Diterpenes and New Antifungal Epimers Derived From Grindelia puberula Hook & Arn. In Vitro and In Silico Studies.

Two new labdane diterpenes, (4S,5R,10S,13S)-19-acetoxy-7-oxo-labd-8(9)-en-15-oic acid-15-methyl ester (1) and (4R,5R,10S,13S)-19-acetoxy-7-oxo-labd-8(9)-en-15-oic acid-15-methyl ester (2), along with two methyl ester derivatives of the known acid compounds, (4R,5S,9S,10R,13S)-ent-7-labden-17-acetoxy-18-hydroxy-15-oic acid (3), and (3R,5S,9S,10S,13S)-ent-7-labden-17-acetoxy-3-α-hydroxy-15-oic acid (4), were obtained from Grindelia puberula Hook & Arn, collected in northern Argentina. Their structures and absolute configurations were elucidated based on one- and two-dimensional nuclear magnetic resonance spectroscopy, mass spectrometry, and circular dichroism analysis. The CHCl sub-extract obtained from the aerial parts of this species, along with the pure compounds, were evaluated for antifungal activity against Botrytis cinerea, a widespread necrotrophic fungal pathogen responsible for significant economic losses worldwide.

A New Depigmenting-Antifungal Methylated Grindelane from Grindelia chiloensis.

The new methylated grindelane diterpenoid, 7β-hydroxy-8(17)-dehydrogrindelic acid (1b), together with the known 7α-hydroxy-8(17)-dehydrogrindelic acid (2a), 6-oxogrindelic acid (3a), 4β-hydroxy-6-oxo-19-norgrindelic (4a), 19-hydroxygrindelic acid (5a), 18-hydroxygrindelic acid (6a), 4α-carboxygrindelic acid (7a), 17-hydroxygrindelic acid (8a), 6α-hydroxygrindelic acid (9a), 8,17-bisnor-8-oxagrindelic acid (10a), 7α,8α-epoxygrindelic acid (11a), and strictanonic acid (12a) as methyl esters were obtained from an Argentine collection of Grindelia chiloensis (Cornel.) Cabrera. Their structures and relative configurations were established on the basis of spectroscopic analysis.