Structure-Activity Relationships of Natural C-9-Methyl-Substituted 10-Membered Lactones and Their Semisynthetic Derivatives.

Fungal 10-membered lactones (TMLs), such as stagonolide A, herbarumin I, pinolidoxin, and putaminoxin, are promising candidates for the development of nature-derived herbicides. The aim of this study was to analyze the structure-activity relationships (SAR) of C-9-methyl-substituted TMLs with a multitarget bioassay approach to reveal compounds with useful (phytotoxic, entomotoxic, antimicrobial) or undesirable (cytotoxic) bioactivities. A new TML, stagonolide L (), along with five known compounds (stagonolides D () and E (), curvulides A () and B/B (,), and pyrenolide C ()), were purified from cultures of the phytopathogenic fungus , and five semisynthetic derivatives of and (-) were obtained.

Structure-Activity Relationship of Phytotoxic Natural 10-Membered Lactones and Their Semisynthetic Derivatives.

Ten-membered lactones (nonenolides) demonstrate phytotoxic, antimicrobial, and fungicidal activity promising for the development of natural product-derived pesticides. The fungus is able to produce phytotoxic stagonolides A (), J (), K () and herbarumin I () with high yield. The aim of this study was to create a set of structurally related nonenolides and to reveal the structural features that affect their biological activity.

Isolation and Bioactivity of Secondary Metabolites from Solid Culture of the Fungus, .

The fungus, is considered to be a potential agent for the biocontrol of perennial sowthistle (). A new chlorinated xanthone, methyl 8-hydroxy-3-methyl-4-chloro-9-oxo-9-xanthene-1-carboxylate () and a new benzophenone derivative, 5-chloromoniliphenone (), were isolated together with eleven structurally related compounds (-) from the solid culture of the fungus, which is used for the production of bioherbicidal inoculum of . Their structures were determined by spectroscopic (mostly by NMR and MS) methods.

Stagonolides J and K and Stagochromene A, Two New Natural Substituted Nonenolides and a New Disubstituted Chromene-4,5-dione Isolated from S-47 Proposed for the Biocontrol of .

Two new natural 10-membered macrolides (, ) and one chromene-4,5-dione derivative (), named stagonolides J and K and stagochromene A, respectively, were isolated from the phytopathogenic fungus S-47, together with two known compounds, stagonolide A () and herbarumin I (). Stagonolides J and K and stagochromene A were characterized as (5,7*,8*,9*)-7,8-dihydroxy-9-propyl-5-nonen-9-olide, (5,7,9)-7-hydroxy-9-propyl-5-nonen-9-olide, and (2*,3*)-3-hydroxy-2-propyltetrahydro-2-chromene-4,5(3,4a)-dione, respectively, by spectroscopic (mostly by NMR and ESIMS) data. Compounds - showed different rates of phytotoxic activity on punctured leaf discs of .

Curvulin and Phaeosphaeride A from sp. VIZR 1.46 Isolated from as Potential Herbicides.

-like fungi are known as producers of diverse spectrum of secondary metabolites, including phytotoxins. Our bioassays had shown that extracts of sp. VIZR 1.

Synthesis of natural phaeosphaeride A derivatives and an in vitro evaluation of their anti-cancer potential.

Derivatives of phaeosphaeride A (PPA) were synthesised and characterised; then anti-cancer studies were carried out on the A549 cancer cell line. It was found that the acetyl derivative (compound 3) displayed comparable in vitro cytotoxicity to that of PPA (EC50=49±7 μM and EC50=46±5 μM, respectively), while chloroacetyl derivative 6 (EC50=33±7 μM) was found to have better efficacy towards the A549 cancer cell line.

Alternethanoxins C-E, Further Polycyclic Ethanones Produced by Alternaria sonchi, a Potential Mycoherbicide for Sonchus arvensis Biocontrol.

Three new polycyclic ethanones, named alternethanoxins C-E, were isolated together with the well-known and closely related alternethanoxins A and B, from the solid culture of Alternaria sonchi, a fungal pathogen proposed for perennial sowthistle (Sonchus arvensis L.) biocontrol. Alternethanoxins C-E were characterized by spectroscopic methods (essentially NMR and HRESI MS) as 2'-dihydroxymethyl-2,5,6,6'-tetrahydroxy-3'-methoxy-biphenyl-3-carboxylic acid methyl ester, 1,4,6,9,10-pentahydroxy-7-methoxy-6H-benzo[c]chromene-2-carboxylic acid methyl ester, and 7,9-dihydroxy-2-methoxy-9H-4,8-dioxa-cyclopenta[def]phenanthrene-5-carboxylic acid methyl ester.