Two new iridoids from selected Penstemon species--antimicrobial activity

Area of Science:

• Phytochemistry
• Natural Products Chemistry
• Microbiology

Background:

• Penstemon species are known sources of diverse secondary metabolites.
• Understanding the chemical constituents and bioactivities of Penstemon is crucial for potential pharmaceutical applications.

Purpose of the Study:

• To isolate and elucidate the structures of secondary metabolites from three Penstemon species.
• To evaluate the antimicrobial potential of the isolated compounds and crude extracts.

Main Methods:

• Methanolic extraction of aerial parts from Penstemon fruticosus, Penstemon palmeri, and Penstemon venustus.
• Structure elucidation of isolated compounds using spectral evidence.
• Antimicrobial assays against Gram-positive and Gram-negative bacteria and human pathogenic fungi.

Main Results:

• Eighteen secondary metabolites were isolated, including six iridoid glucosides, three phenylpropanoid glucosides, and two acetophenone derivatives.
• Two new iridoid glucosides, cis- and trans- 10-O-p-methoxycinnamoylaucubin, were identified from P. fruticosus.
• All isolated compounds and crude extracts demonstrated antimicrobial activities.

Conclusions:

• The study successfully characterized novel and known secondary metabolites from selected Penstemon species.
• The identified compounds and extracts possess significant antimicrobial properties, warranting further investigation.