retrorsine and retronecine

Crotalaria genus belongs to the subfamily Papilionoideae comprising about 600 species spread throughout tropical, neotropical and subtropical regions. In this study, seeds of Crolatalaria pallida were used to the isolation of usaramine, a pyrrolizidine alkaloid. Thus, Pseudomonas aeruginosa and Staphylococcus epidermidis were utilized as strains to test some activities of this alkaloid, such as antibiofilm and antibacterial. Meanwhile, monocrotaline obtained from Crotalaria retusa seeds, was used as the starting material for synthesis of necine base derivatives with anti-Trichomonas vaginalis potential. Alkaloids were characterized by 1D and 2D NMR techniques and GC-MS analysis. Usaramine demonstrated a highlighted antibiofilm activity against S. epidermidis by reducing more than 50% of biofilm formation without killing the bacteria, thus it could be assumed as a prototype for the development of new antibiofilm molecules for pharmaceutical and industrial purposes. Monocrotaline activity against T. vaginalis was evaluated and results indicated inhibition of 80% on parasite growth at 1mg/mL, in addition, neither cytotoxicity against vaginal epithelial cells nor hemolytic activity were observed. On the other hand, retronecine showed no anti-T. vaginalis activity while azido-retronecine was more active than monocrotaline killing 85% of the parasites at 1mg/mL. In conclusion, pyrrolizidine alkaloids are suggested as promising prototypes for new drugs especially for topical use.

Topics: Biofilms; Carbon-13 Magnetic Resonance Spectroscopy; Cell Line; Female; Humans; Microbial Viability; Monocrotaline; Proton Magnetic Resonance Spectroscopy; Pyrrolizidine Alkaloids; Staphylococcus epidermidis; Trichomonas vaginalis

Changes in plant chemical defenses after invasion could have consequences on the invaded ecosystems by modifying the interactions between plants and herbivores and facilitating invasion success. However, no comprehensive biogeographical studies have yet determined the phenotypic levels of plant chemical defenses, as consumed by local herbivores, covering large distributional areas of a species. Senecio pterophorus is a perennial shrub native to Eastern South Africa, expanded into Western South Africa and introduced into Australia and Europe. As other Asteraceae, S. pterophorus contains pyrrolizidine alkaloids (PAs) toxic to vertebrate and invertebrate herbivores. Here we analyzed S. pterophorus PAs by LC-MS/MS on foliage sampled across its entire distributional range, including the native and all non-native areas. PA concentrations and diversity was very high: we found 57 compounds belonging to 6 distinct necine base-types, including the highly toxic 1,2-unsaturated PAs (retronecine and otonecines) and the less toxic 1,2-saturated PAs (platynecine and rosmarinecines). Plants from different origins diverged in their PA absolute and relative concentrations. Rosmarinine was the most abundant compound in Australia and South Africa, but it was nearly absent in Europe. We characterized three plant chemotypes: retrorsine-senkirkine chemotype in Eastern South Africa, rosmarinine chemotype in Australia and Western South Africa, and acetylseneciphylline chemotype in Europe. PA absolute concentrations were highest in Australia. The increased absolute and relative concentrations of retronecine PAs from Australia and Europe, respectively, indicate that S. pterophorus is potentially more toxic in the invasive range than in the native range.

Topics: Australia; Ecosystem; Europe; Herbivory; Molecular Structure; Pyrrolizidine Alkaloids; Senecio; South Africa