Betulinic Acid-Brosimine B Hybrid Compound Has a Synergistic Effect with Imatinib in Chronic Myeloid Leukemia Cell Line, Modulating Apoptosis and Autophagy.

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by the formation of the BCR-ABL (breakpoint cluster region-Abelson) oncoprotein. As many patients display therapeutic resistance, the development of new drugs based on semisynthetic products represents a new potential therapeutic approach for treating the disease. In this study, we investigated the cytotoxic activity, possible mechanism of action of a hybrid compound of betulinic acid (BA) and brosimine B in CML cell lines that are sensitive (K-562) and resistant (K-562R) to imatinib, in addition to evaluating lower doses of imatinib in combination with the hybrid compound. The effects of the compound, and its combination with imatinib, on apoptosis, cell cycle, autophagy and oxidative stress were determined. The compound was cytotoxic in K-562 (23.57 ± 2.87 µM) and K-562R (25.80 ± 3.21 µM) cells, and a synergistic effect was observed when it was associated with imatinib. Apoptosis was mediated by the caspase 3 and 9 intrinsic pathway, and cell cycle evaluation showed arrest at G0/G1. In addition, the hybrid compound increased the production of reactive oxygen species and induced autophagy by increasing LC3II and Beclin-1 mRNA levels. Results suggest that this hybrid compound causes the death of both imatinib-sensitive and -resistant cell lines and may hold potential as a new anticancer treatment against CML.

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling.

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infections in infants. Currently, ribavirin, a nucleoside analog containing a 1,2,4-triazole-3-carboxamide moiety, is a first-line drug for its treatment, however, its clinical use has been limited due to its side effects. Here, we designed two new nitroaryl-1,2,3-triazole triterpene derivatives as novel anti-RSV drugs. Their anti-RSV and cytotoxic activity were evaluated in vitro, RSV protein F gene effects by RT-PCR and molecular modeling with inosine monophosphate dehydrogenase (IMPDH) were performed. Compound 8 was the best performing compound, with an EC50 value of 0.053 µM, a TI of 11160.37 and it inhibited hRSV protein F gene expression by approximately 65%. Molecular docking showed a top-ranked solution located in the same region occupied by crystallographic ligands in their complex with IMPDH. The results obtained in this study suggest that compound 8 might be a new anti-RSV candidate.

Capsicumicine, a New Bioinspired Peptide from Red Peppers Prevents Staphylococcal Biofilm In Vitro and In Vivo via a Matrix Anti-Assembly Mechanism of Action.

Staphylococci are pathogenic biofilm-forming bacteria and a source of multidrug resistance and/or tolerance causing a broad spectrum of infections. These bacteria are enclosed in a matrix that allows them to colonize medical devices, such as catheters and tissues, and that protects against antibiotics and immune systems. Advances in antibiofilm strategies for targeting this matrix are therefore extremely relevant. Here, we describe the development of the Capsicum pepper bioinspired peptide "capsicumicine." By using microbiological, microscopic, and nuclear magnetic resonance (NMR) approaches, we demonstrate that capsicumicine strongly prevents methicillin-resistant Staphylococcus epidermidis biofilm via an extracellular "matrix anti-assembly" mechanism of action. The results were confirmed in vivo in a translational preclinical model that mimics medical device-related infection. Since capsicumicine is not cytotoxic, it is a promising candidate for complementary treatment of infectious diseases. IMPORTANCE Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. So far, no effective treatments targeting the bacteria in biofilms have been developed. Plants are constantly attacked by a wide range of pathogens and have protective factors, such as peptides, to defend themselves. These peptides are common components in Capsicum baccatum (red pepper). Here, we provide insights into an antibiofilm strategy based on the development of capsicumicine, a natural peptide that strongly controls biofilm formation by Staphylococcus epidermidis, the most prevalent pathogen in device-related infections.

Synthesis and antileukemic activity of an ursolic acid derivative: A potential co-drug in combination with imatinib.

Imatinib, a specific Bcr-Abl tyrosine kinase inhibitor, is the most commonly used drug in the treatment of chronic myeloid leukemia. However, optimal response is not achieved in up to 33% of patients. Therefore, development of novel therapeutic strategies for chronic myeloid leukemia is critical. Betulinic (1) and ursolic (2) acids are natural pentacyclic triterpenes that exhibit antileukemic activities. In this study, we evaluated the effects of pharmacomodulations at the C-3 position of the triterpene moiety of betulinic and ursolic acids on their activity against K562 leukemia cells. Six new derivatives (1a-2c) were synthesized and evaluated for pro-apoptotic and anti-proliferative effects in mammalian and leukemic cells. 2c derivative containing an amine group at the C-3 position of ursolic acid was the most active against leukemia cells with an IC50 value of 5.2 µM after 48 h of treatment. 2c did not exhibit cytotoxic effects against VERO and HepG2 cells and human lymphocytes, showing a good selectivity index for cancer over normal cells. Induced cell death by apoptosis via caspases 3 and 8, and also caused cell cycle arrest as evidenced by accumulation of cells in the G1 phase and decreased cell population in the G2 phase. Furthermore, co-treatment of 2c with imatinib, the chemotherapy drug most commonly used to treat leukemia, resulted in a synergistic effect. Our findings provide a strong rationale for further investigation of combination therapy using the 2c derivative and imatinib in pre-clinical studies.

Natural and Semisynthetic Pentacyclic Triterpenes for Chronic Myeloid Leukemia Therapy: Reality, Challenges and Perspectives.

Chronic myeloid leukemia (CML) is a neoplasm characterized by BCR-ABL1, an oncoprotein with vital role in leukemogenesis. Its inhibition by tyrosine kinase inhibitors represents the main choice of treatment. However, therapeutic failure is worrying given the lack of pharmacological options. Pentacyclic triterpenes are phytochemicals with outstanding antitumoral properties and have also been explored as a basis for the design of potential leads. In this review, we have gathered and discuss data regarding both natural and semisynthetic pentacyclic triterpenes applied to CML cell treatment. We found consistent evidence that the class of pentacyclic triterpenes in general exerts promising pro-apoptotic and antiproliferative activities in sensitive and resistant CML cells, and thus represents a rich source for drug development. We also analyze the predicted drug-like properties of the molecules, discuss the structural changes with biological implications and show the great opportunities this class represents, as well as the perspectives they provide on drug discovery for CML treatment.

Ursolic and betulinic semisynthetic derivatives show activity against CQ-resistant Plasmodium falciparum isolated from Amazonia.

ACT's low levels of Plasmodium parasitemia clearance are worrisome since it is the last treatment option against P. falciparum. This scenario has led to investigations of compounds with different mechanisms of action for malaria treatment. Natural compounds like ursolic acid (UA) and betulinic acid (BA), distinguished by their activity against numerous microorganisms, including P. falciparum, have become relevant. This study evaluated the antiplasmodial activity of imidazole derivatives of UA and BA against P. falciparum in vitro. Eight molecules were obtained by semisynthesis and tested against P. falciparum strains (NF54 and CQ-resistant 106/cand isolated in Porto Velho, Brazil); 2a and 2b showed activity against NF54 and 106/cand strains with IC50  < 10 µM. They presented high selectivity indexes (SI > 25) and showed synergism when combined with artemisinin. 2b inhibited the parasite's ring and schizont forms regardless of when the treatment began. In silico analysis presented a tight bind of 2b in the topoisomerase II-DNA complex. This study demonstrates the importance of natural derivate compounds as new candidates for malarial treatment with new mechanisms of action. Semisynthesis led to new triterpenes that are active against P. falciparum and may represent new alternatives for malaria drug development.

Ex vivo potential of a quinoline-derivative nail lacquer as a new alternative for dermatophytic onychomycosis treatment.

Introduction. Onychomycosis infections currently show a significant increase, affecting about 10 % of the world population. Trichophyton rubrum is the main agent responsible for about 80 % of the reported infections. The clinical cure for onychomycosis is extremely difficult and effective new antifungal therapy is needed.Hypothesis/Gap Statement. Ex vivo onychomycosis models using porcine hooves can be an excellent alternative for evaluating the efficacy of new anti-dermatophytic agents in a nail lacquer.Aim. Evaluation of the effectiveness of a nail lacquer containing a quinoline derivative on an ex vivo onychomycosis model using porcine hooves, as well as the proposal of a plausible antifungal mechanism of this derivative against dermatophytic strains.Methodology. The action mechanism of a quinoline derivative was evaluated through the sorbitol protection assay, exogenous ergosterol binding, and the determination of the dose-response curves by time-kill assay. Scanning electron microscopy evaluated the effect of the derivative in the fungal cells. The efficacy of a quinoline-derivative nail lacquer on an ex vivo onychomycosis model using porcine hooves was evaluated as well.Results. The quinoline derivative showed a time-dependent fungicidal effect, demonstrating reduction and damage in the morphology of dermatophytic hyphae. In addition, the ex vivo onychomycosis model was effective in the establishment of infection by T. rubrum.Conclusion. Treatment with the quinoline-derivative lacquer showed a significant inhibitory effect on T. rubrum strain in this infection model. Finally, the compound presents high potential for application in a formulation such as nail lacquer as a possible treatment for dermatophytic onychomycosis.

Quinolines derivatives as promising new antifungal candidates for the treatment of candidiasis and dermatophytosis.

Fungal infections have emerged as a current serious global public health problem. The main problem involving these infections is the expansion of multidrug resistance. Therefore, the prospection of new compounds with efficacy antifungal becomes necessary. Thus, this study evaluated the antifungal profile and toxicological parameters of quinolines derivatives against Candida spp. and dermatophyte strains. As a result, a selective anti-dermatophytic action was demonstrated by compound 5 (geometric means (GM = 19.14 µg ml-1)). However, compounds 2 (GM = 50 µg ml-1) and 3 (GM = 47.19 µg ml-1) have presented only anti-Candida action. Compounds 3 and 5 did not present cytotoxic action. Compound 5 did not produce dermal and mucosal toxicity. In addition, this compound showed the absence of genotoxic potential, suggesting safety for topical and systemic use. Quinolines demonstrated a potent anti-dermatophytic and anti-yeast action. Moreover, compound 5 presented an excellent toxicological profile, acting as a strong candidate for the development of a new effective and safe compound against dermatophytosis of difficult treatment.

Remarkable capacity of brosimine b to disrupt methicillin-resistant Staphylococcus aureus (MRSA) preformed biofilms.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major public health concern representing about 60% of S. aureus isolated from hospitalized patients in countries such as USA and Brazil in the last years. Additionally, the ability to adhere to surfaces and the development of biofilms are important properties of pathogenic bacteria involved in medical device-associated infections, and staphylococci are recognized as the major etiologic agents in these situations. The aim of this study is to evaluate three Brosimum acutifolium flavonoids, 4'-hydroxy-7,8(2″,2″-dimethylpyran)flavan (1), brosimine b (2) and 4-hydroxy-lonchocarpin (3), regarding their antibiofilm, antibacterial and antioxidant activities. Flavonoids 1 and 2 were able to reduce S. aureus viability within preformed biofilms in 73% at 50 µM while 2 also reduced biofilm biomass in 48% at 100 µM. Flavonoid 3 was not able to reduce biofilm biomass at assessed concentrations. When tested against methicillin-resistant S. aureus (MRSA) strains, 2 (100 µM) reduced 70%-98% of viable bacteria within 24h-old biofilms. The minimum inhibitory concentration against the methicillin-sensitive Staphylococcus aureus ATCC 25904 was 50 µM for the three compounds. In preliminary assays to evaluate cytotoxicity, 1 was highly hemolytic at concentrations above 50 µM while 2 and 3 did not cause significant hemolysis at 100 µM. The antioxidant activity was observed only in the ethanolic extract and 2. In vivo toxicity evaluations using Galleria mellonella larvae as alternative host model resulted in 83.3% survival for treatment with 1, 76.7% for 2, and 100% for 3 at 500 mg/kg. This study highlights the potential of these flavonoids, especially 2, as antibiofilm agent to control preformed S. aureus biofilms.

Betulinic Acid and Brosimine B Hybrid Derivatives as Potential Agents against Female Cancers.

BACKGROUND: Cancer is a multifactorial disease, representing one of the leading causes of death worldwide. On a global estimate, breast cancer is the most frequently occurring cancer in women and cervical cancer, the fourth most common. Both types of cancer remain the major cause of cancer-related mortality in developing countries. A strategy for rational drug design is hybridization, which aims to bring together in one molecule, two or more pharmacophores in order to reach several biological targets. OBJECTIVE: The objective of this work was to develop new hybrids based on natural pharmacophores: Betulinic acid (1) and brosimine b (2), active in female cancer cell lines. METHODS: The coupling reactions were carried out by Steglich esterification. Different compounds were designed for the complete and simplified structural hybridization of molecules. The anticancer activities of the compounds were evaluated in human cervical adenocarcinoma (HeLa), human cervical metastatic epidermoid carcinoma (ME-180), and human breast adenocarcinoma (MCF-7) cell lines. RESULTS: Hybrid 3 presented higher potency (IC50 = 9.2 ± 0.5µM) and SI (43.5) selectively in MCF-7 cells (in relation to Vero cells) with its cytotoxic effect occurring via apoptosis. In addition, compound 6 showed activity in MCF-7 and HeLa cells with intermediate potency, but with high efficacy, acting via apoptosis as well. CONCLUSION: In this context, we showed that the combination of two complex structures generated the development of hybrids with differing inhibitory profiles and apoptotic modes of action, thus representing potential alternatives in female cancer treatment.

Red pepper peptide coatings control Staphylococcus epidermidis adhesion and biofilm formation.

Medical devices (indwelling) have greatly improved healthcare. Nevertheless, infections related to the use of these apparatuses continue to be a major clinical concern. Biofilms form on surfaces after bacterial adhesion, and they function as bacterial reservoirs and as resistance and tolerance factors against antibiotics and the host immune response. Technological strategies to control biofilms and bacterial adhesion, such as the use of surface coatings, are being explored more frequently, and natural peptides may promote their development. In this study, we purified and identified antibiofilm peptides from Capsicum baccatum (red pepper) using chromatography-tandem mass spectrometry, MALDI-MS, MS/MS and bioinformatics. These peptides strongly controlled biofilm formation by Staphylococcus epidermidis, the most prevalent pathogen in device-related infections, without any antibiotic activity. Furthermore, natural peptide-coated surfaces dislayed effective antiadhesive proprieties and showed no cytotoxic effects against different representative human cell lines. Finally, we determined the lead peptide predicted by Mascot and identified CSP37, which may be useful as a prime structure for the design of new antibiofilm agents. Together, these results shed light on natural Capsicum peptides as a possible antiadhesive coat to prevent medical device colonization.

A Highly Active Triterpene Derivative Capable |of Biofilm Damage to Control Cryptococcus spp.

Cryptococcus neoformans is an encapsulated yeast responsible for more than 180,000 deaths per year. The standard therapeutic approach against cryptococcosis is a combination of amphotericin B with flucytosine. In countries where cryptococcosis is most prevalent, 5-fluorocytosine is rarely available, and amphotericin B requires intravenous administration. C. neoformans biofilm formation is related to increased drug resistance, which is an important outcome for hospitalized patients. Here, we describe new molecules with anti-cryptococcal activity. A collection of 66 semisynthetic derivatives of ursolic acid and betulinic acid was tested against mature biofilms of C. neoformans at 25 µM. Out of these, eight derivatives including terpenes, benzazoles, flavonoids, and quinolines were able to cause damage and eradicate mature biofilms. Four terpene compounds demonstrated significative growth inhibition of C. neoformans. Our study identified a pentacyclic triterpenoid derived from betulinic acid (LAFIS13) as a potential drug for anti-cryptococcal treatment. This compound appears to be highly active with low toxicity at minimal inhibitory concentration and capable of biofilm eradication.

Triterpene Derivatives as Relevant Scaffold for New Antibiofilm Drugs.

New medicines for the treatment of bacterial biofilm formation are required. For thisreason, this study shows the in vitro activity of betulinic acid (BA), ursolic acid (UA) and their twentyderivatives against planktonic and biofilm cells (gram-positive bacterial pathogens: Enterococcusfaecalis, Staphylococcus aureus and Staphylococcus epidermidis). We evaluated the antibiofilm activity(through the crystal violet method), as well as the antibacterial activity via absorbance (OD600) atconcentrations of 5, 25 and 100 µM. Likewise, the cytotoxicity of all compounds was evaluated on akidney African green monkey (VERO) cell line at the same concentration, by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) methodology. We verified for the first timewhether different groups at carbon 3 (C-3) of triterpenes may interfere in the antibiofilm activity withminimal or no antibacterial effect. After the screening of 22 compounds at three distinctconcentrations, we found antibiofilm activity for eight distinct derivatives without antibiotic effect.In particular, the derivative 2f, with an isopentanoyl ester at position C-3, was an antibiofilm activityagainst S. aureus without any effect upon mammalian cells.

In vitro and in silico Activity of Iridoids Against Leishmania amazonensis.

BACKGROUND: Leishmaniasis reaches millions of people around the world. The control of the disease is difficult due to the restricted access to the diagnosis and medication, and low adherence to the treatment. Thus, more efficient drugs are needed and natural products are good alternatives. Iridoids, natural products with reported leishmanicidal activity, can be exploited for the development of anti- Leishmania drugs. The aim of this study was to isolate and to investigate the in vitro activity of iridoids against Leishmania amazonensis and to compare the activity in silico of these compounds with those reported as active against this parasite. METHODS: Iridoids were isolated by chromatographic methods. The in vitro activity of asperuloside (1) and geniposide (2) from Escalonia bifida, galiridoside (3) from Angelonia integerrima and theveridoside (4) and ipolamiide (5) from Amphilophium crucigerum was investigated against promastigote forms of Leishmania amazonensis. Molecular modeling studies of 1-5 and iridoids cited as active against Leishmania spp. were performed. RESULTS: Compounds 1-5 (5-100 µM) did not inhibit the parasite survival. Physicochemical parameters predicted for 1-5 did not show differences compared to those described in literature. The SAR and the pharmacophoric model confirmed the importance of maintaining the cyclopentane[C]pyran ring of the iridoid, of oxygen-linked substituents at the C1 and C6 positions and of bulky substituents attached to the iridoid ring to present leishmanicidal activity. CONCLUSION: The results obtained in this study indicate that iridoids are a promising group of secondary metabolites and should be further investigated in the search for new anti-Leishmania drugs.

Evaluation of triterpenes derivatives in the viability of Leishmania amazonensis and Trichomonas vaginalis

Trichomonas vaginalis and Leishmania spp. are protozoal species responsible for millions of cases of parasitic diseases worldwide. Considering the potential of natural products and the need for more effective and less toxic alternatives to treat trichomoniasis and leishmaniasis, this study aimed to evaluate the effect of two series of triterpenes derivatives with different modifications at C-3 and C-28 positions of the ursolic acid (UA) and betulinic acid (BA) against trophozoites of Trichomonas vaginalis and promastigotes forms of Leishmania (L.) amazonensis. The compounds modified just at C-3 were the most active. The 3β-acetyl betulinic acid (1b) reduced the trophozoites viability of T. vaginalis at 74%, followed by the 3-oxo ursolic acid and 3-oxo betulinic acid (3a and 3b) compounds (55% of reduction). The compound 3β-isobutyl ursolic acid (7a) inhibited the viability of L. amazonensis promastigotes by 55%. Therefore, analyzing the structure-activity relationship and the data of literature, it is possible to suppose that the inclusion of polar groups in the skeletons could improve the antiprotozoal activity. Overall, further studies are necessary to develop triterpenic derivatives with more powerful trichomonicidal and leishmanicidal properties.

Antileishmanial in vitro activity of essential oil from Myrciaria plinioides, a native species from Southern Brazil

In South American folk medicine members of the genus Myrciaria are used for the treatment of malaria, diarrhoea, asthma, inflammation and post-partum uterine cleansing. The aim of this work was to evaluate its antileishmanial properties (in vitro) of essential oil derived from leaves of Myrciaria plinioides D. Legrand, a plant species that is native in South of Brazil. The essential oil was obtained by hydro-distillation using fresh leaves of M. plinioides. The chemical composition of this essential oil (MPEO, M. plinioides essential oil) was determined by gas chromatography coupled to mass spectrometry (GC-MS). MPEO was assayed in vitro for antileishmanial properties against promastigotes of Leishmania amazonensis and Leishmania infantum, and for cytotoxicity against murine peritoneal macrophages. The MPEO comprised 66 components and was rich in oxygenated sesquiterpenes (82.66%) containing spathulenol (21.12%) as its major constituent. The MPEO was effective against L. amazonensis with IC50 value of 14.16 ± 7.40 µg/mL, while against L. infantum the IC50 value was higher with 101.50 ± 5.78 µg/mL. The MPEO showed significant activity against L. amazonensis, and presented a selectivity index (SI) of 6.60. The results suggest that the essential oil from leaves of M. plinioides is a promising source for new antileishmanial agents against L. amazonensis.

Promising Antibiofilm Activity of Peptidomimetics.

Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. Scientific efforts have been made over the past few decades, but so far there is no effective treatment targeting the bacteria in biofilms. Antimicrobial peptidomimetics have been proposed as promising potential anti-biofilm agents. Indeed, these structurally enhanced molecules can mimic the action of peptides but are not susceptible to proteolysis or immunogenicity, the characteristic limitations of natural peptides. Here, we provide insights into antibiofilm peptidomimetic strategies and molecular targets, and discuss the design of two major peptidomimetics classes: AApeptides (N-acylated-N-aminoethyl-substituted peptides) and peptoids (N-substituted glycine units). In particular, we present details of their structural diversity and discuss the possible improvements that can be implemented in order to develop antibiofilm drug alternatives.

Synthesis of three triterpene series and their activity against respiratory syncytial virus.

The human respiratory syncytial virus (hRSV) is a leading cause of hospitalization due to acute lower respiratory infection especially in infants and young children, sometimes causing fatal cases. The monoclonal antibody palivizumab is one of the available options for preventing this virus, and at the moment there are several hRSV vaccine trials underway. Unfortunately, the only drug option to treat hRSV infection is ribavirin, which can be used in severe high-risk cases. For this reason, new medicines are needed and, in this context, the triterpenes and their derivatives are promising alternatives, since many of them have shown important antiviral activity, such as bevirimat. Therefore, we report three series of triterpene (betulin (BE), betulinic acid (BA), and ursolic acid (UA)) derivatives tested against hRSV. The derivatives were synthesized by using commercial anhydrides in an easy and inexpensive step reaction. For the antiviral assay, A549 cells were infected by hRSV and after 96 h of compound or ribavirin (positive control) treatment, the cell viability was tested by MTT assay. DMSO, non-infected cells and infected cells without treatment were used as negative control. The triterpene esterification at the hydroxyl group resulted in 17 derivatives. The 3,28-di-O-acetylbetulin derivative (1a) showed the best results for cell viability, and real-time PCR amplification was performed for 1a treatment. Remarkably, one new anti-hRSV prototype was obtained through an easy synthesis of BE, which shall represent an alternative for a new lead compound for anti-hRSV therapy.

SERCA plays a crucial role in the toxicity of a betulinic acid derivative with potential antimalarial activity.

Malaria is one of the most significant infectious diseases that affect poor populations in tropical areas throughout the world. Plants have been shown to be a good source for the development of new antimalarial chemotherapeutic agents, as shown for the discovery of quinine and artemisinin derivatives. Our research group has been working with semisynthetic triterpene derivatives that show potential antimalarial activity toward different strains of Plasmodium falciparum by specifically modulating calcium pathways in the parasite. Promising results were obtained for nanomolar concentrations of the semisynthetic betulinic acid derivative LAFIS13 against the P. falciparum 3D7 strain in vitro, with a selectivity index of 18 compared to a mammalian cell line. Continuing these studies, we present here in vitro and in vivo toxicological evaluations of this compound, followed by docking studies with PfATP6, a sarco/endoplasmic reticulum Ca+2-ATPase (SERCA) protein. LAFIS13 showed an LD50 between 300 and 50 mg/kg, and the acute administration of 50 mg/kg (i.p.) had no negative effects on hematological, biochemical and histopathological parameters. Based on the results of the in vitro assays, LAFIS13 not exerted significant effects on coagulation parameters of human peripheral blood, but a hemolytic activity was verified at higher concentrations. According to the molecular docking study, the PfATP6 protein may be a target for LAFIS13, which corroborates its previously reported modulatory effects on calcium homeostasis in the parasite. Notably, LAFIS13 showed a higher selectivity for the mammalian SERCA protein than for PfATP6, thus impairing the selectivity between parasite and host. In summary, the direct interaction with calcium pumps and the hemolytic potential of the compound proved to be plausible mechanism of LAFIS13 toxicity.

Anti-Trichomonas vaginalis activity of ursolic acid derivative: a promising alternative.

Trichomonas vaginalis is an extracellular parasite that binds to the epithelium of the human urogenital tract and causes the sexually transmitted infection, trichomoniasis. In view of increased resistance to drugs belonging to the 5-nitroimidazole class, new treatment alternatives are urgently needed. In this study, eight semisynthetized triterpene derivatives were evaluated for in vitro anti-T. vaginalis activity. Ursolic acid and its derivative, 3-oxime-urs-12-en-28-oic-ursolic acid (9), presented the best anti-T. vaginalis activity when compared to other derivatives, with minimum inhibitory concentration (MIC) at 25 µM. Moreover, 9 was active against several T. vaginalis fresh clinical isolates. Hemolysis assay demonstrated that 9 presented a low hemolytic effect. Importantly, 25 µM 9 was not cytotoxic against the Vero cell lineage. Finally, we demonstrated that compound 9 acts synergistically with metronidazole against a T. vaginalis metronidazole-resistant isolate. This report reveals the high potential of the triterpenoid derivative 9 as trichomonicidal agent.