Fernando Echeverri

Passifloricins, polyketides α-pyrones from Passiflora foetida resin.

Abstract Three polyketides α-pyrones, named passifloricins, were isolated from Passiflora foetida resin; their structures and relative configurations were assigned through 2D NMR spectroscopic analyses. These types of compounds were not detected in other passion flowers.

Phytoalexin Accumulation in Colombian Bean Varieties and Aminosugars as Elicitors

The accumulation of isoflavonoid phytoalexins was studied in several Colombian bean cultivars resistant and susceptible to Colletotrichum lindemuthianum fungus, the causal agent of anthrachnose disease. A time-course accumulation analysis on seedlings treated with CuCl2 showed that phaseollin production was higher in resistant cultivars than in susceptible ones. Also, a defensive role of phytoalexins was demostrated when extracts containing this pterocarpan exhibited antifungal activity against C. lindemuthianum. In addition, the elicitor activity of some aminosugars was also established.

Musanolones : four 9-phenylphenalenones from rhizomes of Musa acuminata

Abstract Four new phenalenone-type phytoalexins, named musanolones C-F, have been isolated from infected rhizomes of banana plants (Musa acuminata; AAA cultivar Grand Nain). These phytoalexins were biosynthesized de novo by the plants upon infection by Fusarium oxysporum f. sp. cubense race 4, Panamas disease causal agent. The structures of the new phytoalexins were elucidated using spectroscopic data and chemical correlations. Hydroxyanigorufone has been previously described as a constitutive natural product, from Anigozanthos rufus, but it was never described as a phytoalexin. The chemical shift for all of the hydrogen and carbon atoms in the musanolones C-F were unambiguously established by mono- and bi-dimensional, homo- and hetero-nuclear NMR experiments (1H NMR, 13C NMR, COSY, HMQC and HMBC). Preliminary in vitro assays of all the musanolones tested until now show a strong inhibitory activity on the growth of the germination tube of F. oxysporum f. sp. cubense race 4.

Phenalenone-type phytoalexins from Musa acuminata. Synthesis of 4-phenyl-phenalenones

Abstract Two new 4-phenyl-phenalenone-type phytoalexins ( 2 , 3 ) have been isolated from rhizomes of Musa acuminata infected with the fungus Fusarium oxysporum . The structures of the new phytoalexins were elucidated on the basis of spectroscopic evidence, chemical correlation and synthesis from commercial phenalen-1-one. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments ( 1 H NMR, 13 C NMR, COSY, HMQC and HMBC). In preliminary “in vitro” assays, the new phytoalexins have shown inhibitory activity on the growth of the germinative tube of Fusarium oxysporum f. sp. cubense race 4 .

Intermediates with biosynthetic implications in de novo production of phenyl-phenalenone-type phytoalexins by Musa acuminata. Revised structure of emenolone

Abstract Three new intermediates ( 1 – 3 ) in de novo biosynthetic pathway to phenyl-phenalenone-type phytoalexins have been isolated from rhizomes of Musa acuminata infected with the fungus Fusarium oxysporum . The structures of the new pre-phytoalexins were elucidated on the basis of spectroscopic evidences, chemical correlation and acid catalyzed biomimetic cyclization of 1 to emenolone ( 4 ), isolated from the same source and whose previously reported structure has been unambiguously corrected by X-ray diffraction analysis. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments ( 1 H NMR, 1 3C NMR, COSY, ROESY, HMQC and HMBC).

ERMANIN : AN INSECT DETERRENT FLAVONOID FROM PASSIFLORA FOETIDA RESIN

Abstract Ten flavonoids were isolated from Passiflora foetida L. resin. One of them, ermanin, has a high deterrent activity at 40 ppm against Dione juno larvae.

Synthesis and Antifungal Activity of Musa Phytoalexins and Structural Analogs

Winston Quinones, Gustavo Escobar, Fernando Echeverri *, Fernando Torres, Yoni Rosero,Vi ctor Arango, Gloria Cardona and Adriana GallegoDepartment of Chemistry, Universidad de Antioquia, P. O. Box 1226, Medellin, ColombiaTel.: (57+4)2105658, Fax: (57+4)2330120, E-mail: echeveri@catios.udea.edu.coReceived : 18 January 2000 ; revised form 14 July 2000 / Accepted : 14 July 2000 / Published : 26 July 2000Abstract: Several perinaphthenone/phenylphenalenone compounds were synthesized to es-tablish a relationship between structure and antifungal activity against Mycosphaerella fijie n-sis. Substitutions on the unsaturated carbonyl system or addition of a phenyl group reducedantibiotic activity.Keywords: phenylphenalenones, synthesis, antifungal activity, Mycosphaerella fijiensis .IntroductionPhytoalexins are natural antibiotic compounds proposed as fungicides or templates for production ofnew pesticides [1]. Recently, the search for novel antifungal compounds has received special attentionas a result of an enhanced microbial resistance to current pesticides.Banana plants are affected by the pathogenic fungi Fusarium oxysporum var. cubensis type 4 andMycosphaerella fijiensis , causal agents of the diseases named Black Sigatoka and Panama Disease, r e-spectively. These diseases can drastically reduce banana production by as much as ca. 20% [2]. Undercolonization by these microorganisms or treatment of the leaves with kanamycin, banana plants producetwo types of phytoalexins, 9-phenylphenalenones (also known as musanolones [3]) and 4-phenylphenalenones [4], The main aim of the present work was to synthesize several structurally-relatedcompounds and to determine the relationship between phytoalexin structure and their antifungal effectsagainst M. fijiensis .Results and DiscussionThe planned synthetic approach involved a 1,4-addition of a Grignard reagent to a perinaphthenone,followed by reduction with DDQ, epoxidation with

Effects of diterpenes from latex of Euphorbia lactea and Euphorbia laurifolia on human immunodeficiency virus type 1 reactivation

The persistence of latent HIV-infected cellular reservoirs represents the major hurdle to virus eradication in patients treated with highly active antiretroviral therapy, referred to as HAART. HIV-1 reservoirs are long-lived resting CD4+ memory cells containing the virus latently integrated. Since the HIV-1 reservoirs are not targeted by HAART, reactivation therapy has been suggested to purge viral latency. Bioassay-guided study of an ethyl acetate extract of Euphorbia laurifolia afforded two isomeric diterpenes that showed differential activity over HIV-1 reactivation. A previously reported compound was isolated too from Euphorbia lactea. This compound showed a potent HIV-1 reactivating effect. Bioassays results showed that HIV-1 reactivation activity is influenced by distinct structural characteristics.

Mitochondrial dysfunction in Trypanosoma cruzi: the role of Serratia marcescens prodigiosin in the alternative treatment of Chagas disease

BackgroundChagas disease is a health threat for many people, mostly those living in Latin America. One of the most important problems in treatment is the limitation of existing drugs. Prodigiosin, produced by Serratia marcescens (Rhodnius prolixus endosymbiont), belongs to the red-pigmented bacterial prodiginine family, which displays numerous biological activities, including antibacterial, antifungal, antiprotozoal, antimalarial, immunosuppressive, and anticancer properties. Here we describe its effects on Trypanosoma cruzi mitochondria belonging to Tc I and Tc II.ResultsParasites exposed to prodigiosin altered the mitochondrial function and oxidative phosphorylation could not have a normal course, probably by inhibition of complex III. Prodigiosin did not produce cytotoxic effects in lymphocytes and Vero cells and has better effects than benznidazole. Our data suggest that the action of prodigiosin on the parasites is mediated by mitochondrial structural and functional disruptions that could lead the parasites to an apoptotic-like cell death process.ConclusionsHere, we propose a potentially useful trypanocidal agent derived from knowledge of an important aspect of the natural life cycle of the parasite: the vector-parasite interaction. Our results indicate that prodigiosin could be a good candidate for the treatment of Chagas disease.

In vitro TRPV1 activity of piperine derived amides.

A series of natural and synthetic piperine amides were evaluated for activity on the human TRPV1 expressed in HEK293 cells. The agonistic effect of piperine amides was mainly dependent on the length of the carbon chain. Structural changes of double bonds and stereochemistry in the aliphatic chain of these compounds did not change their potency or efficacy, indicating that increased rigidity or planarity of the piperine structure does not affect the activity. The opening of the methylenedioxy ring or changes in the heterocyclic ring of the piperine molecule reduced or abolished activity. Furthermore, inactive compounds did not display functional antagonistic activity.