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Author(s): Falk Warnecke [1, 8]; Peter Luginbühl [2, 8]; Natalia Ivanova [1]; Majid Ghassemian [2]; Toby H. Richardson [2, 9]; Justin T. Stege [2]; Michelle Cayouette [2]; Alice C. McHardy [...]

Genomic libraries are constructed from microbial DNA from insect intestinal tracts, the insects used are termites and moths. These DNA libraries are screened for genes that are helpful in encoding proteins with xylanase activity.

Context: Subcutaneous mycoses are chronic infections caused by slow growing environmental fungi. Latin American plants are used in folk medicine to treat these afflictions. Moreover, the potential of the rich Latin American biodiversity for this purpose has not been fully explored. Objectives: The aim of the study was to screen Latin American plant extracts against two species of subcutaneous fungi: Sporothrix schenckii and Fonsecaea pedrosoi. Materials and methods: One hundred ninety-five organic extracts from 151 Latin American plants were screened against two subcutaneous fungi by the agar dilution method at a concentration of 100 µµg/mL, and minimum inhibitory concentrations (MICs) of active extracts were determined. Positive (amphothericin B) and negative (50% ethanol) controls were used. Results and discussion: Twenty eight extracts showed activity at ≤≤100 µµg/mL. Of these, four extracts from Gnaphalium gaudichaudianum DC (Asteraceae), Plumeria rubra L (Apocynaceae), Tecoma stans (L.) Juss. ex Kunth. (Bignoniaceae), and Trichostigma octandum (L.), H. Walter showed activity against F. pedrosoi at MIC 12.5 µµg/mL; and, four extracts from Bourreria huanita (Lex.) Hemsl. (Boraginaceae), Phytolacca bogotensis Kunth (Phytolaccaceae), Monnina xalapensis Kunth (Polygalaceae) and Crataegus pubescens (C. Presl) C. Presl (Rosaceae) against S. schenckii. This is the first report on antifungal activity of the Latin American plants against these two subcutaneous fungi. Conclusion: S. schenkii and F. pedrosoi were inhibited by B. huanita (MIC: 12.5 and 25 µµg/mL), G. gaudichaudianum (MIC: 50 and 12.5 µµg/mL) and T. triflora (MIC: 25 µµg/mL). [ABSTRACT FROM AUTHOR]

Recombinant DNA technologies enable the direct isolation and expression of novel genes from biotopes containing complex consortia of uncultured microorganisms. In this study, genomic libraries were constructed from microbial DNA isolated from insect intestinal tracts from the orders Isoptera (termites) and Lepidoptera (moths). Using a targeted functional assay, these environmental DNA libraries were screened for genes that encode proteins with xylanase activity. Several novel xylanase enzymes with unusual primary sequences and novel domains of unknown function were discovered. Phylogenetic analysis demonstrated remarkable distance between the sequences of these enzymes and other known xylanases. Biochemical analysis confirmed that these enzymes are true xylanases, which catalyze the hydrolysis of a variety of substituted β-1,4-linked xylose oligomeric and polymeric substrates and produce unique hydrolysis products. From detailed polyacrylamide carbohydrate electrophoresis analysis of substrate cleavage patterns, the xylan polymer binding sites of these enzymes are proposed. [ABSTRACT FROM AUTHOR]

Spiroketal naphthodecalins are readily assembled by Barton's base mediated Ullmann binaphthyl ether coupling, Dakin reactions and hypervalent iodine spirocyclization. The core structures can be further diversified by enone addition and Stille coupling reactions. Nanomolar inhibitors for the Trx/TrxR redox control system were prepared by this approach and compared to series of natural product isolates. Cytotoxicity in MCF-7 cell assays ranged from an IC50 of 1.6 to >100 microM.

This study describes the results and collection practices for obtaining arthropod samples to be studied as potential sources of new medicines in a bioprospecting effort. From 1994 to 1998, 1800 arthropod samples of 6-10 g were collected in 21 sites of the Area de Conservaci6n Guancaste (A.C.G) in Northwestern Costa Rica. The samples corresponded to 642 species distributed in 21 orders and 95 families. Most of the collections were obtained in the rainy season and in the tropical rainforest and dry forest of the ACG. Samples were obtained from a diversity of arthropod orders: 49.72% of the samples collected corresponded to Lepidoptera, 15.75% to Coleoptera, 13.33% to Hymenoptera, 11.43% to Orthoptera, 6.75% to Hemiptera, 3.20% to Homoptera and 7.89% to other groups. Different life stages per arthropod species were obtained in most samples, 54.26% of them were adults, 19.90% corresponded to larvae, 6.46% to pupae, 6.12% to pre-pupae, 2.07% to nymphs and 3.74% to other stages. Other materials associated to insects like frass represented 11.20% of the samples collected. Several collecting methods were explored, based on the possibility of accessing the necessary amount of material causing the less impact. Most of the samples were obtained by manual collection (44.38%),. followed by insects breeding (25.73%), light traps (18.80%), different types of nets (10.52%) and other methods (0.16%). In general, collecting methods and practices excluded the use of solvents, mixing different species or life stages in the same bag, which might have introduced undesirable effects in the screening systems for new compounds. Based on the possibility of finding new chemicals in similar samples associated to one arthropod species, the collecting strategy included the generation of several samples from same species, separated according to differences in life stages, collecting sites, ecosystems. seasons, feeding materials or behavioral aspects. This strategy allowed the generation a larger number of samples submitted to bioassays in different areas of pharmaceutical research.