The inhibitory activity of thirty-one sesquiterpenes identified from Brazilian essential oils (Copaifera langsdorffii Desf., Croton cajucara Benth. and Siparuna guianensis Aublet.) were analyzed by in silico molecular docking. The compounds were characterized by gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame-ionization detection (GC-FID), and then, applied against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) proteins and human angiotensin-converting enzyme 2 (hACE2). Applying molecular docking and AutoDock Vina software, a total of 496 individual interactions were detected for sesquiterpenes along with SARS-CoV-2 proteins and hACE2 human angiotensin converting enzyme-2 protein. The findings showed considerable binding affinity of sesquiterpenes with the tested macromolecules. In that, β-selinene from C. langsdorffii displayed the best energy (−7.2 kcal mol-1) and showed strong interactions with the amino acids of the SARS-CoV-2 M-Pro protein. Spathulenol from C. cajucara strongly interacted with human ACE2, with a binding energy of −7.1 kcal mol-1. Meanwhile, γ-eudesmol from S. guianensis presented the lowest binding energy (−7.5 kcal mol-1) by interacting with the SARS-CoV-2 M-Pro complex. Additionally, measurements were performed aiming to evaluate the best sesquiterpenes binding interactions with the main proteins and its homologue files. According to results, these Brazilian essential oils hold antiviral potential being a rich source for further in vitro and in vivo studies focusing on herbal therapeutic adjuvants against SARS-CoV-2 infections.

Self-nanoemulsion drug delivery systems (SNEDDS) represent a potential carrier to improve solubility and bioavailability of health care products. In this sense, copaiba oil (CO) loaded on cosurfactant-free SNEDDS formulations (CO-SNEDDS) were obtained by using phase diagram performed on different concentrations of constituents (oil, surfactant and water). The CO-SNEDDS are composed of 1% (m/m) of oil phase, 20% (m/m) of Tween 80, and 79% (m/m) of double-distilled water. Specifically, varying the oil phase to 1% of CO affords the so-called SNECO system, and 1% of CO blended on a 1:1 ratio with coconut oil or sunflower oil affords, respectively, the SNECO-COO and SNECO-SO derivative systems. CO sample was authenticated by gas chromatography equipped with a flame ionization detector and the CO-SNEDDS samples were characterized by droplet particle size, zeta potential, polarized light microscopy, pH, conductivity, refractive index, rheological and surface tension analyses. According to the antioxidant tests reducing power and hydroxyl inhibiting formation, the findings displayed 47.89 and 72.92% for SNECO, 46.48 and 84.11% for SNECO-COO, and 52.46 and 74.48% for SNECO-SO, respectively. From now on CO-SNEDDS based systems become available as promising targets for novel medicinal investigations and also could be undertaken for the oral administration of poorly water soluble drugs.

The inhibitory ability of an oxazinoquinoxaline derivative (OAQX) against the corrosion of AISI 1018 mild steel induced by aqueous 0.6 mol L-1 NaCl solution is herein evaluated. Linear polarization resistance studies showed the inhibitory efficiency of OAQX varying from 62.75% to 75.93% with OAQX concentration ranged from 0.259 x 10-4 mol L-1 to 3.243 x 10-4 mol L-1. Aiming at to investigate the Tafel curves on the OAQX electrochemical behavior at saline (0.6 mol L-1 NaCl) aqueous media the linear Tafel segments of anodic and cathodic curves were extrapolated to the intersection point which afforded corrosion potential (Ecorr) and corrosion current density (icorr) data. By applying Tafel approach the efficiency of OAQX ranges from 55.30% to 87.60%. In both analysis Langmuir isotherm lead to optimized adsorption parameter. The adsorption mechanism of OAQX is proposed from FTIR experiments and quantum calculations. The theoretical employed method is hybrid B3LYP combined with 6-311++G(d,p). Theoretical results showed OAQX as a promising inhibitor that form a stable protective metal-ligand film on metal surfaces, and differs from several heterocyclic compounds due to its solubility in small amount of DMSO (0.627 x 10-4 mol L-1) which is resistant to a saline aqueous media (0.6 mol L-1 NaCl).

The aim of this study was to develop and characterize poly-ε-caprolactone (PCL) and poly(D,L-lactic-co-glycolic)-acid (PLGA) microparticles containing coencapsulated trans-dehydrocrotonin (t-DCTN) and t-DCTN:hydroxypropyl-β-cyclodextrin inclusion complex (t-DCTN:HP-β-CD), with t-DCTN loaded at concentrations ranging from 11.25 to 45.00 mg. A preformulation study was carried out using a 24-1 fractional factorial design. Microparticles were prepared using the double w/o/w emulsion-solvent evaporation method. The coencapsulated t-DCTN:HP-β-CD-loaded PLGA microparticles (t-DCTN/t-DCTN:HP-β-CD/PLGA-MPs) presented a smaller particle size (9.6 ± 0.1 µm) and higher drug loading (13.93 ± 0.05%, corresponding to 90.1 ± 0.3% of encapsulation efficiency, EE) and t-DCTN-loaded PLGA microparticles (t-DCTN/PLGA-MPs) presented particle size of 37.0 ± 0.2 µm and drug loading of 10.12 ± 0.01% (EE of 71.2 ± 0.1%). The coencapsulation of t-DCTN and t-DCTN:HP-β-CD into PLGA microparticles increased drug loading (50%) and improved the drug controlled release (k2 = 0.0475 and De = 0.0475 × 10-11 cm2 s-1). Taking into account these findings, new oral formulation of PLGA microparticles containing coencapsulated t-DCTN and t-DCTN:HP-β-CD are available as biocompatible drug delivery systems for further pharmacological purposes.

The interaction between 19-nor-clerodane trans-dehydrocrotonin (from Croton cajucara Benth.) and bovine serum albumin was studied, applying spectroscopic techniques (fluorescence and circular dichroism), combined with molecular modeling. Fluorescence quenching of albumin by the nor-clerodane (kq ca. 1011 mol L-1 s-1 and Stern-Volmer, KSV, increase with temperature) indicates a combination of static and dynamic quenching mechanism. The binding constant (Kb ca. 103 mol L-1) and circular dichroism data suggest that this association is weak and causes only a moderate change in the α-helix content of the protein. Thermodynamic parameters indicate a spontaneous (Gibbs free energy, ΔGº, ca. -21.28 kJ mol-1 at 310 K) and probably entropy-driven (ΔSº = 0.072 kJ mol-1 K-1) association, typical of hydrophobic interactions. The number of binding sites (n ca. 1) indicates one main binding site and molecular modeling suggests subdomain IIIA (Sudlow's site II) as the main binding site to the nor-clerodane, which is able to make hydrophobic interactions with leucine (Leu)-24, phenylalanine (Phe)-36, valine (Val)-40 and tryptophan (Trp)-134 residues.

In this paper, thiosemicarbazones 4-N-cinnamoyl-thiosemicarbazone (CTSC), 4-N-(2'-methoxycinnamoyl)-thiosemicarbazone (MCTSC), and 4-N-(4'-hydroxy-3'-methoxybenzoyl)- thiosemicarbazone (HMBTSC) were solubilized in an oil-in-water (O/W) microemulsion system (ME_OCS), forming systems CTSC_ME_OCS, MCTSC_ME_OCS and HMBTSC_ME_OCS. The effectiveness of these systems in the process of inhibiting AISI 1020 carbon steel corrosion was evaluated in a saline solution (NaCl 0.5%), using a galvanostatic method. The tested thiosemicarbazones showed higher inhibitory effects (85.7% for CTSC_ME_OCS, 84.0% for MCTSC_ME_OCS, and 83.3% for HMBTSC_ME_OCS). The surfactant OCS (dissolved in H2O) and the ME_OCS system showed lower efficacies, with 71.0% for OCS and 74.0% for ME_OCS system.

Sistemas microemulsionados (MES) oferecem inúmeras vantagens como liberadores de fármacos já que favorecem a absorção do princípio ativo e são, em muitos casos, mais eficientes do que outros métodos de liberação de substâncias bioativas. Neste trabalho, um MES foi obtido visando uma formulação para uso tópico, contendo extrato etanólico de própolis (PEE). Neste estudo, Diagramas de fase pseudoternários foram utilizados para caracterização das regiões de microemulsão, bem como para definição da região de Winsor IV do sistema PEE-MES (Tween 80 como tensoativo e álcool etílico como co-tensoativo, em baixo percentual). Os resultados obtidos indicaram que o melhor sistema microemulsionado contém C/S (cotensoativo/tensoativo) na razão 1,0, fornecendo uma microemulsão do tipo O/A com ampla região de Winsor IV. A formulação PEE-MES poderá vir a ser utilizada comercialmente para uso tópico no combate a inflamações de boca e garganta. Considerando o amplo uso de própolis em formulações convencionais, onde sua solubilidade representa um dos maiores problemas, o sistema PEE-MES disponibiliza este produto natural para aplicações farmacológicas, com boa solubilidade em um sistema microemulsionado do tipo O/A. Adicionalmente, o efeito bactericida do sistema PEE-MES foi comprovado e uma nova metodologia de extração de própolis é apresentada.

Microemulsion systems (MES) offer advantages as drug delivery systems, among them favour drug absorption, being in most case more efficient than other methods in delivering of drug. In this work a new MES was obtained in order to be applied as a pressurized aerosol formulation containing bee propolis ethanolic extract (PEE). For that, pseudoternary phase diagrams were used to characterize the microemulsions boundaries and also to define the Winsor IV microemulsion region of the PEE-MES system containing Tween 80 as surfactant and the cosurfactant ethyl alcohol in small percentage. The obtained results indicated that the best MES was composed by Tween 80 and ethyl alcohol with C/S (cosurfactant/surfactant) ratio equal to 1.0, since it provided a large boundaries in the obtained O/W microemulsion region. This PEE-MES formulation, in which bee propolis consisting as oil phase, is herein designed for topical uses (PEE-MES spraying) in order to treat mouth and throat inflammatory infections. Considering the very large uses of bee propolis in conventional vehicles, MES type of delivery system has to be compatible with achieving the highest drug aim loadings, determined substantially by the specific MES application (drug solubilization in water systems) improving in this case, propolis farmacological aplications. Additionally, PEE-MES antibacterial effect was evidenced and the microemulsion system PEE-MES was also used as newest chemical approach for extraction of bee propolis material from resinous hive.

Neste estudo avaliou-se o efeito analgésico do diterpeno 19-nor-clerodano trans-desidrocrotonina (DCTN) isolado de Croton cajucara Benth (Euphorbiaceae), bem como seu efeito no sistema nervoso central utilizando-se diferentes tipos de modelos de animais roedores. A administração intraperitoneal deste diterpeno, no teste da placa quente, revelou sua atividade analgésica moderada. No entanto, no teste de contrações abdominais desencadeadas por ácido acético, a DCTN apresentou forte atividade antinociceptiva com DE50 de 44,88 mg/kg. Doses elevadas de DCTN (100 mg/kg) apresentaram moderada atividade depressiva do sistema nervoso central (SNC), não tendo sido evidenciado ação antidepressiva. Após algumas considerações da ação de DCTN em algesia periférica, concluiu-se que esta substância pode ser utilizada como um potente agente analgésico, sem afetar o SNC.

This study examined the effect of trans-dehydrocrotonin (DCTN), a 19-nor-clerodane diterpene isolated from Croton cajucara Benth (Euphorbiaceae), as analgesic and its effect on the central nervous system (CNS) of rodents using different animal models. The DCTN intraperitoneally exhibited mild analgesic activity on hot-plate test, but exhibited strong antinociceptive activity against acetic acid-induced abdominal writhing and the ED50 was calculated to be 44.88 mg/kg. At higher doses (100 mg/kg) it exhibited mild CNS depressant activities in laboratory animals. Moreover, it has negligible antidepressant activity. After taking consideration of the drug interaction, the DCTN can be used as a potent analgesic agent in case of peripheral algesia, without affecting the CNS.

O 19-nor-clerodano trans-crotonina (CTN) e o triterpeno ácido acetil aleuritólico (AAA), isolados das cascas do caule de Croton cajucara Benth (Euphorbiaceae), uma planta tradicional da Região Amazônica do Brasil, bem como o extrato aquoso (EA) das cascas do caule deste Croton, foram submetidos a experimentos farmacológicos utilizando animais, para avaliação das atividades anti-inflamatória e antinociceptiva. A administração oral de AAA (50 mg/kg), CTN (50 mg/kg) ou AE (300 mg/kg) inibiram as contorções em ratos, induzidas por ácido acético. Os terpenóides AAA e CTN, bem como o extrato polar EA, inibiram significativamente o edema de pata em ratos, induzido por carragenina. As inibições foram observadas em todos os intervalos de medições, tendo sido evidenciado melhores inibições para os terpenóides AAA (47,7%, após a primeira hora) e CTN (54,4%, após a segunda hora). Evidenciou-se ainda, após 90 minutos do estímulo, significante inibição no edema induzido por dextrana (31,9% para CTN e 28,5% para AAA) e por histamina (43,2% para CTN e 40,5% para AAA). Estes resultados confirmam o uso popular de Croton cajucara na região Amazônica do Brasil, no combate a inflamações.

The 19-nor-clerodane trans-crotonin (CTN) and the triterpene acetyl aleuritolic acid (AAA), isolated from the stem bark of Croton cajucara Benth (Euphorbiaceae), a traditional medicinal plant from Amazon region of Brazil, as well as the aqueous extract (AE) from its stem bark, were submitted to pharmacological screening for anti-inflammatory and antinociceptive activities in animal models. The oral administration of AAA (50 mg/kg), CTN (50 mg/kg) or AE (300 mg/kg) inhibited the acetic acid-induced writhing in mice. The AE, CTN and AAA had shown significant inhibition of carrageenin-induced edema in rats, in all time intervals measured after the injection of the stimulus, with the greatest inhibition at the first hour for AAA (47.7%) and the second hour for CTN (54.4%). They have also exhibited significant inhibition in the dextran-induced edema 90 minutes after the stimulus: 31.9% for CTN and 28.5% for AAA. In the histamine-induced edema, the inhibition showed by CTN and AAA were 43.2% and 40.5%, respectively, 90 minutes after the injection of stimulus. This study extends and supports the popular medicine and folkloric uses of Croton cajucara in the Amazon region of Brazil.

The effectiveness of microemulsions (ME) of saponified coconut oil (OCS-ME) and diphenylcarbazide (DC-ME) on a carbon steel corrosion inhibition process was evaluated using an electrochemical method of polarization resistance. The ME was prepared with OCS, butanol, kerosene and saline solutions. OCS-ME and DC-ME showed highest inhibitions effects (77% and 92%, respectively) at lower concentrations (0.5% and 0.48 - 0.50%, respectively). The surfactant OCS (in H2O) showed lower efficiency (63% at 0.20 - 0.25% concentration). The greatest inhibitory effect of DC-ME could be correlated with the chemical structure and the rich O/W ME system, which are very important for adsorption phenomena in interfacial ME systems.

Croton cajucara Beth (Euphorbiaceae) uma espécie medicinal nativa da região Amazônica do Brasil, onde é vulgarmente conhecida como 'sacaca', representa um recurso terapêutico eficaz no tratamento e cura de várias doenças. O metabólito majoritário trans-desidrocrotonina (DCTN), isolado das cascas do caule desta planta, encontra-se correlacionado com grande parte das propriedades medicinais da sacaca. Este artigo de revisão, descreve os resultados fitoquímicos e farmacológicos que foram realizados com o diterpeno do tipo clerodano DCTN, bem como seus derivados semi-sintéticos. Adicionalmente, apresenta perspectivas para a biodisponibilização deste protótipo de fármaco em nanosistemas.

Croton cajucara Beth (Euphorbiaceae) is a plant found in the Amazonian Region of North Brazil, where it is popularly known as sacaca. The major secondary metabolite, trans-dehydrocrotonin (DCTN) a clerodane-type diterpene, isolated from the stem bark is a chief bioactive compound of Croton cajucara. This review describes results of extensive pharmacological studies of DCTN, as well as its semi-synthetic derivatives, and also presents insights into the use of DCTN as a therapeutic agent and some potential advantages of its incorporation in drug delivery systems.

O diterpeno clerodano trans-desidrocrotonina (1), constituinte majoritário de Croton cajucara, tem sua ocorrência correlacionada com o uso dessa planta na medicina popular. Investigações fitoquímicas levaram ao isolamento dos metabólitos 1, cajucarinolida (6), isocajucarinolida (7), trans-crotonina (2), trans-cajucarina B (3), cis-cajucarina B (4), trans-cajucarina A (5), N-metiltirosina, ácido vanílico e ácido 4-hidróxi-benzóico. 6 e 7 foram sintetizados em bons rendimentos através da oxidação de 1 com oxigênio-singlete. Todos os clerodanos foram ensaiados frente a células da leucemia humana K562 e do carcinoma de Ehrlich. Os efeitos inibitórios do crescimento celular foram dependentes da dose para os ensaios com o carcinoma de Ehrlich com IC50 = 166 µM (1), 164 µM (2), 65 µM (6) e 10 µM (7). Além disso, atividade citotóxica moderada foi observada contra as células da leucemia K562 com IC50 = 38 µM (3), 33 µM (5), 36 µM (6) e 43 µM (7). Os 6 e 7 semi-sintéticos mostraram resultados semelhantes quando comparados com os correspondentes clerodanos naturais.

The clerodane-type diterpene, trans-dehydrocrotonin (1) the major component of Croton cajucara has shown striking correlation with its therapeutic use in traditional folk medicine. Phytochemical investigations led to the isolation of the metabolites 1, cajucarinolide (6), isocajucarinolide (7), trans-crotonin (2), trans-cajucarin B (3), cis-cajucarin B (4), trans-cajucarin A (5), N-methyltyrosine, vanillic acid and 4-hydroxy-benzoic acid. 6 and 7 were synthesized in good yield by regiospecific oxidation of 1 using singlet-oxygen. All clerodanes were studied for their cytotoxic effects against human K562 leukemia and Ehrlich carcinoma cells. Ehrlich carcinoma assays with IC50 = 166 µM (1), 164 µM (2), 65 µM (6) and 10 µM (7) related to cell growth inhibitory effects were dose dependent. Furthermore, moderate cytotoxic activity against K562 leukemia cells was observed with IC50 = 38 µM (3), 33 µM (5), 36 µM (6) and 43 µM (7). The semi-synthetic 2, 6 and 7 showed similar results when compared to the corresponding natural clerodanes.

Este trabalho objetivou a obtenção de óleos fixos (OF) das cascas do caule de Croton cajucara via percolação [seguido de fracionamento em coluna cromatográfica (CC)] e fluido supercrítico (FS, gás CO2), bem como a avaliação das propriedades fungicidas de OF obtido pelo procedimento CC. Os óleos OF-CC e OF-FS apresentaram rendimentos significativamente diferentes; houve maior rendimento (3,14%) de OF obtido no processo convencional (OF-CC), versus 1,2% de OF-FS. A fração F1 após esterificação, bem como as frações não-esterificadas F2, F3 e F4 (obtidas de OF-CC seguido de outro fracionamento em CC) foram analisadas por CG-FID e CG-EM. A identificação da composição química de OF-CC foi feita por comparação com dados da biblioteca Wiley, bem como pela comparação de índices de kovats. A presença de sesquiterpenos foi comprovada na fração F1, onde o a-copaeno (20,1%) e cipereno (21,8%) foram os componentes majoritários (70% de percentual sesquiterpênico total). A fração F2 mostrou sesquiterpenos minoritários mais oxigenados, incluindo o linalol. Na fração F3 foram observados ácidos graxos, misturas de esteróis e os diterpenos bioativos trans-crotonina, cis-cajucarina B e trans-cajucarina B, onde 40% do total desta fração, foi composta de esteróis e diterpenos; e na fração F4 foram observados majoritariamente os isômeros cis e trans-cajucarina B. O efeito biológico de OF-CC foi avaliado no desenvolvimento in vitro dos fungos fitopatogênicos Fusarium oxysporum, Rhizoctonia solani e Sclerotium rolfsii propagados em meio de cultura Batata-dextrose-agar (BDA). A resposta fisiológica, variou de acordo com o tipo de fungo testado, tendo sido observado que o OF-CC (0,2 mg.mL-1) apresentou efeito fungistático no controle micelial dos fungos testados, sendo que o gênero de fungo Fusarium oxysporum foi o que sofreu efeito inibitório mais estável.

This paper focused on the separation of the fixed oil (FO) from the stem bark of Croton cajucara obtained from the conventional approach extraction with organic solvents [followed by chromatography column (CC)] and supercritical fluid extraction (SFE, carried out with CO2) and also, on the antifungical properties of the FO obtained by CC procedure (FO-CC). The FO contents were 3.14% for FO-CC versus 1.20% in the FO-SFE process. The esterified fraction F1 and non-esterified fractions F2, F3 and F4 obtained from FO-CC after a new CC procedure were analyzed by HRGC-MS. The identification of the chemical composition of FO-CC was made by comparison with MS literature data, computer matching with the Wiley library and by comparison of their kovats indices with the literature. Fraction F1 showed 70% of sesquiterpene components, among them a-copaene (20.1%) and ciperene (21.8%) as major compounds. Fraction F2 was rich in minor oxygenated sesquiterpenes, among them linalool. Meanwhile fraction F3 showed fat acids, steroids and the bioactive clerodane type-diterpene trans-crotonin, cis-cajucarin B (c-CJC-B) and trans-cajucarin B (t-CJC-B). Fractions F3 and F4 showed as major constituents c-CJC-B and t-CJC-B with 40% of the total contents. The biological effect of the FO-CC was evaluated in the in vitro development of the phytopatogen fungi such as Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Significant inhibitory effect of the tested fungi (at 0.2 mg.mL-1 dosage) were proved.

The plant Croton cajucara Benth. (Euphorbiaceae) is a medicinal plant from the Brazilian Amazon where it is commonly known as sacaca. The principal compound isolated from C. cajucara stem-bark extracts is the clerodane-type diterpene trans-dehydrocrotonin (DCTN) which presents several biological activities, including antiulcerogenic, anti-inflammatory, hypoglycemic, antimutagenic and antitumoral activity. However, few studies have been carried out to evaluate the therapeutic potential of raw C. cajucara extracts. We studied mutagenicity and antimutagenicity effects of C. cajucara methanol extract using the micronucleus assay in bone marrow cells and the dominant lethal assay in mice submitted to subchronic treatments. The blood testosterone levels of the mice were also measured to assess the effects of the methanol extract on testes function. Statistical analysis of the data obtained in this study showed no statistically significant mutagenicity attributable to C. cajucara stem-bark extracts, nor did such extracts show antimutagenic activity at the concentrations assessed. The testosterone concentration was normal in all the mice studied.

Plant extracts are usually complex mixtures which contain several molecules of different sizes with varied functional groups. Such extracts are a challenge to the chemist of natural products. Ion exchange chromatography in non-aqueous medium, used for separation of basic or acidic fractions from plant extracts, is an important unit operation in preparative scale separations. Anionic macroporous resin in non-aqueous medium was used with success in this study for separation of the acid fraction of Copaifera multijuga (Copaiba oil), rich in labdanic diterpenes and for the methanolic extract of Croton cajucara (acetyl aleuritoric acid).