Andrea A. Stierle

The Berkeleyamides, Amides from the Acid Lake Fungus Penicillum rubrum

We previously reported several novel bioactive hybrid polyketide-terpenoid metabolites from a deep water Penicillium rubrum isolated from Berkeley Pit Lake, Butte, Montana. In this paper we report the structures of four new amides, berkeleyamides A-D (1, 4, 5, 7), isolated from extracts of this fungus. The structures of these compounds were deduced by analysis of NMR data, chemical derivatization, and comparison of their spectroscopic data to those of known compounds.

A fungal endophyte-tree relationship : Phoma sp. in Taxus wallachiana

Abstract Taxus wallachiana, Nepalase yew, has many associated endophytic fungi. One of these is a Phoma sp. that lives primarily in the intercellular spaces of tissues in the phloem/cambial region of the tree limbs producing two antibiotic substances: altersolanol A and 2-hydroxy-6-methylbenzoic acid. These compounds were isolated from fungal culture, crystallized, bioassayed, and structurally characterized by X-ray crystallography. The presence of endophytic fungi raises the question as to their role in the tree, however, we suggest that the T. wallachiana/Phoma sp. relationship is a mutualistic one. Normally, the organic solvent extract of yew is not antibacterial, however the organic solvent extract of T. media c.v. Hicksii, inoculated with Phoma sp., possessed antibacterial activity. This extract contains altersolanol A as demonstrated by chromatographic and mass spectroscopic analyses.

Pseudomonic acid derivatives from a marine bacterium

The spongeDarwinella rosacea was found to harbor a host of marine microorganisms. One of these bacteria was identified as a marineAlteromonas species. The organic extract of this bacterium was antimicrobial, and the activity was traced to two novel pseudomonic acid derivatives1 and7. The structures of these compounds were elucidated by interpretation of the spectral data and extensive use of 2-dimensional NMR techniques and NOE studies on the parent compounds and the acetate derivatives2 and8.

Berkeleyones and related meroterpenes from a deep water acid mine waste fungus that inhibit the production of interleukin 1-β from induced inflammasomes.

The Berkeley Pit, an acid mine waste lake, is a source of extremophilic microorganisms that produce interesting bioactive compounds. We have previously reported the isolation of berkeleydione (1), berkeleytrione (2), the berkeleyacetals, and the berkeleyamides from the Pit Lake fungus Penicillium rubrum. In this paper we report the isolation and characterization of berkeleyones A-C (4, 5, and 7) as well as previously described preaustinoid A (3) and A1(6) from this same fungus. These compounds were evaluated as inhibitors of the signaling enzyme caspase-1 and as potential inhibitors of interleukin 1-β production by inflammasomes in induced THP-1 cell line assays.

Fusarium avenaceum as a novel pathogen of spotted knapweed and its phytotoxins, acetamido-butenolide and enniatin B

Abstract Fusarium avenaceum is described as a novel fungal pathogen of spotted knapweed ( Centurea maculosa L.), a noxious range, park and pasture land pest of the Pacific Northwest, USA. Pathogenicity of this fungus was established via Kochs postulates. Two phytotoxins were isolated and characterized from the culture filtrate of this fungus, i.e., acetamido-butenolide and enniatin B. These compounds are not host selective, but do act in a synergistic manner to cause necrotic lesions on detached knapweed leaves. Both phytotoxins, acetamido-butenolide and enniatin B are active at 3.5 × 10 −3 M and are produced in culture in a ratio of 1:10.

Factors influencing the in vitro production of radiolabeled taxol by Pacific yew, Taxus brevifolia

Abstract A system for the production of [14C]taxol in vitro has been devised. The aseptic system utilized an appropriate 14C-labeled precursor, a reducing environment (dithiothreitol) and aseptically prepared pieces of the inner bark of Taxus brevifolia (Pacific yew). [14C]Phenylalanine and [14C]leucine are the best precursors, of the compounds tested, for [14C]taxol production. However, in the standard assay sodium [1-14C]acetate is used because of its relatively low price and its ability to label taxol uniformly. Chlorocholine chloride, an inhibitor of plant steroid metabolism, was an effective stimulator of [14C]taxol production, as were certain fungal elicitors. Taxol biosynthetic activity is greatest in the bark from lower portions of the main stem (trunk: 1 m from ground level).

The phytotoxins ofMycosphaerella fijiensis, the causative agent of Black Sigatoka disease of bananas and plantains

Black Sigatoka is the most costly to control disease of bananas and plantains in the world. Currently, a worldwide search is underway either to find or to produce cultivars that are disease-resistant or-tolerant. Phytotoxins isolated from the pathogen might facilitate the discovery of such cultivars. Several aromatic compounds from liquid cultures ofMycosphaerella fijiensis, the causal agent of Black Sigatoka disease of bananas and plantains, have been isolated. The most abundant and phytotoxic of these compounds is 2,4,8-trihydroxytetralone, which induces necrotic lesions at 5 μg/5 μl in less than 12 h on sensitive cultivars of bananas. This compound exhibits host-selectivity that mimics that of the pathogen. Other phytotoxins isolated from this fungus, in lesser amounts, were juglone, the novel compound 2-carboxy-3-hydroxycinnamic acid, isoochracinic acid and 4-hydroxyscytalone. Some of the phytotoxins isolated are melanin shunt pathway metabolites, which makes this fungus unique among plant pathogens.

Taxol formation in yew — Taxus

Abstract In Pacific yew, Taxus brevifolia , taxol is found most abundantly in the vascular cambial region followed by the phloem, sapwood and heartwood. It is in this order that ‘in vitro’ taxol biosynthetic activity was also demonstrated using [1- 14 C]acetate as a precursor. However, only traces of taxol biosynthesis could be demonstrated in the xylem (sapwood-heartwood) suggesting that taxol may be mobilized from its place of greatest biosynthetic activity (vascular cambial region) to the xylem; perhaps via ray parenchyma. Taxol could also be effectively trapped under ‘bark flaps’, over a period of several weeks, using silica gel powder as an adsorbant. In vitro taxol biosynthesis using [1- 14 C]acetate in outer bark samples (cambium-phloem) could only be demonstrated in Taxus brevifolia, Taxus floridana and Taxus canadensis , among 10 of the 11 native Taxus species tested.

Zinniol-related phytotoxins from Alternaria cichorii

Abstract The organic extract of the fungus Alternaria cichorii , a pathogen of Russian knapweed, was analysed. A series of zinniol-related compounds with varying degrees of phytotoxicity have been isolated for the first time from the organic extract of a pathogenic fungus. The structures of all of the compounds, which include cichorine, zinniol, and the four novel compounds zinnimidine, Z-hydroxyzinnimidine, zinnol and zinndiol, were determined by spectroscopic methods.

Metabolism of maculosin, a host-specific phytotoxin produced by Alternaria alternata on spotted knapweed (Centaurea maculosa)

Abstract Maculosin [the diketopiperazine, cyclo ( l -Pro- l -Tyr)] is a host-specific phytotoxin produced by Alternaria alternata on spotted knapweed (Centaurea maculosa) [(Proc. Natn. Acad. Sci. U.S.A., 85, 8008-8011 (1988)]. The metabolism of maculosin was analysed after the application of [U-14C]maculosin on the detached leaves of spotted knapweed. The extracts of treated leaves as early as one day after [14C]maculosin treatment indicated that it was converted to at least three polar compounds. The neutral metabolite was purified and identified as a novel compound, maculosin β-O-glucoside. The glucoside is not phytotoxic towards spotted knapweed or any of several other plants tested.