TOCSY, hydrogen decoupling and computational calculations to an unequivocal structural elucidation of a new sesquiterpene derivative and identification of other constituents from Praxelis sanctopaulensis.

INTRODUCTION: Praxelis genus comprises 24 species, however, only two species of this genus have been chemically investigated. Here we investigated Praxelis sanctopaulensis, a native plant from Brazil, that occurs mainly in Cerrado regions. OBJECTIVE: The goal was to identify the specialised metabolites from P. sanctopaulensis, and compare with those described from Praxelis and Chromolaena species. METHODS: The phytochemical study of P. sanctopaulensis was performed through different chromatography techniques, including high-performance liquid chromatography (HPLC), gas chromatography flame ionisation detector (GC-FID), and ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry (UHPLC-HRMS/MS). The structures of the compounds were established based on spectroscopic analysis, total correlated spectroscopy (TOCSY), hydrogen decoupling and computational calculations was used to an unequivocal structural elucidation of a new sesquiterpene. The antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP), and antimicrobial assay was performed by the microdilution method. Comparison of the flavonoids described P. sanctopaulensis was carried out using principal component analysis. RESULTS: The phytochemical investigation of P. sanctopaulensis led to the isolation of a pair of diastereomers, praxilone A and praxilone B. Seven known compounds were isolated from this species, another 14 fatty acids were detected in hexane fraction, and 26 compounds were identified from ethyl acetate fraction. All these compounds are being described for the first time in this species, with the exception of viridifloric acid. The ethyl acetate fraction showed potent antioxidant activity. CONCLUSIONS: Forty-seven compounds are described from P. sanctopaulensis. The combination of different techniques of nuclear magnetic resonance (NMR) spectroscopy and computational calculations allowed the unequivocal structure elucidation of a new cadinene. The clustering analysis showed similarities between the flavonoids identified in P. sanctopaulensis and in Chromolaena species.

Phytoprostane and phenolic compounds from Chromolaena palmaris.

The chemical investigation of Chromolaena palmaris (Sch.Bip. ex Baker) R.M. King & H. Rob. expands the phytochemical composition knowledge of Chromolaena genus, since this is the first chemical investigation of this species. Twenty-five compounds were identified, including a phytoprostane, 17 flavonoids, 6 phenolic acids, and a caffeoyl-glucoside derivative obtained by classical chromatography and UHPLC-HRMS/MS analysis. Moreover, anti-Mycobacterium tuberculosis and antiproliferative activities of C. palmaris were evaluated. Dichloromethane fraction showed cytotoxicity towards human cancer cell lines, presenting TGI values on glioma (U251) of 27.8 µg mL-1. Furthermore, compounds 1 and 2 exhibited antimicrobial activity against Mycobacterium tuberculosis with MIC of 62.5 and 15.6 µg mL-1, respectively.

ß-carbolines RCC and C5 induce the death of Leishmania amazonensis intracellular amastigotes.

Background: Cutaneous leishmaniasis is caused by Leishmania spp., and its treatment is limited. The ß-carbolines have shown activity against kinetoplastids. Aim: To evaluate the activity and effects of the ß-carbolines, N-{2-[(4,6-bis(isopropylamino)-1,3,5-triazin-2-yl)amino]ethyl}-1-(4-methoxyphenyl)-ß-carboline-3-carboxamide (RCC) and N-benzyl-1-(4-methoxy)phenyl-9H-beta-carboline-3-carboxamide (C5), against L. amazonensis intracellular amastigotes and to suggest their mechanism of action. Methods: We analyzed the activity and cytotoxicity of ß-carbolines and the morphological alterations by electron microscopy. Mitochondrial membrane potential, production nitric oxide, reactive oxygen species, lipidic bodies, autophagic vacuoles and ATP were also evaluated. Results & conclusion: The results showed that RCC and C5 are active against intracellular amastigotes and were able to induce oxidative stress and ultrastructural alterations such as accumulation of lipid bodies and autophagic vacuoles, leading to parasite death.

Chromolaena laevigata (Asteraceae) as a source of endophytic non-aflatoxigenic Aspergillus flavus: chemical profile in different culture conditions and biological applications.

Endophytes are microorganisms that form symbiotic relationships with their host. These microorganisms can produce a variety of secondary metabolites, some of which have inhibitory effects on pests and pathogens or even act to promote plant growth. Due to these characteristics, these microorganisms are used as sources of biologically active substances for a wide range of biotechnological applications. Based on that, the aim of this study was to evaluate the production of metabolites of the endophytic Aspergillus flavus CL7 isolated from Chromolaena laevigata, in four different cultivation conditions, and to determine the antimicrobial, cytotoxic, antiviral, and antioxidant potential of these extracts. The multiphasic approach used to identify this strain was based on morphology and ITS gene sequence analysis. The chemical investigation of A. flavus using potato dextrose and minimal medium, using both stationary and agitated methods, resulted in the isolation of kojic acid, α-cyclopiazonic acid, and 20,25-dihydroxyaflavinine. Another 18 compounds in these extracts were identified by UHPLC-HRMS/MS, of which dideacetyl parasiticolide A has been described for the first time from A. flavus. Aflatoxins, important chemomarkers of A. flavus, were not detected in any of the extracts, thus indicating that the CL7 strain is non-aflatoxigenic. The biological potential of all extracts was evaluated, and the best results were observed for the extract obtained using minimal medium against Trichophyton rubrum and Mycobacterium tuberculosis.

Cytotoxic sesquiterpene lactones from Campuloclinium macrocephalum (=Eupatorium macrocephalum).

Three undescribed germacranolide sesquiterpene lactones, named macrocephalides A-C, along with known steroids, triterpenes and flavonoids were isolated from the aerial parts of Campuloclinium macrocephalum. The structures of the undescribed compounds were elucidated with basis on their 1D and 2D-NMR, and HR-ESI-MS data. Their absolute configurations were assigned by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Additionally, macrocephalides A-C were evaluated for their in vitro cytotoxic activities against nine human cancer cell lines. Macrocephalides A and B exhibited moderate to potent cytotoxic activity, inhibiting 50% of cell growth (GI50) at concentrations ranging from 0.576 to 6.37 µM.

Mycenolide A, new butenolide from a marine sediment-derived bacterium Streptomyces sp. 4054.

Streptomyces sp. 4054, isolated from marine sediments, produced a new butenolide, mycenolide A (1), along with five known butenolide derivatives (2-6). The structures of the compounds were established based on 1D- and 2D-NMR spectroscopic analysis, circular dichroism, and mass spectrometry data. The antimicrobial activity of the crude extract of the marine bacteria Streptomyces sp. 4054 was evaluated, showing good results against Bacillus subtilis and MRSA.

Structural Characterization and Biological Evaluation of 18-Nor-ent-labdane Diterpenoids from Grazielia gaudichaudeana.

The phytochemical investigation of Grazielia gaudichaudeana aerial parts yielded 15 compounds, including diterpenes, triterpenes, sterols and flavonoids. With exception to ent-kaurenoic acid diterpenes, the compounds isolated are being described for the first time in this species. Some unusual 1 H-NMR chemical shifts of 18-nor-ent-labdane (7-9) led us carry out a conformational analysis by theoretical calculations in order to support the experimental data. Moreover, due to the limitation of studies focused on pharmacological potential of Grazielia gaudichaudeana, the present study was carried out to investigate the antioxidant, antiproliferative, antiviral, antileishmanial and antimicrobial activities from the extract, fractions and isolated compounds obtained from this species. Ethyl acetate fraction showed significant activity in the antiproliferative assay, with GI50 range of 3.9 to 27.2 µg mL-1 . Dichloromethane fraction, rich in diterpenoids, inhibited all human tumor cell lines tested, and the nor-labdane 7 showed potent cytotoxic activity against glioma and ovary cancer cell lines.

Computational & experimental evaluation of the structure/activity relationship of ß-carbolines as DYRK1A inhibitors.

DYRK1A has been associated with Down's syndrome and neurodegenerative diseases, therefore it is an important target for novel pharmacological interventions. We combined a ligand-based pharmacophore design with a structure-based protein/ligand docking using the software MOE in order to evaluate the underlying structure/activity relationship. Based on this knowledge we synthesized several novel ß-carboline derivatives to validate the theoretical model. Furthermore we identified a modified lead structure as a potent DYRK1A inhibitor (IC50=130 nM) with significant selectivity against MAO-A, DYRK2, DYRK3, DYRK4 & CLK2.

Morphoanatomy and pharmacognostic study of the wood of Croton echioides, the Northeastern Marapuama

Croton echioides Baill., Euphorbiaceae, is a small tree found in Bahia, Northeastern Brazil. Its stem bark has been widely sold as an aphrodisiac and tonic, as a substitute for the roots of Ptychopetalum olacoides Benth. Olacaceae, the Amazon Muira Puama or Marapuama, and C. echioides is characterized as the "Northeastern Marapuama". This contribution describes a morphoanatomical analysis and pharmacognostic study of stem bark of this species. The stem has a thick cortex with compound starch grains and laticifers; a sclerenchymatic sheath which consists of brachysclereids with large crystals externally to the phloem, and abundant fiber in the secondary xylem, as the main features of the species. The data obtained for water content (9.26±0.07%), water-soluble extractives (3.92±0.19%), total ash (1.24±0.06%) and acid-insoluble ash (0.16±0.01%), together with the chromatographic profile obtained by TLC, contribute to the quality control and standardization for the plant drug. The pharmacological screening indicated LD50 values above 500 mg/kg orally and equal to 500 mg/kg by the i.p. route, as well as some stimulant potential, depending on the dose.

Estudo fitoquímico e avaliação da toxicidade frente a Artemia salina e da atividade antimicrobiana de Calycorectes psidiiflorus (O. Berg) Sobral, Myrtaceae / Phytochemical study and evaluation of toxicity against Artemia salina and antimicrobial activity of Calycorectes psidiiflorus (O. Berg) Sobral, Myrtaceae

O estudo fitoquímico das folhas de Calycorectes psidiiflorus (O. Berg) Sobral, Myrtaceae, resultou no isolamento e identificação de: sesquiterpeno [8-hidroxicalameneno (1)], triterpenos [α-amirina (2a) e β-amirina (2b)], flavonóide [3-O-α-ramnopiranosil-7-O-bglucopiranosil canferol (3)], e alcalóide [1,2,3,4-tetraidro-1-metil-β-carbolina (4)]. As estruturas das substâncias isoladas foram elucidadas com base nos seus dados de RMN em comparação com os da literatura. A substância 8-hydroxicalameneno apresentou atividade antibacteriana (MIC = 7,8 µg/mL) e antifúngica (MIC = 15,6 µg/mL).

The phytochemical study of Calycorectes psidiiflorus (O. Berg) Sobral leaves resulted in isolation and identification of the sesquiterpene 8-hydroxycalamenene (1), triterpenes α-amyrin (2a) and β-amyrin (2b), flavonoid 3-O-α-rhamnopyranosyl-7-O-β-glucopyranosyl kaempferol (3), and of the alkaloid 1,2,3,4-tetrahydro-1-methyl-β-carboline (4). The structures of the isolated compounds were elucidated based on their spectroscopic NMR data and comparison with those reported in literature. Substance 1 presented antibacterial (MIC = 7.8 µg/mL) and antifungal (MIC = 15.6 µg/ mL) activities.

Evaluation of the molluscicidal and Schistosoma mansoni cercariae activity of Croton floribundus extracts and kaurenoic acid / Avaliação das atividades moluscicida e cercaricida (Schistosoma mansoni) dos extratos de Croton floribundus e do ácido caurenóico

Extratos de Croton fluribundus (Euphorbiaceae), ácido caurenóico e dois derivados do ácido caurenóico foram avaliados como moluscicida, cercaricida e também foi verificada a letalidade destas amostras frente a larvas de Artemia salina Leach. Nestes ensaios foram observadas significantes atividades moluscicida e cercaricida associadas a uma reduzida toxicidade frente ao camarão de água salgada.

Lethality of the extracts of Croton floribundus (Euphorbiaceae), a medicinal plant from south Brazil, and of the kaurenoic acid, an isolated compound, and two of its derivatives against adult Biomphalaria glabrata snails, Schistosoma mansoni cercariae and Artemia salina Leach. brine shrimp larvae are reported. Both extracts and the isolated compound showed significant molluscicidal and cercaricidal activities and reduced toxicity in brine shrimp assays.

Antimicrobial and phytochemical studies on Pedilanthus tithymaloides.

The antibacterial and antifungal properties of ethanolic extract of the leaves of Pedilanthus tithymaloides and some of its constituents were investigated by the dilution method.

Synthesis and Biological Evaluation of Novel Paclitaxel (Taxol) D-Ring Modified Analogues.

The semisynthesis and biological activity of paclitaxel (Taxol) analogues in which the oxygen atom in ring D is substituted by a sulfur or a selenium atom is presented. These derivatives were synthesized and tested in order to make more transparent the role of the oxetane ring in the biological activity of paclitaxel. The sulfur derivatives were found to be less active than paclitaxel in biological assays, while the selenium derivative could not be converted to its 4-acyl analogue. The results with the sulfur analogues suggest that the oxygen atom in the oxetane ring plays an important role in the mechanism by which paclitaxel exhibits its anticancer activity.