methoxy-benzyl 3,4,5-trimethoxybenzoate (9) presented an IC50 of 46.21 µM, high selectively (SI > 16), and caused apoptosis in SCC9 cancer cells. The molecular modeling study suggested a multi-target mechanism of action for the antitumor activity of compound 9 with CRM1 as the main target receptor.

3,5-Dinitrobenzoate and 3,5-Dinitrobenzamide Derivatives: Mechanistic, Antifungal, and In Silico Studies

Fungal infections, including those caused by Candida spp., are recognized in immunocompromised individuals for their high rates of morbidity and mortality. Microorganism resistance to conventional drugs compromises treatment effectiveness and yet also reveals the need to develop new drugs. In many compounds, nitro groups contribute to antimicrobial activity; thus, the inhibitory activity of a collection of twenty esters and amides (derived from 3,5-dinitrobenzoic acid) against Candida spp. was elucidated using microdilution methods to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicide Concentration (MFC), as well as probable mechanisms of action. The structures of the synthesized compounds were characterized by FTIR spectroscopy, 1H-NMR, 13C NMR, and HRMS. Of the tested derivatives, ten presented fungicidal activity against at least one of the tested strains. Ethyl 3,5-dinitrobenzoate (2) exhibited the most potent antifungal activity against Candida albicans (MIC = 125 µg/mL; 0.52 mM), Candida krusei (MIC = 100 µg/mL; 4.16 mM), and Candida tropicalis (MIC = 500 µg/ml; 2.08 mM). The structure of the second most potent derivative (propyl 3,5-dinitrobenzoate (3) reveals that esters with short alkyl side chains exhibit better biological activity profiles. Compounds 2 and 3 presented a mechanism of action involving the fungal cell membrane. Though compound 2 modeling against C. albicans revealed a multitarget antifungal mechanism of action, involving various cellular processes, interference in the synthesis of ergosterol was observed. Our results demonstrate that certain ester derivatives containing aromatic ring nitro groups may be useful in the search for new antifungal drugs.

Synthesis of Coumarin and Homoisoflavonoid Derivatives and Analogs: The Search for New Antifungal Agents

A set of twenty-four synthetic derivatives, with coumarin and homoisoflavonoid cores and structural analogs, were submitted for evaluation of antifungal activity against various species of Candida. The broth microdilution test was used to determine the Minimum Inhibitory Concentration (MIC) of the compounds and to verify the possible antifungal action mechanisms. The synthetic derivatives were obtained using various reaction methods, and six new compounds were obtained. The structures of the synthesized products were characterized by FTIR spectroscopy: ¹H-NMR, ¹³C-NMR, and HRMS. The coumarin derivative 8 presented the best antifungal profile, suggesting that the pentyloxy substituent at the C-7 position of coumarin ring could potentiate the bioactivity. Compound 8 was then evaluated against the biofilm of C. tropicalis ATCC 13803, which showed a statistically significant reduction in biofilm at concentrations of 0.268 µmol/mL and 0.067 µmol/mL, when compared to the growth control group. For a better understanding of their antifungal activity, compounds 8 and 21 were submitted to a study of the mode of action on the fungal cell wall and plasma membrane. It was observed that neither compound interacted directly with ergosterol present in the fungal plasma membrane or with the fungal cell wall. This suggests that their bioactivity was due to interaction involving other pharmacological targets. Compound 8 was also subjected to a molecular modeling study, which showed that its antifungal action mechanism occurred mainly through interference in the redox balance of the fungal cell, and by compromising the plasma membrane; not by direct interaction, but by interference in ergosterol synthesis. Another important finding was the antifungal capacity of homoisoflavonoids 23 and 24. Derivative 23 presented slightly higher antifungal activity, possibly due to the presence of the methoxyl substituent in the meta position in ring B.

Trypanocidal effect of alcoholic extract of Castanedia santamartensis (Asteraceae) leaves is based on altered mitochondrial function

The deficit of effective treatments for Chagas disease has led to searching for new substances with therapeutic potential. Natural products possess a wide variety of chemical structural motifs and are thus a valuable source of diverse lead compounds for the development of new drugs. Castanedia santamartensis is endemic to Colombia, and local indigenous communities often use it to treat skin sores from leishmaniasis; however, its mechanism of action against the infective form of Trypanosoma cruzi has not been determined. Thus, we performed chemical and biological studies of two alcoholic leaf extracts of C. santamartensis to identify their active fractions and relate them to a trypanocidal effect and evaluate their mechanism of action. Alcoholic extracts were obtained through cold maceration at room temperature and fractionated using classical column chromatography. Both ethanolic and methanolic extracts displayed activity against T. cruzi. Chemical studies revealed that kaurenoic acid was the major component of one fraction of the methanolic extract and two fractions of the ethanolic extract of C. santamartensis leaves. Moreover, caryophyllene oxide, kaurenol, taraxasterol acetate, pentadecanone, and methyl and ethyl esters of palmitate, as well as a group of phenolic compounds, including ferulic acid, caffeic acid, chlorogenic acid, myricetin, quercitrin, and cryptochlorogenic acid were identified in the most active fractions. Kaurenoic acid and the most active fractions CS400 and CS402 collapsed the mitochondrial membrane potential in trypomastigotes, demonstrating for the first time the likely mechanism against T. cruzi, probably due to interactions with other components of the fractions.

Optimization of physicochemical properties is a strategy to improve drug-likeness associated with activity: novel active and selective compounds against Trypanosoma cruzi

Trypanosoma cruzi is the causing agent of Chagas disease, a parasitic infection without efficient treatment for chronic patients. Despite the efforts, no new drugs have been approved for this disease in the last 60 years. Molecular modifications based on a natural product led to the development of a series of compounds (LINS03 series) with promising antitrypanosomal activity, however previous chemometric analysis revealed a significant impact of excessive lipophilicity and low aqueous solubility on potency of amine and amide derivatives. Therefore, this work reports different modifications in the core structure to achieve adequate balance of the physicochemical properties along with biological activity. A set of 34 analogues were designed considering predicted properties related to lipophilicity/hydrosolubility and synthesized to assess their activity and selective toxicity towards the parasite. Results showed that this strategy contributed to improve the drug-likeness of the series while considerable impacts on potency were observed. The rational analysis of the obtained data led to the identification of seven active piperazine amides (28-34, IC₅₀ 8.7 to 35.3 µM against intracellular amastigotes), devoid of significant cytotoxicity to mammalian cells. The addition of water-solubilizing groups and privileged substructures such as piperazines improved the physicochemical properties and overall drug-likeness of these compounds, increased potency and maintained selectivity towards the parasite. The obtained results brought important structure-activity relationship (SAR) data and new lead structures for further modifications were identified to achieve improved antitrypanosoma compounds.

Antifungal Activity of N-(4-Halobenzyl)amides against Candida spp. and Molecular Modeling Studies

Fungal infections remain a high-incidence worldwide health problem that is aggravated by limited therapeutic options and the emergence of drug-resistant strains. Cinnamic and benzoic acid amides have previously shown bioactivity against different species belonging to the Candida genus. Here, 20 cinnamic and benzoic acid amides were synthesized and tested for inhibition of C. krusei ATCC 14243 and C. parapsilosis ATCC 22019. Five compounds inhibited the Candida strains tested, with compound 16 (MIC = 7.8 µg/mL) producing stronger antifungal activity than fluconazole (MIC = 16 µg/mL) against C. krusei ATCC 14243. It was also tested against eight Candida strains, including five clinical strains resistant to fluconazole, and showed an inhibitory effect against all strains tested (MIC = 85.3–341.3 µg/mL). The MIC value against C. krusei ATCC 6258 was 85.3 mcg/mL, while against C. krusei ATCC 14243, it was 10.9 times smaller. This strain had greater sensitivity to the antifungal action of compound 16. The inhibition of C. krusei ATCC 14243 and C. parapsilosis ATCC 22019 was also achieved by compounds 2, 9, 12, 14 and 15. Computational experiments combining target fishing, molecular docking and molecular dynamics simulations were performed to study the potential mechanism of action of compound 16 against C. krusei. From these, a multi-target mechanism of action is proposed for this compound that involves proteins related to critical cellular processes such as the redox balance, kinases-mediated signaling, protein folding and cell wall synthesis. The modeling results might guide future experiments focusing on the wet-lab investigation of the mechanism of action of this series of compounds, as well as on the optimization of their inhibitory potency.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.

Bioactive Terpenes and Their Derivatives as Potential SARS-CoV-2 Proteases Inhibitors from Molecular Modeling Studies

The coronavirus disease 2019 (COVID-19) pandemic is caused by a novel coronavirus; the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Millions of cases and deaths to date have resulted in a global challenge for healthcare systems. COVID-19 has a high mortality rate, especially in elderly individuals with pre-existing chronic comorbidities. There are currently no effective therapeutic approaches for the prevention and treatment of COVID-19. Therefore, the identification of effective therapeutics is a necessity. Terpenes are the largest class of natural products that could serve as a source of new drugs or as prototypes for the development of effective pharmacotherapeutic agents. In the present study, we discuss the antiviral activity of these natural products and we perform simulations against the M^pro and PL^pro enzymes of SARS-CoV-2. Our results strongly suggest the potential of these compounds against human coronaviruses, including SARS-CoV-2.

Larvicidal Activity of Cinnamic Acid Derivatives: Investigating Alternative Products for Aedes aegypti L. Control

The mosquito Aedes aegypti transmits the virus that causes dengue, yellow fever, Zika and Chikungunya viruses, and in several regions of the planet represents a vector of great clinical importance. In terms of mortality and morbidity, infections caused by Ae. aegypti are among the most serious arthropod transmitted viral diseases. The present study investigated the larvicidal potential of seventeen cinnamic acid derivatives against fourth stage Ae. aegypti larvae. The larvicide assays were performed using larval mortality rates to determine lethal concentration (LC₅₀). Compounds containing the medium alkyl chains butyl cinnamate (7) and pentyl cinnamate (8) presented excellent larvicidal activity with LC₅₀ values of around 0.21-0.17 mM, respectively. While among the derivatives with aryl substituents, the best LC₅₀ result was 0.55 mM for benzyl cinnamate (13). The tested derivatives were natural compounds and in pharmacology and antiparasitic studies, many have been evaluated using biological models for environmental and toxicological safety. Molecular modeling analyses suggest that the larvicidal activity of these compounds might be due to a multi-target mechanism of action involving inhibition of a carbonic anhydrase (CA), a histone deacetylase (HDAC2), and two sodium-dependent cation-chloride co-transporters (CCC2 e CCC3).

Drugs Repurposing Using QSAR, Docking and Molecular Dynamics for Possible Inhibitors of the SARS-CoV-2 Mpro Protease

Wuhan, China was the epicenter of the first zoonotic transmission of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2) in December 2019 and it is the causative agent of the novel human coronavirus disease 2019 (COVID-19). Almost from the beginning of the COVID-19 outbreak several attempts were made to predict possible drugs capable of inhibiting the virus replication. In the present work a drug repurposing study is performed to identify potential SARS-CoV-2 protease inhibitors. We created a Quantitative Structure-Activity Relationship (QSAR) model based on a machine learning strategy using hundreds of inhibitor molecules of the main protease (Mpro) of the SARS-CoV coronavirus. The QSAR model was used for virtual screening of a large list of drugs from the DrugBank database. The best 20 candidates were then evaluated in-silico against the Mpro of SARS-CoV-2 by using docking and molecular dynamics analyses. Docking was done by using the Gold software, and the free energies of binding were predicted with the MM-PBSA method as implemented in AMBER. Our results indicate that levothyroxine, amobarbital and ABP-700 are the best potential inhibitors of the SARS-CoV-2 virus through their binding to the Mpro enzyme. Five other compounds showed also a negative but small free energy of binding: nikethamide, nifurtimox, rebimastat, apomine and rebastinib.

Alkyl and Aryl Derivatives Based on p-Coumaric Acid Modification and Inhibitory Action against Leishmania braziliensis and Plasmodium falciparum

In low-income populations, neglected diseases are the principal cause of mortality. Of these, leishmaniasis and malaria, being parasitic, protozoan infections, affect millions of people worldwide and are creating a public health problem. The present work evaluates the leishmanicidal and antiplasmodial action of a series of twelve p-coumaric acid derivatives. Of the tested derivatives, eight presented antiparasitic activities 1–3, 8–12. The hexyl p-coumarate derivative (9) (4.14 ± 0.55 μg/mL; selectivity index (SI) = 2.72) showed the highest leishmanicidal potency against the Leishmania braziliensis amastigote form. The results of the molecular docking study suggest that this compound inhibits aldehyde dehydrogenase (ALDH), mitogen-activated kinase protein (MPK4), and DNA topoisomerase 2 (TOP2), all of which are key enzymes in the development of Leishmania braziliensis. The data indicate that these enzymes interact via Van der Waals bonds, hydrophobic interactions, and hydrogen bonds with phenolic and aliphatic parts of this same compound. Of the other compounds analyzed, methyl p-coumarate (64.59 ± 2.89 μg/mL; IS = 0.1) demonstrated bioactivity against Plasmodium falciparum. The study reveals that esters presenting a p-coumarate substructure are promising for use in synthesis of derivatives with good antiparasitic profiles.

Bioactivity and Molecular Docking Studies of Derivatives from Cinnamic and Benzoic Acids

Over the last decade, there has been a dramatic increase in the prevalence and gravity of systemic fungal diseases. This study aimed therefore at evaluating the antifungal potential of ester derivatives of benzoic and cinnamic acids from three Candida species. The compounds were prepared via Fischer esterification, and the antifungal assay was performed by the microdilution method in 96-well microplates for determining the minimal inhibitory concentrations (MICs). The findings of the antifungal tests revealed that the analogue compound methyl ferulate, methyl o-coumarate, and methyl biphenyl-3-carboxylate displayed an interesting antifungal activity against all Candida strains tested, with MIC values of 31.25-62.5, 62.5-125, and 62.5 μg/ml, respectively. A preliminary Structure-Activity Relationship study of benzoic and cinnamic acid derivatives has led to the recognition of some important structural requirements for antifungal activity. The results of molecular docking indicate that the presence of the enoate moiety along with hydroxyl and one methoxy substitution in the phenyl ring has a positive effect on the bioactivity of compound 7 against Candida albicans. These observations further support the hypothesis that the antifungal activity of compound 7 could be due to its binding to multiple targets, specifically to QR, TS, and ST-PK. Additional experiments are required in the future to test this hypothesis and to propose novel compounds with improved antifungal activity.