Julio Alarcón

Production and Purification of Statins from Pleurotus ostreatus (Basidiomycetes) Strains

Pleurotus ostreatus strains were cultured in liquid medium and on wheat straw. The yields of lovastatin were compared

Lovastatin Production by Pleurotus ostreatus: Effects of the C:N Ratio

Abstract The types of carbon source and nitrogen source used as well as the C:N ratio in the medium influenced lovastatin production by Pleurotus ostreatus. The maximum value of the lovastatin yield was obtained in a medium that contained organic nitrogen

Production of Exopolysaccharides by a Submerged Culture of an Entomopathogenic Fungus, Paecilomyces sp.

Exopolysaccharide basic was obtained from a submerged culture of a native Paecilomyces sp. strain isolated from Chilean soil

In the search for new secondary metabolites with biopesticidal properties

Secondary metabolites are involved in diverse functions in plants, including defense and protective processes. Information concerning the biosynthesis of secondary metabolites in plants points at a constitutive or induced chemical defense, generated for protection against a variety of phytopathogenic attacks. Our phytochemical studies are aimed at finding biopesticides of botanical origin. Some plant taxa of American distribution are toxic to selected insects, fungi and bacterial strains, and their effect has been associated with the presence of phenolics, phenylpropanoids and terpenes. We have isolated some diterpenes, triterpenes, sesquiterpene lactones, flavonoids, and phenylpropanoids from members of the plant families Araucariaceae, Asteraceae, Calceolariaceae, Celastraceae, and Rhamnaceae. In addition, we have identified a number of chemical derivatives of these compound classes from the plants. A major finding indicates that compounds or their derivatives that possess antioxidant, antifungal, insect growth regulator or insecticidal activity and enzymatic inhibitors are natural compounds. Insecticidal activities were assayed against strains of lepidopteran, dipteran, and coleopteran insect pests that affect many crops. Antifungal and antibacterial activities were assayed against phytopathogenic species of filamentous fungi and bacterial strains that are pests on many crops. Our results indicate that the plant-derived compounds obtained from the abovementioned plants have excellent insect growth regulatory activity and a good potency as antifungal agents. However, little is known about the effects of these natural compounds and their derivatives on insect pests. The natural compounds that we have isolated represent a valuable resource for future studies of plant chemical defense and the role of these substances in chemical ecology.

Biotransformation of indole derivatives by mycelial cultures.

Biotransformation of tryptophan to tryptamine and 3-methyl-indole by Psilocybe coprophila was performed. On the other hand, Aspergillus niger was able to transform tryptophan to 5-hydroxy-tryptophan. P. coprophila biotransformed 5-hydroxy-tryptophan to 5-hydroxytryptamine. These results prove once more that fungi are good tools to establish hydroxyindole derivatives.

Bioreduction of Some Common Carbonylic Compounds Mediated by Yeasts

Bioreduction of several prochiral carbonylic compounds such as acetophenone (1), ethyl acetoacetate (2) and ethyl phenylpropionate (3) to the corresponding optically active secalcohols 1a - 3a was performed using wild-type strains of Pichia pastoris UBB 1500, Rhodotorula sp., and Saccharomyces cerevisiae. The reductions showed moderate to excellent conversion and high enantiomeric excess, in an extremely mild and environmentally benign manner in aqueous medium, using glucose as cofactor regeneration system. The obtained alcohols follow Prelog’s rule, but in the reduction of 1 with P. pastoris UBB 1500 the anti- Prelog enantiopreference was observed

Structural Studies of Native Paecilomyces sp. Exopolysaccharide

A polysaccharide separated from Paecilomyces sp. was determined by gel permeation chromatography to be homogeneous. HPLC showed a monosaccharide containing d-glucose and d-fructose at a ratio of about 2:1. The results obtained from IR, 1H NMR, and 13C NMR analyses confirmed the proposed structure.

Biotransformation of Tryptophan by Liquid Medium Culture of Psilocybe coprophila (Basidiomycetes)

Abstract Chemical reactions performed by fungi have been used as a modern tool in chemistry. In this work, we show the tryptophan biotransformation with Psilocybe coprophila on liquid culture medium. The results prove once more the versatility of fungi in performing a wide range of industrially attractive chemical reactions.

REGIO AND STEREOSELECTIVE HYDROXYLATION OF 5a-HYDROXY-14-EUDESM-11-EN-3-ONE EUDESMANE BY BIOTRANSFORMATION OF RHIZOPUS NIGRICANS

Departamento de Ciencias Basicas, Facultad de Ciencias, Universidad del Bio-Bio, Chillan, Chile.ABSTRACTThis paper describes a combined synthesis of b-hydroxy-sesquiterpen eudesmane derivative using amicrobiological hydroxylation sesquiterpen eudesmane derivative as the key reaction. Thestereochemistry of the biohydroxylation was identified using mono and bi-dimensional