Ent-kaurane diterpenoids and other constituents from the stem of Xylopia laevigata (Annonaceae)

Phytochemical investigation of the hexane extract from the stem of Xylopia laevigata led to the isolation of the ent-kaurane diterpenoids, ent-kaur-16-en-19-oic acid, 4-epi-kaurenic acid, ent-16β-hydroxy-17-acetoxy-kauran-19-al, ent-3β-hydroxy-kaur-16-en-19-oic acid, and ent-16β,17-dihydroxy-kauran-19-oic acid, as well as spathulenol and a mixture of β-sitosterol, stigmasterol and campesterol. The identification of the compounds was performed on the basis of spectrometric methods including GC-MS, IR, and 1D and 2D NMR. Potent larvicidal activity against Aedes aegypti larvae with LC50 of 62.7 µg mL-1 was found for ent-3β-hydroxy-kaur-16-en-19-oic acid. This compound also showed significant antifungal activity against Candida glabrata and Candida dubliniensis with MIC values of 62.5 µg mL-1.

Ent-kaurane diterpenoids and other constituents from the stem of Xylopia laevigata (Annonaceae)

Phytochemical investigation of the hexane extract from the stem of Xylopia laevigata led to the isolation of the ent-kaurane diterpenoids, ent-kaur-16-en-19-oic acid, 4-epi-kaurenic acid, ent-16β-hydroxy-17-acetoxy-kauran-19-al, ent-3β-hydroxy-kaur-16-en-19-oic acid, and ent-16β,17-dihydroxy-kauran-19-oic acid, as well as spathulenol and a mixture of β-sitosterol, stigmasterol and campesterol. The identification of the compounds was performed on the basis of spectrometric methods including GC-MS, IR, and 1D and 2D NMR. Potent larvicidal activity against Aedes aegypti larvae with LC50 of 62.7 µg mL-1 was found for ent-3β-hydroxy-kaur-16-en-19-oic acid. This compound also showed significant antifungal activity against Candida glabrata and Candida dubliniensis with MIC values of 62.5 µg mL-1.

Antibacterial activity of labdane diterpenoids from Stemodia foliosa

As part of a continuing interest in exploring the chemistry of Brazilian medicinal plants, three new labdane diterpenoids, 6 alpha-acetoxymanoyl oxide (1), 6 alpha-malonyloxymanoyl oxide (2), and 6 alpha-malonyloxy-n-butyl ester manoyl oxide (3), together with the known betulinic acid, lupeol, sitosterol, and stigmasterol, were isolated from the aerial parts of Stemodia foliosa. The structures of 1-3 were established on the basis of interpretation of spectroscopic data, including HRESIMS, and 1D and 2D NMR techniques. All compounds were tested against a bacteria panel consisting of Staphylococcus aureus, Bacillus cereus, B. subtilis, B. anthracis, Micrococcus luteus, Mycobacterium smegmatis, and M. phlei. Compound 2 showed, moderate activity against these strains, with MIC values in the range 7-20 mu g/mL.

Ent-labdane and beyerane diterpenes from Erythroxylum betulaceum Mart

•Diterpenes were isolated from wood of Erythroxylum betulaceum Mart.•Two ent-labdanes and one ent-beyrane diterpenes were isolated.•Diterpenes together tropanic alkaloid and may be useful as a chemotaxonomic markers of Erythroxylum. © 2013 Elsevier Ltd.

Diterpenos de Copaifera reticulata Ducke com atividade larvicida contra Aedes aegypti (L.) (Diptera, Culicidae)

The objective of this study was to evaluate the larvicidal activity of diterpenoids obtained from the oil-resin of Copaifera reticulata against Aedes aegypti larvae, the principal vector of dengue and urban yellow fever. Four diterpenes were obtained from oil-resin extraction with organic solvents and subsequent chromatographic and spectroscopic procedures allowed to isolation and identification of these compounds as 3-b-acetoxylabdan-8(17)-13-dien-15-oic acid (1), alepterolic acid (2), 3-b-hidroxylabdan-8(17)-en-15-oic acid (3), and ent-agatic acid (4). Each compound was previously dissolved in dimethylsulphoxide, and distilled water was added to obtain the desired concentrations. Twenty larvae of third instars were placed into plastic beckers, containing the solution test (25 mL), in a five repetitions scheme, and their mortality, indicated by torpor and darkening of the cephalic capsule, was recorded after 48h. Probit analyses were used to determine lethal concentrations (LC50 and LC90) and their respective 95% confidence intervals. This study showed that only diterpenoids 1 and 2 exhibited larvicidal properties with LC50 of 0.8 ppm and 87.3 ppm, respectively, revealing the former as the most toxic compound against third instars of Ae. aegypti. Therefore, this compound seems to be an interesting source for new metabolite to be exploited.

Investigation phytochimique des plantes aquatiques Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. et P. crispus L. (Potamogetonaceae)

Dans le cadre de la recherche de nouveaux composés naturels, les métabolites secondaires de plantes aquatiques indigènes, les potamots Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. et P. crispus L. (Potamogetonaceae), ont été étudiés. Par leur position écologique et évolutive particulière entre environnement terrestre et aquatique, les plantes aquatiques ou macrophytes pourraient en effet avoir sélectionné des composés avec des caractéristiques originales. Les extraits dichlorométhaniques (apolaires) des potamots ont été analysés par HPLCUV, HPLC-MS, HPLC-RMN et GC-MS, et testés contre diverses cibles biologiques. Sur la base de ces résultats, les extraits apolaires de P. pectinatus et P. lucens ont été étudiés de manière plus approfondie. Ils ont été fractionnés sur des colonnes ouvertes et par VLC, LPLC, MPLC, CPC et HPLC semi-préparative. Une partie de leurs constituants ont été isolés et leurs structures déterminées par des méthodes spectroscopiques, en particulier par RMN et par MS. Quinze composés ont été ainsi isolés de P. pectinatus et P. lucens, dont sept sont des nouveaux produits naturels. Parmi ces quinze produits, neuf sont des diterpènes ent-labdanes contenant un noyau furane ou un groupe lactonique, dont six sont décrits ici pour la première fois. Certains de ces diterpènes ont montré une activité algicide, ce qui indique une de leurs fonctions possible dans les potamots, et un de ces labdanes, le méthyl-15,16-époxy-12-oxo-8(17),13(16),14-ent-labatrièn-19-oate, a également des propriétés anti-inflammatoires. Les composés présents dans les extraits méthanoliques (polaires) n?ont pas été isolés, mais quatorze d?entre eux ont pu être identifiés par HPLC-UV, HPLC-MS et HPLCRMN. Une majorité de ces constituants sont des flavonoïdes connus, des dérivés glycosylés de l?apigénine, la lutéoline et le chrysoériol, également présents en tant qu?aglycones. Plusieurs ent-labdanes glycosylés ont pu être également identifiés dans ces extraits, parmi lesquels un nouveau composé dont la structure a pu être partiellement déterminée. En conclusion, ce travail a permis de mieux connaître la phytochimie de plusieurs plantes aquatiques de Suisse, et d?isoler de nouveaux produits naturels avec des propriétés biologiques et pharmacologiques intéressantes.<br/><br/>The secondary metabolites of Swiss freshwater plants, the pondweeds Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. and P. crispus L. (Potamogetonaceae), were investigated. Because of their peculiar habitat, in-between aquatic and terrestrial life, aquatic plants should produce secondary metabolites with original chemical or biological features. Their apolar extracts were analysed by HPLC-UV, HPLC-MS, HPLC-NMR and GCMS, and were tested with different bioassays. Based on these results, the apolar extracts of P. pectinatus and P. lucens were investigated more extensively. They were fractionated on open columns, and by VLC, LPLC, MPLC, CPC and semi-preparative HPLC. Their constituents were isolated and their structures elucidated by spectroscopic methods as MS and NMR. Fifteen compounds could be isolated from P. pectinatus and P. lucens, and seven were new natural products. Nine of them were ent-labdane diterpenes with a furan moiety or a lactone group, and six of these labdanes were reported here for the first time as natural products. Some of these diterpenes showed an algaecide effect. This activity indicated their potential ecological function in pondweeds. One compound, methyl-15,16-epoxy-12-oxo-8(17),13(16),14-ent-labatrien-19-oate, revealed also some anti-inflammatory properties. The constituents of polar extracts were not isolated, but fourteen of them could be identified by HPLC-UV, HPLC-MS and HPLC-NMR. The major part of these compounds was known flavonoids as apigenin, lutolin, chrysoeriol and their glycosylated derivatives. Several glycosylated ent-labdanes were also identified, and the structure of a new labdane dihexoside was partially elucidated. In conclusion this study allowed a better knowledge of the phytochemistry of Swiss aquatic plants, and the isolation of new natural products with interesting biological and pharmacological properties.

Lignans and diterpenes of three Aristolochia species

Phytochemical examination of Aristolochia cymbifera, A. esperanzae and A. galeata led to the isolation of furofuran and dibenzylbutyrolactone type lignans, as well as of clerodane and ent-labdane type diterpenes. Structural assignments for two new ent-labdans are presented and discussed. © 1988.

The Labdane Ent-3-Acetoxy-Labda-8(17), 13-Dien-15-Oic Decreases Blood Pressure In Hypertensive Rats

Abstract Background: Labdane-type diterpenes induce lower blood pressure via relaxation of vascular smooth muscle; however, there are no studies describing the effects of labdanes in hypertensive rats. Objective: The present study was designed to investigate the cardiovascular actions of the labdane-type diterpene ent-3-acetoxy-labda-8(17), 13-dien-15-oic acid (labda-15-oic acid) in two-kidney 1 clip (2K-1C) renal hypertension. Methods: Vascular reactivity experiments were performed in aortic rings isolated from 2K-1C and normotensive (2K) male Wistar rats. Nitrate/nitrite (NOx) measurement was performed in aortas by colorimetric assay. Blood pressure measurements were performed in conscious rats. Results: Labda-15-oic acid (0.1-300 µmol/l) and forskolin (0.1 nmol/l - 1 µmol/l) relaxed endothelium-intact and endothelium-denuded aortas from both 2K-1C and 2K rats. Labda-15-oic acid was more effective at inducing relaxation in endothelium-intact aortas from 2K pre-contracted with phenylephrine when compared to the endothelium-denuded ones. Forskolin was more potent than labda-15-oic acid at inducing vascular relaxation in arteries from both 2K and 2K-1C rats. Labda-15-oic acid-induced increase in NOx levels was lower in arteries from 2K-1C rats when compared to 2K rats. Intravenous administration of labda-15-oic acid (0.3-3 mg/kg) or forskolin (0.1-1 mg/kg) induced hypotension in conscious 2K-1C and 2K rats. Conclusion: The present findings show that labda-15-oic acid induces vascular relaxation and hypotension in hypertensive rats.

New alkamide and ent-kaurane diterpenoid derivatives from Senecio erechtitoides (Asteraceae)

Fractionation of a MeOH/CH2Cl2 (1/1) extract of the aerial parts of Senecio erechtitoides led to the isolation of six compounds including the hitherto unknown N-phenethylamide derivative named N-(p-hydroxyphenethyl)pentacosanamide (1), and a kauranoid derivative named derivative named ent-7-oxo-16 alpha,17-dihydroxykauran-19-oic acid (2), as well as four known compounds, ent-Kaur-16-en-19-oic acid (3), ent-7 beta-hydroxykaur-16-en-19-oic acid (4), ent-7-oxokaur-16-en-19-oic acid (5), steppogenin 4′-O-beta-d-glucoside (6). Their structures and relative configurations were elucidated on the basis of spectroscopic methods, chemical reactions, and comparison with previously known analogs. All isolates were evaluated for their antimicrobial activity and only diterpenoids were found to possess a potent inhibitor effect against the range of microorganism.

Labdane dimers from Xylopia aromatica

From the stem bark of Xylopia aromatica (Annonaceae), have been isolated two new labdane dimers as their methyl esters, together with the known compounds ent-labda-8(17),13(16),14-trien-18-oic acid, sitosterol and stigmasterol. The structures of the dimers were elucidated on the basis of detailed spectroscopic analyses. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Structure and absolute configuration of diterpenoids from hymenaea stigonocarpa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anticariogenic Properties of ent-Pimarane Diterpenes Obtained by Microbial Transformation

In the present work, the anticariogenic activities of three pimarane-type diterpenes obtained by fungal biotransformation were investigated. Among these metabolites, ent-8(14), 15-pimaradien-19-ol was the most active compound, displaying very promising MIC values (ranging from 1.5 to 4.0 mu g mL(-1)) against the main microorganisms responsible for dental caries: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, and Lactobacillus casei. Time kill assays performed with ent-8(14), 15-pimaradien-19-ol against the primary causative agent S. mutans revealed that this compound only avoids growth of the inoculum in the first 12 h (bacteriostatic effect). However, its bactericidal effect is clearly noted thereafter (between 12 and 24 h). The curve profile obtained by combining ent-8(14), 15-pimaradien-19-ol and chlorhexidine revealed a significant reduction in the time necessary for killing S. mutans compared with each of these two chemicals alone. However, no synergistic effect was observed using the same combination in the checkerboard assays against this microorganism. In conclusion, our results point out that ent-8(14), 15-pimaradien-19-ol is an important metabolite in the search for new effective anticariogenic agents.

Secondary metabolites produced by Propionicimonas sp (ENT-18) induce histological abnormalities in the sclerotia of Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is a highly aggressive pathogen that causes great economic losses, especially in temperate climates. Several biological control agents are available, but actinobacteria have seldom been used to control this fungus. Our objective was to evaluate the efficiency and ultrastructural effects of the secondary metabolites produced by the ant-associated actinobacterium Propionicimonas sp. ENT-18 in controlling the sclerotia of S. sclerotiorum. We demonstrated total inhibition of sclerotia treated with 62.5 mu g/10 mu l of an ethyl acetate extract of compounds produced by ENT-18, and calculated an LC(50) of 1.69 mu g/sclerotia. Histological and ultrastructural analysis indicated that the cells of the treated sclerotia were severely damaged, suggesting direct action of the biomolecule(s) produced by the actinobacterium ENT-18 on the cell structure of the medullae and rind cell wall. This is the first report demonstrating a novel property of Propionicimonas sp.-antifungal activity against S. sclerotiorum.

The semi-synthetic kaurane ent-16 alpha-methoxykauran-19-oic acid induces vascular relaxation and hypotension in rats

The present work investigates the mechanisms involved in the vasorelaxant effect of ent-16 alpha-methoxykauran-19-oic acid (KA-OCH(3)), a semi-synthetic derivative obtained from the kaurane-type diterpene ent-kaur-16-en-19-oic acid (kaurenoic acid). Vascular reactivity experiments were performed in aortic rings isolated from male Wistar rats using standard muscle bath procedures. The cytosolic calcium concentration ([Ca(2+)]c) was measured by confocal microscopy using the fluorescent probe Fluo-3 AM. Blood pressure measurements were performed in conscious rats. KA-OCH(3) (10,50 and 100 mu mol/l) inhibited phenylephrine-induced contraction in either endothelium-intact or endothelium-denuded rat aortic rings. KA-OCH(3) also reduced CaCl(2)-induced contraction in a Ca(2+)-free solution containing KCl (30 mmol/l) or phenylephrine (0.1 mu mol/l). KA-OCH(3) (0.1-300 mu mol/l) concentration-dependently relaxed endothelium-intact and endothelium-denuded aortas pre-contracted with either phenylephrine or KCl, to a greater extent than kaurenoic acid. Moreover, a Ca(2+) mobilisation study showed that KA-OCH(3) (100 mu mol/l) inhibited the increase in Ca(2+) concentration in smooth muscle and endothelial cells induced by phenylephrine or KCl. Pre-incubation of intact or denuded aortic rings with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 mu mol/l), 7-nitroindazole (100 mu mol/l), wortmannin (0.5 mu mol/l) and 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ 1 mu mol/l) produced a rightward displacement of the KA-OCH(3) concentration-response curve. Intravenous administration of KA-OCH(3) (1-10 mg/kg) reduced mean arterial blood pressure in normotensive rats. Collectively, our results show that KA-OCH(3) induces vascular relaxation and hypotension. The mechanisms underlying the cardiovascular actions of KA-OCH(3) involve blockade of Ca(2+) influx and activation of the NO-cGMP pathway. (C) 2011 Elsevier B.V. All rights reserved.

Mechanisms underlying the vasorelaxant action of the pimarane ent-8(14),15-pimaradien-3 beta-ol in the isolated rat aorta

Pimarane-type diterpenes were described to exert antispasmodic and relaxant activities. Based on this observation we hypothesized that the diterpene ent-8(14),15-pimaradien-3 beta-ol (PA-3 beta-ol) induced vascular relaxation. With this purpose, the present work investigates the mechanisms involved in the vasorelaxant effect of the pimarane-type diterpene PA-3 beta-ol. Vascular reactivity experiments, using standard muscle bath procedures, were performed in isolated aortic rings from male Wistar rats. Cytosolic calcium concentration ([Ca(2+)]c) was measured by confocal microscopy using the fluorescent probe Fluo-3AM. PA-3 beta-ol (10, 50 and 100 mu mol/l) inhibited phenylephrine and KCl-induced contraction in either endothelium-intact or denuded rat aortic rings. PA-3 beta-ol also reduced CaCl(2)-induced contraction in Ca(2+)-free solution containing KCl (30 mmol/l) or phenylephrine (0.1 mu mol/l). PA-3 beta-ol (1-300 mu mol/l) concentration dependently relaxed phenylephrine-pre-contracted rings with intact or denuded endothelium. The diterpene also relaxed KCl-pre-contracted rings with intact or denuded endothelium. Moreover, Ca(2+) mobilization study showed that PA-3 beta-ol (100 mu mol/l) and verapamil (1 mu mol/l) inhibited the increase in Ca(2+)-concentration in smooth muscle and endothelial cells induced by phenylephrine (10 mu mol/l) or KCl (60 mmol/l). Pre-incubation of intact or denuded aortic rings with N(G)-nitro-L-arginine methyl ester (L-NAME, 100 mu mol/l) and 1H-[1,2,4] Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ 1 mu mol/l) produced a rightward displacement of the PA-3 beta-ol concentration-response curves. On the other hand, 7-nitroindazole (100 mu mol/l), 1400 W (1 mu mol/l), indomethacin (10 mu mol/l) and tetraethylammonium (1 mmol/l) did not affect PA-3 beta-ol-induced relaxation. Collectively, our results provide evidence that the effects elicited by PA-3 beta-ol involve extracellular Ca(2+) influx blockade. Its effects are also partly mediated by the activation of NO-cGMP pathway. (C) 2009 Elsevier B.V. All rights reserved.