Natural Products from Chilean and Antarctic Marine Fungi and Their Biomedical Relevance.

Fungi are a prolific source of bioactive molecules. During the past few decades, many bioactive natural products have been isolated from marine fungi. Chile is a country with 6435 Km of coastline along the Pacific Ocean and houses a unique fungal biodiversity. This review summarizes the field of fungal natural products isolated from Antarctic and Chilean marine environments and their biological activities.

Synthesis, characterisation, crystal structure and antimicrobial evaluation of novel 6-alkoxyergosta-4,6,8(14),22-tetraen-3-one derived from natural ergosta-5,7,22-trien-3ß-ol.

In this study, we report a facile transformation starting from 5α-hydroxyergosta-7,22-dien-3,6-dione (1) to afford two novel compounds: 6-methoxyergosta-4,6,8(14),22-tetraen-3-one (2) and 6-ethoxyergosta-4,6,8(14),22-tetraen-3-one (3) using alcoholic acid catalysis. Their structures were elucidated using NMR experiments, FT-IR, MS and X-ray analysis. These compounds were evaluated for antibacterial activity using the disk and broth diffusion test. In those tests, compound 3 was found to be the most significant antibacterial agent. In general, compounds 1-3 showed inhibition zone in the range of 7.00-12.3 mm for S. aureus and S. mutans, meanwhile for Gram-negative bacteria E. coli and Pseudomonas sp. was found to be in the range of 7.00-8.00 mm. For the most active, compound 3, MIC was significantly lower than that reported for ergosterol, in a value of 160 µg/mL. Overall, these compounds were more active than their natural precursor.

Secondary Metabolites Isolated from Chilean Marine Algae: A Review.

Chile is in the extreme southwestern part of America, and it has an extreme length, of approximately 4300 km that increases to 8000 km considering the Chilean Antarctic Territory. Despite the large extent of its coastal territory and the diversity of geographic environments and climates associated with Chilean coasts, the research on marine resources in Chile has been rather scarce. From marine organisms found in Chilean coastal waters, algae have been the most studied, since they contain a wide range of interesting secondary metabolites that have some structural traits that make them unique and uncharacteristic. Thus, a wide structural variety of natural products including terpenoids (monoterpenes, sesquiterpenes, diterpenes, and meroterpenoids), furanones, and C15-acetogenins have been isolated and identified. This review describes the existing literature on bioprospecting and exploration of secondary metabolites from Chilean coasts.

Phytochemistry and biological properties of Drimys winteri JR et G. Forster var chilensis (DC) A / Fitoquímica y propiedades biológicas de Drimys winteri JR et G. Forster var chilensis (DC) A

Drimys winteri JR et G. Forster var chilensis (DC) A. is a tree native to central and southern Chile. Also it found in part of Argentina. It is abundant in wet swampy localities from sea level to an altitude of 1700 m. This tree is sacred for the Mapuche culture; it is used in folk medicine in such as inflammatory and painful processes. Phytochemical studies have demonstrated that this plant contains mainly sesquiterpenes of the drimane type, flavonoids, essential oils, phytosterols and some lignans. These drimanes have attracted interest because of their antifeedant, plant growth regulation, cytotoxic, antimicrobial and insecticidal properties. The objective of this review is to establish clearly the phytochemistry and biological activity of Drimys winteri JR et G. Forster var chilensis (DC) A. Articles based on other varieties are not considered.

Drimys winteri JR et G. Forster var chilensis (DC) A. es un árbol nativo del centro y sur de Chile. También se encuentra en parte de Argentina. Es abundante en localidades pantanosas y húmedas desde el nivel del mar hasta una altitud de 1700 m. Este árbol es sagrado para la cultura mapuche. Se utiliza en la medicina popular para tratar enfermedades como procesos inflamatorios y dolorosos. Los estudios fitoquímicos han demostrado que esta planta contiene principalmente sesquiterpenos del tipo drimano, flavonoides, aceites esenciales, fitoesteroles y algunos lignanos. Estos drimanos han despertado interés debido a sus propiedades antialimentarias, regulación del crecimiento de las plantas, propiedades citotóxicas, antimicrobianas e insecticidas. El objetivo de este examen es establecer claramente la fitoquímica y la actividad biológica de Drimys winteri JR et G. Forster var chilensis (DC) A. No se consideran los artículos basados en otras variedades D. winteri var winteri.

Antileishmanial activity and cytotoxicity of ent-beyerene diterpenoids.

We describe the in vitro activity of two natural isomeric ent-beyerene diterpenes, several derivatives and synthetic intermediates. Beyerenols 1 and 2 showed EC50 of 4.6 ±â€¯9.4 and 5.3 ±â€¯9.4 µg/mL against amastigotes of L. (V) brazilensis, with SI of 5.1 and 7.7, respectively. Beyerenol 1 was synthesized from stevioside. In vivo experiments with bereyenols showed cure in 50% of hamsters infected with L. (V) brazilensis topically applied as Cream I (beyerenol 1, 0.81%, w/w) and Cream III (beyerenol 2, 1.96%, w/w). These results suggest that beyerenols are potential candidates for cutaneous leishmaniasis chemotherapy by topical application. In vitro assays of amastigotes of L. (V) brazilensis showed EC50 of 1.1 ±â€¯0.1 and 1.3 ±â€¯0.04 µg/mL, with SI of 3.1 and 3.5 for hydrazone intermediates 10 and 11, respectively.

A set of biogenetically interesting polyhalogenated acetogenins from Ptilonia magellanica.

Ptilonines A-F, pyranosylmagellanicus D-E and magellenediol are previously undescribed acetogenins isolated from the red alga Ptilonia magellanica. Their structures were determined from spectroscopic evidence. The absolute configuration of the known pyranosylmagellanicus A, was established by derivatization with (R)- and (S)-α-methoxy -α-phenylacetic acids (MPA). Ptilonines exhibit an unusual halogenation pattern, that may confer evolutionary advantages to Ptilonia magellanica, for which a biogenetic origin is proposed. The antimicrobial effect of some of these compounds was evaluated.

Vibrational Circular Dichroism Absolute Configuration of 9,12-Cyclomulin-13-ol, a Diterpene from Azorella and Laretia Species.

The absolute configuration of the diterpenoid 9,12-cyclomulin-13-ol (1), a constituent of Azorella and Laretia species, has been established by vibrational circular dichroism spectroscopy in combination with density functional theory calculations. The obtained normal diterpene absolute configuration confirms that of azorellanol (2), which was determined by single crystal X-ray diffraction.

Molecular Docking Studies of the Antitumoral Activity and Characterization of New Chalcone.

Phytochemical investigation of Azorella madreporica led to the isolation of four known compounds and an unknown chalcone. The structure of the new compound was identified by spectroscopy, including two-dimensional NMR techniques and comparison with published spectral data. The antioxidant activity of chalcone (compound 1) was measured using the 1,2-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay, and the bioactivity was evaluated against five bacteria (Mycobacterium smegmatis ATCC 14468, clinical isolates of Staphylococcus aureus, Klebsiella granulomatis, Morganella morganii and Escherichia coli) and four cancer cell lines. Docking studies with the tested cancer related proteins revealed nearby values of energy between doxorubicin and compound 1. Besides, protein-ligand interactions correlate with these energy values.

Antimicrobial Diterpenes from Azorella Species Against Gram-Positive Bacteria.

The present study was aimed at evaluating the antibacterial activity of mulinane and azorellane diterpenes isolated from the Andean plants Azorella compacta and A. trifoliolata and semisynthetic derivatives against reference and multidrug-resistant strains. The results revealed that the semisynthetic compound 7-acetoxy-mulin-9,12-diene (5) exhibited antibacterial activity against reference and multidrug-resistant strains of Staphylococcus aureus and moderate antimycobacterial activity against Mycobacterium smegmatis ATCC 14468.

An unusual mulinane diterpenoid from the Chilean plant Azorella trifurcata (Gaertn) Pers.

Four new mulinane-type diterpenoids besides the known compounds mulin-11,13-dien-20-oic acid, 13α-hydroxyazorellane, 13ß-hydroxyazorellane, mulinolic acid, azorellanol, and mulin-11,13-dien-18-acetoxy-16,20-dioic acid were isolated from the Chilean plant Azorella trifurcata. One of the new metabolites isolated, 7α-acetoxy-9-epi-13ß-hydroxymulinane, possesses a new trans-syn-trans arrangement in a tricyclic ring system not previously encountered in nature. Among the mulinane diterpenoids isolated, mulin-11,13-dien-20-oic acid showed the gastroprotective effect on HCl-EtOH-induced gastric lesions in mice (ED50 = 55 mg kg(-1)). Regarding the mode of gastroprotective action for this active compound, its effect was reduced by pre-treatment of the mice with indomethacin and N-ethylmaleimide, suggesting that prostaglandins and sulfhydryl compounds are positively involved in the gastroprotective activity using this model.

New diterpenes from Azorella spinosa.

Two new diterpenes,2-acetoxy-13-hydroxy-mulin-11-ene and 2-acetoxy-mulin-11, 13-diene,have been isolated from the aerial parts of Azorella spinosa and their structures determined by spectroscopic and conventional chemical methods. Furthermore, 2, 13-dihydroxy-mulin-11-ene was obtained using a basic hydrolysis of the first compound. Two diterpenes reported for other Azorella species have also been found, namely mulinolic acid and 13beta-hydroxyazorellane, as well as the triterpene lactone of ursolic acid,quercetin, and 7-hydroxycoumarin. The compounds were evaluated using antibacterial, antioxidant and enzymatic assays; no significant activity was detected.

Diversity of cultivable fungi associated with Antarctic marine sponges and screening for their antimicrobial, antitumoral and antioxidant potential.

The diversity of sponge-associated fungi has been poorly investigated in remote geographical areas like Antarctica. In this study, 101 phenotypically different fungal isolates were obtained from 11 sponge samples collected in King George Island, Antarctica. The analysis of ITS sequences revealed that they belong to the phylum Ascomycota. Sixty-five isolates belong to the genera Geomyces, Penicillium, Epicoccum, Pseudeurotium, Thelebolus, Cladosporium, Aspergillus, Aureobasidium, Phoma, and Trichocladium but 36 isolates could not be identified at genus level. In order to estimate the potential of these isolates as producers of interesting bioactivities, antimicrobial, antitumoral and antioxidant activities of fungal culture extracts were assayed. Around 51% of the extracts, mainly from the genus Geomyces and non identified relatives, showed antimicrobial activity against some of the bacteria tested. On the other hand, around 42% of the extracts showed potent antitumoral activity, Geomyces sp. having the best performance. Finally, the potential of the isolated fungi as producers of antioxidant activity seems to be moderate. Our results suggest that fungi associated with Antarctic sponges, particularly Geomyces, would be valuable sources of antimicrobial and antitumoral compounds. To our knowledge, this is the first report describing the biodiversity and the metabolic potential of fungi associated with Antarctic marine sponges.

Induction of defensive response in Eucalyptus globulus plants and its persistence in vegetative propagation.

The expression of defensive compounds derived from secondary metabolism in plants of Eucalyptus globulus Labill, and the persistence of these in vegetative propagation was evaluated by gas chromatography with flame ionization (GC-FID) and mass spectrometry (MS). The plants were induced by attack from the insect Ctenarytaina eucalypti ("blue gum psyllid") and by mechanical damage. Defense responses were activated in plants for the different types of tested induction. We identified four defensive compounds present in the leaves of plants induced in entomological form (beta-terpineol, aromadendrene, caryophyllene-oxide and eremophilene); all remained in the vegetative propagation. After mechanical induction, we identified three compounds (beta-terpineol, aromadendrene and ledol), of which ledol and aromadendrene persisted in the vegetative propagation. Virtually all the compounds detected, in addition to persisting in the vegetative propagation, showed specificity for the induction type, whether entomological or mechanical, except for aromadendrene, which was expressed in both types of induction.

Determination of antibacterial, antioxidant, antiplatelet and inhibition of cholinesterase activities from the methanolic extracts of Azorella species (Apiaceae) / Determinación de la actividad antibacteriana, antioxidante, antiagregante plaquetaria e inhibición de la colinesterasa a partir de los extractos metanólicos de especies Azorella (Apiaceae)

In this study, we investigated the potential antibacterial, antioxidant and anti-platelet activities and the inhibition of cholinesterase from the methanolic extracts obtained from aerial parts of the two species of Azorella: A. spinosa (Constitution, Chile) and A. monantha (Torres del Paine, Enladrillado and Paso Vergara). All extracts showed only moderate inhibitory activity on acetylcholinesterase (AChE), the most active extract with IC50 = 27ug/mL was A. spinosa. Inhibition of platelet aggregation induced by ADP presented maximal aggregation to 70 and 57 percent on extracts of A. spinosa and A. monantha (Paso Vergara), respectively. The most active extract with antioxidant effect was A. spinosa with IC50 of 28.72ug/mL. Antibacterial activity of the extract on Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii was not present. The extracts of A. spinosa and A. monantha (Paso Vergara) presented the best results on the activities that were evaluated.

En este estudio se investigó las potenciales actividades antibacteriana, antioxidante, antiplaquetaria e inhibición de la colinesterasa de extractos metanólicos a partir de las partes aéreas de dos especies de Azorella: A. spinosa (Constitución, Chile) y A. monantha (Torres del Paine, Enladrillado y Paso Vergara). Todos los extractos mostraron actividad inhibidora moderada solamente sobre acetilcolinesterasa (AChE), siendo el más activo el extracto de A. spinosa con IC50= 27ug/mL. La inhibición de la agregación plaquetaria inducida por ADP presentó máxima agregación al 70 y 57 por ciento sobre los extractos de A. spinosa y A. monantha (Paso Vergara) respectivamente. El extracto más activo con efecto antioxidante fue el de A. spinosa con un IC50 de 28,72ug/mL,). No se presentó actividad antibacteriana de ningún extracto sobre Escherichia coli, Pseudomonas aeuroginosa y Acinetobacter baumannii. Los extractos de A. spinosa y A. monantha (Paso Vergara) presentan los mejores resultados sobre las actividades evaluadas, lo que permite el estudio bioguiado de los metabolitos presentes en estos extractos.

A new labdane diterpene from the limpet Trimusculus peruvianus / Un nuevo diterpeno labdano aislado del molusco Trimusculus peruvianus

The family Trimusculidae produces labdane diterpenes, which differ in the degree and type of esterification with acetoxy and isovaleroyl ester predominantly. Here we describe the isolation from the marine pulmonate Trimusculus peruvianus, collected on intertidal rocks of Chilean coasts, of a new diterpene closely related to the above mentioned characteristics. It structure was determined by spectroscopic data. The compounds were subjected to toxicity tests using nauplii and cysts of Artemia salina. The known compounds isolated in this study have shown an ability to inhibit egg hatch of A. salina.

La familia Trimusculidae produce diterpenos tipo labdano, que difieren en el grado y tipo de esterificación con esteres acetato e isovalérico predominantemente. En este trabajo describimos el aislamiento de un nuevo diterpeno con las características ya mencionadas y de otros ya conocidos desde el molusco marino pulmonado Trimusculus peruvianus, recolectado en la zona intermareal del litoral chileno. Su estructura fue determinada a través de métodos espectroscopicos. Los compuestos fueron sometidos a ensayos de toxicidad y eclosión de los huevos de Artemia salina.

Biological activity of isoflavonoids from Azorella madreporica.

Four isoflavones, isolated from the whole plant of Azorella madreporica, were identified as angustone C (1), alpinumisoflavone (2), licoisoflavone A (3) and isolupalbigenin (4) by spectroscopic studies. The compounds were evaluated for antibacterial and gastroprotective activities. This is the first time that isoflavonoids have been reported in this genus.

Molecules of the quinoline family block tau self-aggregation: implications toward a therapeutic approach for Alzheimer's disease.

The neurofibrillary tangles (NFTs) generated by self-aggregation of anomalous forms of tau represent a neuropathological hallmark of Alzheimer's disease (AD). These lesions begin to form long before the clinical manifestation of AD, and its severity is correlated with cognitive impairment in patients. We focused on the search for molecules that interact with aggregated tau of the Alzheimer's type and that may block its aggregation before the formation of NFTs. We show that molecules from a family of quinolines interact specifically with oligomeric forms of tau, inhibiting their assembly into AD filaments. The quinolines 2-(4-methylphenyl)-6-methyl quinoline (THQ-4S) and 2-(4-aminophenyl)-6-methylquinoline (THQ-55) inhibited in vitro aggregation of heparin-induced polymers of purified brain tau and aggregates of human recombinant tau. They also interact with paired helical filaments (PHFs) purified from AD postmortem brains. In vitro studies indicated a significantly lower inhibitory effect of amyloid-ß42 on the aggregation, suggesting that tau aggregates are specific targets for quinoline interactions. These compounds showed highly lipophilic properties as corroborated with the analysis of total polar surface areas, and evaluation of their molecular properties. Moreover, these quinolines exhibit physical chemical properties similar to drugs able to penetrate the human brain blood barrier. Docking studies based on tau modeling, as a structural approach to the analysis of the interaction of tau-binding ligands, indicated that a C-terminal tau moiety, involved in the formation of PHFs, seems to be a site for binding of quinolines. Studies suggest the potential clinical use of these quinolines and of their derivatives to inhibit tau aggregation and possible therapeutic routes for AD.

Gastroprotective activity of epitaondiol and sargaol.

The effects of epitaondiol (1) and sargaol (2), isolated from the brown alga Stypopodium flabelliforme on HCl/ethanol-induced gastric lesions in mice were evaluated and compared with that of lansoprazole. Epitaondiol and sargaol (6.25 - 50 mg/kg) dose-dependently inhibited the appearance of gastric lesions in mice, displaying similar values to lansoprazole at 20 mg/kg. Both epitaondiol and sargaol showed gastroprotective activity with ED50 values of 40 mg/kg and 35 mg/kg, respectively. The results suggest that epitaondiol and sargaol protect the gastric mucosa in the HCl/EtOH model in mice.

Anti-proliferative activity of meroditerpenoids isolated from the brown alga Stypopodium flabelliforme against several cancer cell lines.

The sea constitutes one of the most promising sources of novel compounds with potential application in human therapeutics. In particular, algae have proved to be an interesting source of new bioactive compounds. In this work, six meroditerpenoids (epitaondiol, epitaondiol diacetate, epitaondiol monoacetate, stypotriol triacetate, 14-ketostypodiol diacetate and stypodiol) isolated from the brown alga Stypopodium flabelliforme were tested for their cell proliferation inhibitory activity in five cell lines. Cell lines tested included human colon adenocarcinoma (Caco-2), human neuroblastoma (SH-SY5Y), rat basophilic leukemia (RBL-2H3), murine macrophages (RAW.267) and Chinese hamster fibroblasts (V79). Antimicrobial activity of the compounds was also evaluated against Staphylococcus aureus, Salmonella typhimurium, Proteus mirabilis, Bacillus cereus, Enterococcus faecalis and Micrococcus luteus. Overall, the compounds showed good activity against all cell lines, with SH-SY5Y and RAW.267 being the most susceptible. Antimicrobial capacity was observed for epitaondiol monoacetate, stypotriol triacetate and stypodiol, with the first being the most active. The results suggest that these molecules deserve further studies in order to evaluate their potential as therapeutic agents.

A new azorellane diterpenoid from Azorella madreporica.

A new azorellane diterpenoid has been isolated and identified from the aerial parts of Azorella madreporica Clos. The structure of 1 was established by one- and two-dimensional NMR techniques.