1 J CH Coupling in Benzaldehyde Derivatives: Ortho Substitution Effect.

The natural J-coupling (NJC) method is applied to analyze the Fermi contact contribution of the NMR spin-spin coupling constant decomposing this contribution in terms of natural localized molecular orbitals. We investigated the influence of the basis set on the NJC analysis for the formyl group coupling constant (1 J CHf) of benzaldehyde derivatives. NJC and other NBO analyses, like steric and natural Coulombic energy, were chosen to explain the influence of electron-donating and electron-withdrawing groups on 1 J CHf for some substituted benzaldehydes (Me, OH, OMe, F, Cl, Br, I, and NO2). For the ortho derivatives, electronegative substituents near the C-Hf bond increase the 1 J CHf coupling. This effect could be related to an increase in formyl carbon s character and changes in the carbon and hydrogen natural charges. This indicates that the substituents in ortho have a proximity effect on 1 J CHf coupling mainly of electrostatic origin instead of the expected hyperconjugative interactions.

Evaluation of (-)-borneol derivatives against the Zika vector, Aedes aegypti and a non-target species, Artemia sp.

Zika, dengue, and chikungunya are vector-borne diseases of pronounced concern transmitted by the mosquito Aedes aegypti Linn. (Diptera: Culicidae). The most important method to avoid outbreaks is to control mosquito spreading by the employment of insecticides and larvicides. Failure to control mosquito dispersal is mostly accounted to Ae. aegypti resistance to currently available larvicides and insecticides, encouraging the development of novel pesticides. In addition, the excessive use of larvicides poses serious threats to human health and the environment. Evaluation of natural products as larvicides in an attempt to overcome this situation is often found in the literature because products originated from nature are considered less toxic to non-target species and more eco-friendly. (-)-Borneol is a bicyclic monoterpene present in essential oils with moderate larvicidal activity. On account of these facts, it was of our interest to synthesize (-)-borneol ester derivatives aiming to study its structure-activity relationships against Ae. aegypti larvae. With the goal to estimate toxicity to a non-target species, evaluation of the lethal concentration 50% (LC50) on Artemia sp. (Artemiidae) and calculation of selectivity towards Ae. aegypti were carried out. The most potent derivative, (-)-Bornyl chloroacetate, exhibited the highest suitability index, demonstrating lower environmental toxicity than other borneol ester derivatives. A parabolic relationship between (-)-borneol esters larvicidal activity and partition coefficient (Log P) was achieved and a correlation equation obtained, validating the importance of lipophilicity to the larvicidal activity of these compounds.

Synthesis and Chemometrics of Thymol and Carvacrol Derivatives as Larvicides against Aedes aegypti.

BACKGROUND: Thymol and carvacrol have previously demonstrated larvicidal activity against Aedes aegypti (Diptera: Culicidae). In view of this fact, it was of our interest to obtain synthetic derivatives and evaluate their larvicidal activity on Ae. aegypti larvae. METHODS: Structural modifications were performed on thymol and carvacrol in an effort to understand the functional groups necessary for modulating their activities and to lead possibly to more effective larvae control agents. The derivatives were further subjected to SAR and computational studies (molecular modeling and chemometric tools (CPCA and PCA)) to extract structural information regarding their larvicidal properties. Field collected and Rockefeller populations of Ae. aegypti were used. RESULTS: Carvacrol and thymol exhibited LC50 of 51 and 58ppm for field collected larvae, respectively. Carvacrol derivatives exhibited LC50 ranging from 39 to 169ppm, while thymol derivatives exhibited LC50 ranging from 18 to 465ppm. Substitution of the acidic proton of carvacrol by esters, ethers, and acetic acid resulted in either maintenance or reduction of potency. CONCLUSION: Thymol derivatives were, to a certain extent, more efficient larvicides against Ae. aegypti than carvacrol derivatives, particularly to Rockefeller larvae. The chemometrics tools applied in this study showed that the independent variables indicate a mixed profile. Nevertheless, hydrophobic interactions increased the larvicidal activity.

In vitro Antiproliferative and Antibacterial Activities of Essential Oils from Four Species of Guatteria.

The essential oils (EOs) extracted from four species of the genus Guatteria, G. australis, G. ferruginea, G. latifolia, and G. sellowiana were analyzed. A total of 24, 22, 25, and 19 constituents of the oils from four species, respectively, were identified by GC/MS. These oils showed qualitative and quantitative differences. All the oils contained the oxygenated sesquiterpenes spathulenol (11.04 - 40.29%) and caryophyllene oxide (7.74 - 40.13%) as predominant constituents. Evaluation of antiproliferative activity of the EOs showed strong selectivity (1.1 - 4.1 µg/ml) against the tumor cell line OVCAR-03 (ovarian cancer), i.e., more active than the positive control doxorubicin (11.7 µg/ml). All EOs showed strong antibacterial activity (minimum inhibitory concentrations of 0.062 - 0.25 mg/ml) against strains of Rhodococcus equi.

Cytotoxic Alkaloids from the Stem of Xylopia laevigata.

Xylopia laevigata (Annonaceae), known locally as "meiú" or "pindaíba", is widely used in folk medicine in Northeastern Brazil. In the present work, we performed phytochemical analyses of the stem of X. laevigata, which led to the isolation of 19 alkaloids: (-)-roemerine, (+)-anonaine, lanuginosine, (+)-glaucine, (+)-xylopine, oxoglaucine, (+)-norglaucine, asimilobine, (-)-xylopinine, (+)-norpurpureine, (+)-N-methyllaurotetanine, (+)-norpredicentrine, (+)-discretine, (+)-calycinine, (+)-laurotetanine, (+)-reticuline, (-)-corytenchine, (+)-discretamine and (+)-flavinantine. The in vitro cytotoxic activity toward the tumor cell lines B16-F10 (mouse melanoma), HepG2 (human hepatocellular carcinoma), K562 (human chronic myelocytic leukemia) and HL-60 (human promyelocytic leukemia) and non-tumor peripheral blood mononuclear cells (PBMCs) was tested using the Alamar Blue assay. Lanuginosine, (+)-xylopine and (+)-norglaucine had the highest cytotoxic activity. Additionally, the pro-apoptotic effects of lanuginosine and (+)-xylopine were investigated in HepG2 cells using light and fluorescence microscopies and flow cytometry-based assays. Cell morphology consistent with apoptosis and a marked phosphatidylserine externalization were observed in lanuginosine- and (+)-xylopine-treated cells, suggesting induction of apoptotic cell death. In addition, (+)-xylopine treatment caused G2/M cell cycle arrest in HepG2 cells. These data suggest that X. laevigata is a potential source for cytotoxic alkaloids.

Cytotoxic biomonitored study of Euphorbia umbellata (Pax) Bruyns.

ETHNOPHARMACOLOGICAL RELEVANCE: Euphorbia umbellata latex (sap) has normally been used in folk medicine in southern Brazil to treat different types of cancers. AIM OF STUDY: To carry out a biomonitored investigation of partitioned latex using in vitro assay, to identify the main mechanisms related with the action of the most active fraction as well as to develop a phytochemical study with this material. MATERIALS AND METHODS: Biological screening was performed with hexane, chloroform, ethyl acetate and methanol fractions from the latex of E. umbellata using MTT, trypan blue, and neutral red assays to determine the cytotoxicity against HRT-18, HeLa and Jurkat cells and flow cytometry, DNA quantification, acridine orange and Hoechst 33342 staining to investigate mechanisms of action for the hexane extract. The phytochemical study of the hexane fraction was performed by chromatographic procedures and the substances were identified by NMR analysis. The isolated terpenes were evaluated using MTT to determine the cytotoxicity against Jurkat cells. RESULTS: All the fractions presented concentration and time dependent cytotoxicity. The hexane fraction showed the highest cytotoxicity; whereas the Jurkat cell was the lineage with the highest sensitivity (IC50 1.87µg/mL). Fragmentation of DNA and apoptosis are two mechanisms related with the toxicity of hexane fraction. The hexane fraction arrested the cell cycle in the G0/G1 phase, and the selectivity index was 4.30. Phytochemical study of the hexane fraction led to isolation of euphol (main compound) and germanicol acetate. Both substances demonstrated some slight cytotoxic activity against Jurkat cells after 72h; however the activity was minimal compared to vincristine (anticancer standard drug). CONCLUSION: The current research proves that the fractions of the latex from E. umbellata have a cytotoxic effect against three different cancer cells lines. The hexane fraction showed high in vitro cytotoxic effects against Jurkat cells demonstrating that the effect may be due to non-polar constituents. The two isolated terpenes (euphol and germanicol acetate) showed poor cytotoxic activity indicating that the anticancer properties of the extract may be caused by other substances present in the hexane fraction.

Influence of Culturing Conditions on Bioprospecting and the Antimicrobial Potential of Endophytic Fungi from Schinus terebinthifolius.

In this study, we analyzed the antimicrobial activity of extracts harvested from 17 endophytic fungi isolated from the medicinal plant Schinus terebinthifolius. Morphological and molecular analyses indicated that these fungal species belonged to the genera Alternaria, Bjerkandera, Colletotrichum, Diaporthe, Penicillium, and Xylaria. Of the endophytes analyzed, 64.7 % produced antimicrobial compounds under at least one of the fermentation conditions tested. Nine isolates produced compounds that inhibited growth of Staphylococcus aureus, four produced compounds that inhibited Candida albicans, and two that inhibited Pseudomonas aeruginosa. The fermentation conditions of the following endophytes were optimized: Alternaria sp. Sect. Alternata-LGMF626, Xylaria sp.-LGMF673, and Bjerkandera sp.-LGMF713. Specifically, the carbon and nitrogen sources, initial pH, temperature, and length of incubation were varied. In general, production of antimicrobial compounds was greatest when galactose was used as a carbon source, and acidification of the growth medium enhanced the production of compounds that inhibited C. albicans. Upon large-scale fermentation, Alternaria sp. Sect. Alternata-LGMF626 produced an extract containing two fractions that were active against methicillin-resistant S. aureus. One of the extracts exhibited high activity (minimum inhibitory concentration of 18.52 µg/mL), and the other exhibited moderate activity (minimum inhibitory concentration of 55.55 µg/mL). The compounds E-2-hexyl-cinnamaldehyde and two compounds of the pyrrolopyrazine alkaloids class were identified in the active fractions by gas chromatography-mass spectrometry.

Hypolipidemic effects of Solidago chilensis hydroalcoholic extract and its major isolated constituent quercetrin in cholesterol-fed rats.

CONTEXT: Despite several studies on the effects of Solidago chilensis Meyen (Asteraceae), the phytochemical and hypolipidemic properties remain underappreciated. OBJECTIVE: This study evaluates the hypolipidemic and antioxidant effects of hydroalcoholic extract (HE) and quercetrin from S. chilensis aerial parts in cholesterol-fed rats. MATERIALS AND METHODS: The HE was analyzed by high-performance liquid chromatography, followed by quercetrin isolation. Hypercholesterolemic rats (1% cholesterol and 0.5% cholic acid for 15 d) were treated with HE (150, 300, and 600 mg/kg p.o.; n = 6), simvastatin (4 mg/kg p.o.; n = 6), or quercetrin (10 mg/kg p.o.; n = 6) once a day for 30 d. During this period, a high-cholesterol diet was maintained until the 30th day of treatment. RESULTS: Rats treated with HE (150, 300, and 600 mg/kg) and quercetrin showed decreased serum levels of total cholesterol (-19.9, -27.5, -31.0, and -39.4%), lipoprotein-cholesterol (-36.0, -37.5, -43.3, and -59.4%), and triacylglycerides (-15.6, -23.5, -29.8, and -27.2%) when compared with the control group similar to simvastatin. Moreover, treatment with HE and quercetrin decreased hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity (35.1% on average) and increased fecal cholesterol levels (38.2% on average). DISCUSSION AND CONCLUSIONS: Our results suggest that hypolipidemic effects of HE are associated with it modulating the activity of HMG-CoA reductase and its interference in the reabsorption and/or excretion of intestinal lipids. Solidago chilensis and its main constituent, quercetrin, may thus be effective as cholesterol-lowering agents and in preventing atherosclerosis.

A new source of (R)-limonene and rotundifolone from leaves of Lippia pedunculosa (verbenaceae) and their trypanocidal properties.

Investigation by GC-FID and GC-MS of the essential oil (LPOE) from the leaves of Lippia pedunculosa revealed, as the major compounds, the monoterpenes rotundifolone (71.7%) and (R)-limonene (21.8%). These two compounds and the minor constituent piperitenone (1.2%) were also isolated from the leaves and identified by spectrometric analysis. LPOE and isolated compounds were evaluated for their trypanocidal activity against epimastigote and trypomastigote forms of Trypanosoma cruzi. Significant results with IC50 values lower than 34.0 microg.mL(-1) were observed against these forms of T. cruzi for LPOE and isolated compounds. Rotundifolone was the most active compound with an ICso lower than 10.0 ig.mL"' for both forms of T. cruzi. The effects of LPOE and isolated compounds were also evaluated in cultures of macrophages infected with T. cruzi. Treatment with (R)-limonene and rotundifolone caused a moderate reduction in the percentage of macrophages infected by T. cruzi and in the number of intracellular parasites at concentrations non-toxic to macrophages.

ent-Kaurane diterpenes from the stem bark of Annona vepretorum (Annonaceae) and cytotoxic evaluation.

This work describes a novel ent-kaurane diterpene, ent-3ß-hydroxy-kaur-16-en-19-al along with five known ent-kaurane diterpenes, ent-3ß,19-dihydroxy-kaur-16-eno, ent-3ß-hydroxy-kaur-16-eno, ent-3ß-acetoxy-kaur-16-eno, ent-3ß-hydroxy-kaurenoic acid and kaurenoic acid, as well as caryophyllene oxide, humulene epoxide II, ß-sitosterol, stigmasterol and campesterol from the stem bark of Annona vepretorum Mart. (Annonaceae). Cytotoxic activities towards tumor B16-F10, HepG2, K562 and HL60 and non-tumor PBMC cell lines were evaluated for ent-kaurane diterpenes. Among them, ent-3ß-hydroxy-kaur-16-en-19-al was the most active compound with higher cytotoxic effect over K562 cell line (IC50 of 2.49 µg/mL) and lower over B16-F10 cell line (IC50 of 21.02 µg/mL).

Chemical and pharmacological investigation of the stem bark of Synadenium grantii.

Based on the fact that Synadenium grantii is used in folk medicine for the treatment of peptic ulcers and inflammatory diseases, this work describes its chemical and pharmacological properties. Pharmacological investigation of the crude bark extract showed a high antioxidant activity over several scavenger systems, such as 2,2'-azino-bis (3-ethylenebenzothiazoline-6-sulfonic acid)• +, 1-diphenyl-2-picrylhydrazyl•, O2 • - , and HOCl, as well as an enzymatic system with human myeloperoxidase and an ex vivo hemolysis system. Furthermore, the oral administration of the crude bark extract was able to reduce carrageenan-induced rat paw edema as effectively as ibuprofen. These biological activities may be associated with the presence of flavonoids and terpenes, as revealed by HPLC and NMR analyses of the crude stem bark extract. The phytochemical investigations in this study resulted in the isolation of friedelin and 3ß-friedelinol for the first time, while euphol and lanosterol were also isolated.

Synthesis, activity, and QSAR studies of tryptamine derivatives on third-instar larvae of Aedes aegypti Linn.

Special attention has been given to the mosquito Aedes aegypti Linn. (Diptera: Culicidae) owing to numerous dengue epidemic outbreaks worldwide. Failure to control vector spreading is accounted for unorganized urban growth and resistance to larvicides and insecticides. Therefore, researchers are currently searching for new and more efficient larvicides and insecticides to aid dengue control measures. Triptamine is known to affect insect behavior, development, and physiology. Expression of this compound in plants has reduced the growth rate of herbivore insects. In view of these facts, it was of our interest to synthesize triptamine amide derivatives as potential larvicides against Ae. aegypti, establishing a Structure-Activity Relationship. Eleven amide derivatives of triptamine were synthesized, characterized, and evaluated for their larvicidal activity against third-instar Ae. aegypti larvae. N-(2-(1H-indol-3-yl)ethyl)-2,2,2-trichloroacetamide exhibited the highest overall larvicidal potency, while N-(2-(1H-Indol-3-yl)ethyl) acetamide displayed the lowest larvicidal potency. A regression equation correlating the larvicidal activity with Log P was obtained. We have found a clear relationship between the larvicidal activity of non-chlorinated compounds and Log P. Analysis of the relationship between Log P and larvicidal activity against Ae. aegypti may be useful in the evaluation of potential larvicidal compounds.

Antitumoural effect of Synadenium grantii Hook f. (Euphorbiaceae) latex.

ETHNOPHARMACOLOGICAL RELEVANCE: Synadenium grantii Hook f. has traditionally been used to treat various neoplastic diseases in southern Brazil. AIM OF STUDY: Evaluation of the antitumoural potential of Synadenium grantii latex against B16F10 melanoma cell line using in vitro and in vivo models, as well as a phytochemical study of the latex. MATERIALS AND METHODS: The in vitro antitumoural activity was performed using MTT and trypan blue assays with different latex concentrations (1.7 µg-7.0 µg/well and 1.22 mg-4.88 mg/well). Flow cytometry was used to determine the progression of the cell cycle. The in vivo activity was performed by subcutaneously injecting melanoma cells in the dorsum of C57BL6 mice, followed by treating the mice with a popular form of use of the latex (garrafada) administered orally. After sacrificing the animals, histological analysis of the organs was performed by hematoxylin-eosin staining. The phytochemical study of the latex was performed by NMR and chromatographic procedures and the extracts and isolated substances were evaluated by IR, 1D and 2D NMR analysis. RESULTS: The Synadenium grantii latex exhibited decreased cell viability of the melanoma line in a concentration and time-dependent manner, and also cell cycle arrest in the S-G2/M phase. The latex caused a 40% reduction in the volume of tumours of the mice with melanomas. Histological examination of the organs of these animals showed no differences between groups. The phytochemical investigation resulted in the isolation and identification of triterpene euphol and the steroid citrostadienol, which were tested against the strain of melanoma. Euphol showed no antitumoural activity, while the steroid citrostadienol showed reduced cytotoxic activity. CONCLUSION: The Synadenium grantii latex presented in vitro and in vivo cytotoxic effects with antitumoural activity against B16F10 melanoma cells.

Polyacetylenes from the leaves of Vernonia scorpioides (Asteraceae) and their antiproliferative and antiherpetic activities.

Polyacetylenes constitute an underexplored and unstable class of compounds that are found mainly in the Apiaceae, Araliaceae and Asteraceae families. Vernonia scorpioides (Lam.) Pers., Asteraceae is a lianous neotropical herb that usually grows in soils that have been deforested and are of poor quality. It is used in folk medicine for the treatment of several skin conditions. This study addresses the characterisation of eight polyacetylenes isolated from the leaves of V. scorpioides. Their structures were established on the basis of 1D and 2D NMR spectroscopy and MS analysis. Ab initio calculations including solvent effects were employed to aid the elucidation of the absolute configurations of the compounds. The in vitro antiproliferative and anti-herpetic activities of the polyacetylenes were determined. The isolated compounds presented no inhibitory effect against a human cell line of non-small cell lung cancer, but presented a mild non-selective in vitro antiviral activity, although their corresponding glycosides were inactive.