Relationships between the stereochemistry and biological activity of fungal phytotoxins

Abstract

Toxins produced by phytopathogenic fungi assume great importance because of their involvement in several plant diseases. Although such pathogens are known to have seriously damaged crops, forest, and environmental resources, they represent a very important tool to develop new environmentally friendly herbicides and fungicides. This review deals with the relationships between the biological activity of some phytotoxins produced by pathogenic fungi for major forest plants and for damaging weeds and their stereochemistry. In particular, the methods used to determine their relative and/or absolute configuration will be illustrated. These include the application of Mosher's and Murata's methods, X-ray diffractometric analysis, circular dichroism, and the use of computational methods to determine the theoretical optical rotatory power as well as the CD spectrum. The importance of determining the absolute configuration to achieve the total synthesis of some phytotoxins, interesting for their potential practical application, is also discussed.

Pimarane diterpenes: Natural source, stereochemical configuration, and biological activity

“…[114][115][116] Furthermore, for pimarane diterpenes, the assignment of AC is even more important because these tricyclic diterpenes are classified on the basis of the different stereogenic centers into 4 types. [114][115][116] Furthermore, for pimarane diterpenes, the assignment of AC is even more important because these tricyclic diterpenes are classified on the basis of the different stereogenic centers into 4 types.…”

Absolute configurations of chiral molecules with multiple stereogenic centers without prior knowledge of the relative configurations: A case study of inuloxin C

“…This activity was also preserved by inuloxin C as well as inuloxins A and D . As the relation between absolute configuration (AC) and the biological activity and mode of action of natural compounds, including bio‐pesticides was extensively reported, the ACs of inuloxins A‐C were previously studied by chiroptical methods …”

“…3 Inula viscosa was chosen among other 10 allelopathic Mediterranean plants as its organic extract inhibited both broomrapes and dodders, in particular Orobanche crenata and Cuscuta campestris. 4 This activity was also preserved by inuloxin C as well as inuloxins A and D. 1 As the relation between absolute configuration (AC) and the biological activity and mode of action of natural compounds, including bio-pesticides 5,6 was extensively reported, 7,8 the ACs of inuloxins A-C were previously studied by chiroptical methods. 9,10 When relative configuration of a chiral compound with multiple stereogenic centers is known with a high degree of certainty, chiroptical spectroscopic analysis is considerably simplified because quantum chemical (QC) calculations of chiroptical properties can then be restricted to only one diastereomer.…”

Fungal phytotoxins with potential herbicidal activity: chemical and biological characterization

“…On the other hand, the use of chemical pesticides differing widely in respect to spectrum, unit activity, crop safety, toxicology, and environmental effects has increased herbicidal resistance and environmental and toxicological concerns raise a question mark over their large scale use. 15 Also, strategic approaches for discovering fungal phytotoxins, 14,16,17 their modes of action, 13,18,19 and the relationships between the stereochemistry and biological activity 20,21 were recently reviewed. [5][6][7] Fungal phytotoxins are secondary metabolites that play an important role in the induction of disease symptoms in agrarian and forest plants and weeds.…”