Microbial Biotransformation of Iridoid Glycosides from Gentiana Rigescens by Penicillium Brasilianum.

This study aimed to investigate the metabolic effects of endophytic fungi in Gentiana rigescens. From the 100 selected morphospecies, strain 7-2 (Penicillium brasilianum) showed a remarkable biocatalytic activity for gentiopicroside and swertiamarin, yielding seven products, including one new compound, 5-ethylidene-8-hydroxy-4,5,6,8-tetrahydropyrano[3,4-c]pyran-1-one (M04), alongside six known compounds. Gentianine (M01) was the only metabolite of swertiamarin in this study, while the remaining ones were all gentiopicroside metabolites. Among these, five compounds: gentianine (M01), (5S,6S)-5-(hydroxymethyl)-6-methyl-5,6-dihydro-1H,3H-pyrano[3,4-c]pyran-1-one (M02), (5R,6S)-5-(hydroxymethyl)-6-methyl-5,6-dihydro-1H,3H-pyrano[3,4-c]pyran-1-one (M03), 2-(3-formyl-2-oxo-3,6-dihydro-2H-pyran-4-yl)but-3-enoic acid (M06), and 2-oxo-4-(1-oxobut-3-en-2-yl)-3,6-dihydro-2H-pyran-3-carboxylic acid (M07) were similar to gentiopicroside metabolites in humans. Screening the metabolic potential of endophytic fungi in Gentiana rigescens provides an outstanding source for assessing the bioactive metabolites of iridoid glycosides. The above findings suggested that the endophytic fungi of G. rigescens possess multi-enzyme systems that mimic metabolic reactions in mammalian organisms.

Iridoids and Amino Acid Derivatives from the Paraguayan Crude Drug Adenocalymma marginatum (ysypó hû).

The crude drug ysypó hû (Adenocalymma marginatum DC., Bignoniaceae) is used traditionally by the Guarani of Eastern Paraguayan as a male sexual enhancer. The aim of the present study was to identify the main constituents of the crude drug and to evaluate the in vitro inhibitory activity towards the enzyme phosphodiesterase-5 (PDE-5). The main compounds were isolated by counter-current chromatography (CCC). The metabolites were identified by spectroscopic and spectrometric means. The chemical profiling of the extracts was assessed by high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS/MS). The crude extract and main isolated compounds were tested for their PDE-5 inhibitory activity using commercial kits. The iridoid theviridoside and 4-hydroxy-1-methylproline were isolated as the main constituent of the crude drug. Four chlortheviridoside hexoside derivatives were detected for the first time as natural products. Chemical profiling by HPLC-MS/MS led to the tentative identification of nine iridoids, six phenolics, and five amino acids. The crude extracts and main compounds were inactive towards PDE-5 at concentrations up to 500 µg/mL. Iridoids and amino acid derivatives were the main compounds occurring in the Paraguayan crude drug. The potential of ysypó hû as a male sexual enhancer cannot be discarded, since other mechanisms may be involved.

Plant and herbivore ontogeny interact to shape the preference, performance and chemical defense of a specialist herbivore.

The amount of damage that herbivorous insects impose on plants varies as a function of plant ontogenetic trajectories in tissue quality and defenses, and the herbivores' own developmental trajectories in body size, mandible shape and detoxification enzymes, among others. However, little is known about how host plant and herbivore ontogeny interact. Using four ontogenetic stages of Plantago lanceolata (Plantaginaceae) and three to five larval stages of the specialist caterpillar Junonia coenia (Nymphalidae), we evaluated how ontogenies in both of these trophic levels shape: (i) caterpillar feeding choice, (ii) performance, and (iii) sequestration of plant allelochemicals. Plant physical (leaf toughness) and chemical (iridoid glycosides) defenses increased, while nutritional quality (water and nitrogen content) decreased, as plants aged. These plant ontogenetic trajectories strongly altered the behavior and physiology of this specialist herbivore, but the magnitude of the response varied with larval stage. In feeding experiments, while first instar larvae showed little preference among plant stages, older larvae significantly preferred juvenile over reproductive stages. In turn, larval consumption increased and digestive efficiency decreased, potentially explaining their decrease in relative growth rate, as larvae and host plant aged, but differences were greater for younger than older caterpillars. Finally, sequestration of plant allelochemicals increased through plant and larval development; however, the major differences due to diet occurred earlier during larval development. Our results highlight that changes in plant ontogeny most strongly influence early herbivore instars, emphasizing the need to consider the developmental stage of both trophic levels to better understand temporal variation in herbivore damage.

Cardioprotection against experimental myocardial ischemic injury using cornin.

Phosphorylated-cyclic adenosine monophosphate response element-binding protein (Phospho-CREB) has an important role in the pathogenesis of myocardial ischemia. We isolated the iridoid glycoside cornin from the fruit of Verbena officinalis L, investigated its effects against myocardial ischemia and reperfusion (I/R) injury in vivo, and elucidated its potential mechanism in vitro. Effects of cornin on cell viability, as well as expression of phospho-CREB and phospho-Akt in hypoxic H9c2 cells in vitro, and myocardial I/R injury in vivo, were investigated. Cornin attenuated hypoxia-induced cytotoxicity significantly in H9c2 cells in a concentration-dependent manner. Treatment of H9c2 cells with cornin (10 µM) blocked the reduction of expression of phospho-CREB and phospho-Akt in a hypoxic condition. Treatment of rats with cornin (30 mg/kg, iv) protected them from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics, and reduction of severity of myocardial damage. Cornin treatment also attenuated the reduction of expression of phospho-CREB and phospho-Akt in ischemic myocardial tissue. These data suggest that cornin exerts protective effects due to an increase in expression of phospho-CREB and phospho-Akt.

Cardioprotection against experimental myocardial ischemic injury using cornin

Phosphorylated-cyclic adenosine monophosphate response element-binding protein (Phospho-CREB) has an important role in the pathogenesis of myocardial ischemia. We isolated the iridoid glycoside cornin from the fruit of Verbena officinalis L, investigated its effects against myocardial ischemia and reperfusion (I/R) injury in vivo, and elucidated its potential mechanism in vitro. Effects of cornin on cell viability, as well as expression of phospho-CREB and phospho-Akt in hypoxic H9c2 cells in vitro, and myocardial I/R injury in vivo, were investigated. Cornin attenuated hypoxia-induced cytotoxicity significantly in H9c2 cells in a concentration-dependent manner. Treatment of H9c2 cells with cornin (10 µM) blocked the reduction of expression of phospho-CREB and phospho-Akt in a hypoxic condition. Treatment of rats with cornin (30 mg/kg, iv) protected them from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics, and reduction of severity of myocardial damage. Cornin treatment also attenuated the reduction of expression of phospho-CREB and phospho-Akt in ischemic myocardial tissue. These data suggest that cornin exerts protective effects due to an increase in expression of phospho-CREB and phospho-Akt.

Iridoid glycosides from Alonsoa meridionalis.

A new iridoid glucoside has been isolated from the Chilean native Alonsoa meridionalis (L.f.) Kuntze. Its structure has been assigned as 6'-O-ß-d-glucopyranosyl-8-O-acetylharpagide (1) by using spectroscopic methods. Harpagoside (2), laterioside (3) and verbascoside (4) were also identified.

Biocompatibility of nanostructured chitosan/ poly(vinyl alcohol) blends chemically crosslinked with genipin for biomedical applications.

In the present research it is reported the development and characterization of novel polymer blends based on chitosan and poly(vinyl alcohol) (PVA). The hybrid polymeric network was synthesized and modified by chemical crosslinking using genipin for potential use in a variety of biomedical applications. The micro and nanostructures of the blended hydrogels and hybrids were characterized through Fourier Transform Infrared spectroscopy (FTIR) and swelling test analysis. Moreover, cytotoxicity and cell viability were also performed by MTT assay with cell culture. The chemical crosslinking was achieved via the relative intensity of the band at 1650 cm(-1) which is mostly associated with the reaction of genipin carboxymethyl group with the amino group of chitosan forming amides. It was found that by increasing the chitosan content relative to PVA the swelling index of the blend has decreased, reflecting the reduction on the mobility of polymer network and the hydrophilic behavior of the blend. The tested hydrogels have clearly presented adequate cell viability, non-toxicity and suitable properties which can be tailored for potential use in bioengineering applications.

Effect of genipin collagen crosslinking on porcine corneas.

PURPOSE: To evaluate the effect of genipin, a natural crosslinker, on porcine corneas. SETTING: Department of Ophthalmology, Universidad Nacional de Colombia, Bogota, Colombia. METHODS: Corneal strips (12.0 mm x 2.3 mm) were harvested from porcine eyes and treated by incubation with genipin at concentrations of 1.00%, 0.25%, and 0.10%. Parallel corneal strips from the same eye were used as untreated controls. After treatment at 20 degrees C for 40 minutes, tensile strain measurements were performed in a biomaterial tester. Porcine button corneas were treated with genipin 0.25% for 15 minutes and then digested by bacterial collagenase. Treated and untreated corneas were evaluated by light microscopy. RESULTS: Young modulus and stiffness in treated corneas increased in a concentration-dependent manner. Genipin increased resistance to corneal collagenase 5-fold in comparison with the controls. A decrease in the interlamellar space in treated corneas was also observed. CONCLUSIONS: Corneal collagen crosslinking induced with genipin produced a significant increase in biomechanical strength and resistance to bacterial collagenase. This crosslinker could be useful in treating corneal ectasia and corneal infectious and noninfectious diseases involving corneal melting.

Molecularly imprinted chitosan-genipin hydrogels with recognition capacity toward o-xylene.

A molecularly imprinted material was developed from hydrogels of chitosan (CS) cross-linked with genipin (GNP) using o-xylene as the template molecule. Gelling time, mechanical, and diffusion properties of CS-GNP hydrogels were initially investigated to establish optimal conditions to prepare molecularly imprinted hydrogels (MIHs). The elastic modulus was found to be directly proportional to the degree of cross-linking (R = moles of genipin/moles of glucosamine) while the diffusion of water, as monitored by magnetic resonance imaging, decreased with R. CS-GNP hydrogels of varying R were imprinted with o-xylene (MIH(o-xylene)). The adsorption capacity of o-xylene by MIH(o-xylene) was greater than the corresponding control hydrogels, particularly at R = 0.25. Freundlich isotherms yielded a better fitness than Langmuir ones and afforded n and Q(max)values of 2.55 and 103.3 mg/g, respectively. The imprinted hydrogel showed the highest adsorption capacity for o-xylene; however, the material was not highly selective as it also exhibited the capacity to adsorb m- and p-xylene isomers. In turn, the MIH(o-xylene) showed a low adsorption when 2-fluorotoluene was used in rebinding experiments, suggesting that molecular recognition by the binding sites is influenced by the electronic and steric properties of the analyte molecule, thus effectively confirming the imprinting effect within the MIH(o-xylene) network. This work opens the possibility to future development of materials with the capacity to adsorb o-xylene analogue molecules such as contaminants bearing chlorinated aromatic structures.

Iridoids as allelochemicals and DNA polymerase inhibitors.

Growth inhibitory activities and nutritional indices of catalpol (1), 8-O-acetylharpagide (2), and harpagide (3) were determinated in larvae and adults of Tribolium castaneum, respectively. Compound 1 produced a series of allelochemical effects probably related with the DNA synthesis. This iridoid possessed the highest inhibitory activity against DNA polymerase. Molecular orbital calculations suggest that a pi-pi charge transfer recognition model could explain the action of iridioids toward nucleic acid synthesis.