Emilie Adelin

Bicyclic and tetracyclic diterpenes from a Trichoderma symbiont of Taxus baccata.

Trichoderma atroviridae UB-LMA is an endophytic fungus isolated from Taxus baccata trees. Liquid-state fermentation coupled to in situ solid phase extraction (SPE) was applied, and four compounds were discovered. Compounds 2-4 belong to the harziane tetracyclic diterpene family. Bicylic compound 1 may represent the biosynthetic precursor of this scarce family of compounds.

Isolation, structure elucidation and biological activity of metabolites from Sch-642305-producing endophytic fungus Phomopsis sp. CMU-LMA.

Eight polyketide compounds were isolated from the cultivation broth of Phomopsis sp. CMU-LMA. We have recently described LMA-P1, a bicyclic 10-membered macrolide, obtained as a bioconversion derivative of Sch-642305, the major compound isolated in this study. Benquinol is the ethyl ester derivative of the 13-dihydroxytetradeca-2,4,8-trienoic acid produced by Valsa ambiens. This compound is concomitantly produced with the 6,13-dihydroxytetradeca-2,4,8-trienoic acid (DHTTA) previously isolated from Mycosphaerellarubella. The absolute configuration of the new compound, (2R,3R,4S,5R)-3-hydroxy-2,4-dimethyl-5-[(S,Z)-3-methylpentenyl]-tetrahydro-pyranone LMA-P2 was confirmed by X-ray crystallography. The δ-lactone 2,3-dihydroxytetradecan-5-olide (DHTO) was previously isolated from Seiridium unicorne. This compound may form through the cyclization of the methyl-2,3,5-trihydroxytridecanoate LMA-P3, a new linear polyketide isolated in this study. Benquoine, a new 14-membered lactone generated from the cyclization of benquinol, is proposed as the key precursor for the biosynthesis of Sch-642305. Antimicrobial activity and cancer cell viability inhibition by the new compounds were investigated. Benquoine exhibits antimicrobial activity against Gram positive bacteria, and cytotoxicity against HCT-116 cancer cell line.

Isolation and Characterization of Unusual Hydrazides from Streptomyces sp. Impact of the Cultivation Support and Extraction Procedure

Three novel hydrazides, geralcins C-E (1-3), were isolated from Streptomyces sp. LMA-545, together with MH-031 and geralcins A and B. This unusual family of compounds was isolated from liquid-state and agar-supported fermentation using Amberlite XAD-16 solid-phase extraction during the cultivation step. The use of such neutral resin during the cultivation step allowed the specific adsorption of microbial secondary metabolites, avoiding any contamination of the crude extracts by the constituents of the culture medium. The trapped compounds were eluted from the resin with methanol, and their structures elucidated using (1)H, (13)C, and (15)N NMR spectroscopic analysis and high-resolution mass spectrometry. Molecular modeling calculations were applied in order to support structural attributions. No antimicrobial, cytotoxic, or DnaG-inhibition activities were detected for geralcins D and E. Geralcin C has no antimicrobial activity but exhibited an IC(50) of 0.8 μM against KB and HCT116 cancer cell lines. Furthermore, geralcin C inhibited the E. coli DnaG primase, a Gram-negative antimicrobial target, with an IC(50) of 0.7 mM.

Biotransformation of natural compounds: Unexpected thio conjugation of Sch-642305 with 3-mercaptolactate catalyzed by Aspergillus niger ATCC 16404 cells

Sch-642305 is produced by the endophytic fungi Phomopsis sp. CMU-LMA and exhibits both antimicrobial and cytotoxic activities. The incubation of Sch-642305 with Aspergillus niger ATCC 16404 resting cells leads to two unexpected thio conjugates. Compound (1) is formed by the addition of the cysteine metabolite 3-mercaptolactate to the double bond of Sch-642305. Compound (1) undergoes an intramolecular rearrangement to give compound (2), which contains two rings: a five-membered hydroxylactone ring and a five-membered thiophene ring. The absolute configuration of compound (1) is similar to that of the parent compound, but the configuration of the mercaptolactate side-chain was not determined. The absolute configuration of compound (2) was deduced from the crystal structure and confirmed by the anomal effect of the sulfur atom. To the best of our knowledge, this is the first time such a conjugation rearrangement reactions were observed. The biological significance and the reaction mechanisms are discussed. Compound (1) exhibits a weak antimicrobial activity against Gram-positive bacteria, whereas derivatives (1) and (2) showed an IC₅₀ of 1 and 1.2 μM, respectively, against colonic epithelial cancer cells.

Biotransformation of natural compounds. Oxido-reduction of Sch-642305 by Aspergillus ochraceus ATCC 1009

Sch-642305 is the major compound produced by the endophytic fungi Phomopsis sp. CMU-LMA. Incubation of Sch-642305 with Aspergillus ochraceus ATCC 1009 resting cells leads to three new derivatives through an oxido-reduction of the six-membered ring of the molecule. Reduction of the double bound leads to compound (1), which subsequently undergoes carbonyl reduction to (2) and ring hydroxylation to (3). According to the previously solved crystal structure of Sch-642305 coupled with (1)H NMR NOE correlation and the crystal structure of compound 1, the absolute configurations of the new derivatives were established. In contrast to the parent compound Sch-642305, compound (1) exhibits antimicrobial activity against gram-negative bacteria. Furthermore, while all derivatives exhibit cytotoxic activity against various cancer cell lines, compound (2) achieved an IC(50) of 4 nM against human myelogenous leukemia K 562, compared to 20 nM for the parent Sch-642305.

Bioactive polyketides isolated from agar-supported fermentation of Phomopsis sp. CMU-LMA, taking advantage of the scale-up device, Platotex

Phomopsis sp. CMU-LMA was cultivated on agar-supported fermentation (Ag-SF) using the scale-up prototype Platotex. In total nine compounds were isolated from the ethyl acetate extract of the culture. Among them, compounds LMA-P1, Sch-642305, DHTO and LMA-P2 had already been reported in our previous work on liquid state fermentation. The trihydroxybenzene lactone cytosporone D and dothiorelone A has been recently isolated from Phomopsis and Magnaporthe species. In addition, three compounds were isolated consisting in the reduced methoxy derivative of Sch-642305 (1), a hydroxylated derivative of LMA-P2 (2) and a linear ethyl ester polyketide (3) similar to the previously reported LMA-P3. Antimicrobial activity and inhibition of Escherichia coli DnaG primase were investigated. Cytosporone D inhibited the E. coli DnaG primase, a Gram-negative antimicrobial target, with an IC50 of 0.25 mM.

Viability-reducing activity of Coryllus avellana L. extracts against human cancer cell lines

The increasing rate of cancer incidence has encouraged the search for novel natural sources of anticancer compounds. The presence of small quantities of taxol and taxanes in Corylus avellana L. has impelled new potential applications for this plant in the field of biomedicine. In the present work, the cell viability-reducing activity of stems and leaves from three different hazel trees was studiedagainst three human-derived cancer cell lines (HeLa, HepG2 and MCF-7). Both leaf and stem extracts significantly reduced viability of the three cell lines either after maceration with methanol or using taxane extraction methods. Since maceration reduced cell viability to a greater extent than taxane extraction methods, we scaled up the maceration extraction process using a method for solid/liquid extraction (Zippertex technology). Methanol leaf extracts promoted a higher reduction in viability of all cell lines assayed than stem extracts. Fractionation of methanol leaf extracts using silica gel chormatography led to the purification and identification of two compounds by HPLC-MS and NMR: (3R,5R)-3,5-dihydroxy-1,7-bis(4-hydroxyphenyl) heptane 3-O-β-d-glucopyranoside and quercetin-3-O-rhamnoside. The isolated compounds decreased viability of HeLa and HepG2 cells to a greater extent than MCF-7 cells. Our results suggest a potential use of C. avellana extracts in the pharmacotherapy of cervical cancer and hepatocarcinoma and, to a lesser extent, breast cancer.

Isolation of the antibiotic methyl ( R , E )-3-(1-hydroxy-4-oxocyclopent-2-en-1-yl)-acrylate EA-2801 from Trichoderma atroviridae

The endophytic Trichoderma atroviridae UB-LMA was isolated as a symbiont of Taxus baccata and analyzed for its antimicrobial activity. By applying an original approach consisting of solid-state cultivation coupled with solid-phase extraction, a new methyl (R,E)-3-(1-hydroxy-4-oxocyclopent-2-en-1-yl)-acrylate derivative named EA-2801 (1) was isolated together with the previously reported isonitrin A and dermadin methyl ester. The chemical structure of 1 was determined by NMR and MS. Compound 1 showed antimicrobial activity against a panel of Gram-positive and -negative bacteria.