Cytotoxic Cyclolignans Obtained by the Enlargement of the Cyclolignan Skeleton of Podophyllic Aldehyde, a Selective Podophyllotoxin-Derived Cyclolignan.

Podophyllotoxin, a cyclolignan natural product, has been the object of extensive chemomodulation to obtain better chemotherapeutic agents. Among the obtained podophyllotoxin derivatives, podophyllic aldehyde showed very interesting potency and selectivity against several tumoral cell lines, so it became our lead compound for further modifications, as described in this work, oriented toward the enlargement of the cyclolignan skeleton. Thus, modifications performed at the aldehyde function included nucleophilic addition reactions and the incorporation of the aldehyde carbon into several five-membered rings, such as thiazolidinones and benzo-fused azoles. The synthesized derivatives were evaluated against several types of cancer cells, and although some compounds were cytotoxic at the nanomolar range, most of them were less potent and less selective than the parent compound podophyllic aldehyde, with the most potent being those having the lactone ring of podophyllotoxin. In silico ADME evaluation predicted good druggability for most of them. The results indicate that the γ-lactone ring is important for potency, while the α,ß-unsaturated aldehyde is necessary to induce selectivity in these cyclolignans.

In vitro bioevaluation and docking study of dihydrosphingosine and ethambutol analogues against sensitive and multi-drug resistant Mycobacterium tuberculosis.

Tuberculosis remains a major public health problem and one of the top ten causes of death worldwide. The alarming increase in multidrug-resistant and extensively resistant variants (MDR, pre-XDR, and XDR) makes the disease more difficult to treat and control. New drugs that act against MDR/XDR strains are needed for programs to contain this major epidemic. The present study aimed to evaluate new compounds related to dihydro-sphingosine and ethambutol against sensitive and pre-XDR Mycobacterium strains, as well as to characterize the pharmacological activity through in vitro and in silico approaches in mmpL3 protein. Of the 48 compounds analyzed, 11 demonstrated good to moderate activity on sensitive and MDR Mycobacterium tuberculosis (Mtb), with a Minimum Inhibitory Concentration (MIC) ranging from 1.5 to 8 µM. They presented 2 to 14 times greater potency of activity when compared to ethambutol in pre-XDR strain, and demonstrated a selectivity index varying between 2.21 and 82.17. The substance 12b when combined with rifampicin, showed a synergistic effect (FICI = 0.5) on sensitive and MDR Mtb. It has also been shown to have a concentration-dependent intracellular bactericidal effect, and a time-dependent bactericidal effect in M. smegmatis and pre-XDR M. tuberculosis. The binding mode of the compounds in its cavity was identified through molecular docking and using a predicted structural model of mmpL3. Finally, we observed by transmission electron microscopy the induction of damage to the cell wall integrity of M. tuberculosis treated with the substance 12b. With these findings, we demonstrate the potential of a 2-aminoalkanol derivative to be a prototype substance and candidate for further optimization of molecular structure and anti-tubercular activity in preclinical studies.

Improving Properties of Podophyllic Aldehyde-Derived Cyclolignans: Design, Synthesis and Evaluation of Novel Lignohydroquinones, Dual-Selective Hybrids against Colorectal Cancer Cells.

New lignohydroquinone conjugates (L-HQs) were designed and synthesized using the hybridization strategy, and evaluated as cytotoxics against several cancer cell lines. The L-HQs were obtained from the natural product podophyllotoxin and some semisynthetic terpenylnaphthohydroquinones, prepared from natural terpenoids. Both entities of the conjugates were connected through different aliphatic or aromatic linkers. Among the evaluated hybrids, the L-HQ with the aromatic spacer clearly displayed the in vitro dual cytotoxic effect derived from each starting component, retaining the selectivity and showing a high cytotoxicity at short (24 h) and long (72 h) incubation times (4.12 and 0.0450 µM, respectively) against colorectal cancer cells. In addition, the cell cycle blockade observed by flow cytometry studies, molecular dynamics, and tubulin interaction studies demonstrated the interest of this kind of hybrids, which docked adequately into the colchicine binding site of tubulin despite their large size. These results prove the validity of the hybridization strategy and encourage further research on non-lactonic cyclolignans.

Novel compound shows in vivo anthelmintic activity in gerbils and sheep infected by Haemonchus contortus.

The control of gastrointestinal nematodes in livestock is becoming increasingly difficult due to the limited number of available drugs and the rapid development of anthelmintic resistance. Therefore, it is imperative to develop new anthelmintics that are effective against nematodes. Under this context, we tested the potential toxicity of three compounds in mice and their potential anthelmintic efficacy in Mongolian gerbils infected with Haemonchus contortus. The compounds were selected from previous in vitro experiments: two diamine (AAD-1 and AAD-2) and one benzimidazole (2aBZ) derivatives. 2aBZ was also selected to test its efficacy in sheep. In Mongolian gerbils, the benzimidazole reduced the percentage of pre-adults present in the stomach of gerbils by 95% at a dose of 200 mg/kg. In sheep, there was a 99% reduction in the number of eggs shed in faeces after 7 days at a dose of 120 mg/kg and a 95% reduction in the number of worm adults present in the abomasum. In conclusion, 2aBZ could be considered a promising candidate for the treatment of helminth infections in small ruminants.

Two New Dihydrosphingosine Analogs Against Mycobacterium tuberculosis Affect gltA1, lprQ, and rpsO Expression.

The emergence of multidrug-resistant (MDR) Mycobacterium tuberculosis strains threaten the control of tuberculosis. New antitubercular dihydrosphingosine analogs, named UCIs, have been evaluated in preclinical studies but their cellular and molecular mechanisms of action against M. tuberculosis are still unknown. The aim of this study was to evaluate the effect of UCI exposure on gene expression of drug-sensitive H37Rv and MDR CIBIN:UMF:15:99 clones of M. tuberculosis which were isolated, phenotypically, and genetically characterized, cultured to log phase and treated with UCI compounds; followed by total RNA isolation, reverse transcription and hybridization assays on Affymetrix genomic microarrays. Data were validated with RT-qPCR assays. As results, UCI-05 and UCI-14 exposure increased gltA1 expression in drug-sensitive H37Rv clones. Furthermore, UCI-05 increased lprQ expression in MDR CIBIN:UMF:15:99 M. tuberculosis clones while UCI-14 reduced the expression of this gene in drug-sensitive H37Rv clones. In addition, UCI-05 reduced rpsO expression in drug-sensitive H37Rv clones. We found gene expression alterations that suggest these molecules may alter carbon and lipid metabolism as well as interfere in the protein-producing machinery in M. tuberculosis.

Anthelmintic activity of aminoalcohol and diamine derivatives against the gastrointestinal nematode Teladorsagia circumcincta.

Gastrointestinal nematodes (GIN) infections are a serious problem in livestock production due to the great economic losses they cause. Their control is increasingly difficult because of the rapid development of drug resistance and the limited number of available drugs. Therefore, this study evaluated 18 aminoalcohol and 16 diamine derivatives against eggs, first and third stage larvae from a susceptible and a resistant isolate of Teladorsagia circumcincta collected from sheep. The effectiveness of the in vitro anthelmintic activity of the compounds was evaluated using three different procedures: Egg Hatch Test (EHT), Larval Mortality Test (LMT) and Larval Migration Inhibition Test (LMIT). Those compounds with activities higher than 90 % in the initial screening at 50 µM were selected to determine their half maximal effective concentration (EC50). In parallel, cytotoxicity assays were conducted on Caco2 and HepG2 cell lines to calculate Selectivity Indexes (SI) for each compound. The diamine 30 presented the best results in preventing egg hatching, displaying the lowest EC50 value (1.01 ±â€¯0.04 µM) of all compounds tested and the highest SI (21.21 vs. Caco-2 cells). For the LMIT, the diamine 34 showed the highest efficacy, with EC50 values of 2.67 ±â€¯0.08 and 3.02 ±â€¯0.09 µM on the susceptible and resistant isolate of the parasite, respectively.

New Antineoplastic Naphthohydroquinones Attached to Labdane and Rearranged Diterpene Skeletons.

Terpenylquinones are mixed biogenesis primary or secondary metabolites widespread in Nature with many biological activities, including the antineoplastic cytotoxicity, that have inspired this work. Here, we present a cytotoxic structure-activity relationship of several diterpenylhydroquinone (DTHQ) derivatives, obtained from the natural labdane diterpenoid myrceocommunic acid used as starting material. Different structural modifications, that changed the functionality and stereochemistry of the decalin, have been implemented on the bicyclic core through epoxidation, ozonolysis or decarboxylation, and through induction of biomimetic breaks and rearrangements of the diterpene skeleton. All the isomers generated were completely characterized by spectroscopic procedures. The resulting compounds have been tested in vitro on cultured cancer cells, showing their relevant antineoplastic cytotoxicity, with GI50 values in the µM and sub-µM range. The rearranged compound 8 showed the best cytotoxic results, with GI50 at the submicromolar range, retaining the cytotoxicity level of the parent compounds. In this report, the versatility of the labdane skeleton for chemical transformation and the interest to continue using structural modifications to obtain new bioactive compounds are demonstrated.

Synthesis, bioevaluation and docking studies of some 2-phenyl-1H-benzimidazole derivatives as anthelminthic agents against the nematode Teladorsagia circumcincta.

Gastrointestinal nematode infections are the main diseases in herds of small ruminants. Resistance to the main established drugs has become a worldwide problem. The purpose of this study is to obtain and evaluate the in vitro ovicidal and larvicidal activity of some 2-phenylbenzimidazole derivatives on susceptible and resistant strains of Teladorsagia circumcincta. Compounds were prepared by known procedures from substituted o-phenylenediamines and arylaldehydes or intermediate sodium 1-hydroxyphenylmethanesulfonate derivatives. Egg Hatch Test (EHT), Larval Mortality Test (LMT) and Larval Migration Inhibition Test (LMIT) were used in the initial screening of compounds at 50 µM concentration, and EC50 values were determined for the most potent compounds. Cytotoxicity evaluation of compounds was conducted on human Caco-2 and HepG2 cell lines to calculate their Selectivity Indexes (SI). At 50 µM concentration, nine out of twenty-four compounds displayed more than 98% ovicidal activity on a susceptible strain, and four of them showed more than 86% on one resistant strain. The most potent ovicidal benzimidazole (BZ) 3 showed EC50 = 6.30 µM, for the susceptible strain, while BZ 2 showed the lowest EC50 value of 14.5 µM for the resistant strain. Docking studies of most potent compounds in a modelled Teladorsagia tubulin indicated an inverted orientation for BZ 1 in the colchicine binding site, probably due to its fair interaction with glutamic acid at codon 198, which could justify its inactivity against the resistant strain of T. circumcincta.

Vascular mechanisms of monodesmosidic triterpene saponins isolated from Passiflora quadrangularis L / Mecanismos vasculares de saponinas triterpénicas monodesmosídicas aisladas de Passiflora quadrangularis L

Background: Passiflora quadrangularis L. has antihypertensive and anxiolytic properties observed in experimental models. Objectives: The aim of this work was to establish the vascular effects exerted by two known monodesmosidic triterpene saponins, 3-O-ß-D-glucopyranosyloleanolic acid (Compound 1) (not previously described for this plant) and, 3-O-[ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranosyl] oleanolic acid (Compound 2), isolated from the ethanolic extract of Passiflora quadrangularis L. leaves. Methods: The structural elucidation was achieved by Nuclear Magnetic Resonance (NMR) experiments and High-Resolution Mass Spectrometry (HRMS). Aortic rings from Wistar rats, previously stimulated with phenylephrine (PE, 1µM) and washed, were exposed to cumulatively concentrations of compound 1 and compound 2 (10 to 400 µM). Ethanolic extract from leaves of P. quadrangularis L. (10 to 320 µg/ mL) and clonidine (1nM to 100µM) were also used for comparison. Concentration response curves of compounds 1 and 2 were examined in presence and absence of: endothelium, the alpha-2 antagonist yohimbine (1 and 100 µM), the alpha non selective antagonist phentolamine (1µM), the alpha-1 antagonist prazosin (1µM) and the calcium channel blocker verapamil (10 and 100 µM). In addition, cumulatively response curve of acetylcholine (ACh, 10nM to 10µM) and sodium nitroprusside (SNP, 1nM to 100µM) were assayed in rings precontracted with compounds 1 and 2 (400 µM). Results: Compounds 1 and 2 elicited a vasoconstriction response in intact aorta rings in similar way (pEC50: 3.92±0.01 and 4.09±0.01, respectively), effect that did not change in denuded rings (pEC50: 3.90±0.01 and 4.11±0.01). The potency order (pEC50) of compounds 1 and 2 decreased according to the following: verapamil (3.53±0.01 and 3.90±0.02; p<0.05) < yohimbine (3.65±0.01 and 3.94±0.02; p<0.05) < prazosin (3.86±0.01 and 4.30±0.02) < phentolamine (4.05±0.02 and 4.05±0.01). SNP but not ACh, was able to decrease the vasopressor effect of compounds 1 and 2 (pIC50: 8.61±0.01 and 8.24 ± 0.15, respectively). Conclusions: Compounds 1 and 2 are key metabolites responsible for the ex vivo vasoconstrictor response induced by P. quadrangularis L. Activation of voltage-dependent calcium channels and/or α2-adrenergic receptors stimulation could be mechanisms implicated.

Antecedentes: Passiflora quadrangularis L. tiene propiedades antihipertensivas y ansiolíticas observadas en modelos animales. Objetivos: El objetivo de este trabajo fue establecer los efectos vasculares ejercidos por dos conocidas saponinas triterpénicas monodesmosídicas: el ácido 3-O-ß-D glucopiranosiloleanólico (Compuesto 1) (no descrito previamente para esta especie vegetal) y el ácido 3-O-[ß-D-glucopiranosil- (1→2)-ß-D-glucopiranosil]oleanólico (Compuesto 2), aisladas del extracto etanólico de las hojas de Passiflora quadrangularis L. Métodos: La elucidación estructural se llevó a cabo mediante experimentos de Resonancia Magnética Nuclear (NMR) y determinaciones de Espectrometría de Masas de Alta Resolución (HRMS). Los anillos aórticos de ratas Wistar, previamente estimulados con fenilefrina (PE, 1 µM) y lavados, fueron expuestos a concentraciones acumulativas del compuesto 1 y compuesto 2 (10 a 400 µM). El extracto etanólico de las hojas de P. quadrangularis L. (10 a 320 µg / ml) y clonidina (1 nM a 100 µM) se utilizaron para la comparación. Las curvas de concentración respuesta de los compuestos 1 y 2 se examinaron en presencia y ausencia de: endotelio, el antagonista alfa-2 yohimbina (1 y 100 µM), el antagonista alfa no selectivo fentolamina (1 µM), el antagonista alfa-1 prazosina (1 µM) y el bloqueador de canales de calcio verapamilo (10 y 100 µM). Además, la curva de concentraciones acumulativas de acetilcolina (ACh, 10 nM a 10 µM) y nitroprusiato de sodio (SNP, 1 nM a 100 µM) se ensayó en anillos pre-contraídos con los compuestos 1 y 2 (400 µM). Resultados: Los compuestos 1 y 2 provocaron una respuesta de vasoconstricción en los anillos de aorta intactos de manera similar (pEC50: 3.92 ± 0.01 y 4.09 ± 0.01, respectivamente), este efecto no cambió en los anillos denudados (pEC50: 3.90 ± 0.01 y 4.11 ± 0.01). El orden de potencia (pEC50) de los compuestos 1 y 2 disminuyó de la siguiente manera: verapamilo (3.53 ± 0.01 y 3.90 ± 0.02; p <0.05) < yohimbina (3.65 ± 0.01 y 3.94 ± 0.02; p <0.05) < prazosina (3.86 ± 0.01 y 4.30 ± 0.02)

Antileishmanial activity of terpenylquinones on Leishmania infantum and their effects on Leishmania topoisomerase IB.

Leishmania is the aethiological agent responsible for the visceral leishmaniasis, a serious parasite-borne disease widely spread all over the World. The emergence of resistant strains makes classical treatments less effective; therefore, new and better drugs are necessary. Naphthoquinones are interesting compounds for which many pharmacological properties have been described, including leishmanicidal activity. This work shows the antileishmanial effect of two series of terpenyl-1,4-naphthoquinones (NQ) and 1,4-anthraquinones (AQ) obtained from natural terpenoids, such as myrcene and myrceocommunic acid. They were evaluated both in vitro and ex vivo against the transgenic iRFP-Leishmania infantum strain and also tested on liver HepG2 cells to determine their selectivity indexes. The results indicated that NQ derivatives showed better antileishmanial activity than AQ analogues, and among them, compounds with a diacetylated hydroquinone moiety provided better results than their corresponding quinones. Regarding the terpenic precursor, compounds obtained from the monoterpenoid myrcene displayed good antiparasitic efficiency and low cytotoxicity for mammalian cells, whereas those derived from the diterpenoid showed better antileishmanial activity without selectivity. In order to explore their mechanism of action, all the compounds have been tested as potential inhibitors of Leishmania type IB DNA topoisomerases, but only some compounds that displayed the quinone ring were able to inhibit the recombinant enzyme in vitro. This fact together with the docking studies performed on LTopIB suggested the existence of another mechanism of action, alternative or complementary to LTopIB inhibition. In silico druglikeness and ADME evaluation of the best leishmanicidal compounds has shown good predictable druggability.

Imidazo[2,1-a]isoindole scaffold as an uncharted structure active on Leishmania donovani.

The human protozoan parasites Leishmania donovani and L. infantum are the causative agents of visceral leishmaniasis, as such, responsible for approximately 30,000 deaths annually. The available chemotherapeutic treatments are reduced to a few drugs whose effectiveness is limited by rising drug resistance/therapeutic failure, and noxious side-effects. Therefore, new therapeutic hits are needed. Compounds displaying the imidazo[2,1-a]isoindole skeleton have shown antichagasic, anti-HIV, antimalarial and anorectic activities. Here, we report the leishmanicidal activity of thirty one imidazo[2,1-a]isoindol-5-ol derivatives on promastigotes and intracellular amastigotes of L. donovani. Eight out of thirty one assayed compounds showed EC50 values ranging between 1 and 2 µM with selectivity indexes from 29 to 69 on infected THP-1 cells. Six compounds were selected for further elucidation of their leishmanicidal mechanism. In this regard, compound 29, the imidazoisoindolol with the highest activity on intracellular amastigotes, induced an early decrease of intracellular ATP levels, as well as mitochondrial depolarization, together with a partial plasma membrane destructuration, as assessed by transmission electron microscopy. Consequently, the inhibition of the energy metabolism of Leishmania plays an important role in the leishmanicidal mechanism of this compound, even when other additional targets cannot be ruled out. In all, the results supported the inclusion of the imidazoisoindole scaffold for the development of new leishmanicidal drugs.

Antiproliferative Benzoindazolequinones as Potential Cyclooxygenase-2 Inhibitors.

Quinones and nitrogen heterocyclic moieties have been recognized as important pharmacophores in the development of antitumor agents. This study aimed to establish whether there was any correlation between the in silico predicted parameters and the in vitro antiproliferative activity of a family of benzoindazolequinones (BIZQs), and to evaluate overexpressed proteins in human cancer cells as potential biomolecular targets of these compounds. For this purpose, this study was carried out using KATO-III and MCF-7 cell lines as in vitro models. Docking results showed that these BIZQs present better binding energies (ΔGbin) values for cyclooxygenase-2 (COX-2) than for other cancer-related proteins. The predicted ∆Gbin values of these BIZQs, classified in three series, positively correlated with IC50 measured in both cell lines (KATO-III: 0.72, 0.41, and 0.90; MCF-7: 0.79, 0.55, and 0.87 for Series I, II, and III, respectively). The results also indicated that compounds 2a, 2c, 6g, and 6k are the most prominent BIZQs, because they showed better IC50 and ∆Gbin values than the other derivatives. In silico drug absorption, distribution, metabolism, and excretion (ADME) properties of the three series were also analyzed and showed that several BIZQs could be selected as potential candidates for cancer pre-clinical assays.

Anti-Herpetic, Anti-Dengue and Antineoplastic Activities of Simple and Heterocycle-Fused Derivatives of Terpenyl-1,4-Naphthoquinone and 1,4-Anthraquinone.

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herpesvirus (HHV) type 1 and 2, and Dengue virus serotype 2 (DENV-2). The cytotoxicity on HeLa and Jurkat tumor cell lines was also tested. Using plaque forming unit assays, cell viability assays and molecular docking, we found that NQ 4 was the best antiviral compound, while AQ 11 was the most active and selective molecule on the tested tumor cells. NQ 4 showed a fair antiviral activity against Herpesviruses (EC50: <0.4 µg/mL, <1.28 µM) and DENV-2 (1.6 µg/mL, 5.1 µM) on pre-infective stages. Additionally, NQ 4 disrupted the viral attachment of HHV-1 to Vero cells (EC50: 0.12 µg/mL, 0.38 µM) with a very high selectivity index (SI = 1728). The in silico analysis predicted that this quinone could bind to the prefusion form of the E glycoprotein of DENV-2. These findings demonstrate that NQ 4 is a potent and highly selective antiviral compound, while suggesting its ability to prevent Herpes and Dengue infections. Additionally, AQ 11 can be considered of interest as a leader for the design of new anticancer agents.

New pharmacological insights of Galactia glaucescens.

Galactia glaucescens leaves are popularly used against snakebites in Brazil. The hydroethanolic extract from aerial parts of G. glaucescens (HEGg) was assayed against the neurotoxicity and myotoxicity induced by Bothrops jararacussu venom. A traditional myographic technique was applied for neurotoxicity and the resulting muscles were treated routinely by light microscopy analysis for myotoxicity. Additionally, the antimicrobial potential of HEGg was evaluated against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa strains, as well as Rutin was isolated for the first time in this specie using chromatographic and spectroscopic methods and its antiophidian property was assessed. HEGg totally prevents the neurotoxicity and myotoxicity effects caused by B. jararacussu, but did not show any antimicrobial effect. Concluding, HEGg and Rutin were able to counteract the toxic effects of the venom and confirmed the antiophidian potential, but not antimicrobial, of G. glaucescens as an alternative for neutralization of B. jararacussu venom.

Bioactive Prenyl- and Terpenyl-Quinones/Hydroquinones of Marine Origin †.

The sea is a rich source of biological active compounds, among which terpenyl-quinones/hydroquinones constitute a family of secondary metabolites with diverse pharmacological properties. The chemical diversity and bioactivity of those isolated from marine organisms in the last 10 years are summarized in this review. Aspects related to synthetic approaches towards the preparation of improved bioactive analogues from inactive terpenoids are also outlined.

Anti-hyperalgesic effects of two sphingosine derivatives in different acute and chronic models of hyperalgesia in mice.

BACKGROUND: The study evaluated the effects of two sphingosine derivatives N-(2-tert-butoxycarbamylhexadecyl)glutaramide (AA) and N-(1-benzyloxyhexadec-2-yl)glutaramide (OA) in different models of hypersensitivity in mice. METHODS: Male Swiss mice were orally pre-treated with AA or OA (0.3-3mg/kg). After 1h, they received λ-carrageenan (300µg/paw), lipopolysaccharide (LPS; 100ng/paw), bradykinin (BK; 500ng/paw) or prostaglandin E2 (PGE2; 0.1nmol/paw) or epinephrine (100ng/paw), and the mechanical withdrawal thresholds were evaluated using von Frey filament (0.6g) at different time points. The effect of the compounds against inflammatory and neuropathic pain was also evaluated using complete Freund's adjuvant (CFA), or by performing partial sciatic nerve ligation (PSNL). RESULTS: Animals pre-treated with AA and OA reduced hypersensitivity induced by carrageenan, LPS and BK, and modest inhibition of PGE2-induced hypersensitivity and carrageenan-induced paw oedema were observed in mice treated with OA. Though the partial effect presented by AA and OA, when dosed once a day, both compounds were able to significantly reduce the persistent inflammatory and neuropathic pain induced by CFA and PSNL, respectively. CONCLUSION: These results demonstrate that the sphingosine derivatives AA and OA present important anti-hypersensitive effects, suggesting a possible interaction with the kinin signalling pathway. This may represent an interesting tool for the management of acute and chronic pain, with good bioavailability and safety.

New Hybrids Derived from Podophyllic Aldehyde and Diterpenylhydroquinones with Selectivity toward Osteosarcoma Cells.

A new family of molecular hybrids, between cyclolignans related to podophyllic aldehyde and several diterpenylnaphthohydroquinones (DNHQ), was prepared and its biological activity evaluated in several human solid tumor cell lines, which are representative of the most prevalent solid tumors in the Western world. Both cyclolignan and quinone fragments were linked through aliphatic or aromatic spacers. The new hybrid family was evaluated for its cytotoxicity, and it was found that the hybrids were several times more potent against the osteosarcoma cell line MG-63 than against MCF-7 and HT-29 cell lines. The presence of an aromatic ring in the linker gave the most potent and selective agent, improving the cytotoxicity of the parent compounds. Cell cycle studies demonstrated that this hybrid induces a strong and rapid apoptotic effect and arrests cells at the G2/M phase of the cell cycle, in the same way that the parent compound podophyllic aldehyde does.

Antileishmanial activity and tubulin polymerization inhibition of podophyllotoxin derivatives on Leishmania infantum.

Leishmania microtubules play an important role not only in cell division, but also in keeping the shape of the parasite and motility of its free-living stages. Microtubules result from the self-assembly of alpha and beta tubulins, two phylogenetically conserved and very abundant eukaryotic proteins in kinetoplastids. The colchicine binding domain has inspired the discovery and development of several drugs currently in clinical use against parasites. However, this domain is less conserved in kinetoplastids and may be selectively targeted by new compounds. This report shows the antileishmanial effect of several series of compounds (53), derived from podophyllotoxin (a natural cyclolignan isolated from rhizomes of Podophyllum spp.) and podophyllic aldehyde, on a transgenic, fluorescence-emitting strain of Leishmania infantum. These compounds were tested on both promastigotes and amastigote-infected mouse splenocytes, and in mammalian - mouse non-infected splenocytes and liver HepG2 cells - in order to determine selective indexes of the drugs. Results obtained with podophyllotoxin derivatives showed that the hydroxyl group at position C-7α was a structural requisite to kill the parasites. On regards podophyllic aldehyde, derivatives with C9-aldehyde group integrated into a bicyclic heterostructure displayed more potent antileishmanial effects and were relatively safe for host cells. Docking studies of podophyllotoxin and podophyllic aldehyde derivatives showed that these compounds share a similar pattern of interaction at the colchicine site of Leishmania tubulin, thus pointing to a common mechanism of action. However, the results obtained suggested that despite tubulin is a remarkable target against leishmaniasis, there is a poor correlation between inhibition of tubulin polymerization and antileishmanial effect of many of the compounds tested, fact that points to alternative pathways to kill the parasites.

Passiflora quadrangularis L. prevents experimental hypertension and vascular remodelling in rats exposed to nitric oxide deficit / Passiflora quadrangularis L. previene la hipertensión experimental y el remodelado vascular en ratas expuestas a déficit de óxido nítrico

Background: Passiflora quadrangularis L. is among the species used in Colombian folk medicine for hypertension, but until now it has not been studied in experimental models. Objectives: To assess the capacity of P. quadrangularis L. EtOH extract to prevent the hypertension and vascular remodelling induced by nitric oxide (NO) deficit in Wistar rats. Methods: The nitric oxide (NO) synthase inhibitor L-NAME (10 mg/kg, i.p (intraperitoneal), every 48h) was administered for seven weeks to the following groups of rats: P. quadrangularis L.75, 150 and 300 mg/kg/d, p.o. (oral route); enalapril as reference agent, 10 mg/kg/d, p.o. and vehicle as control (mixture of propylene glycol 10%, glycerine 10% and polysorbate 2%). Arterial blood pressure (BP) and heart rate (HR) were measured twice a week. After sacrifice, the aortic rings were isolated, contraction was triggered with phenylephrine (PE 10-6 M) and then the relaxant response achieved with cumulative concentrations of acetylcholine (ACh, 10-10 ­ 10-5 M) or sodium nitroprusside (SNP, 10-10 ­ 10-5 M) was assessed. Histopathologic measures of thickness/lumen ratio from both the left ventricle and aorta walls, as well as phytochemical screening, were also performed. Results: As for enalapril, all doses of P. quadrangularis L. prevented the hypertension induced by L-NAME (122±1.2 versus 155±1.3 mmHg at seventh week). P. quadrangularis L. significantly increased the relaxant effect induced by ACh in isolated aorta and decreased the thickness/lumen ratio of aorta wall specimens. Conclusions: P. quadrangularis L. prevents experimental hypertension induced in rats with nitric oxide deficits improving the endothelium vasodilatation response and protecting against vascular remodelling.

Antecedentes: Passiflora quadrangularis L. es una de las especies utilizadas en medicina tradicional en Colombia para la hipertensión pero hasta el momento no se ha evaluado en modelos experimentales. Objetivos: Evaluar la capacidad del extracto etanólico de P. quadrangularis L. para prevenir la hipertensión y el remodelado vascular inducidos por déficit de óxido nítrico (NO) en ratas Wistar. Métodos: El inhibidor de la óxido nítrico (NO) sintasa L-NAME (10 mg/kg, i.p, cada 48 h) se administró durante siete semanas a los siguientes grupos de tratamiento: P. quadrangularis L. 75, 150 y 300 mg/kg/d, p.o; Enalapril como agente de referencia, 10 mg/kg/d, p.o., y vehículo como control (mezcla de propilenglicol 10%, glicerina 10% y polisorbato 2%). Se midió la presión arterial (BP) y la frecuencia cardiaca (HR) dos veces por semana. Después del sacrificio, se aislaron los anillos aórticos, se desencadenó la contracción con fenilefrina (PE 10-6 M) y la respuesta relajante con concentraciones acumulativas de acetilcolina (ACh, 10-10 ­ 10-5 M) o nitroprusiato de sodio (SNP, 10-10 ­ 10-5 M). También se realizaron estudios histopatológicos de la relación entre el espesor y el lumen tanto en el ventrículo izquierdo como en las paredes de la aorta, así como un cribado fitoquímico. Resultados: Enalapril y todas las dosis de P. quadrangularis L. evitaron la hipertensión inducida por L-NAME (122 ± 1,2 frente a 155 ± 1,3 mm Hg a la séptima semana). P. quadrangularis L. aumentó significativamente el efecto relajante inducido por ACh en la aorta aislada y disminuyó la relación entre el espesor y la luz de los especímenes en la pared de la aorta. Conclusiones: P. quadrangularis L. previene la hipertensión experimental inducida por déficit de óxido nítrico en ratas, mejorando la respuesta del endotelio y protegiendo frente al remodelado vascular.

Efficacious In Vitro and In Vivo Effects of Dihydrosphingosine-Ethambutol Analogues Against Susceptible and Multi-drug-resistant Mycobacterium tuberculosis.

BACKGROUND AND AIMS: Tuberculosis (TB) is a major worldwide health problem in part due to the lack of new drugs and the emergence of multidrug-resistant strains (MDR). The aim of this study was to select anti-tuberculosis drug candidates from a collection of 69 synthetic sphingosine-ethambutol analogues through in vitro and in vivo evaluations. METHODS: The 69 compounds were evaluated in vitro against two Mycobacterium tuberculosis strains, a drug susceptible (H37Rv) and a MDR clinical isolate (CIBIN-99). Four selected compounds, those that exhibited the highest potency in vitro, were tested in vivo using a model of progressive TB in BALB/c mice infected with the drug susceptible strain, either alone or combined with conventional chemotherapy, as well as in mice infected with the MDR strain. The acute toxicity was evaluated on male and female adult BALB/c mice. RESULTS: Ten of the evaluated compounds resulted more potent in vitro than ethambutol. The experimental compound 2b (2-aminopalmitol benzyl ether) was the most efficacious and also showed additive effects in combination with conventional chemotherapy. It did not exhibit toxicity (LD50 >2000 mg/kg). CONCLUSIONS: Compound 2b can be considered as a new drug candidate to continue its development against M. tuberculosis MDR strains.